U.S. patent application number 13/370747 was filed with the patent office on 2012-12-13 for autonomous coverage robot.
This patent application is currently assigned to IROBOT CORPORATION. Invention is credited to Duane L. Gilbert, JR., Jeffrey N. Masters.
Application Number | 20120311810 13/370747 |
Document ID | / |
Family ID | 45554798 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120311810 |
Kind Code |
A1 |
Gilbert, JR.; Duane L. ; et
al. |
December 13, 2012 |
AUTONOMOUS COVERAGE ROBOT
Abstract
A surface treatment robot including a robot body, a differential
drive system mounted on the robot body and configured to maneuver
the robot over a cleaning surface, a liquid applicator carried by
the robot body, and a collection assembly carried by the robot body
and configured to remove waste from the cleaning surface. The robot
body has a forward portion and a rear portion, with the forward
portion preceding the rear portion as the robot moves in a forward
direction over the cleaning surface. The liquid applicator is
configured to dispense a liquid to the cleaning surface such that
at least a portion of the liquid is dispensed rear of the
collection assembly as the robot moves in the forward
direction.
Inventors: |
Gilbert, JR.; Duane L.;
(Goffstown, NH) ; Masters; Jeffrey N.; (Boston,
MA) |
Assignee: |
IROBOT CORPORATION
Bedford
MA
|
Family ID: |
45554798 |
Appl. No.: |
13/370747 |
Filed: |
February 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12983837 |
Jan 3, 2011 |
|
|
|
13370747 |
|
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Current U.S.
Class: |
15/320 ;
15/300.1 |
Current CPC
Class: |
A47L 11/408 20130101;
A47L 2201/00 20130101; A47L 11/4044 20130101 |
Class at
Publication: |
15/320 ;
15/300.1 |
International
Class: |
A47L 11/32 20060101
A47L011/32; A47L 7/00 20060101 A47L007/00 |
Claims
1. A surface treatment robot comprising: a robot body having a
forward portion, a rear portion, the forward portion preceding the
rear portion as the robot moves in a forward direction over a
cleaning surface; a cleaning assembly carried by the robot body and
configured to remove debris from the cleaning surface; and a right
drive wheel and a left drive wheel, each drive wheel rotatable
about an axis parallel to the cleaning surface and transverse to
the forward direction of movement of the robot over the cleaning
surface, each drive wheel comprising a rim a tire disposed about a
circumference of a respective drive wheel, the tire comprising a
base having a first side and a second side substantially opposite
the first side, a first and second set of treads, each tread of the
first and second set of treads extending radially from the first
side of the base toward the cleaning surface, each tread of the
first and second set of treads being elongate in a direction
substantially parallel to the transverse axis, and each tread of
the first set of treads circumferentially offset from each of the
treads of the second set of treads.
2. The surface treatment robot of claim 1 wherein each tread of the
first and second set of treads has at least one substantially
square edge disposed toward the cleaning surface.
3. The surface treatment robot of claim 1 wherein each tread of the
first and second set of treads has substantially the same width in
the circumferential direction of the tire.
4. The surface treatment robot of claim 3 wherein each tread of the
first and second set of treads is circumferentially spaced from a
preceding tread of the respective set of treads by a distance about
three times the circumferential width of the tread.
5. The surface treatment robot of claim 1 wherein each tread
extends radially from the base by a distance between about 1/5 to
about 1/2 of a radial thickness of the base.
6. The surface treatment robot of claim 1 wherein the tire
comprises natural rubber and between about 20 percent and about 30
percent particulate matter.
7. The surface treatment robot of claim 6 wherein the particulate
matter includes one or more of the following: kaolin clay and
calcium carbonate.
8. The surface treatment robot of claim 1 wherein each wheel is
disposed rear of at least a portion of the cleaning assembly as the
robot moves in the forward direction over the cleaning surface.
9. The surface treatment robot of claim 8 wherein the cleaning
assembly comprises a liquid applicator, and at least a portion of
the liquid applicator is disposed forward of each wheel as the
robot moves in the forward direction over the cleaning surface.
10. The surface treatment robot of claim 9 wherein the cleaning
assembly comprises a vacuum assembly, and at least a portion of the
vacuum assembly is disposed rear of each wheel as the robot moves
in the forward direction over the cleaning surface.
11. The surface treatment robot of claim 1 wherein each tire
comprises a third and fourth set of treads extending radially from
the second side of the base toward the respective rim.
12. The surface treatment robot of claim 11 wherein the third set
of treads is substantially opposite the first set of treads and the
fourth set of treads is substantially opposite the second set of
treads.
13. The surface treatment robot of claim 12 wherein each tread of
third set of treads is circumferentially offset from each tread of
the first set of treads and each tread of the fourth set of treads
is circumferentially offset from each tread of the second set of
treads.
14. The surface treatment robot of claim 13 wherein at least a
portion of the base is movable toward the wheel when a tread of the
first or second set of treads contacts the cleaning surface.
15. The surface treatment robot of claim 11 wherein the third set
of treads and the fourth set of treads define at least a portion of
channel extending circumferentially around the tire, along the
second surface of the base.
16. The surface treatment robot of claim 15 wherein each wheel
includes a circumferential ridge extending radially outward, toward
the cleaning surface, the circumferential ridge engageable with the
channel at least partially defined by the third and fourth set of
treads.
17. The surface treatment robot of claim 11 wherein the tire is
reversible such that the third and fourth sets of treads extend
toward the cleaning surface and the first and second sets of treads
extend toward the respective rim.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This U.S. patent application is a continuation, and claims
priority under 35 U.S.C. .sctn.120, from U.S. patent application
Ser. No. 12/983,837, filed Jan. 3, 2011, entitled AUTONOMOUS
COVERAGE ROBOT, now pending, the disclosure of which is considered
part of the disclosure of this application and is hereby
incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The disclosure relates to surface cleaning robots, such as
robots configured to perform autonomous cleaning tasks.
BACKGROUND
[0003] Wet cleaning of household surfaces has long been done
manually using a wet mop or sponge. The mop or sponge is dipped
into a container filled with a cleaning fluid to allow the mop or
sponge to absorb an amount of the cleaning fluid. The mop or sponge
is then moved over the surface to apply a cleaning fluid onto the
surface. The cleaning fluid interacts with contaminants on the
surface and may dissolve or otherwise emulsify contaminants into
the cleaning fluid. The cleaning fluid is therefore transformed
into a waste liquid that includes the cleaning fluid and
contaminants held in suspension within the cleaning fluid.
Thereafter, the sponge or mop is used to absorb the waste liquid
from the surface. While clean water is somewhat effective for use
as a cleaning fluid applied to household surfaces, most cleaning is
done with a cleaning fluid that is a mixture of clean water and
soap or detergent that reacts with contaminants to emulsify the
contaminants into the water. In addition, it is known to clean
household surfaces with water and detergent mixed with other agents
such as a solvent, a fragrance, a disinfectant, a drying agent,
abrasive particulates and the like to increase the effectiveness of
the cleaning process.
[0004] The sponge or mop may also be used as a scrubbing element
for scrubbing the floor surface, and especially in areas where
contaminants are particularly difficult to remove from the
household surface. The scrubbing action serves to agitate the
cleaning fluid for mixing with contaminants as well as to apply a
friction force for loosening contaminants from the floor surface.
Agitation enhances the dissolving and emulsifying action of the
cleaning fluid and the friction force helps to break bonds between
the surface and contaminants.
[0005] After cleaning an area of the floor surface, the waste
liquid must be rinsed from the mop or sponge. This is typically
done by dipping the mop or sponge back into the container filled
with cleaning fluid. The rinsing step contaminates the cleaning
fluid with waste liquid and the cleaning fluid becomes more
contaminated each time the mop or sponge is rinsed. As a result,
the effectiveness of the cleaning fluid deteriorates as more of the
floor surface area is cleaned.
[0006] Some manual floor cleaning devices have a handle with a
cleaning fluid supply container supported on the handle and a
scrubbing sponge at one end of the handle. These devices include a
cleaning fluid dispensing nozzle supported on the handle for
spraying cleaning fluid onto the floor. These devices also include
a mechanical device for wringing waste liquid out of the scrubbing
sponge and into a waste container.
[0007] Manual methods of cleaning floors can be labor intensive and
time consuming. Thus, in many large buildings, such as hospitals,
large retail stores, cafeterias, and the like, floors are wet
cleaned on a daily or nightly basis. Industrial floor cleaning
"robots" capable of wet cleaning floors have been developed. To
implement wet cleaning techniques required in large industrial
areas, these robots are typically large, costly, and complex. These
robots have a drive assembly that provides a motive force to
autonomously move the wet cleaning device along a cleaning path.
However, because these industrial-sized wet cleaning devices weigh
hundreds of pounds, these devices are usually attended by an
operator. For example, an operator can turn off the device and,
thus, avoid significant damage that can arise in the event of a
sensor failure or an unanticipated control variable. As another
example, an operator can assist in moving the wet cleaning device
to physically escape or navigate among confined areas or
obstacles.
SUMMARY
[0008] Presently disclosed is an autonomous robot for treating
surfaces, such as floors and countertops, which has a form factor
that facilitates cleaning in tightly dimensioned spaces, such as
those found in many households. In one example, the robot may
include a weight distribution that remains substantially constant
throughout the cleaning process, the weight distributed between a
cleaning element, a squeegee, and drive wheels. The weight
distribution can provide sufficient pressure to the wetting
assembly and the squeegee while allowing sufficient thrust to be
applied at drive wheels. As an advantage, the robot can have a
small volume required to navigate in tightly dimensioned spaces
while having a weight distribution configured for wet-cleaning a
surface.
[0009] A surface treatment robot includes a robot body, a
differential drive system, a liquid applicator, a controller, and a
potting material. The robot body has a forward portion, a rear
portion, an upper portion, and a lower portion, the forward portion
preceding the rear portion as the robot moves in a forward
direction over a cleaning surface, and the upper portion disposed
above the lower portion as the robot moves over the cleaning
surface. The differential drive system is mounted on the robot body
and configured to maneuver the robot over a cleaning surface. The
liquid applicator is carried by the robot body and defines a liquid
storage volume. The liquid applicator is configured to dispense a
liquid from the liquid storage volume to the cleaning surface.
[0010] The controller is carried by the robot body and is in
communication with the differential drive system to direct the
robot over the cleaning surface. The potting material has a
coefficient of linear thermal expansion of less than about 250
ppm/.degree. C., and the potting material is disposed about the
controller such that the potting material substantially isolates
the controller from fluid communication with the liquid
applicator.
[0011] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, the potting material has a glass transition
temperature less than about -40.degree. C. The potting material can
be a two-component urethane with a set time of less than about ten
minutes.
[0012] In certain implementations, the potting material is between
about 5 percent and about 20 percent of the mass of the robot. For
example, the potting material can have a mass of between about 110
g and about 140 g. Additionally or alternatively, the potting
material can have a specific gravity of between about 1.2 and about
1.6. In certain examples, the potting material has a thermal
conductivity of about 0.15 W/(mK) to about 0.40 W/(mK).
[0013] In some implementations, the potting material is disposed
along the lower portion of the robot body. In certain
implementations, the robot body defines an orifice configured to
receive the potting material into the robot body. For example, the
orifice can be defined along the lower portion of the robot body.
Additionally or alternatively, the robot body can have a
substantially flat side portion and the orifice is defined toward
the substantially flat side portion. The potting material can have
an uncured viscosity at room temperature of between about 8000
centipoise and about 10000 centipoise and is heatable to an uncured
viscosity of between about 3000 centipoise and about 5000
centipoise.
[0014] In certain implementations, the robot further includes a
liquid collection assembly carried by the robot body and defining a
liquid collection volume. The liquid collection assembly can be
configured to remove at least a portion of the dispensed liquid
from the cleaning surface into the liquid collection volume, and
the potting material can substantially isolate the controller from
fluid communication with the liquid collection assembly. For
example, the controller can include a circuit board, a plurality of
proximity sensors, and a plurality cliff sensors.
[0015] A method of assembling a surface treatment robot includes
introducing a potting material into a body of the surface treatment
robot, moving the potting material in a vertical direction through
the body such that the potting material moves over a controller
disposed within the body, and curing the potting material to
isolate the controller from fluid communication with a liquid
applicator carried by the body. The potting material is introduced
through an orifice defined by the body
[0016] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, the body is oriented substantially
perpendicular to the orientation of the body as the robot moves
over a cleaning surface such that a forward portion of the robot
body is above a rear portion of the robot body in the substantially
perpendicular orientation. In certain implementations, the
substantially perpendicular orientation of the body is
substantially parallel to the vertical direction of movement of the
potting material through the body.
[0017] In certain implementations, the orifice is disposed toward a
rear portion of the body and movement of the potting material in a
vertical direction includes moving air out of the body. For
example, the air can be moved out of the body through a forward
portion of the body. Additionally or alternatively, the rear
portion of the body includes a substantially flat portion and
orienting the body substantially perpendicular to the orientation
of the body as the robot moves over the cleaning surface can
include positioning the substantially flat portion of the body on a
surface.
[0018] In some implementations, the orifice is defined through a
portion of the robot body disposed toward a cleaning surface as the
robot moves over the cleaning surface. For example, the orifice can
be an x-shaped orifice, and the cured potting material can seal the
orifice.
[0019] In certain implementations, introducing the potting material
into the body of the surface treatment robot includes introducing
between about 110 g and about 140 g of potting material into the
robot body. The potting material can have a specific gravity of
between about 1.2 and about 1.6. Additionally or alternatively, the
potting material can have a coefficient of linear thermal expansion
of less than about 250 ppm/degrees C.
[0020] In some implementations, the potting material has a thermal
conductivity of about 0.15 W/(mK) to about 0.40 W/(mK). In some
implementations, the potting material is a two-part urethane. The
potting material can have a viscosity at room temperature of about
8000 centipoise to about 10000 centipoise viscosity at room
temperature. Additionally or alternatively, the potting material
can be heated to reduce the viscosity of the potting material to
about 3000 centipoise to about 5000 centipoise. In some
implementations, cured potting material isolates the controller
from fluid communication with a liquid storage volume at least
partially defined by the body.
[0021] A surface treatment robot includes a robot body, a cleaning
assembly, and a right drive wheel and a left drive wheel. The robot
body has a forward portion, a rear portion, the forward portion
preceding the rear portion as the robot moves in a forward
direction over a cleaning surface. The cleaning assembly is carried
by the robot body and configured to remove debris from the cleaning
surface. Each drive wheel is rotatable about an axis parallel to
the cleaning surface and transverse to the forward direction of
movement of the robot over the cleaning surface. Each drive wheel
includes a rim and a right tire and a left tire disposed about a
circumference of a respective drive wheel. Each tire includes a
base having a first side and a second side substantially opposite
the first side, a first and second set of treads, each tread of the
first and second set of treads extending radially from the first
side of the base toward the cleaning surface. Each tread of the
first and second set of treads is elongate in a direction
substantially parallel to the transverse axis, and each tread of
the first set of treads is circumferentially offset from each of
the treads of the second set of treads.
[0022] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, each tread of the first and second set of
treads has at least one substantially square edge disposed toward
the cleaning surface. Additionally or alternatively, each tread of
the first and second set of treads has substantially the same
circumferential width. In certain implementations, each tread of
the first and second set of treads is circumferentially spaced from
a preceding tread of the respective set of treads by a distance
about three times the circumferential width of the tread.
Additionally or alternatively, each tread can extend radially from
the base by a distance between about 1/5 to about 1/2 the radial
thickness of the base.
[0023] In some implementations, the tire includes natural rubber
and between about 20 percent and about 30 percent particulate
matter. For example, the particulate matter can include one or more
of the following: kaolin clay and calcium carbonate.
[0024] In certain implementations, each wheel is disposed rear of
at least a portion of the cleaning assembly as the robot moves in
the forward direction over the cleaning surface. The cleaning
assembly can include a liquid applicator. For example, at least a
portion of the liquid applicator is disposed forward of each wheel
as the robot moves in the forward direction over the cleaning
surface. In some implementations, the cleaning assembly includes a
vacuum assembly. For example, at least a portion of the vacuum
assembly is disposed rear of each wheel as the robot moves in the
forward direction over the cleaning surface.
[0025] In some implementations, each tire includes a third and
fourth set of treads extending radially from the second side of the
base toward the respective rim. For example, the third set of
treads can be substantially opposite the first set of treads and
the fourth set of treads can be substantially opposite the second
set of treads. Additionally or alternatively, each tread of third
set of treads is circumferentially offset from each tread of the
first set of treads and each tread of the fourth set of treads is
circumferentially offset from each tread of the second set of
treads.
[0026] In certain implementations, at least a portion of the base
is movable toward the wheel when a tread of the first or second set
of treads contacts the cleaning surface. In some implementations,
the third set of treads and the fourth set of treads define at
least a portion of channel extending circumferentially around the
tire, along the second surface of the base. Additionally or
alternatively, each wheel can include a circumferential ridge
extending radially outward, toward the cleaning surface, the
circumferential ridge engageable with the channel defined by the
respective tire. In some implementations, the tire is reversible
such that the third and fourth sets of treads extend toward the
cleaning surface and the first and second sets of treads extend
toward the respective rim.
[0027] A surface treatment robot includes a robot body, a
differential drive system mounted on the robot body and configured
to maneuver the robot over a cleaning surface, a collection
assembly carried by the robot body and configured to remove waste
from the cleaning surface, a liquid applicator carried by the robot
body and a wetting assembly. The robot has a forward portion and a
rear portion, with the forward portion preceding the rear portion
as the robot moves in a forward direction over a cleaning surface.
The liquid applicator defines a liquid storage volume and the
liquid applicator is configured to dispense a liquid rear of the
collection assembly as the robot moves in the forward direction.
The wetting assembly includes a plurality of rows of bristles
forward of the collection assembly and a row of bristles rear of
the collection assembly. The row of bristles rear of the collection
assembly has an angle of incidence of about 45 degrees with the
cleaning surface as the robot moves in the forward direction.
[0028] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, the base of the robot is supported about 4 mm
above the cleaning surface as the robot moves across the cleaning
surface in the forward direction and the bristles of the row of
bristles rear of the collection assembly have a length of about 5
mm to about 6 mm. In certain implementations, the collection
assembly includes a squeegee formed with a longitudinal ridge
disposed proximate to the cleaning surface and extending across a
cleaning width for providing a liquid collection volume at a
forward edge of the ridge as the robot moves in the forward
direction. The longitudinal ridge can have about 0.25 mm to about
0.75 mm of interference with the cleaning surface. Additionally or
alternatively, the longitudinal ridge can be movable in a direction
away from the cleaning surface by between about 2 mm and about 4
mm.
[0029] In certain implementations, a baseplate is carried on the
robot body, and the wetting assembly is disposed on the baseplate.
Additionally or alternatively, at least a portion of the collection
assembly can be disposed on the baseplate and the baseplate can be
releasably attachable to the robot body.
[0030] In some implementations, the plurality of rows of bristles
forward of the collection assembly includes at least one row of
bristles having about zero interference with the cleaning surface
and a row of bristles having an interference with the cleaning
surface. For example, the row of bristles having an interference
with the cleaning surface can be disposed rear of the at least one
row of bristles having about zero interference with the cleaning
surface as the robot moves across the cleaning surface in the
forward direction. Additionally or alternatively, the bristles of
the at least one row of bristles having about zero interference
with the cleaning surface are longer than the bristles of the row
of bristles having an interference with the cleaning surface.
[0031] In certain implementations, a baseplate is carried on the
robot body, and the baseplate has a recessed portion and an
unrecessed portion. The at least one row of bristles having about
zero interference with the cleaning surface can be disposed along
the recessed portion. Additionally or alternatively, the row of
bristles having an interference with the cleaning surface can be
disposed along the unrecessed portion.
[0032] In some implementations, the differential drive system
includes a right drive wheel and a left drive wheel and the
collection assembly is disposed rear of the right and left drive
wheels. In certain implementations, the surface treatment robot has
a center of gravity substantially at the center of the robot as
viewed from the above the robot as the robot moves across the
cleaning surface and the liquid storage volume is full of
liquid.
[0033] In certain implementations, the diameter of each bristle of
the row of bristles rear of the collection assembly is about twice
the diameter of each bristle of the plurality of rows of bristles
forward of the collection assembly. Additionally or alternatively,
the diameter of the bristles of the row of bristles rear of the
collection assembly is about 0.05 mm to about 0.2 mm. In another
additional or alternative example, the coefficient of friction of
the bristles of each row of bristles is about 0.1 to about 0.3 on a
wet cleaning surface. In certain implementations, each row of
bristles comprises a plurality of plugs about 1 mm in diameter.
[0034] A surface treatment robot including a robot body, a
differential drive system mounted on the robot body and configured
to maneuver the robot over a cleaning surface, a liquid applicator
carried by the robot body, and a collection assembly carried by the
robot body and configured to remove waste from the cleaning
surface. The robot body has a forward portion and a rear portion,
with the forward portion preceding the rear portion as the robot
moves in a forward direction over the cleaning surface. The liquid
applicator is configured to dispense a liquid to the cleaning
surface such that at least a portion of the liquid is dispensed
rear of the collection assembly as the robot moves in the forward
direction.
[0035] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, the liquid applicator dispenses between about
30 percent and about 70 percent of the liquid forward of the
collection assembly and at least about 30 percent of the liquid
rear of the collection assembly. For example, the liquid applicator
can dispense about 60 percent of the liquid forward of the
collection assembly and about 40 percent of the liquid rear of the
collection assembly.
[0036] In certain implementations, the liquid applicator includes a
spray nozzle arranged to dispense liquid rear of the collection
assembly as the robot moves in the forward direction. Additionally
or alternatively, the liquid applicator can include a drip assembly
configured to drip liquid rear of the collection assembly as the
robot moves in the forward direction.
[0037] In some implementations, the collection assembly is a vacuum
assembly including a collection region and a suction region in
fluid communication with the collection region.
[0038] In certain implementations, a collection volume carried is
carried by the robot body, and the collection volume is in fluid
communication with the vacuum assembly to collect waste removed by
the vacuum assembly.
[0039] In some implementations, the collection assembly includes a
surface agitation assembly. The surface agitation assembly can
include one or more of the following: a stationary brush, a
rotating brush, a woven cloth, a nonwoven cloth, a sponge, and a
compliant blade.
[0040] In some implementations, the robot includes a humidity
sensor and the surface agitation assembly includes an active
scrubbing element configured to act on the cleaning surface based
at least in part on detection of humidity on the cleaning
surface.
[0041] In certain implementations, the differential drive system
includes right and left drive wheels and the collection assembly is
disposed rear of the right and left drive wheels.
[0042] In some implementations, a wetting assembly is carried by
the robot body. At least a portion of the wetting assembly can be
disposed rear of the collection assembly and rear of the liquid
applicator as the robot moves in the forward direction. At least a
portion of the wetting assembly can contact the cleaning surface as
the robot moves in the forward direction.
[0043] In some implementations, the wetting assembly includes a
compliant blade extending in a direction substantially parallel to
the cleaning surface. In certain implementations, the wetting
assembly includes a plurality of bristles extending from the robot
body, toward the cleaning surface. For example, at least some of
the plurality of bristles and the cleaning surface define an
oblique angle therebetween (e.g., an acute angle in the direction
toward the forward portion of the robot).
[0044] A method of surface treatment includes maneuvering a surface
treatment robot over a cleaning surface, dispensing a liquid from
the liquid applicator to the cleaning surface, and collecting waste
into the collection assembly from the cleaning surface. The robot
has a forward portion and a rear portion, with the forward portion
preceding the rear portion over the cleaning surface as the robot
moves in a forward direction, and the robot includes a liquid
applicator and a collection assembly. At least a portion of the
liquid is dispensed rear of the collection assembly as the robot
moves in the forward direction.
[0045] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, dispensing liquid from the liquid applicator
to the cleaning surface includes dispensing between about 30
percent and about 70 percent of the liquid forward of the
collection assembly and at least about 30 percent of the liquid
rear of the collection assembly. For example, dispensing liquid
from the liquid applicator to the cleaning surface includes
dispensing about 60 percent of the liquid forward of the collection
assembly and about 40 percent of the liquid rear of the collection
assembly.
[0046] In certain implementations, maneuvering the surface
treatment robot includes returning to a portion of the cleaning
surface to collect the liquid dispensed rear of the collection
assembly.
[0047] A surface treatment robot includes a robot body, a drive
system mounted on the robot body and configured to maneuver the
robot over a cleaning surface, a base plate detachably coupled to
the robot body, and a squeegee disposed on the base plate. The
robot body has a forward portion and a rear portion, with the
forward portion preceding the rear portion as the robot moves in a
forward direction over a cleaning surface. The squeegee is formed
with a longitudinal ridge disposed proximate to the cleaning
surface and extending across a cleaning width for providing a
liquid collection volume at a forward edge of the ridge as the
robot moves in the forward direction. The squeegee includes a first
edge portion and a second edge portion disposed on respective sides
of the longitudinal ridge. The first edge portion is releasably
attached to the base plate and the second edge portion is
unattached to the base plate.
[0048] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, the squeegee is at least partially pivotable
about the first edge portion as the second edge portion is moved
away from the base plate. In certain implementations, the
releasable attachment of the first edge portion of the squeegee to
the base plate includes an interference fit. In some
implementations, the first edge portion is disposed forward of the
second edge portion as the robot moves over the cleaning surface in
the forward direction.
[0049] In certain implementations, a vacuum chamber is at least
partially formed by the squeegee. The vacuum chamber can be
disposed proximate to the longitudinal ridge such that suction
applied at the vacuum chamber holds the second edge portion of the
squeegee in a substantially fixed position relative to the base
plate. Additionally or alternatively, the vacuum chamber is in
fluid communication with the liquid collection volume by a
plurality of suction ports defined by the squeegee.
[0050] In some implementations, the drive system includes right and
left drive wheels and the base plate defines at least a portion of
a wheel well of each drive wheel.
[0051] In certain implementations, the squeegee is disposed rear of
the right and left drive wheels as the robot moves in the forward
direction over the cleaning surface. In some implementations, an
interference between the longitudinal ridge and the cleaning
surface is between about 0.5 mm and about 2.5 mm.
[0052] In some implementations, a wetting assembly is disposed on
the base plate. At least a portion of the wetting assembly can be
disposed rear of the squeegee as the robot moves in the forward
direction over the cleaning surface.
[0053] A method of assembling a surface treatment robot includes
testing performance of a plurality of motors on an encoder station,
classifying each motor based at least in part on the performance
test results; selecting a first and a second motor from the same
class;
[0054] and mounting the first and second motors on a robot body of
an autonomous surface coverage robot. The first motor drives a
right drive wheel of the robot and the second motor drives a left
drive wheel of the robot.
[0055] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, testing performance of the plurality of
motors includes providing power to each motor and determining the
speed of the output shaft of the respective motor. In certain
implementations, classifying each motor includes identifying motors
with output shaft speed varying by less than about ten percent from
one another as a function of power to each motor.
[0056] In some implementations, the robot body is driven in a
substantially straight line by providing substantially the same
amount of power to the first drive motor and the second drive
motor.
[0057] A surface treatment robot includes a robot body, a
differential drive system mounted on the robot body and configured
to maneuver the robot over a cleaning surface, a liquid applicator
carried by the robot body, a pump, an encoder arranged to measure
speed of the pump, and a controller carried by the robot body. The
robot body has a forward portion, a rear portion, an upper portion,
and a lower portion. The forward portion precedes the rear portion
as the robot moves in a forward direction over a cleaning surface.
The upper portion is disposed above the lower portion as the robot
moves over the cleaning surface. The liquid applicator defines a
liquid storage volume. The liquid applicator includes a pump in
fluid communication with the liquid storage volume and an encoder.
The pump is configured to move a liquid from the liquid storage
volume to the cleaning surface, and the encoder is arranged to
measure speed of the pump. The controller is in communication with
the encoder and configured to receive a signal from the encoder to
determine speed of the pump as a function of voltage supplied to
the pump.
[0058] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
some implementations, the controller is further configured to
determine the speed of the pump as a function of voltage supplied
to the pump during a start-up period and to control the speed of
the pump based at least in part on controlling voltage supplied to
the pump after the start-up period. For example, the start-up
period can be greater than about 5 seconds and less than about 300
seconds.
[0059] In certain implementations, the controller is further
configured to receive the signal from the encoder at a first rate
during the start-up period and to receive the signal from the
encoder at a second rate after the start-up period, wherein the
first rate is greater than the second rate.
[0060] In some implementations, the encoder is an optical encoder
including an emitter and receiver pair. The emitter can be arranged
to direct a signal toward the pump and the receiver can be arranged
to receive the signal reflected from the pump.
[0061] A surface treatment robot includes a robot body, a drive
system mounted on the robot body and configured to maneuver the
robot over a cleaning surface, and a vacuum assembly carried by the
robot body. The vacuum assembly defines an intake conduit and a
vacuum chamber in fluid communication with the intake conduit. The
vacuum assembly includes a fan in fluid communication with the
intake conduit. The fan is configured to draw air through the
intake conduit to draw waste liquid from the cleaning surface into
the vacuum chamber and a first portion of the fan is disposed in
the intake conduit in the path of air drawn through the intake
conduit.
[0062] Implementations of one or more of these aspects of the
disclosure may include one or more of the following features. In
certain implementations, the first portion of the fan disposed in
the intake conduit includes a heat sink. In certain
implementations, a potting material is disposed about a second
portion of the fan. The potting material can have a thermal
conductivity greater than the thermal conductivity of air.
Additionally or alternatively, the potting material substantially
isolates the fan and the intake conduit from fluid communication
with the robot body. In certain implementations, a liquid
applicator carried by the robot body and defining a liquid storage
volume, the liquid applicator configured to dispense a liquid from
the liquid storage volume to the cleaning surface, wherein the
potting material substantially isolates the fan from fluid
communication with the liquid applicator.
[0063] Other aspects, features, and advantages will be apparent
from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
[0064] FIG. 1 is a schematic block diagram showing the
interrelationship of subsystems of an autonomous cleaning
robot.
[0065] FIG. 2 is a perspective view of an autonomous cleaning
robot.
[0066] FIG. 3 is a bottom view of the autonomous cleaning robot of
FIG. 2.
[0067] FIG. 4 is a side view of the autonomous cleaning robot of
FIG. 2.
[0068] FIG. 5 is a front view of the autonomous cleaning robot of
FIG. 2.
[0069] FIG. 6 is a rear view of the autonomous cleaning robot of
FIG. 2.
[0070] FIG. 7 is an exploded perspective view of the autonomous
cleaning robot of FIG. 2.
[0071] FIG. 8 is a schematic representation of a liquid applicator
module of the autonomous cleaning robot of FIG. 2.
[0072] FIG. 9 is a block diagram of a pump control routine of an
autonomous cleaning robot.
[0073] FIG. 10A is a perspective view of a baseplate of the
autonomous cleaning robot of FIG. 2.
[0074] FIG. 10B is a bottom view of the baseplate of the autonomous
cleaning robot of FIG. 2.
[0075] FIG. 10C is a top view of the baseplate of the autonomous
cleaning robot of FIG. 2.
[0076] FIG. 10D is a front view of the baseplate of the autonomous
cleaning robot of FIG. 2.
[0077] FIG. 10E is a side view of the baseplate of the autonomous
cleaning robot of FIG. 2.
[0078] FIG. 11 is a perspective view of an active brush
element.
[0079] FIG. 12 is a schematic representation of a vacuum module of
an autonomous cleaning robot.
[0080] FIG. 13 is a perspective view of a squeegee of the
autonomous cleaning robot of FIG. 2.
[0081] FIG. 14 is a side view of the squeegee of the autonomous
cleaning robot of FIG. 2.
[0082] FIG. 15 is a bottom view of the squeegee of the autonomous
cleaning robot of FIG. 1.
[0083] FIG. 16 is a block diagram of a method of selecting motors
for an autonomous cleaning robot.
[0084] FIG. 17 is an exploded perspective view of a wheel of an
autonomous cleaning robot.
[0085] FIG. 18A is a front view of a tire of the wheel of FIG.
17.
[0086] FIG. 18B is a side view of the tire of the wheel of FIG.
17.
[0087] FIG. 19 is an exploded perspective view of a signal
channeler and omni-directional receiver of an autonomous cleaning
robot.
[0088] FIG. 20 is a schematic side view of a potted printed circuit
board of an autonomous cleaning robot.
[0089] FIGS. 21A-C are schematic top views of a method of potting a
printed circuit board of an autonomous cleaning robot.
[0090] FIG. 22 is a perspective view of a printed circuit board
cover of an autonomous cleaning robot.
[0091] FIG. 23 is a perspective exploded view of a printed circuit
board cover of an autonomous cleaning robot.
[0092] FIG. 24 is a bottom view of a printed circuit board cover
mounted on an autonomous cleaning robot.
[0093] FIG. 25 is a perspective exploded view of a trough of an
autonomous cleaning robot.
DETAILED DESCRIPTION
[0094] An autonomous robot may be designed to clean flooring. For
example, the autonomous robot may vacuum carpeted or hard-surfaces
and wash floors via liquid-assisted washing and/or wiping and/or
electrostatic wiping of tile, vinyl or other such surfaces. U.S.
application Ser. No. 11/359,961 by Ziegler et al. entitled
AUTONOMOUS SURFACE CLEANING ROBOT FOR WET AND DRY CLEANING, the
disclosure of which is herein incorporated by reference in its
entirety, discloses an autonomous cleaning robot.
[0095] An autonomous robot is movably supported on a surface and is
used to clean the surface while traversing the surface. The robot
can wet clean the surface by applying a cleaning liquid to the
surface, spreading (e.g., smearing, scrubbing) the cleaning liquid
on the surface, and collecting the waste (e.g., substantially all
of the cleaning liquid and debris mixed therein) from the surface.
As compared to comparable-sized autonomous dry cleaning robots, an
autonomous wet cleaning robot can remove more debris from a
surface.
[0096] FIG. 1 is a schematic block diagram showing the
interrelationship of subsystems of an autonomous cleaning robot. A
controller 1000 is powered by a power module 1200 and receives
inputs from a sensor module 1100 and an interface module 1700. The
controller 1000 combines the inputs from the sensor module 1100
with information (e.g., behaviors) preprogrammed on the controller
1000 to control a liquid storage module 1500, a liquid applicator
module 1400, and a collection module 1300 (e.g., a dry vacuum
module, a wet-dry vacuum module, a woven cloth, a nonwoven cloth
and/or a sponge) while also controlling a transport drive 1600 to
maneuver the autonomous cleaning robot across a cleaning surface
(also referred to hereinafter to as a "surface").
[0097] A controller 1000 (e.g., a controller on the robot) controls
the autonomous movement of the robot across the surface by
directing motion of the drive wheels that are used to propel the
robot across the surface. The controller 1000 can redirect the
motion of the robot in response to any of various different signals
from sensors (e.g., sensors carried on the robot, a navigation
beacon). Additionally or alternatively, the controller can direct
the robot across the surface in a substantially random pattern to
improve the cleaning coverage provided by the robot.
[0098] Prior to the cleaning operation, cleaning liquid can be
added to the liquid storage module 1500 via an external source of
cleaning liquid. The robot can then be set on a surface to be
cleaned, and cleaning can be initiated through an interface module
1700 (e.g., a user interface carried by the robot). The controller
1000 controls the transport drive 1600 to maneuver the robot in a
desired pattern across the surface. As the controller 1000 controls
the movements of the robot across the surface, the controller also
controls a liquid applicator module 1400 to supply cleaning liquid
to the surface and a collection module 1300 to collect waste from
the surface. For example, as described below, the controller 1000
can control the liquid applicator module 1400 to dispense at least
a portion of the total volume of dispensed liquid rear of the
collection module 1300 as the drive 1600 maneuvers the robot in a
forward direction over the surface. The collection module 1300 can
collect the dispensed liquid from the surface as the robot returns
to the area of the dispensed liquid. Additionally or alternatively,
the liquid dispensed rear of the collection module 1300 can remain
on the surface (e.g., to evaporate over time).
[0099] After the cleaning operation is complete (e.g., after all of
the cleaning liquid has been dispensed from the robot, after the
robot has completed a routine, after an elapsed period of time),
waste can be removed from the robot. The robot is lightweight and
has a compact form factor that each facilitate, for example,
handling of the robot such that the robot can be moved to another
area to be cleaned or put in storage until a subsequent use. The
robot is substantially sealable (e.g., passively sealable, actively
sealable) to minimize spillage of cleaning liquid and/or waste from
the robot while the robot is in use or while the robot is being
handled.
[0100] Referring to FIGS. 2-7, a robot 10 includes a chassis 100
carrying a baseplate 200, a bumper 300, a user interface 400, and
wheel modules 500, 501. Wheel modules 500, 501 are substantially
opposed along a transverse axis defined by the chassis 100.
Baseplate 200 is carried on a substantially bottom portion of
chassis 100 and at least partially supports a front portion of the
chassis 100 above the surface. As wheel modules 500, 501 propel the
robot 10 across the surface during a cleaning routine, the
baseplate 200 makes slidable contact with the surface and can
wet-vacuum the surface by delivering a portion of the cleaning
liquid to the surface forward of the wet-vacuum assembly, as
described below. The baseplate 200 can spread the cleaning liquid
on the surface, and collect waste from the surface and into the
volume defined by the robot 10. A user interface 400 is carried on
a substantially top portion of the chassis 100 and configured to
receive one or more user commands and/or display a status of the
robot 10. The user interface 400 is in communication with a
controller (described in detail below) carried by the robot 10 such
that one or more commands to the user interface 400 can initiate a
cleaning routine to be executed by the robot 10. A bumper 300 is
carried on a forward portion of the chassis 100 and configured to
detect one or more events in the path of the robot 10 (e.g., as
wheel modules 500, 501 propel the robot 10 across a surface during
a cleaning routine). As described below, the robot 10 can respond
to events (e.g., obstacles, cliffs, walls) detected by the bumper
300 by controlling wheel modules 500, 501 to maneuver the robot 10
in response to the event (e.g., away from the event). While some
sensors are described herein as being arranged on the bumper, these
sensors can additionally or alternatively be arranged at any of
various different positions on the robot 10.
[0101] The robot 10 stores cleaning fluid and waste and, thus,
substantially the entire electrical system is fluid-sealed and/or
isolated from cleaning liquid and/or waste stored on the robot 10.
Examples of sealing that can be used to separate electrical
components of the robot 10 from the cleaning liquid and/or waste
include covers, plastic or resin modules, potting, shrink fit,
gaskets, or the like. Any and all elements described herein as a
circuit board, PCB, detector, or sensor can be sealed using any of
various different methods. An example of the use of a potting
material to isolate electrical components of the robot from the
cleaning liquid and/or waste is described below.
[0102] The robot 10 can move across a surface through any of
various different combinations of movements relative to three
mutually perpendicular axes defined by the chassis: a central
vertical axis 20, a fore-aft axis 22 and a transverse axis 24. The
forward travel direction along the fore-aft axis 22 is designated F
(sometimes referred to hereinafter as "forward"), and the aft
travel direction along the fore-aft axis 22 is designated A
(sometimes referred to hereinafter as "rearward"). The transverse
axis extends between a right side, designated R, and a left side,
designated L, of the robot 10 substantially along an axis defined
by center points of wheel modules 500, 501. In subsequent figures,
the R and L directions remain consistent with the top view, but may
be reversed on the printed page.
[0103] In use, a user opens a fill door 304 disposed along the
bumper 300 and adds cleaning fluid to the volume within the robot
10. After adding cleaning fluid to the robot 10, the user then
closes the fill door 304 such that the fill door 304 forms a
substantially water-tight seal with the bumper 300 or, in some
implementations, with a port extending through the bumper 300. The
user then sets the robot 10 on a surface to be cleaned and
initiates cleaning by entering one or more commands on the user
interface 400.
[0104] The controller carried by the robot 10 directs motion of the
wheel modules 500, 501. The controller can control the rotational
speed and direction of each wheel module 500, 501 independently
such that the controller can maneuver the robot 10 in any of
various different directions. For example, the controller can
maneuver the robot 10 in the forward, reverse, right, and left
directions. For example, as the robot 10 moves substantially along
the fore-aft axis 22, the robot 10 can make repeated alternating
right and left turns such that the robot 10 rotates back and forth
around the center vertical axis 20 (hereinafter referred to as a
wiggle motion). As described in detail below, such a wiggle motion
of the robot 10 can allow the robot 10 to operate as a scrubber
during the cleaning operation. Additionally or alternatively, a
wiggle motion of the robot 10 can be used by the controller to
detect stasis of the robot 10. The controller can maneuver the
robot 10 to rotate substantially in place such that, for example,
the robot can maneuver out of a corner or away from an obstacle. In
some implementations, the controller directs the robot 10 over a
substantially random (e.g., pseudo-random) path traversing the
surface to be cleaned. The controller is responsive to any of
various different sensors (e.g., bump sensors, proximity sensors,
walls, stasis conditions, and cliffs) disposed about the robot 10.
The controller can redirect wheel modules 500, 501 in response to
signals from the sensors such that the robot 10 wet vacuums the
surface while avoiding obstacles and clutter. If the robot 10
becomes stuck or entangled during use, the controller is configured
to direct wheel modules 500, 501 through a series of escape
behaviors such that the robot 10 can resume normal cleaning of the
surface.
[0105] The robot 10 is generally advanced in a forward direction
during cleaning operations. The robot 10 is generally not advanced
in the aft (rear) direction during cleaning operations but may be
advanced in the aft direction to avoid an object or maneuver out of
a corner or the like. All or a portion of a cleaning operation can
continue or be suspended during aft transport. For example, the
robot 10 can dispense liquid rear of a vacuum assembly as the robot
is advanced in a forward direction and can suspend dispensing this
liquid as the robot is advanced in the aft direction.
[0106] During wet vacuuming, cleaning liquid can be dispensed to
the surface through an applicator mounted directly to the chassis
(e.g., to be used as an attachment point for the bumper and/or to
conceal wires). Additionally or alternatively, the cleaning liquid
can be dispensed to the surface through an applicator mounted to a
baseplate. For example, cleaning liquid can be dispensed through
troughs 202a,b carried on the baseplate 200. The trough 202a is
carried along a substantially forward portion of the robot 10, and
trough 202b is carried along a substantially rear portion of the
robot 10 such that the trough 202a is disposed forward of a
collection assembly (e.g., a squeegee 208) and the trough 202b is
disposed rear of the collection assembly. Each trough 202a,b can
define respective injection orifices 210a,b to produce a spray or
drip pattern of cleaning fluid to the surface. For example, a pump
upstream of the trough 202a,b can force cleaning liquid through
injection orifices 210a,b to deliver cleaning liquid to the
surface. In some implementations, injection orifices 210a,b are
substantially equally spaced along the length of each trough 202a,b
to produce a substantially uniform spray pattern of cleaning liquid
on the surface. In some embodiments, the injection orifices 210a,b
are configured to allow cleaning liquid to drip from the injection
orifices 210a,b.
[0107] A wetting assembly 204 is carried on the baseplate 200,
substantially rearward of the trough 202a. The wetting assembly 204
includes rows 205 and row 206 of bristles substantially forward of
the squeegee 208 and row 207 of bristles substantially rear of the
squeegee 208. Rows 205 of bristles extend in a transverse direction
substantially the entire width (e.g., diameter) of the robot 10. In
use, at least a portion of the wetting assembly 204 slidably
contacts the surface to support a forward portion and/or a rear
portion of the robot 10 above the cleaning surface. As the robot 10
moves in a substantially forward direction, the sliding contact
between the wetting assembly 204 and the surface spreads the
cleaning liquid on the surface. In some implementations, additional
rows of bristles and/or other types of wetting elements are carried
on the baseplate 200 to further spread and/or agitate the cleaning
liquid on the surface. As the robot continues to move forward,
wheel modules 500, 501 pass through the cleaning liquid spread on
the surface by rows 205 forward of the squeegee 208. A combination
of weight distribution (e.g., drag) of the robot 10, material
selection and tread geometry for the tires of the wheel modules
500, 501, and a biased-to-drop suspension system improve the
traction of wheel modules 500, 501 through the cleaning liquid such
that wheel modules 500, 501 can pass over the cleaning liquid
without substantial slipping and can navigate small obstacles
(e.g., grout lines, tile edges, etc.) that may be wet.
[0108] A squeegee 208 formed with a longitudinal ridge is carried
on the baseplate 200 and, during use, extends from the baseplate
200 to movably contact the surface. The squeegee 208 is positioned
substantially rearward of the wheel modules 500, 501. As compared
to a robot including a squeegee in a more forward position, such
rearward positioning of the squeegee 208 can increase the dwell
time of the cleaning liquid dispensed through the trough 202a on
the surface and, thus, increase the effectiveness of the cleaning
operation. Additionally or alternatively, such a rearward
positioned squeegee 208 can stabilize the robot 10 by reducing
rearward tipping of the robot 10 in response to thrust created by
the wheel modules 500, 501 propelling the robot 10 in a forward
direction. In another example, the rearward positioned squeegee 208
can stabilize the robot 10 by reducing rearward tipping of the
robot 10 as the robot 10 climbs a grout line. In yet another
example, squeegee 208 has about 0.25 mm to about 0.75 mm of
interference with the cleaning surface such that the squeegee 208
biases the weight of the robot 10 toward the forward direction as
the robot 10 maneuvers over an obstacle. In some implementations,
the squeegee 208 is movable away from the cleaning surface by about
2 mm to about 4 mm to facilitate, for example, movement of the
robot 10 over an obstacle such as a grout line.
[0109] As described in detail below, the movable contact between
the squeegee 208 acts to lift waste (e.g., a mixture of cleaning
liquid and debris) from the cleaning surface as the robot 10 is
propelled in a forward direction. The squeegee 208 is configured to
pool the waste substantially near suction apertures 262 defined by
the squeegee 208. A vacuum assembly carried by the robot 10
suctions the waste from the cleaning surface and into the robot 10,
leaving behind a wet vacuumed surface.
[0110] After all of the cleaning fluid has been dispensed from the
robot 10, the controller stops movement of the robot 10 and
provides an alert (e.g., a visual alert or an audible alert) to the
user via the user interface 400. The user can then open an empty
door 104 to expose a waste port defined by the waste collection
volume remove collected waste from the robot 10. Because the fill
door 304 and the empty door 104 are disposed along substantially
opposite sides of the chassis, the fill door 304 and the empty door
104 can be opened simultaneously to allow waste to drain out of the
robot 10 while cleaning liquid is added to the robot 10.
[0111] If the user wishes to move the robot 10 between uses, the
user may move (e.g., rotate) a handle 401 away from the chassis 100
and lift the robot 10 using the handle 401. The handle 401 can
pivot about a transverse axis (e.g., a center transverse axis)
including the center of gravity of the robot 10 such that the
handle 401 can be used to carry the robot 10 substantially like a
pail. The robot 10 includes a sealing system 601 (e.g., a passive
sealing system and/or an active sealing system) such that the robot
10 remains substantially water-tight during transport. The sealing
system 601 can reduce the escape of waste and/or cleaning fluid
from the robot 10 as the robot is moved from one area to another.
Accordingly, the robot 10 can be moved and stored with little risk
of creating hazardous, slippery conditions resulting from liquid
dripping from the robot. Additionally or alternatively, the robot
10 can be moved and stored with little risk of dripping liquid on
the user or on surfaces that have already been cleaned.
[0112] After moving the robot 10, the user can position the handle
401 back into a position substantially flush with the top portion
of the robot to reduce the potential for the handle 401 becoming
entangled with an object while the robot 10 is in use. In some
implementations, the handle 401 can be magnetized to bias the
handle 401 toward a position flush with the top portion of the
robot. In some implementations, the handle 401 includes a spring
that biases the handle 401 toward a position substantially flush
with the top portion of the robot 10.
[0113] Between uses, the user can recharge a power supply carried
on-board the robot 10. To charge the power supply, the user can
open a charge port door 106 on a back portion of the chassis 100.
With the charge port door 106 open, the user can connect a wall
charger to a charge port behind the charge port door 106. The wall
charger is configured to plug into a standard household electrical
outlet. During the charging process, one or more indicators (e.g.,
visual indicators, audible indicators) on the user interface 400
can alert the user to the state of charge of the power supply. Once
the power supply has been recharged (e.g., as indicated by the user
interface 400), the user can disconnect the robot 10 from the wall
charger and close the charge port door 106. The charge port door
106 forms a substantially water-tight seal with the chassis 100
such that the charge port remains substantially free of liquid when
the charge port door 106 is closed. In some implementations, the
power supply is removed from the robot 10 and charged separately
from the robot 10. In some implementations, the power supply is
removed and replaced with a new power supply. In some
implementations, the robot 10 is recharged through inductive
coupling between the robot 10 and an inductive transmitter. Such
inductive coupling can improve the safety of the robot 10 by
reducing the need for physical access to electronic components of
the robot 10.
[0114] Form Factor
[0115] The chassis 100, baseplate 200, bumper 300, user interface
400, and wheel modules 500, 501 fit together such that robot 10 has
a substantially cylindrical shape with a top surface and a bottom
surface that is substantially parallel to and opposite the top
surface. Such a substantially cylindrical shape can reduce the
potential for the robot 10 to become entangled (e.g., snagged)
and/or break on obstacles as the robot 10 traverses a surface.
[0116] In some implementations, the substantially cylindrical shape
of the robot 10 has a form factor that allows a user to lift and
manipulate the robot 10 in a manner similar to the manipulation of
a typical canteen carried by hikers. For example, a user can fill
the robot 10 with cleaning liquid by placing the robot 10 under a
typical bathroom or kitchen faucet. With the robot 10 in the same
orientation used to fill the robot with cleaning liquid, the robot
can be emptied into the bathroom or kitchen sink. The robot 10
includes a front face 302 and a back face 102, each of which are
substantially flat and configured to balance the robot 10 on end.
For example, a user can place back face 102 on a substantially flat
surface (e.g., a countertop, bottom of a kitchen sink, bottom of a
bathtub) such that the robot 10 is balanced on the countertop with
front face 302 facing upward toward the user. Such an orientation
can allow a user to fill the robot 10 with cleaning liquid without
holding the robot. Additionally or alternatively, a user can place
front face 302 on a substantially flat surface to allow a user to
more easily access components of the robot 10 (e.g., a battery
compartment, a charging port).
[0117] The robot 10 performs cleaning operations in tightly
dimensioned areas. In some implementations, the robot 10 can have a
compact form factor for avoiding clutter or obstacles while
dispensing liquid on a surface and/or removing waste from the
surface. For example, the robot 10 can be dimensioned to navigate
household doorways, under toe kicks, and under many typical chairs,
tables, portable islands, and stools, and behind and beside some
toilets, sink stands, and other porcelain fixtures. In certain
implementations, the overall height of the robot 10 is less than a
standard height of a toe-kick panel of a standard North American
bathroom vanity. For example, the overall height of the robot 10
can be less than about 18 centimeters (e.g., about 15 centimeters,
about 12 centimeters, about 9 centimeters). In certain
implementations, the overall diameter of the robot 10 is
approximately equal to the standard distance between the base of an
installed toilet and a bathroom wall. As compared to larger
diameter robots, such a diameter of the robot 10 can improve
cleaning around the base of a toilet, e.g., substantially between
the toilet and the wall. For example, the overall diameter of the
robot 10 can be less than about 26 centimeters (e.g., about 12-18
cm to permit, for example, going behind many bathroom surfaces not
reachable by conventional robots). In certain implementations, the
wheel modules 500, 501 are configured to maneuver the robot 10 in
such tightly dimensioned spaces (e.g., in a volume of less than
about 3 L).
[0118] While the robot 10 is described as having a substantially
cylindrical shape in the range of dimensions described above, the
robot 10 can have other cross-sectional diameter and height
dimensions, as well as other cross-sectional shapes (e.g. square,
rectangular and triangular, and volumetric shapes, e.g. cube, bar,
and pyramidal) to facilitate wet cleaning narrow or hard-to-reach
surfaces.
[0119] Within a given size envelope, larger volumes of cleaning
liquid can be stored by reducing, for example, the volume required
for the other functions (e.g., liquid dispensing, collecting) of
the robot 10. For example, the volume of cleaning liquid that can
be stored can be increased by increasing the fraction of cleaning
liquid dispensed rear of the squeegee 208 as the robot moves in the
forward direction such that a larger portion of the dispensed
cleaning liquid can evaporate before the robot 10 can return to
collect the cleaning liquid. In some implementations, the robot 10
carries a volume of cleaning fluid that is at least about 20
percent (e.g. at least about 30 percent, at least about 40 percent)
of the volume of the robot 10.
[0120] Physics and Mobility
[0121] The robot 10 is configured to clean approximately 150 square
feet of cleaning surface in a single cleaning operation. A larger
or smaller tank may permit this to range from 100 square feet to
400 square feet. The duration of the cleaning operation is
approximately 45 minutes. In implementations with smaller, larger,
or 2 or more batteries on board, the cleaning time can range down
to 20 minutes or up to 2 hours. Accordingly, the robot 10 is
configured (physically, and as programmed) for unattended
autonomous cleaning for 45 minutes or more without the need to
recharge a power supply, refill the supply of cleaning fluid or
empty the waste materials collected by the robot.
[0122] In implementations in which the robot 10 is configured to
collect substantially all of the cleaning fluid delivered to the
surface upstream of the squeegee 208 in a single pass, the average
forward travel speed of the robot 10 can be a function of the
cleaning quality and/or the surface coverage area required for a
given implementation. For example, slower forward travel speeds can
allow a longer soak time (e.g., longer contact time) between the
cleaning fluid (e.g., cleaning fluid dispensed through trough 202a)
and the debris on the surface such that the debris can be more
easily removed from the surface through suction with the squeegee
208. In some implementations, the average forward travel speed of
the robot 10 can be increased by dispensing at least some of the
cleaning liquid rear of the squeegee as the robot moves in the
forward direction.
[0123] Additionally or alternatively, faster forward travel speeds
can allow the robot 10 to clean a larger surface area before
requiring refilling with cleaning liquid and/or recharging the
power supply. Accordingly cleaning quality and surface coverage
that is acceptable to consumers is achieved by configuring the
robot 10 to dispense between about 30 percent and about 70 percent
(e.g., about 60 percent by volume) of a cleaning liquid through the
trough 202a forward of the squeegee, dispensing at least about 30
percent (e.g., about 40 percent by volume) of the cleaning liquid
through the trough 202b rear of the squeegee, and allowing between
about 0.3 and about 0.7 seconds of contact between the cleaning
liquid dispensed through trough 202a and the surface before the
cleaning liquid dispensed through the trough 202a is collected into
the robot 10 through squeegee 208. In some implementations,
substantially all of the liquid dispensed through the trough 202a
is collected (e.g., vacuumed) through the squeegee 208.
Additionally or alternatively, the robot 10 may return to collect
at least a portion of the liquid dispensed through the trough 202b.
Given that the liquid dispensed through the trough 202a and
collected through squeegee 208 cleans the surface in advance of
application of liquid through the trough 202b as the robot moves in
the forward direction, the liquid dispensed through the trough 202b
is dispensed onto a substantially clean surface and, therefore, may
be left on the cleaning surface to evaporate.
[0124] In one example, when the robot 10 has a diameter of about 17
centimeters and travels at a forward rate of about 25
centimeters/second, the contact time between the cleaning liquid
and the surface is about 0.25 to about 0.6 seconds, the variation
in contact time depending on the positioning of the cleaning fluid
distribution relative to the forward edge of the robot 10 and the
positioning of the collection assembly (e.g., squeegee 208)
relative to the rearward edge of the robot.
[0125] In some implementations, the robot 10 the controller 1000 is
configured to allow the robot 10 to subsequently return (e.g.,
through navigation) to collect from the surface at least some of
the cleaning liquid dispensed, through trough 202b, rear of the
squeegee 208. For example, the robot 10 may make multiple passes
over the cleaning surface to collect at least a portion of the
liquid left on the cleaning surface. As compared to dispensing all
of the cleaning liquid forward of the squeegee 208 (e.g., through
trough 202a), dispensing at least some of the cleaning liquid rear
of the squeegee 208 allows cleaning liquid to be left on the
surface for a longer period of time (e.g., to allow the cleaning
liquid to react chemically with debris on the surface) while the
robot 10 travels at a higher rate of speed. The controller 1000
allows the robot 10 to return to positions where the cleaning fluid
has been deposited on the surface but not yet collected. In some
implementations, the controller 1000 can maneuver the robot in a
pseudo-random pattern across the surface such that the robot is
likely to return to the portion of the surface upon which cleaning
fluid has remained.
[0126] As described above, the transverse distance between wheel
modules 500, 501 (e.g., the wheel base of robot 10) is
substantially equal to the transverse cleaning width (e.g., the
transverse width of the wetting assembly 204. Thus, during a
cleaning operation, wheel modules 500, 501 are configured to grip a
portion of the surface, including obstacles such as grout lines
that may form part of the surface, covered with cleaning liquid.
With sufficient traction force, the wheel modules 500, 501 can
propel the robot 10 through the cleaning liquid. With insufficient
traction force, however, the wheel modules 500, 501 can slip on the
cleaning liquid and the robot 10 can become stuck in place. As
described below, the wheel modules 500, 501 include tires with a
surface roughness sufficient to penetrate the surface tension of
the cleaning liquid on the surface to facilitate gripping the
surface. As also described below, the wheel modules 5001, 501
include tires with tread patterns that facilitate gripping small
obstacles (e.g., the edges) to propel the robot 10 over such small
obstacles.
[0127] Heavier robots can apply sufficient pressure at wheels to
avoid slipping as the wheels pass over the cleaning liquid. As
compared to lighter robots, however, heavier robots are more
difficult to handle (e.g., for refilling at a sink, for carrying to
storage). Accordingly, the robot 10 is configured to weigh less
than 3 kg (fully loaded with cleaning liquid) while wheel modules
500, 501 provide sufficient traction to propel robot 10 through
cleaning liquid on distributed on the surface.
[0128] In some implementations, the center of gravity of the robot
10 is substantially along the transverse axis 24 such that much of
the weight of the robot 10 is over the wheel modules 500, 501
during a cleaning operation. Such a weight distribution of robot 10
can exert a sufficient downward force on wheel modules 500, 501 to
overcome slippage while also allowing wheel modules 500, 501 to
overcome drag forces created as wetting assembly 204 and squeegee
208 movably contact the surface. In some implementations, the
weight of the robot is distributed to overcome such drag forces
while applying sufficient cleaning pressure to the surface (e.g.,
sufficient pressure to wetting assembly 204 and squeegee 208). For
example, the wheel modules 500, 501 can support about 50% to about
70% of the weight of the robot 10 above the surface. The wetting
assembly 204 can support at least about 10% of the weight of the
robot above the surface, along the forward portion of the robot.
The squeegee 208 can support at least about 20% of the weight of
the robot above the surface, along the rearward portion of the
robot. As described in detail below, the supply volume and the
collection volume are configured to maintain the center of gravity
of the robot substantially over the transverse axis 24 while at
least about 25 percent of the total volume of the robot shifts from
cleaning liquid in the supply volume to waste in the collection
volume as the cleaning cycle progresses from start to finish.
[0129] In certain implementations, a robot of between 12-18 cm in
diameter and less than 15 cm high is between 1-2 kg when full of
fluid, the volume being largely occupied by water (specific gravity
1), plastic (close to specific gravity 1) and a few heavier
components (ballast, motors, batteries). Exemplary ranges for
physical dimensions of a robot intended to reach narrower bathroom
areas (such as beside toilets) include: a full mass of 0.5-4 kg; a
cleaning width of 5 cm-20 cm within a diameter of 10-20 cm; a wheel
diameter 1.5 cm-8 cm; drive wheel contact line 1 cm-3 cm for all
drive wheels (two, three, four drive wheels); drive wheel contact
patch for all wheels 0.5-1.5 cm.sup.2 or higher.
[0130] The robot 10 can be less than about 0.5 kg empty, and less
than approximately 3 kg full, and carry about 0.5 kg to about 2.5
kg (or 500-2500 ml) of clean or dirty fluid (in the case where the
robot applies fluid as well as picks it up). The waste tank can be
sized according to the efficiency of the pick-up process and/or
according to the fraction of liquid dispensed rear of the squeegee
208. For example, with a comparatively inefficient squeegee
designed to or arranged to leave a predetermined amount of wet
fluid on each pass (e.g., so that the cleaning fluid can dwell and
progressively work on stains or dried food patches), the waste tank
can be designed to be equal in size or smaller than the clean tank.
A portion of the deposited fluid will never be picked up, and
another portion will evaporate before it can be picked up. In an
additional or alternative example, at least a portion of the liquid
dispensed rear of the squeegee 208 will evaporate before the robot
10 returns to pick up this dispensed liquid and, in some instances,
the robot 10 may not return to pick up the dispensed liquid. In
implementations in which an efficient squeegee is used (e.g.,
silicone) and substantially all of the cleaning liquid is dispensed
forward of the squeegee 208, then it may be necessary to size the
waste tank to be equal to or bigger than the clean fluid tank. A
proportion of the tank volume, e.g., 5% or higher, may also be
devoted to foam accommodation or control, which can increase the
size of the waste tank.
[0131] To effectively brush, wipe, or scrub the surface, the
wetting assembly 204 and the squeegee 208 create drag that acts to
agitate debris on the surface. For a robot under 3 kg, the wetting
assembly 204 (e.g., rows 205, row 206, and row 207 of bristles)
should have a length, stiffness, and height to balance (whether
full or empty) at least about 1/3 of the empty weight of the robot
per wheel (e.g., for an empty robot of 1 kg, at least 300 weight
borne by each wheel). Drag forces (total drag associated with any
blades, squeegees, dragging components such as bristles) should not
exceed 25% of robot weight to ensure good mobility in the absence
of active suspensions/constant weight systems, as any lifting will
otherwise remove weight from the tires and affect motive force.
Maximum available traction typically is no more than about 40% of
robot weight on slick surfaces with a surfactant based (low surface
tension) cleaning fluid, perhaps as high as 50% in best case
situations, and traction/thrust must exceed drag/parasitic forces.
However, in order to successfully navigate autonomously, to have
sufficient thrust to overcome minor hazards and obstacles, to climb
thresholds which may encounter the scrubbing or brushing member
differently from the wheels, and to escape from jams and other
panic circumstances, the robot 10 can have a thrust/traction,
provided mostly by the driven wheels, of about 150% or more of
average drag/parasitic force. In implementations including a
rotating brush, depending on the direction of rotation, the
rotating brush can create drag or thrust.
[0132] In some implementations, the robot 10 has a weight of about
1.4 kg fully loaded, with less than about 100 gram-force of drag
(on a surface with a static coefficient of friction of about 0.38)
caused by the wetting assembly 204 and less than about 320
gram-force of drag (on a surface with a static coefficient of
friction of about 0.77) caused by the squeegee 208, but more than
1100 gram-force of thrust contributed by wheel modules 500, 501 to
propel the robot 10 at a maximum forward rate of about 200 mm/s to
about 400 mm/s. In certain implementations, weight is added to the
robot 10 to improve traction of wheel modules 500, 501 by putting
more weight on the wheels (e.g., metal handle, clevis-like pivot
mount, larger motor than needed, and/or ballast in one embodiment
of the present device). With or without added weight, in some
implementations, the robot can include a rotating brush and derive
a functional percentage of thrust from a forwardly rotating brush
(which is turned off generally in reverse), which is not a feature
needed in a large industrial cleaner.
[0133] The width of the cleaning head for the mass of a household
cleaning robot, under 10 kg (or even under 20 kg), differs from
industrial self-propelled cleaners. This is especially true for wet
cleaning. In some implementations, the robot 10 has at least about
1 cm of (wet) cleaning width for every 1 kg of robot mass (e.g.,
about 4, 5, or 6 cm of cleaning width for every 1 kg of robot
mass), and up to about 20 cm of cleaning width for every kg of
robot mass (the higher ratios generally apply to lower masses). For
example, the robot 10 can weigh approximately 1.5 kg when fully
loaded with cleaning liquid and can have a wet cleaning width of
about 16.5 cm, such that the robot 10 can have about 11 cm of wet
cleaning width for every 1 kg of robot mass.
[0134] In implementations in which cleaning liquid is dispensed
rear of the squeegee 208 to remain on the cleaning surface as the
robot 10 moves in the forward direction, larger cleaning widths per
kg are possible. In such implementations, the use of mechanical
agitation (e.g., wiping or scrubbing force) to remove debris from
the cleaning surface is augmented by the increased chemical
reactivity between cleaning liquid and the debris on the cleaning
surface. For example, the increased time available for the liquid
to remain in contact with the debris can increase the amount of
chemical reaction that occurs between the cleaning liquid and the
debris. Thus, as compared to implementations in which all of the
cleaning liquid is dispensed forward of the squeegee 208 and is
collected by the squeegee 208, larger cleaning widths for every kg
of robot mass can result in effective cleaning of the surface.
Thus, in implementations in which at least about 30 percent of the
total dispensed volume of the cleaning liquid is dispensed rear of
a collection assembly (e.g., rear of the squeegee 208), the robot
can have up to about 50 cm of cleaning width for every kg of robot
mass. For example, by dispensing higher percentages of cleaning
fluid rear of the squeegee, higher ratios of cleaning width to
robot mass can be used to achieve effective cleaning of the
surface.
[0135] Lower cleaning widths per 1 kg of robot mass can lead to
either an ineffective cleaning width or a very heavy robot
unsuitable for consumer use, i.e., that cannot be carried easily by
an ordinary (or frail) person. Self-propelled industrial cleaning
machines typically have 1/3 cm of cleaning width or less per kg
machine mass.
[0136] Ratios of these dimensions or properties determine whether a
robot under 5 kg, and in some cases under 10 kg, will be effective
for general household use. Although some such ratios are described
explicitly above, such ratios (e.g., cm squared area of wheel
contact per kg of robot mass, cm of wheel contact line per kg-force
of drag, and the like) are expressly considered to be inherently
disclosed herein, albeit limited to the set of different robot
configurations discussed herein.
[0137] In certain implementations, the robot 10 includes tires
having a 3 mm foam tire thickness with 2 mm deep sipes. This
configuration performs best when supporting no more than 3 to 4 kg
per tire. The ideal combination of sipes, cell structure and
absorbency for a tire is affected by robot weight. In some
implementations, rubber or vinyl tires are configured with surface
features to reduce slippage.
[0138] As indicated above, the robot 10 includes the wetting
assembly 204 and the collection assembly 1300 including, for
example, the squeegee 208. In some implementations, a wet vacuum
portion can be closely followed by a longitudinal ridge of the
squeegee 208 to build up the thickness of a deposited water film
for pick-up. The squeegee 208 can have sufficient flexibility and
range of motion to clear any obstacle taller than 2 mm, but ideally
to clear the ground clearance of the robot (e.g., about a 41/2 mm
minimum height or the ground clearance of the robot).
[0139] Any reactionary force exhibited by the squeegee 208 that is
directionally opposite to gravity, i.e., up, subtracts from
available traction and should be less than about 20% of robot
weight (e.g., less than about 10% of robot weight). A certain
amount of edge pressure, which has an equal reactionary force, is
necessary for the squeegee 208 to wipe and collect fluid. In order
to obtain an effective combination of fluid collection, reactionary
force, wear, and flexible response to obstacles, the physical
parameters of the squeegee are controlled and balanced. In certain
implementations, the squeegee 208 includes a working edge radius of
3/10 mm for a squeegee less than 300 mm. In some implementations,
the squeegee 208 can have a working edge of about 1/10 to 5/10 mm.
Wear, squeegee performance and drag force can be improved with a
squeegee of substantially rectangular cross section (optionally
trapezoidal) and/or 1 mm (optionally about 1/2 mm to 11/2 mm)
thickness, 90 degree corners (optionally about 60 to 120 degrees),
parallel to the floor within 1/2 mm over its working length
(optionally within up to 3/4 mm), and straight to within 1/500 mm
per unit length (optionally within up to 1/100), with a working
edge equal to or less than about 3/10 mm as noted above. Deviations
from the above parameters can require greater edge pressure (force
opposite to gravity) to compensate, thus decreasing available
traction.
[0140] The wetting assembly 204 and the squeegee 208 are configured
to contact the floor over a broad range of surface variations
(e.g., in wet cleaning scenarios, including tiled, flat, wood, deep
grout floors). In some implementations, the wetting assembly 204
and/or the squeegee 208 are mounted using a floating mount (e.g.,
on springs, elastomers, guides, or the like) to improve contact
with the broad range of surface variations. In certain
implementations, the wetting assembly 204 and the squeegee 208 are
mounted to the chassis 100 with sufficient flexibility for the
designed amount of interference or engagement of the wetting
assembly 204 and/or the squeegee 208 to the surface. As described
above, any reactionary force exhibited by the brushes/scrubbing
apparatus that is opposite to gravity (up) subtracts from available
fraction and should not exceed 10% of robot weight.
[0141] In certain implementations, the robot includes more than one
brush, e.g., two counter-rotating brushes with one or more brush on
either fore-aft side of the center line of the robot, or more. The
robot can also include a differential rotation brush such that two
brushes, each substantially half the width of the robot at the
diameter of rotation, are placed on either lateral side of the
fore-aft axis 22, each extending along half of the diameter. Each
brush can be connected to a separate drive and motor, and can
rotate in opposite directions or in the same direction or in the
same direction, at different speeds in either direction, which
would provide rotational and translational impetus for the
robot.
[0142] The center of gravity of the robot 10 will tend to move
during recovery of fluids unless the cleaner and waste tanks are
balanced to continually maintain the same center of gravity
location. Maintaining the same center of gravity location (by tank
compartment design) can allow a passive suspension system to
deliver the maximum available traction. The robot 10 includes a
tank design that includes a first compartment having a profile that
substantially maintains the position of the compartment center of
gravity as it empties, a second compartment having a profile that
substantially maintains the position of the compartment center of
gravity as it fills, wherein the center of gravity of the combined
tanks is maintained substantially within the wheel diameter, as
viewed from the top of the robot 10, and over the wheels, as viewed
from the side of the robot 10. In some implementations, the robot
10 includes tanks stacked in a substantially vertical direction and
configured to maintain the same location of the center of gravity
of the robot 10.
[0143] In certain implementations, absent perfect fluid recovery or
active suspension, superior mobility is achieved either by modeling
or assuming a minimum percentage of fluid recovered across all
surfaces (70% of fluid put down for example) and designing the
profile of the compartments and center of gravity positions
according to this assumption/model. In some implementations,
superior mobility is achieved by assuming perfect (or near perfect)
fluid and dispensing least about 30 percent by volume of cleaning
liquid is dispensed rear of the squeegee 208 as the robot moves in
the forward direction and designing the profile of the compartments
and the center of gravity positions based on this configuration. In
the alternative, or in addition, setting spring force equal to the
maximum unladen (empty tank) condition can contribute to superior
traction and mobility. In some implementations, suspension travel
is at least equal the maximum obstacle allowed by the bumper (and
other edge barriers) to travel under the robot.
[0144] Maximizing the diameter of the wheels of the robot can
decrease the energy and traction requirements for a given obstacle
or depression. In certain implementations, maximum designed
obstacle climbing capability should be 10% of wheel diameter or
less. A 4.5 mm obstacle or depression should be overcome or tackled
by a 45 mm diameter wheel. In certain implementations, the
clearance of the robot is low for several reasons. The bumper is
set low to distinguish between carpet, thresholds, and hard floors
such that a bumper 3 mm from the ground will prevent the robot from
mounting most carpets (2-5 mm bumper ground clearance, 3 mm being
preferable). The remainder of the robot working surface, e.g., the
collection assembly, also have members extending toward the floor
(air guides, squeegees, brushes) that are made more effective by a
lower ground clearance. Because the ground clearance of one
embodiment is between 3-6 mm, the wheels need only be 30 mm-60 mm.
Other wheel sizes can also be used.
[0145] Assembly
[0146] Referring to FIG. 7, chassis 100 carries a liquid volume 600
substantially along an inner portion of the chassis 100. As
described in detail below, portions of the liquid volume 600 are in
fluid communication with liquid delivery and air handling systems
carried on the chassis 100 to allow cleaning fluid to be pumped
from the liquid volume 600 and to allow waste to be suctioned into
the liquid volume 600. To allow the addition of cleaning liquid and
the removal of waste, liquid volume 600 can be accessed through
fill door 304 (not shown in FIG. 7) and empty door 104.
[0147] The wheel modules 500, 501 include respective drive motors
502, 503 and wheels 504, 505. The drive motors 502, 503 releasably
connect to the chassis 100 on either side of the liquid volume 600
with the drive motors 502, 503 positioned substantially over
respective wheels 504, 505. In some implementations, drive motors
502, 503 are positioned substantially horizontal to respective
wheels 504, 505 to increase the size of the liquid volume 600
carried on chassis 100. In some implementations, wheel modules 500,
501 are releasably connected to chassis 100 and can be removed
without the use of tools to facilitate, for example, repair,
replacement, and cleaning of the wheel modules 500, 501. A signal
channeler 402 is connected to a top portion of chassis 100 and
substantially covers the liquid volume 600 to allow components to
be attached along a substantially top portion of the robot 10. An
edge 404 of the signal channeler is visible from substantially the
entire outer circumference of the robot 10 to allow the signal
channeler 404 to receive a light signal (e.g., an infrared light
signal) from substantially any direction. As described in detail
below, the signal channeler 402 receives light from a light source
(e.g., a navigation beacon) and internally reflects the light
toward a receiver disposed within the signal channeler 402. For
example, the signal channeler 402 can be at least partially formed
of a material (e.g., polycarbonate resin thermoplastic) having an
index of refraction of about 1.4 or greater to allow substantially
total internal reflection within the signal channeler. Additionally
or alternatively, the signal channeler 402 can include a first
mirror disposed along a top surface of the signal channeler 402 and
a second mirror disposed along a bottom surface of the signal
channeler 402 and facing the first mirror. In this configuration,
the first and second mirrors can internally reflect light within
the signal channeler 402.
[0148] The signal channeler 402 includes a recessed portion 406
that can support at least a portion of the user interface 400. A
user interface printed circuit board (PCB) can be arranged in the
recessed portion 406 and covered by a membrane and/or a potting
material, to form a substantially water-tight user interface 400.
As described in detail below, a bottom portion of signal channeler
402 can form a top portion of the liquid volume 600.
[0149] Bumper 300 connects to the hinges 110 arranged substantially
along the forward portion of the chassis 100. The hinged connection
between bumper 300 and chassis 100 can allow the bumper to move a
short distance relative to the chassis 100 when the bumper 300
contacts an obstacle. Bumper 300 is flexibly connected to a fill
port 602 of the liquid volume 600 such that the bumper 300 and the
fill port 602 can flex relative to one another as the bumper 300
moves relative to the chassis 100 upon contact with an
obstacle.
[0150] The bumper 300 includes a substantially transparent section
306 near a top portion of the bumper. The transparent section 306
can extend substantially along the entire perimeter of the bumper
300. The transparent section 306 can be substantially transparent
to a signal receivable by an omni-directional receiver disposed
substantially near a center portion of the signal channeler 402
such that the omni-directional receiver can receive a signal from a
transmitter positioned substantially forward of the bumper 300.
[0151] The baseplate 200 is carried on a substantially bottom
portion of chassis 100. The baseplate 200 includes pivot hinges 212
that extend from a forward portion of the baseplate 200 and can
allow the baseplate 200 to be snapped into complementary hinge
features on the chassis 100. In some implementations, a user can
unhinge the baseplate 200 from the chassis 100 without the use of
tools. The baseplate 200 defines at least a portion of the trough
202b along a rear portion of the robot 10. The wetting assembly 204
is substantially rearward of the trough 202a. The baseplate 200
extends around a portion of each wheel module 500, 501 to form
portion of wheel wells for wheels 504, 505, substantially rearward
of the wetting assembly 204. Rearward of the wheels 504, 505, the
baseplate 200 carries a collection assembly including the squeegee
208 configured in slidable contact with the surface to pool waste
near the contact edge between the squeegee 208 and the surface. As
described in detail below, the squeegee 208 defines a plurality of
orifices substantially near the contact edge between the squeegee
208 and the surface. The collection assembly 1300 can create
suction such that waste is lifted from the surface and into the
robot 10 through the plurality of orifices defined by the squeegee
208.
[0152] In some implementations, a user can unhinge the baseplate
200 from the chassis 100 in order to clean the baseplate 200. In
certain implementations, the user can remove the trough 202b, the
wetting assembly 204, and/or the squeegee 208 from the baseplate
200 to repair or replace these components. Additionally or
alternatively, as described below, a portion of the squeegee 208
can be unattached to the baseplate such that the user can move the
unattached portion of the squeegee 208 to facilitate cleaning and,
during use, negative pressure created by a vacuum holds the
unattached portion of the squeegee 208 in place relative to the
baseplate 200.
[0153] Liquid Storage
[0154] Referring to FIG. 8, in some implementations, liquid volume
600 can function as both a liquid supply volume S and a waste
collection volume W. Liquid volume 600 is configured such that
liquid moves from the liquid supply volume S to the surface and
then is picked up and returned to a waste collection volume W. In
some implementations, the supply volume S and the waste collection
volume W are configured to maintain a substantially constant center
of gravity along the transverse axis 24 (see FIG. 2) while at least
25 percent of the total volume of the robot 10 shifts from cleaning
liquid in the supply volume S to waste in the collection volume W
as cleaning liquid is dispensed from the applicator and waste is
collected by the vacuum assembly.
[0155] In some implementations, all or a portion of the supply
volume S is a flexible bladder within the waste collection volume W
and surrounded by the waste collection volume W such that the
bladder compresses as cleaning liquid exits the bladder and waste
filling the waste collection volume W takes place of the cleaning
liquid that has exited the bladder. Such a system can be a
self-regulating system which can keep the center of gravity of the
robot 10 substantially in place (e.g., over the transverse axis
24). For example, at the start of a cleaning routine, the bladder
can be full such that the bladder is expanded to substantially fill
the waste collection volume W. As cleaning liquid is dispensed from
the robot 10, the volume of the bladder decreases such that waste
entering the waste collection volume W replaces the displaced
cleaning fluid that has exited the flexible bladder. Toward the end
of the cleaning routine, the flexible bladder is substantially
collapsed within the waste collection volume W and the waste
collection volume is substantially full of waste.
[0156] In some implementations, the maximum volume of the flexible
bladder (e.g., the maximum storage volume of cleaning liquid) is
substantially equal to the volume of the waste collection volume W.
In certain implementations, the volume of the waste collection
volume W is larger (e.g., about 10 percent to about 20 percent
larger) than the maximum volume of the flexible bladder. Such a
larger waste collection volume W can allow the robot 10 to operate
in an environment in which the volume of the waste collected is
larger than the volume of the cleaning liquid dispensed forward of
the collection assembly (e.g., when the robot 10 maneuvers over
substantial spills).
[0157] While the supply volume S has been described as a flexible
bladder substantially surrounded by the waste collection volume W,
other configurations are possible. For example, the supply volume S
and the waste collection volume W can be compartments that are
stacked or partially stacked on top of one another with their
compartment-full center of gravity within 10 cm of one another.
Additionally or alternatively, the supply volume S and the waste
collection volume W can be concentric (concentric such that one is
inside the other in the lateral direction); or can be interleaved
(e.g., interleaved L shapes or fingers in the lateral
direction).
[0158] Liquid Applicator
[0159] Referring to FIGS. 3 and 8, a liquid applicator module 1400
applies a first volume of cleaning liquid onto the surface, through
trough 202a, forward of the rows 205 and row 206 and applies a
second volume of cleaning liquid onto the surface, through trough
202b, rear of the rows 205 and row 206 and forward of the row 207
as the robot 10 moves in the forward direction. In some
implementations, the second volume of cleaning liquid is at least
about 30 percent (e.g., about 50 percent) of the total volume of
cleaning liquid dispensed by the liquid applicator module 1400 to
the surface, and the first volume of cleaning liquid can be about
30 percent to about 70 percent of the total volume of liquid
dispensed by the liquid applicator module 1400. For example, the
first volume can be about 60 percent of the total volume of liquid
dispensed by the liquid applicator module 1400 and the second
volume can be about 40 percent of the total volume of liquid
dispensed by the liquid applicator module. This ratio can result in
superior cleaning of the surface by allowing the first volume of
cleaning liquid to be mechanically agitated (e.g., by rows 205
and/or row 206 of bristles) in contact with debris on the surface
and the second volume of cleaning liquid can remain on the cleaning
surface to react chemically with debris that may remain on the
cleaning surface after the first volume of cleaning liquid has been
removed from the surface.
[0160] The liquid applicator module can spray the floor directly,
spray a fluid-bearing brush or roller, or apply fluid by dripping
or capillary action to the floor, brush, roller, or pad. The liquid
applicator module 1400 receives a supply of cleaning liquid from a
supply volume S within the liquid volume 600 carried by the chassis
100. In some implementations, the liquid of the composition of the
liquid of the first volume of cleaning liquid is the same as the
composition of the liquid of the second volume of cleaning liquid.
In certain implementations, the liquid of the first volume of
cleaning liquid differs in composition from the liquid of the
second volume of cleaning liquid. For example, the liquid of the
second volume of cleaning liquid can be water.
[0161] A pump 240 (e.g., a peristaltic pump) pumps the cleaning
fluid through the liquid applicator module 1400, through one or
more injection orifices 210a,b defined by the trough 202a and the
trough 202b (see, e.g. FIG. 3). In some implementations, the pump
240 pumps liquid to the trough 202a and the trough 202b and the
relative distribution of cleaning liquid between the troughs is
achieved by adjusting the total open area of the orifices 210a,b
defined by each respective trough. Each injection orifice 210a,b is
oriented to dispense cleaning liquid toward the cleaning surface.
For example, at least a portion of the injection orifices 210a,b
can be oriented to dispense cleaning liquid toward the cleaning
surface, in a direction substantially toward the forward direction
of travel of the robot 10. Additionally or alternatively, at least
a portion of the injection orifices 210a,b can be oriented to spray
cleaning liquid toward the cleaning surface, in a direction
substantially toward the rear of the robot 10. The size of orifices
210a,b and the delivery pressure of pump 240 can be any of various
different combinations such that the fluid can be dispensed toward
the cleaning surface in a drip (e.g., with substantially large
droplets and/or substantially continuous flow) and/or in a spray.
For example, the orifices 210b can be sized to be one or more spray
nozzles, dispensing substantially atomized droplets of cleaning
liquid toward the cleaning surface rear of the squeegee 208. Such
atomization facilitate exposure of a large surface area of the
cleaning liquid to air, thus facilitating evaporation of the
cleaning liquid. Additionally or alternatively, in another example,
the orifices 210b can be sized to drip cleaning liquid toward the
cleaning surface rear of the squeegee 208.
[0162] The speed of the pump 240 can be determined based at least
in part on a signal received an encoder 605. For example, the
encoder can be an optical encoder including an emitter/receiver
pair, with the emitter arranged to direct a signal toward the pump
240 and the receiver arranged to receive the signal reflected from
the pump 240. Additionally or alternatively, the controller 1000
can be in communication with the encoder 605 and configured to
receive a signal from the encoder 605 to determine speed of the
pump 240 as a function of voltage supplied to the pump.
[0163] Referring to FIGS. 5, 7, 8, and 9, encoderless pumping 1002
includes receiving 1004a signal from an encoder (e.g., encoder 605)
directed at a pump, determining 1006 the speed of the pump as a
function of voltage supplied to the pump during a start-up period,
and controlling 1008 the speed of the pump based at least in part
on controlling voltage supplied to the pump after the start-up
period. The start-up period can be greater than about 5 seconds and
less than about 300 seconds. In some implementations, the
controller 1000 receives 1002 the signal from the encoder at a
first rate during the start-up period and receives 1002 the signal
from the encoder at a second rate after the start-up period (e.g.,
the first rate is greater than the second rate).
[0164] The liquid applicator module 1400 includes a supply volume S
which is a compartment within liquid volume 600. However, in some
implementations, supply volume S is a separate volume carried by
the chassis 100. Supply volume S defines an exit aperture 604 in
fluid communication with a fluid conduit 606. During use, fluid
conduit 606 delivers a supply of cleaning liquid to a pump assembly
240 (e.g., a peristaltic pump assembly). Pressure created by pump
assembly 240 forces liquid to troughs 202a,b and through the
respective injection orifices 210a,b toward the surface. In some
embodiments, pump assembly 240 includes separate pumps to force
liquid to respective troughs 202a, b.
[0165] The liquid applicator module 1400 applies cleaning liquid to
the surface at a volumetric rate ranging from about 0.1 mL per
square foot to about 6.0 mL per square foot (e.g., about 3 mL per
square foot). However, depending upon the application, the liquid
applicator module 1400 can apply any desired volume of cleaning
liquid onto the surface. For example, the liquid applicator module
1400 can adjust the relative volumetric fraction of cleaning liquid
dispensed through trough 202a and trough 202b (e.g., by adjusting
the pressure drop along the respective paths between the pump
assembly 240 and the orifices 210a,b of the respective troughs 202a
and 202b). Additionally or alternatively, the liquid applicator
module 1400 can be used to apply other liquids onto the surface
such as water, disinfectant, chemical coatings, and the like.
[0166] The liquid applicator module 1400 can be a closed system
(e.g., when pump 240 is a peristaltic pump) such that the liquid
applicator module 1400 can be used to deliver a wide variety of
cleaning solutions, without damaging other components (e.g., seals)
of the robot 10. For example, as described below, a potting
material can be disposed between the liquid applicator module 1400
and electrical components carried by the robot to isolate the
liquid applicator module 1400 from fluid communication with the
electrical components.
[0167] A user can fill the supply container S with a measured
volume of clean water and a corresponding measured volume of a
cleaning agent. The water and cleaning agent can be poured into the
supply volume S through fill port 602 accessible through fill door
304 in bumper 300. The fill port 602 can include a funnel to allow
for easier pouring of the cleaning liquid into the supply volume S.
In some implementations, a filter is disposed between fill port 602
and the supply volume S to inhibit foreign material from entering
the supply volume S and potentially damaging the liquid applicator
module 1400. The supply volume S has a liquid volume capacity of
about 500 mL to about 2000 mL.
[0168] FIG. 22 depicts the PCB cover 103, which seals the PCB in a
hermetically sealed enclosed volume (which is later filled with a
potting compound via the shown valve 157, as disclosed herein) and
a support for a bypass channel 155 formed from a T-shaped channel
155a in the PCB cover 103 wall and a T-shaped cover assembly 155b
which hermetically seals the channel 155a and provides 3-5
(preferably 5) nozzles 155c to dispense liquid therefrom. The seal
is ideally air-tight, but may be hermetic or hydraulically
sealed.
[0169] As shown in FIG. 23, the T-shaped cover assembly 155b is
optionally formed separately from the PCB cover 103, and is then
welded (e.g., shear welded using conventional plastics forming
process) to the channel in the PCB cover. The T-shape of the
channel 155, divides to cover the cleaning width of the robot
and/or rows of bristles 205, and connects both T-arms of the bypass
channel 155 to the pump 240 system. The nozzles 155c and fluid
pressure of the pump 240 system are arranged to eject fluid (either
spraying and/or dripping, depending on factors such as back
pressure, viscosity, nozzle diameter, process variation), but in
any event dispensing sufficient fluid to fall into or through the
orifices 210b in rear trough 202b. The nozzles 155c can be arranged
to face the orifices 210b in the trough 202b (to spray, drip, or
flow onto the floor surface) and/or face walls of the trough 202b
(so as to distribute fluid to orifices 210b that are not facing a
nozzle 155c).
[0170] FIG. 24 shows a bottom view of the PCB cover 103 assembled
to the robot 10, before the T-shaped channel cover assembly 155b is
in place. In this view, portions of the robot remain unassembled
(e.g., the bumper, wheel drives, peristaltic pump tube, and front
trough 202a.
[0171] The leading trough 202a, as shown in FIGS. 3 and 25, is
formed as a substantially actuate (following the bumper profile,
therefore flattened if the bumper is also flattened to provide a
flat resting surface for the robot 10) hermetically sealed trough
which directs (again, spraying or dripping depending on various
factors) fluid substantially rearwards, ideally spraying onto the
wetting assembly 204 formed in part by the immediately following
row of bristles 205 (the leading row of bristles 205) so that the
row of bristles 205 wicks the sprayed water and evenly dispenses it
to the floor. As shown in FIG. 25, each dispensing orifice 210a is
formed as an arched orifice 210a-1 in a channel portion 202a-1 of
the trough 202a matched to an arched plug 210a-2 in a cover portion
202a-2 of the trough 202s. In this manner, the orifices (nozzles)
210a can be formed by welding a channel to a cover. It is
sufficient for operation if either spraying or dripping directly
onto the bristles 205 or floor occurs. The T-shaped bypass channel
155 is arranged at a bypass end 155d to mate to a corresponding
receptacle 202a-3 in the leading trough 202a together forming a
sealed connection controlled to distribute fluid in differing
proportions as disclosed herein. The leading trough 202a is
assembled after the T-shaped channel 155 is formed in the PCB cover
103 so as to close and mate the receptacle 202a-3 to the bypass
orifice end 155d--these are welded to form a hermetic/hydraulic
seal (alternatively, solvent bonded).
[0172] While the T-shaped bypass channel 155 has been described as
directing a fraction of the total amount of cleaning liquid rear of
the squeegee 208, other implementations are possible. For example,
in some implementations, the squeegee 208 can be lifted (e.g.,
through an actuator) from the cleaning surface such that liquid
dispensed through the forward trough 202a remains distributed on
the cleaning surface. Additionally or alternatively, the T-shaped
bypass channel 155 can allow water to be dispensed forward and rear
of the squeegee 208 such that, when all of the clean water is
dispensed from the robot 10 to the cleaning surface, the robot 10
only picks up water.
[0173] In one implementation, a lesser proportion of cleaning
liquid is dispensed rear of the squeegee 208. For example, about 50
to about 90 percent of the cleaning liquid is dispensed forward of
the squeegee 208 and about 50 to about 10 percent of the cleaning
liquid is dispensed rear of the squeegee 208. The robot 10 can
clean with a random component such that the robot partially cleans
with the fore wetting even if the robot 10 never returns to the
same spot on the cleaning surface, but will have the significant
benefit of the rear wetting if it does return to the same spot.
Additionally or alternatively, dispensing a lesser proportion of
cleaning fluid rear of the squeegee 208 can be desirable if there
is a reason to avoid leaving fluid on the floor (e.g., cultural
preference, hardwood floors, etc). In still another example, a
robot 10 with a navigation approach and a single-pass requirement
would also benefit from more wetting in front of the squeegee 208,
along with a slow speed.
[0174] In another implementation, a lesser proportion of cleaning
liquid is dispensed forward of the squeegee 208. For example, about
0 to about 40 percent of the cleaning liquid is dispensed forward
of the squeegee 208 and about 100 to about 60 percent of the
cleaning liquid is dispensed rear of the squeegee 208. Such a
distribution of cleaning liquid rear of the squeegee 208 can be
coupled with a navigation component mandating two passes such that
the robot is highly likely (e.g., greater than about 75 percent
likely) to return to each spot twice (once for dispensing the
cleaning liquid and once for picking up the cleaning liquid).
[0175] In yet another implementation, the relative proportions of
cleaning liquid dispensed forward of the squeegee 208 and rear of
the squeegee 208 can be adjusted (e.g., manually or through an
actuator) to match the requirements of a particular application.
For example, the robot in a single pass approach can be wetter in
front and the robot in a double pass mode can be wetter in the
rear.
[0176] Referring to FIGS. 2 and 10A-E, the wetting element 204 can
slidably contact the surface such that the movement of the robot 10
across the surface causes the wetting assembly 204 to spread the
cleaning liquid across the surface. At least some of rows 205 are
arranged substantially parallel to trough 202a and extend past each
end of the trough 202a to allow, for example, for suitable smearing
near the edges of the trough 202a. Ends 215, 216 of rows 205 extend
substantially in front of respective wheels 504, 505, and the
bristles disposed along the ends 215, 216 are disposed at an angle.
By smearing cleaning liquid directly in front of wheels 504, 505,
rows 205 can improve the traction between the wheels 504, 505 and
the surface.
[0177] At least some of the rows 205 of bristles can have a
substantially arcuate shape that extends substantially parallel to
the forward perimeter of the robot 10. As the substantially arcuate
rows make slidable contact with the floor during operation of the
robot 10, the substantially arcuate shape can facilitate movement
of the robot 10 across the surface. For example, as compared to a
substantially straight row of bristles, the substantially arcuate
shape of the forwardmost of rows 205 can gradually engage a grout
line (e.g., of a tiled floor) such the robot 10 can adjust to the
force required to traverse the grout line.
[0178] While the wetting element 204 has been described as rows
205, 206, and 207 of bristles, other implementations are possible.
For example, the wetting element 204 can include one or more
compliant blades extending in a direction substantially parallel to
the cleaning surface. The compliant blade can be in contact with
the cleaning surface to smear the cleaning liquid on the surface as
the robot moves in the forward direction.
[0179] Referring to FIG. 10B, in some implementations, rows 205,
206, and 207 are disposed on the baseplate 200. The rows 205, 206,
and 207 include a plurality of bristle clusters 222 extending from
the baseplate 200 toward the cleaning surface. The bristle clusters
222 are spaced (e.g., substantially evenly spaced) along each row
205, 206, and 207. Bristle clusters 222 can each include a
plurality of soft compliant bristles. In some implementations, a
first end of each bristle is secured in a holder such as a crimped
metal channel, or other suitable holding element. In certain
implementations, bristle clusters 222 are individual plugs press
fit into the baseplate 200. A second end of each bristle is free to
bend as each bristle makes contact with the cleaning surface.
Additionally or alternatively, bristle clusters 222 are plugs
(e.g., about 1 mm in diameter) with respective ends of each bristle
cluster 222 disposed toward the cleaning surface and a middle
portion of each bristle cluster 222 glued and/or stapled to the
baseplate 200. These multiple points of contact between the
bristles of each bristle cluster 222 and the surface can allow the
robot 10 to traverse smoothly over perturbations in the surface
(e.g., grout lines).
[0180] The length and diameter of the bristles of bristle clusters
222, as well as a nominal interference dimension that the smearing
bristles make with respect to the cleaning surface can be varied to
adjust bristle stiffness and to thereby affect the smearing action
and drag. In certain implementations, the bristle clusters 222
includes nylon bristles with an average bristle diameter in the
range of about 0.05-0.2 mm (0.002-0.008 inches) and an average
coefficient of friction on a wet cleaning surface of about 0.1 to
about 0.3 (e.g., about 0.2).
[0181] The rows 205 and 206 of bristles have an angle of incidence
of about 90 degrees with the cleaning surface as the robot moves in
the forward direction. At least some of the rows 205 have about
zero interference with the cleaning surface and at least row 206
has an interference with the cleaning surface. For example, rows
205 closest to the forward portion of the chassis 100 can have
about zero interference with the cleaning surface while row 206
(e.g., the row closest to the squeegee 208) has an interference
with the cleaning surface. This combination balances the scrubbing
action of the rows 205 and 206 with mobility of the robot 10 (e.g.,
reducing drag and/or reducing the likelihood that the robot will
attempt to climb an obstacle that it cannot surmount).
[0182] In some implementations, the bristles of rows 205 having
about zero interference with the cleaning surface are longer than
the bristles of row 206 having an interference with the cleaning
surface. For example, rows 205 can be disposed along a recessed
portion 221 of the baseplate 200 while row 206 can be disposed
along an unrecessed portion 223 of the baseplate 200. In this
configuration, 205 can have a longer effective beam length than row
206.
[0183] The baseplate 200 of the robot can be supported about 4 mm
above the cleaning surface as the robot 10 moves across the
cleaning surface in the forward direction. The bristles of the row
207 rear of the squeegee 208 have an average length of about 5 mm
to about 6 mm (e.g., about 5.4 mm). The bristles of row 207 also
have an angle of incidence of about 45 degrees with the cleaning
surface as the robot moves in the forward direction. This angled
orientation of the bristles of row 207 can allow the bristles to
act as a spring to assist the robot 10 in climbing obstacles. For
example, as the bristles of row 207 move over an obstacle, each
bristle has a tendency to return to the angle of about 45 degrees
relative to the surface. The tendency to return to this position
results in each bristle exerting a force on the obstacle.
Additionally or alternatively, the 45 degree orientation of the
bristles of row 207 can facilitate smearing of the cleaning liquid
on the surface.
[0184] While wetting assembly 204 has been described as having rows
205, 206, and 207 of bristles, other implementations are
additionally or alternatively possible. For example, the wetting
assembly 204 can include a woven or nonwoven material, e.g., a
scrubbing pad or sheet material configured to contact the
surface.
[0185] Cleaning liquid can be introduced to the rows 205, row 206,
and row 207 in any of various different ways. For example, cleaning
liquid can be injected or dripped on the surface immediately
forward of the scrubbing brush. Additionally or alternatively,
cleaning liquid can be introduced through bristle clusters 222 such
that the bristle clusters 222 substantially wick the cleaning
liquid toward the surface. Additionally or alternatively, the
baseplate 200 can carry other elements configured to spread the
cleaning liquid on the surface. For example, the baseplate 200 can
carry a sponge or a rolling member in contact with the surface.
[0186] In some implementations, the baseplate 200 carries one or
more active scrubbing elements that are movable with respect to the
cleaning surface and with respect to the robot chassis. Movement of
the active scrubbing elements can increase the work done between
the scrubbing element and the cleaning surface. Each active
scrubbing element can be driven for movement with respect to the
chassis 100 by a drive module, also attached to the chassis 100.
Active scrubbing element can also include a scrubbing pad or sheet
material held in contact with the cleaning surface, or a compliant
solid element such a sponge or other compliant porous solid foam
element held in contact with the surface and vibrated by a vibrated
backing element. Additionally or alternatively, active scrubbing
elements can include a plurality of scrubbing bristles, and/or any
movably supported conventional scrubbing brush, sponge, or
scrubbing pad used for scrubbing. In certain implementations, an
ultrasound emitter is used to generate scrubbing action. The
relative motion between active scrubbing elements and the chassis
can include linear and/or rotary motion and the active scrubbing
elements can be configured to be replaceable or cleanable by a
user.
[0187] Referring to FIG. 11, in some implementations, surface
agitation assembly 604 includes a rotatable brush assembly disposed
across the cleaning width, rearward of injection orifices 210, for
actively scrubbing the surface after the cleaning fluid has been
applied thereon. The surface agitation assembly 604 includes a
cylindrical bristle holder element 618 defining a longitudinal axis
629. The bristle holder element 618 supports scrubbing bristles 616
extending radially outward therefrom. The surface agitation
assembly 604 can be supported on chassis 100 for rotation about a
rotation axis that extends substantially parallel with the cleaning
width. The scrubbing bristles 616 are long enough to interfere with
the cleaning surface during rotation such that the scrubbing
bristles 616 are bent by the contact with the cleaning surface.
Additional bristles can be introduced into receiving holes 620. The
spacing between adjacent bristle clusters (e.g., bristle clusters
622, 624) can be reduced to increase scrubbing intensity.
[0188] Scrubbing bristles 616 can be installed in the brush
assembly in groups or clumps with each clump including a plurality
of bristles held by a single attaching device or holder. Clump
locations can be disposed along a longitudinal length of the
bristle holder element 618 in one or more patterns 626, 628. The
one or more patterns 626, 628 place at least one bristle clump in
contact with cleaning surface across the cleaning width during each
revolution of the rotatable brush element 604. The rotation of the
brush element 604 is clockwise as viewed from the right side such
that relative motion between the scrubbing bristles 616 and the
cleaning surface tends to move loose contaminants and waste liquid
toward the rearward direction. Additionally or alternatively, the
friction force generated by clockwise rotation of the brush element
604 can drive the robot in the forward direction thereby adding to
the forward driving force of the robot transport drive system. The
nominal dimension of each scrubbing bristles 616 extended from the
cylindrical holder 618 can cause the bristle to interfere with the
cleaning surface and there for bend as it makes contact with the
surface. The interference dimension is the length of bristle that
is in excess of the length required to make contact with the
cleaning surface. Each of these dimensions along with the nominal
diameter of the scrubbing bristles 616 may be varied to affect
bristle stiffness and therefore the resulting scrubbing action. For
example, scrubbing brush element 604 can include nylon bristles
having a bend dimension of approximately 16-40 mm (0.62-1.6
inches), a bristle diameter of approximately 0.15 mm (0.006
inches), and an interference dimension of approximately 0.75 mm
(0.03 inches) to provide scrubbing performance suitable for many
household scrubbing applications.
[0189] While the surface agitation assembly 604 has been described
as including a rotating brush, other implementations are possible.
For example, the surface agitation assembly 604 can be one or more
of the following: a stationary brush, a woven cloth, a nonwoven
cloth, a sponge, and a compliant blade. Additionally or
alternatively, the sensor module 1100 can include a humidity sensor
and the agitation assembly 604 can act on the cleaning surface
based at least in part on detection of humidity on the cleaning
surface. Details of such a humidity sensor are disclosed in U.S.
patent application Ser. No. 11/688,225, entitled "Lawn Care Robot,"
the entire contents of which are incorporated herein by
reference.
[0190] In some implementations, an autonomous cleaning robot
includes an extension element 230 carried by the robot along a
substantially forward portion of the robot such that the extension
element extends beyond the perimeter of the robot. Details of such
an extension element are disclosed in U.S. patent application Ser.
No. 12/118,250, entitled "Autonomous Coverage Robot Sensing," the
entire contents of which are incorporated herein by reference.
[0191] Air Moving
[0192] Referring to FIG. 12, a collection module 1300 is a vacuum
assembly including a fan 112 in fluid communication with the waste
collection volume W and the squeegee 208 in contact with the
surface. In use, the fan 112 creates a low pressure region along
the fluid communication path including the waste collection volume
W and the squeegee 208. As described in further detail below, the
fan 112 creates a pressure differential across the squeegee 208,
resulting in suction of waste from the surface and through the
squeegee 208. The suction force created by the fan 112 can further
suction the waste through one or more waste intake conduits 232
(e.g., conduits disposed on either end of the squeegee 208) toward
a top portion of the waste collection volume W.
[0193] The top portion of the waste collection volume W defines a
plenum 608 between exit apertures 234 of waste inlet conduits 232
and inlet aperture 115 of fan intake conduit 114. While the fan 112
is in operation, the flow of air and waste through plenum 608
generally moves from exit apertures 234 toward the inlet aperture
115. In some implementations, plenum 608 has a flow area greater
than the combined flow area of the one or more waste intake
conduits 232 such that, upon expanding in the top portion of the
waste collection volume W, the velocity of the moving waste
decreases. At this lower velocity, heavier portions of the moving
waste (e.g. water and debris) will tend to fall into the waste
collection volume W under the force of gravity while lighter
portions (e.g., air) of the moving waste will continue to move
toward one or more fan inlet conduits 114. The flow of air
continues through the fan inlet conduit 114, through the fan 112,
and exits the robot 10 through a fan exit aperture 116.
[0194] In some implementations, at least a portion of the fan 112
is disposed in the fan inlet conduit 114 such that air drawn
through the fan inlet conduit can cool the fan. For example, the
portion of the fan disposed in the fan inlet conduit 114 can be a
heat sink (e.g., a finned heat sink). In some implementations, a
portion of the fan 112 that is not disposed in the fan inlet
conduit is disposed in a potting material (e.g., potting material
105). The thermal conductivity of the potting material can be
greater than the thermal conductivity of air and the potting
material can isolate the fan 112 and the fan inlet conduit 114 from
fluid communication with at least a portion of the chassis 100
(shown in FIG. 7). Additionally or alternatively, the potting
material can substantially isolate the fan 112 from fluid
communication with the liquid applicator 1400. The collection
module 1300 can include an anti-spill system 601 (e.g., a passive
anti-spill system and/or an active anti-spill system) that
substantially prevents waste from exiting waste collection volume W
when the robot 10 is not in use (e.g., when a user lifts the robot
10 from the surface). By reducing the likelihood that waste will
spill from the robot, such anti-spill systems can protect the user
from coming into contact with the waste during handling.
Additionally or alternatively, such anti-spill systems can reduce
the likelihood that waste will contact the fan and potentially
diminish the performance of the fan over time. Details of the
anti-spill system 601 are disclosed in U.S. patent application Ser.
No. 12/118,250, entitled "Autonomous Coverage Robot Sensing," the
entire contents of which are incorporated herein by reference.
[0195] Details of the fan 112 are disclosed in U.S. patent
application Ser. No. 12/118,250, entitled "Autonomous Coverage
Robot Sensing," the entire contents of which are incorporate herein
by reference.
[0196] The air flow rate of the fan 112 may range from about 60-100
CFM in free air and about 60 CFM in the robot. In some
implementations, the collection module 1300 includes both a wet
vacuum subsystem and a dry vacuum subsystem and the air flow rate
of the fan can split (e.g., manually adjusted) between the wet and
dry vacuum subsystems. Additionally or alternatively, a multi-stage
fan design can produce a similar air flow rate, but higher static
pressure and velocity, which can help to maintain flow. Higher
velocity also enables the device to entrain dry particles and lift
and pull fluids (e.g., debris mixed with cleaning liquid).
[0197] Referring again to FIGS. 3 and 7, the squeegee 208 is
configured in slidable contact with the surface while the robot 10
is in motion. The positioning of the squeegee 208 and row 207
substantially rearward of the wheels 504, 505 can stabilize the
motion of the robot 10. For example, during sudden acceleration of
the robot 10, the squeegee 208 and row 207 can prevent the robot
from substantially rotating about the transverse axis 24. By
providing such stabilization, the squeegee 208 and/or row 207 can
prevent the rows 205 carried on a forward portion of the robot 10
from substantially lifting from the surface. When the overall
weight of the robot 10 is less than 3.6 kg, for example, such
positioning of the squeegee 208 and/or row 207 can be particularly
useful for providing stabilization. For such lightweight robots,
the center of gravity of the robot 10 can be positioned
substantially over the transverse axis 24 of the robot such that
substantial weight is placed over the wheels 504, 505 for traction
while the squeegee 208 and/or row 207 provide stabilization for the
forward direction of travel and the rows 205 and/or row 206 provide
stabilization for the reverse direction of travel. For example, the
center of gravity of the robot 10 can be positioned substantially
at the center of the robot as viewed from the above the robot as
the robot moves across the cleaning surface and the robot is full
of cleaning liquid.
[0198] Referring to FIGS. 3 and 13-15, the squeegee 208 includes a
base 250 extending substantially the entire width of the baseplate
200. A substantially horizontal lower section 252 extends
downwardly from the base 250 toward the surface. Edge guides 253,
254 are disposed near each transverse end of the base 250 and
extend downwardly from the base 250. A plurality of fastener
elements 256 extend upwardly from the base 250 and are configured
to fit (e.g., interference fit) within corresponding apertures
defined by baseplate 200 to hold a forward edge portion 257 of the
squeegee 208 securely in place as the robot 10 moves in the forward
direction about the surface. A rear edge portion 259 of the
squeegee 208 is unattached to the baseplate 200 such that a user
can move the rear edge portion 259 of the squeegee away from the
baseplate 200 to clean the squeegee 208 and/or the baseplate 200.
During use, the rear edge portion 259 of the vacuum created by the
fan 112 holds the rear edge 259 of the squeegee 208 in place
relative to the base plate 200.
[0199] The horizontal lower section 252 includes a scraper section
258 extending substantially downwardly from an intake section 260.
The scraper section 258 defines a substantially rearward edge of
the horizontal lower section 252. During use, the scraper section
258 forms a slidable contact edge between the squeegee 208 and the
surface. The scraper section 258 is a substantially longitudinal
ridge disposed between the forward edge portion 257 and the rear
edge portion 259. The scraper section 258 is substantially thin and
formed of a substantially compliant material to allow the scraper
section 258 to flex during slidable contact with the surface. In
some implementations, the scraper section 258 is angled slightly
forward to improve collection of waste from the surface. In certain
implementations, the scraper section 258 is angled slightly
rearward to reduce the frictional force required to propel the
robot 10 in the forward direction.
[0200] The intake section 260 defines a plurality of suction ports
262 substantially evenly spaced in the direction of the transverse
axis 24 to allow, for example, substantially uniform suction in the
direction of the transverse axis 24 as the robot 10 moves in the
forward direction to perform cleaning operations. The suction ports
262 each extend through the squeegee 208 (e.g., from a lower
portion of the horizontal lower section 252 to a top portion of the
base 250). The suction ports 262 extend through the base such that
a lower portion of each suction port 262 is substantially near the
forward edge of the scraper section 258. When negative air pressure
(e.g., a vacuum) is generated by the fan 112, waste is suctioned
from the forward edge of the scraper section 258, through the
suction ports 262, and toward the waste collection volume W (e.g.,
as described above).
[0201] Edge guides 253, 254 are arranged on respective ends of
squeegee 208 and extend downwardly from the base 250 to contact the
surface during a cleaning operation. The edge guides 253, 254 can
be configured to push waste toward the fore-aft axis 22 of the
robot 10. By guiding waste toward a center portion of the squeegee
208, the edge guides 253, 254 can improve the efficiency of waste
collection at the transverse edges of the robot 10. For example, as
compared to robots without edge guides 253, 254, the edge guides
253, 254 can reduce streaks left behind by the robot 10.
[0202] Edge guides 253, 254 include respective fasteners 263, 264
extending upward from the edge guides 253, 254 and through the base
250. The edge guide fasteners 263, 264 extend further from the base
250 than fastener elements 256 and, in some implementations, fasten
into the baseplate 200 to reduce the likelihood that the squeegee
250 will become detached from the robot 10 during a cleaning
operation. In some implementations, fasteners 263, 264 are pressed
into the baseplate 200 and held in place through an interference
fit. In certain implementations fasteners 263, 264 are screwed into
the chassis 100. Additionally or alternatively, the edge guide
fasteners 263 can be fastened to the chassis 100.
[0203] Fastener elements 256 extend upwardly from the base 250,
along the forward edge portion 257 of the base 250. Each fastener
element 256 is substantially elongate along the transverse axis 24
and includes a stem portion 265 and a head portion 266. The
squeegee 208 is secured to the baseplate 200 by pushing fastener
elements 256 into corresponding apertures on the baseplate 200. As
the fastener elements 256 are pushed into apertures on the
baseplate 200, the head portions 266 deform to pass through the
apertures. Upon passing through the apertures, each head portion
266 expands to its substantially original shape and the head
portion 266 substantially resists passing through the aperture in
the opposite direction. Accordingly, fastener elements 256
substantially secure the forward edge portion 257 of the squeegee
208 to the baseplate 200. As described above, the rear edge portion
259 of the squeegee 208 can be unattached to the baseplate 200 such
that a user can move the rear edge portion 259 away from the
baseplate 200 (e.g., pivoting away from the baseplate 200 about the
forward edge portion 257) to access the portion of the squeegee 208
in contact with the baseplate 200 and, during use, suction created
by the fan 112 (see FIG. 12) can hold the rear edge portion 259 of
the squeegee 208 in place.
[0204] While the squeegee 208 has been described as being fixed
relative to the baseplate 200, other implementations are possible.
In some implementations, the squeegee can pivot relative to the
baseplate 200. For example, the squeegee can pivot about the
central vertical axis 20 (FIG. 7) when a lower edge of the squeegee
encounters a bump or discontinuity in the cleaning surface. When
the lower edge of the squeegee is free of the bump or
discontinuity, the squeegee can return to its normal operating
position.
[0205] As shown in FIG. 14, the squeegee 208 is a split squeegee
such that the scraper section 258 and the intake section 260 define
a channel 261 extending across the width of the squeegee 208. In
some implementations, the squeegee can include a forward portion
and a rearward portion as two separate pieces that can be
separately removed from the baseplate for repair and
replacement.
[0206] In certain implementations, the squeegee is split into a
left portion and a right portion. As the robot spins in place or
turns, the squeegee can assume a configuration in which one side is
bent backward and one side is bent forward. For non-split
squeegees, the point at which the bend switches from backward to
forward can act as a more or less solid column under the robot,
tending to high center it and interfere with mobility. By providing
a split in the center of the squeegee, this tendency can be
mitigated or eliminated, increasing mobility.
[0207] Transport Drive System
[0208] Referring again to FIGS. 1-7, the robot 10 is supported for
transport over the surface by a transport system 1600. The
transport system 1600 includes a pair of independent wheel modules
500, 501 respectively arranged on the right side and the left side
of the chassis. The wetting assembly 204 and the squeegee 208 are
in slidable contact with the surface and form part of the transport
system 1600. In some implementations, the transport system 1600 can
include a caster positioned substantially forward and/or
substantially rearward of the wheel modules 500, 501. The wheel
modules 500, 501 are rotatable about and aligned along the
transverse axis 24 of the robot 10. The wheel modules 500, 501 are
independently driven and controlled by the controller 1000 to
advance the robot 10 in any direction along the surface. The wheel
modules 500, 501 each include a respective motor 502, 503 and each
is coupled to a gear assembly. Outputs of the respective gear
assemblies drive the respective wheel 504, 505.
[0209] The controller 1000 measures the voltage and current to each
motor and calculates the derivative of the measured current to each
motor. The controller 1000 uses the measured voltage, measured
current, and the calculated derivative of the measured current to
determine the speed of the motor. For example, the controller 1000
can use a mathematical model (e.g., a DC motor equation) to
determine motor speed from the measured voltage, measured current,
and the calculated derivative. In certain implementations, the same
mathematical model can be used for each drive motor. The
mathematical model can include one or more constants (e.g.,
mechanical constants) are calibrated for a given motor. The one or
more constants can be calibrated using any of various different
methods. For example, motors 502, 503 can be matched at the factory
to have the same constant. As another example, the constants can be
calibrated at the factory and stored onboard the robot 10 (e.g. on
the controller 1000). As another example, the controller 1000 can
include code that learns (e.g., using a neural network) the motor
constants over time.
[0210] As yet another example, referring to FIGS. 1, 7, and 16,
binning 800 includes testing 802 performance of a plurality of
motors on an encoder station (e.g., at a factory), classifying 804
each motor based at least in part on the performance test results,
selecting 806 a first and a second motor (e.g., motors 502, 503)
from the same class, and mounting 808 the first and second motors
on a robot body (e.g., chassis 100) of an autonomous coverage robot
(e.g., robot 10) such that the first motor drives a right wheel of
the robot and the second motor drives a left wheel of the robot.
Testing 802 performance of the plurality of motors on the encoder
station includes providing power to each motor and determining the
speed of the output shaft of each respective motor. In some
implementations, based on this testing 802, a relationship between
motor voltage and speed can be determined. Classifying 804 each
motor can include identifying motors with output speed varying by
less than about ten percent from one another as a function of power
to each motor. By selecting motors from the same class, the robot
can be driven in a substantially straight line by providing
substantially the same amount of power to the first and second
drive motors disposed on respective sides of the robot. Selection
of motors based on binning 800 can allow the robot to be driven in
a substantially straight line without the use of an encoder.
[0211] The wheel modules 500, 501 are releasably attached to the
chassis 100 and forced into engagement with the surface by
respective springs. The wheel modules 500, 501 are substantially
sealed from contact with water using one or more the following:
epoxy, ultrasonic welding, potting welds, welded interfaces, plugs,
and membranes.
[0212] The springs are calibrated to apply substantially uniform
force to the wheels along the entire distance of travel of the
suspension. The wheel modules 500, 501 can each move independently
in a vertical direction to act as a suspension system. For example,
the wheel modules 500, 501 can allow about 4 mm of suspension
travel to about 8 mm of suspension travel (e.g., about 5 mm of
suspension travel) to allow the robot 10 to navigate over obstacles
on the surface, but to prevent the robot 10 from crossing larger
thresholds that mark the separation of cleaning areas (e.g.,
marking the separation between a kitchen floor and a living room
floor). When the robot 10 is lifted from the surface, the
respective suspension systems of wheel modules 500, 501 drop the
wheel modules 500, 501 to the lowest point of travel of the
respective suspension system. This configuration is sometimes
referred to as a biased-to-drop suspension system. In some
implementations, the wheel modules 500, 501 can include a wheel
drop sensor that senses when a wheel 504, 505 of wheel modules 500,
501 moves down and sends a signal to the controller 1000.
Additionally or alternatively, the controller 1000 can initiate
behaviors that can allow the robot 10 to navigate toward a more
stable position on the surface.
[0213] The biased-to-drop suspension system of the robot 10
includes a pivoted wheel assembly including resilience and/or
damping, having a ride height designed considering up and down
force. In some implementations, the suspension system delivers
within 1-5% (e.g., about 2%) of the minimum downward force of the
robot 10 (i.e., robot mass or weight minus upward forces from the
resilient or compliant contacting members such as
brushes/squeegees, etc). That is, the suspension is resting against
"hard stops" with only 2% of the available downward force applied
(spring stops having the other 98%, optionally 99%-95%), such that
almost any obstacle or perturbation capable of generating an upward
force will result in the suspension lifting or floating the robot
over the obstacle while maintaining maximum available force on the
tire contact patch. This spring force (and in corollary, robot
traction) can be maximized by having an active system that varies
its force relative to the changing robot payload (relative clean
and dirty tank level). In some implementations, actuation for an
active suspension is provided by electrical actuators or solenoids,
fluid power, or the like, with appropriate damping and spring
resistance. While a pivoted wheel assembly has been described,
other implementations are possible. For example, the biased-to-drop
suspension system can include a vertically traveling wheel module
including conical springs to produce a biased-to-drop suspension
system.
[0214] Wheels 504, 505 are configured to propel the robot 10 across
a wet soapy surface. Referring to FIGS. 17 and 18A-B, wheel 504
includes a rim 512, snaps 513 slidable into a recesses defined by
the rim 512 to couple to the rim 512 to the wheel module 500, and
an annular tire 516. For the sake of clarity of explanation, wheel
504 is explained. However, it should be appreciated that wheel 505
is analogous to wheel 504. The drive wheel module includes a drive
motor and a drive train transmission for driving the wheel for
transport. The drive wheel module can also include a sensor for
detecting wheel slip with respect to the surface.
[0215] The rim 512 is formed from a stiff material such as a hard
molded plastic to maintain the wheel shape and to provide
stiffness. The rim 512 provides an outer diameter sized to receive
an annular tire 516 thereon. The annular tire 516 is configured to
provide a non-slip, high friction drive surface for contacting the
surface and for maintaining traction on the soapy surface.
[0216] In one implementation, the annular tire 516 has an internal
diameter of approximately 37 mm and is sized to fit appropriately
over the outer diameter 514 of rim 512. The rim 516 includes a
ridge 517 extending radially outward from the outer diameter 514 of
the rim and extending around the circumference of the rim. The
annular tire 516 defines a circumferential channel 518 that is
engageable with the ridge 517 such that the ridge 517 can serve as
an alignment feature for mounting the annular tire 516 and can hold
the annular tire 516 in place. In certain implementations, the
annular tire 516 can be removed from the rim 512, and the annular
tire 516 can be reversed such that the inner diameter of the
annular tire 516 becomes the outer diameter of the annular tire
516. For example, as discussed below, the annular tire 516 can have
a tread pattern on the outer diameter and a treat pattern on the
inner diameter. As the tread pattern on the outer diameter of the
annular tire 516 wears down over time, the annular tire 516 can be
reversed such that the tread pattern on the inner diameter becomes
exposed toward the cleaning surface. In some implementations, the
annular tire 516 can be additionally or alternatively bonded, taped
or otherwise interference fit to the outer diameter 514 to prevent
slipping between an inside diameter of the annular tire 516 and the
outer diameter 514 of the rim 512.
[0217] The annular tire 516 includes a base 520 having a first side
522 and a second side 524 substantially opposite the first side.
The base 520 can have a radial thickness sufficient to allow the
annular tire 516 to be easily reversed by the user while resisting
tearing. For example, the base 520 can have a radial thickness of
about 3 mm.
[0218] The annular tire 516 also includes a first set of treads 526
and a second set of treads 528. Each tread 530 of the first and
second set of treads 526, 528 extends radially from the first side
522 of the base 520 toward the cleaning surface and is an elongate
rib extending in a direction substantially parallel to the
transverse axis. In this transverse orientation, each tread 530 can
grip an obstacle (e.g., a tile edge and/or a discontinuity in the
cleaning surface) to move a wet cleaning robot under about 3 kg
over the obstacle, which may be wet.
[0219] Each tread 530 of the first set of treads 526 is
circumferentially offset from each of the treads of the second set
of treads 528 such that, as viewed along the transverse axis,
treads 530 of the first set of treads 526 are not aligned with the
treads 530 of the second set of treads 530. This offset
configuration of the treads can facilitate movement of the robot 10
over an uneven surface. Each tread 530 can have at least one
substantially square edge disposed toward the cleaning surface.
Such a substantially square edge can reduce the likelihood that the
tread 530 will become disengaged from an obstacle once the tread
engages the obstacle.
[0220] Each tread 530 of each of the first and second set of treads
526, 528 can be substantially identical to facilitate smooth
movement of the robot 10 over the surface. For example, each tread
530 can have substantially the same width in the circumferential
direction. Additionally or alternatively, each tread 530 of a given
set of treads 526, 528 can be circumferentially spaced from a
preceding tread of the respective set of treads 526, 528 by a
distance about three times the circumferential width of the tread.
This circumferential spacing of the treads 530 can provide spacing
that allows the annular tire 516 to engage an obstacle between the
treads 530 such that each tread 530 can come into contact with the
obstacle and act as a lever to move the robot 10 over the obstacle.
To achieve sufficient leverage while maintaining a smooth ride for
efficient cleaning, each tread 530 can extend radially from the
base 520 by a distance between about 1/5 to about 1/2 the radial
thickness of the base.
[0221] The annular tire 516 also includes a third set of treads 532
and a fourth set of treads 534. The third set of treads 532 extends
radially inward from the second side 524 of the base 520,
substantially opposite the first set of treads 526. Similarly, the
fourth set of treads 534 extends radially inward from the second
side 524 of the base 520, substantially opposite the second set of
treads 528. Each tread 530 of the third set of treads 532 is
circumferentially offset from each tread of the first set of treads
526, and each tread 530 of the fourth set of treads 534 is
circumferentially offset from each tread of the second set of
treads 528. In some implementations, this offset allows the base to
move toward the wheel when a tread 530 of the first or second set
of treads 526, 528 contacts the cleaning surface. Such movement of
the base can provide some cushioning to the ride of the robot 10 to
reduce the likelihood that cleaning functions of the robot 10 will
be adversely impacted as the robot moves over a rough surface.
[0222] The relative orientation of the third set of treads 532
relative to the fourth set of treads 534 is analogous to the
relative orientation of the first set of treads 526 relative to the
second set of treads 528. For example, each tread of the third set
of treads 532 is circumferentially offset from each tread of the
fourth set of treads 534.
[0223] The third set of treads 532 is spaced from the fourth set of
treads 534 in the transverse direction to define at least a portion
of the circumferential channel 518. As indicated above, the
circumferential channel 518 can be disengaged from the ridge 517
and the annular tire 516 can be reversed. For example, the annular
tire can be reversed such that the third and fourth sets of treads
532, 534 extend radially outward and toward the cleaning surface
while the first and second sets of treads 526, 528 extend radially
inward toward the rim 512.
[0224] The tire material includes particulate matter suspended in
rubber (e.g., natural rubber). At least some of the particulate
matter is disposed toward the portion of the annular tire 516 in
contact with the cleaning surface such that the particulate matter
penetrates the surface tension of liquid disposed on the cleaning
surface. Thus, as compared to natural rubber without particulate
matter, the particulate matter disposed in the natural rubber can
improve traction of the annular tire 516. In some implementations,
the tire material is about 20 percent to about 30 percent
particulate matter (e.g., about 25 percent particulate matter).
Examples of the particulate matter disposed in the natural rubber
can include one or more of the following: kaolin clay and calcium
carbonate. These materials improve traction of the annular tire to
propel a wet-cleaning robot under about 3 kg across a wet surface
without creating a surface roughness that can damage (e.g.,
scratch) the cleaning surface.
[0225] Other tire materials are contemplated, depending on the
particular application. For example, the tire material can include
a chloroprene homopolymer stabilized with thiuram disulfide black
with a density of 14-16 pounds per cubic foot, or approximately 15
pounds per cubic foot foamed to a cell size of 0.1 mm plus or minus
0.02 mm. The tire has a post-foamed hardness of about 69 to 75
Shore 00. The tire material is sold by Monmouth Rubber and Plastics
Corporation under the trade name DURAFOAM DK5151HD.
[0226] Still other tire materials are contemplated, depending on
the particular application, including, for example, those made of
neoprene and chloroprene, and other closed cell rubber sponge
materials. Tires made of polyvinyl chloride (PVC) (e.g., injection
molded, extruded) and acrylonitrile-butadiene (ABS) (with or
without other extractables, hydrocarbons, carbon black, and ash)
may also be used. Additionally, tires of shredded foam construction
may provide some squeegee-like functionality, as the tires drive
over the wet surface being cleaned. Tires made from materials
marketed under the trade names RUBATEX R411, R421, R428, R451, and
R4261 (manufactured and sold by Rubatex International, LLC);
ENSOLITE (manufactured and sold by Armacell LLC); and products
manufactured and sold by American Converters/VAS, Inc.; are also
functional substitutions for the DURAFOAM DK5151 HD identified
above.
[0227] In certain embodiments, the tire material may contain
natural rubber(s) and/or synthetic rubber(s), for example, nitrile
rubber (acrylonitrile), styrene-butadiene rubber (SBR),
ethylene-propylene rubber (EPDM), silicone rubber, fluorocarbon
rubber, latex rubber, silicone rubber, butyl rubber, styrene
rubber, polybutadiene rubber, hydrogenated nitrile rubber (HNBR),
neoprene (polychloroprene), and mixtures thereof.
[0228] In certain embodiments, the tire material may contain one or
more elastomers, for example, polyacrylics (i.e. polyacrylonitrile
and polymethylmethacrylate (PMMA)), polychlorocarbons (i.e. PVC),
polyfluorocarbons (i.e. polytetrafluoromethylene), polyolefins
(i.e. polyethylene, polypropylene, and polybutylene), polyesters
(i.e. polyetheylene terephthalate and polybutylene terephthalate),
polycarbonates, polyamides, polyimides, polysulfones, and mixtures
and/or copolymers thereof. The elastomers may include homopolymers,
copolymers, polymer blends, interpenetrating networks, chemically
modified polymers, grafted polymers, surface-coated polymers,
and/or surface-treated polymers.
[0229] In certain embodiments, the tire material may contain one or
more fillers, for example, reinforcing agents such as carbon black
and silica, non-reinforcing fillers, sulfur, cross linking agents,
coupling agents, clays, silicates, calcium carbonate, waxes, oils,
antioxidants (i.e. para-phenylene diamine antiozonant (PPDA),
octylated diphenylamine, and polymeric
1,2-dihydro-2,2,4-trimethylquinoline), and other additives.
[0230] In certain embodiments, the tire material may be formulated
to have advantageous properties, for example, desired traction,
stiffness, modulus, hardness, tensile strength, impact strength,
density, tear strength, rupture energy, cracking resistance,
resilience, dynamic properties, flex life, abrasion resistance,
wear resistance, color retention, and/or chemical resistance (i.e.
resistance to substances present in the cleaning solution and the
surface being cleaned, for example, dilute acids, dilute alkalis,
oils and greases, aliphatic hydrocarbons, aromatic hydrocarbons,
halogenated hydrocarbons, and/or alcohols).
[0231] It is noted that cell size of the closed cell foam tires may
impact functionality, in terms of traction, resistance to
contaminants, durability, and other factors. Cell sizes ranging
from approximately 20 .mu.m to approximately 400 .mu.m may provide
acceptable performance, depending on the weight of the robot and
the condition of the surface being cleaned. Particular ranges
include approximately 20 .mu.m to approximately 120 .mu.m, with a
mean cell size of 60 .mu.m, and more particularly approximately 20
.mu.m to approximately 40 .mu.m, for acceptable traction across a
variety of surface and contaminant conditions.
[0232] In certain embodiments, the tires are approximately 13 mm
wide, although wider tires may provide additional traction. As
indicated above, tires may be approximately 3 mm thick, although
tires of 4 mm-5 mm in thickness or more may be utilized for
increased traction. Thinner tires of approximately 1.5 mm and
thicker tires of approximately 4.5 mm may be beneficial, depending
on the weight of the robot, operating speed, movement patterns, and
surface textures. Thicker tires may be subject to compression set.
If the cleaning robot is heavier, larger tires may be desirable
nonetheless. Tires with outer rounded or square edges may also be
employed.
[0233] To increase traction, the outside diameter of the tire can
be siped. Siping generally provides traction by (a) reducing the
transport distance for fluid removal from the contact patch by
providing a void for the fluid to move into, (b) allowing more of
the tire to conform to the floor, thereby increasing tread
mobility, and (c) providing a wiping mechanism that aids in fluid
removal. In at least one instance, the term "siped" refers to
slicing the tire material to provide a pattern of thin grooves 1110
in the tire outside diameter. In one embodiment, each groove has a
depth of approximately 1.5 mm and a width or approximately 20 to
300 microns. The siping may leave as little as 1/2 mm or less of
tire base, for example, 3.5 mm deep siping on a 4 mm thick tire.
The groove pattern can provide grooves that are substantially
evenly spaced apart, with approximately 2 to 200 mm spaces between
adjacent grooves. "Evenly spaced" may mean, in one instance, spaced
apart and with a repeating pattern, not necessarily that every
siped cut is the same distance from the next. The groove cut axis
makes an angle G with the tire longitudinal axis. The angle G
ranges from about 10-50 degrees, in certain embodiments.
[0234] In other embodiments, the siping pattern is a diamond-shaped
cross hatch at 3.5 mm intervals, which may be cut at alternating 45
degree angles (.+.-.10 degrees) from the rotational axis.
Substantially circumferential siping, siping that forces away
liquid via channels, and other siping patterns are also
contemplated. Depth and angle of siping may be modified, depending
on particular applications. Moreover, while increased depth or
width of siping may increase traction, this benefit should be
balanced against impacting the structural integrity of the tire
foam. In certain embodiments, for example, it has been determined
that 3 mm-4 mm thick tires with diamond crossed siping at 7 mm
intervals provides good tire traction. Larger tires may accommodate
a finer pattern, deeper siping, and/or wider siping. Additionally,
particularly wide tires or tires made from certain materials may
not require any siping for effective traction. While certain siping
patterns may be more useful on wet or dry surfaces, or on different
types of surfaces, siping that provides consistent traction across
a variety of applications may be the most desirable for a general
purpose robot cleaner.
[0235] While the tires have been described as including a siped
outside diameter and/or elongate ribs, other implementations are
possible. For example, the tires can be Natural Rubber tires with
an aggressive diagonal V-rib pattern.
[0236] The various tire materials, sizes, configurations, siping,
etc., impact the traction of the robot during use. In certain
embodiments, the robot's wheels roll directly through the spray of
cleaning solution, which affects the traction, as do the
contaminants encountered during cleaning. A loss of fraction of the
wheels may cause operating inefficiencies in the form of wheel
slippage, which can lead to the robot deviating from its projected
path. This deviation can increase cleaning time and reduce battery
life. Accordingly, the robot's wheels should be of a configuration
that provides good to excellent fraction on all surfaces, with the
smallest corresponding motor size.
[0237] Typical contaminants encountered during cleaning include
chemicals, either discharged by the robot or otherwise. Whether in
a liquid state (e.g., pine oil, hand soap, ammonium chloride, etc.)
or a dry state (e.g., laundry powder, talcum powder, etc.), these
chemicals may break down the tire material. Additionally, the robot
tires may encounter moist or wet food-type contaminants (e.g.,
soda, milk, honey, mustard, egg, etc.), dry contaminants (e.g.,
crumbs, rice, flour, sugar, etc.), and oils (e.g., corn oil,
butter, mayonnaise, etc.). All of these contaminants may be
encountered as residues, pools or slicks, or dried patches. The
tire materials described above have proven effective in resisting
the material breakdown caused by these various chemicals and oils.
Additionally, the cell size and tire siping described has proven
beneficial in maintaining traction while encountering both wet and
dry contaminants, chemical or otherwise. Dry contaminants at
certain concentrations, however, may become lodged within the
siping. The chemical cleaner used in the device, described below,
also helps emulsify certain of the contaminants, which may reduce
the possible damage caused by other chemical contaminants by
diluting those chemicals.
[0238] In addition to contaminants that may be encountered during
use, the various cleaning accessories (e.g., brushes, squeegees,
etc.) of the device affect the traction of the device. The drag
created by these devices, the character of contact (i.e., round,
sharp, smooth, flexible, rough, etc.) of the devices, as well as
the possibility of slippage caused by contaminants, varies
depending on the surface being cleaned. Limiting the areas of
contact between the robot and the surface being cleaned reduces
attendant friction, which improves tracking and motion. One and
one-half pounds of drag force versus three to five pounds of thrust
has proven effective in robots weighing approximately 5-15 pounds.
Depending on the weight of the robot cleaner, these numbers may
vary, but it is noted that acceptable performance occurs at less
than about 50% drag, and is improved with less than about 30%
drag.
[0239] The tire materials (and corresponding cell size, density,
hardness, etc.), siping, robot weight, contaminants encountered,
degree of robot autonomy, floor material, and so forth, all impact
the total traction coefficients of the robot tires. For certain
robot cleaners, the coefficient of traction (COT) for the minimum
mobility threshold has been established by dividing a 0.9 kg-force
drag (as measured during squeegee testing) by 2.7 kg-force of
normal force, as applied to the tires. Thus, this minimum mobility
threshold is approximately 0.33. A target threshold of 0.50 was
determined by measuring the performance of shredded black foam
tires. Traction coefficients of many of the materials described
above fell within a COT range of 0.25 to 0.47, thus within the
acceptable range between the mobility threshold and the target
threshold. Additionally, tires that exhibit little variability in
traction coefficients between wet and dry surfaces are desirable,
given the variety of working conditions to which a cleaning robot
is exposed.
[0240] The robot cleaning device may also benefit by utilizing
sheaths or booties that at least partially or fully surround the
tires. Absorbent materials, such as cotton, linen, paper, silk,
porous leather, chamois, etc., may be used in conjunction with the
tires to increase traction. Alternatively, these sheaths may
replace rubberized wheels entirely, by simply mounting them to the
outer diameter of the cup shaped wheel element. Whether used as
sheaths for rubber tires or as complete replacements for the rubber
tires, the materials may be interchangeable by the user or may be
removed and replaced via automation at a base or charging station.
Additionally, the robot may be provided to the end user with sets
of tires of different material, with instructions to use particular
tires on particular floor surfaces.
[0241] The cleaning solution utilized in the robot cleaner should
be able to readily emulsify contaminants and debond dried waste
from surfaces, without damaging the robot or surface itself. Given
the adverse effects described above with regard to robot tires and
certain chemicals, the aggressiveness of the cleaning solution
should be balanced against the short and long-term negative impacts
on the tires and other robot components. In view of these issues,
virtually any cleaning material that meets the particular cleaning
requirements may be utilized with the cleaning robot. In general,
for example, a solution that includes both a surfactant and a
chelating agent may be utilized. Additionally, a pH balancing agent
such as citric acid may be added. Adding a scent agent, such as
eucalyptus, lavender, and/or lime, for example, may improve the
marketability of such a cleaner, contributing to the perception on
the part of the consumer that the device is cleaning effectively. A
blue, green, or other noticeable color may also help distinguish
the cleaner for safety or other reasons. The solution may also be
diluted and still effectively clean when used in conjunction with
the robot cleaner. During operation, there is a high likelihood
that the robot cleaner may pass over a particular floor area
several times, thus reducing the need to use a full strength
cleaner. Also, diluted cleaner reduces the wear issues on the tires
and other components, as described above. One such cleaner that has
proven effective in cleaning, without causing damage to the robot
components, includes alkyl polyglucoside (for example, at 1-3%
concentration) and tetrapotassium ethylenediamine-tetraacetate
(tetrapotassium EDTA) (for example, at 0.5-1.5% concentration).
During use, this cleaning solution is diluted with water to produce
a cleaning solution having, for example, approximately 3-6% cleaner
and approximately 94-97% water. Accordingly, in this case, the
cleaning solution actually applied to the floor may be as little as
0.03% to 0.18% surfactant and 0.01 to 0.1% chelating agent. Of
course, other cleaners and concentrations thereof may be used with
the disclosed robot cleaner. In certain embodiments, the cleaning
solution utilized in the robot cleaner includes (or is) one or more
embodiments of the hard surface cleaners described in U.S. Pat.
Nos. 5,573,710, 5,814,591, 5,972,876, 6,004,916, 6,200,941, and
6,214,784, and 6,774,098, and U.S. patent application Ser. No.
12/118,250, entitled "Autonomous Coverage Robot Sensing," all of
which are incorporated herein by reference.
[0242] Controller Module
[0243] Referring to FIGS. 1-7, control module 1000 is
interconnected for two-way communication with each of a plurality
of other robot subsystems. The interconnection of the robot
subsystems is provided via network of interconnected wires and or
conductive elements, e.g. conductive paths formed on an integrated
printed circuit board or the like, as is well known. In some
implementations, the two-way communication between the control
module 1000 one or more of the robot subsystems occurs through a
wireless communication path. The control module 1000 at least
includes a programmable or preprogrammed digital data processor,
e.g. a microprocessor, for performing program steps, algorithms and
or mathematical and logical operations as may be required. The
control module 1000 also includes a digital data memory in
communication with the data processor for storing program steps and
other digital data therein. The control module 1000 also includes
one or more clock elements for generating timing signals as may be
required.
[0244] In general, the robot 10 is configured to clean uncarpeted
indoor hard floor surface, e.g. floors covered with tiles, wood,
vinyl, linoleum, smooth stone or concrete and other manufactured
floor covering layers that are not overly abrasive and that do not
readily absorb liquid. Other implementations, however, can be
adapted to clean, process, treat, or otherwise traverse abrasive,
liquid-absorbing, and other surfaces. Additionally or
alternatively, the robot 10 can be configured to autonomously
transport over the floors of small enclosed furnished rooms such as
are typical of residential homes and smaller commercial
establishments. The robot 10 is not required to operate over
predefined cleaning paths but may move over substantially all of
the cleaning surface area under the control of various transport
algorithms designed to operate irrespective of the enclosure shape
or obstacle distribution. For example, the robot 10 can move over
cleaning paths in accordance with preprogrammed procedures
implemented in hardware, software, firmware, or combinations
thereof to implement a variety of modes, such as three basic
operational modes, i.e., movement patterns, that can be categorized
as: (1) a "spot-coverage" mode; (2) a "wall/obstacle following"
mode; and (3) a "bounce" mode. In addition, the robot 10 is
preprogrammed to initiate actions based upon signals received from
sensors incorporated therein, where such actions include, but are
not limited to, implementing one of the movement patterns above, an
emergency stop of the robot 10, or issuing an audible alert. These
operational modes of the robot are specifically described in U.S.
Pat. No. 6,809,490, by Jones et al., entitled, Method and System
for Multi-Mode Coverage for an Autonomous Robot, the entire
disclosure of which is herein incorporated by reference it its
entirety. However, the present disclosure also describes
alternative operational modes.
[0245] The robot 10 also includes the user interface 400. The user
interface 400 provides one or more user input interfaces that
generate an electrical signal in response to a user input and
communicate the signal to the controller 1000. A user can input
user commands to initiate actions such as power on/off, start, stop
or to change a cleaning mode, set a cleaning duration, program
cleaning parameters such as start time and duration, and or many
other user initiated commands. While the user interface 400 has
been described as a user interface carried on the robot 10, other
implementations are additionally or alternatively possible. For
example, a user interface can include a remote control device
(e.g., a hand held device) configured to transmit instructions to
the robot 10. Additionally or alternatively, a user interface can
include a programmable computer or other programmable device
configured to transmit instructions to the robot 10. In some
implementations, the robot can include a voice recognition module
and can respond to voice commands provided by the user. User input
commands, functions, and components contemplated for use with the
present invention are specifically described in U.S. patent
application Ser. No. 11/166,891, by Dubrovsky et al., filed on Jun.
24, 2005, entitled Remote Control Scheduler and Method for
Autonomous Robotic Device, the entire disclosure of which is herein
incorporated by reference it its entirety. Specific modes of user
interaction are also described herein.
[0246] Sensor Module
[0247] The robot 10 includes a sensor module 1100. The sensor
module 1100 includes a plurality of sensors attached to the chassis
and integrated with the robot subsystems for sensing external
conditions and for sensing internal conditions. In response to
sensing various conditions, the sensor module 1100 can generate
electrical signals and communicate the electrical signals to the
controller 1100. Individual sensors can perform any of various
different functions including, but not limited to, detecting walls
and other obstacles, detecting drop offs in the surface (sometimes
referred to as cliffs), detecting debris on the surface, detecting
low battery power, detecting an empty cleaning fluid container,
detecting a full waste container, measuring or detecting drive
wheel velocity distance traveled or slippage, detecting cliff drop
off, detecting cleaning system problems such rotating brush stalls
or vacuum system clogs or pump malfunctions, detecting inefficient
cleaning, cleaning surface type, system status, temperature, and
many other conditions. In particular, several aspects of the sensor
module 1100 as well as its operation, especially as it relates to
sensing external elements and conditions are specifically described
in U.S. Pat. No. 6,594,844, by Jones, entitled Robot Obstacle
Detection System, and U.S. patent application Ser. No. 11/166,986,
by Casey et al., filed on Jun. 24, 2005, entitled Obstacle
Following Sensor Scheme for a Mobile Robot, the entire disclosures
of which are herein incorporated by reference it their
entireties.
[0248] The robot 10 includes control and sensor components in close
proximity to the wet cleaning components. As described above, the
robot 10 can be sized to fit within any of various different
confined spaces typically encountered in household cleaning
applications. Accordingly, much of the volume of robot 10 is
occupied by the liquid storage 1500, liquid applicator 1400, and
collection subsystems 1300, each of which can include the transport
of water, solvents, and/or waste throughout the robot 10. As
distinguished from many dry vacuuming robots that do not use wet
cleaners and do not generate waste, some of the sensors and control
elements of the robot 10 are sealed and/or positioned to minimize
exposure to water or more damaging cleaning fluids or solvents. As
distinguished from many industrial cleaners, some of the sensors
and control elements of the robot 10 are packaged in close
proximity to (e.g., within less than about an inch of) cleaning
elements, cleaning fluids, and/or waste.
[0249] Referring to FIGS. 7, 20, and 21A-C, the controller 1000 can
be implemented using a printed circuit board (PCB) 101 carried by
the chassis 100 and secured in any of various different positions
along the chassis. For example, the PCB can be carried between a
bottom portion of the chassis 100 and a PCB cover 103 such that, as
described below, a potting material can be introduced around the
PCB 101 and the weight of the potting material can act as a ballast
to lower the center of gravity of the robot 10. The entire PCB 101
can be fluid sealed, either in a water resistant or waterproof
housing having at least JIS grade 3 (mild spray) water/fluid
resistance, but grade 5 (strong spray), grade 7 (temporary
immersion), and ANSI/IEC 60529-2004 standards for equivalent water
ingress protection are also desirable. In some implementations, the
main control PCB is sealed in a JIS grade 3-7 housing (1) by a
screwed-down and gasketed cover over the main housing; (2) by a
welded, caulked, sealed, or glued cover secured to the main
housing; (3) by being pre-assembled in a water resistant,
water-tight, water-proof, or hermetically sealed compartment or
module; or (4) by being positioned in a volume suitable for potting
or pre-potted in resin or the like.
[0250] Referring to FIGS. 20-21A-C, in one implementation, the PCB
101 is disposed between the chassis 100 (e.g., a bottom portion of
the chassis) and the PCB cover 103, which is engageable with the
baseplate 200 (see FIG. 7). The space defined between the chassis
100 and the PCB cover 103 is filled with a potting material 105
such that the potting material substantially surrounds the PCB 101
to isolate the PCB from fluid communication with the liquid
applicator 1400 and/or from fluid communication with the collection
assembly 1300. In some implementations, the controller 1000
includes components in addition or to the PCB. For example, the
controller can include a plurality of proximity sensors and/or a
plurality cliff sensors, and the potting material 105 can be
disposed about these components as well.
[0251] The potting material is a surface mount component grade
potting material which, as used herein, is a potting material that
having a low coefficient of linear thermal expansion (e.g., a
coefficient of linear thermal expansion of less than about 250
ppm/.degree. C.) and/or a low glass transition temperature (e.g., a
glass transition temperature of less than about -40.degree. C.).
The expansion and contraction of such potting material through
temperature extremes spanning -40.degree. C. to 150.degree. C.
places an acceptable amount of stress on surface mount components
embedded in the potting material such that the surface mount
components do not become dislodged.
[0252] The potting material 105 is a two-component urethane with a
set time of less than about ten minutes. Such a ratio can be
useful, for example, for simplifying the mixing process used during
manufacturing.
[0253] As indicated above, the potting material 105 can be added to
the robot 10 in a quantity sufficient to act as a ballast to lower
the center of gravity of the robot. In some implementations, the
potting material is between about 5 percent and about 20 percent of
the overall mass of the robot 10. For example, the potting material
105 can have a mass of between about 110 g and about 140 g. Given
the volume available for the addition of the potting material 105,
a potting material with a specific gravity of between about 1.2 and
about 1.6 can be used to add this range of mass to the robot
10.
[0254] In addition to isolating the PCB 101 from fluid
communication with the liquid applicator 1400, the potting material
105 has a higher thermal conductivity than air and can, thus,
facilitate dissipation of heat generated by the PCB 101 during
operation of the robot 10. For example, the potting material can
have a thermal conductivity of about 0.15 W/(mK) to about 0.40
W/(mK).
[0255] The potting material 105 is disposed around the PCB 105 by
placing the chassis 100 in a substantially vertical orientation,
with a substantially flat rear portion 102 of the chassis below a
forward portion 111 of the chassis 100 (e.g., by placing the
substantially flat rear portion 102 of the chassis on a table).
With the chassis 100 in this vertical orientation, the potting
material 105 is introduced into the space between the chassis 100
and the PCB cover 103 by introducing the potting material through a
valve 107 defined by the PCB cover 103. The valve 107 is defined
through the portion of the PCB cover 103 disposed toward the rear
portion 102 of the chassis. Accordingly, the potting material 105
is moved in a vertical direction over the PCB 100 disposed between
the chassis 100 and the PCB cover 103. Through such vertical
movement, the potting material 105 displaces air from the space
between the chassis 100 and the PCB cover 103 such that the air
exits through the forward portion 111 of the chassis 100.
[0256] The potting material 105 has an uncured viscosity at room
temperature between about 8000 centipoise and about 10000
centipoise for curing in a short period of time (e.g., less than an
hour). However, in some implementations, the potting material 105
is heated to an uncured viscosity of between about 3000 centipoise
to about 5000 centipoise before the potting material is introduced
through the valve 107. Such heating can facilitate flow of the
potting material 105 around wires 115 while reducing the likelihood
of formation of air pockets around the wires 115. After a
predetermined mass of potting material 105 is introduced into the
volume in which the PCB 101 is disposed, the potting material cures
around the PCB 101. In some implementations, the potting material
105 seals the orifice 107. For example, the orifice can be an
x-shape and the cured potting material 105 seals together the
portions of material forming the x-shape.
[0257] Many sensor elements have a local small circuit board,
sometimes with a local microprocessor and/or A/D converter and the
like, and these components are often sensitive to fluids and
corrosion. In some implementations, sensor circuit boards
distributed throughout the body of the robot 10 are sealed in a JIS
grade 3-7 housing in a similar manner. In some implementations,
multiple circuit boards, including at least the main circuit board
and one remote circuit board (e.g., a user interface circuit board)
several centimeters from the main board, may be sealed by a single
matching housing or cover. For example, all or some of the circuit
boards can be arranged in a single plastic or resin module having
extensions which reach to local sensor sites. Additionally or
alternatively, a distributed cover can be secured over all of the
circuit boards. Exposed electrical connections and terminals of
sensors, motors, or communication lines can be sealed in a similar
manner, with covers, modules, potting, shrink fit, gaskets, or the
like. In this manner, substantially the entire electrical system is
fluid-sealed and/or isolated from cleaning liquid and/or waste. Any
and all electrical or electronic elements defined herein as a
circuit board, PCB, detector, sensor, etc., are candidates for such
sealing.
[0258] In some implementations, electrical components (e.g., a PCB,
the fan 112) of the robot 10 can be substantially isolated from
moisture and/or waste using a wire seal. Details of such a wire
seal are disclosed in U.S. patent application Ser. No. 12/118,250,
entitled "Autonomous Coverage Robot Sensing," the entire contents
of which are incorporated herein by reference.
[0259] Omni-Directional Receiver
[0260] Referring to FIGS. 7, 12, and 19, the robot 10 includes an
omni-directional receiver 410 disposed along a bottom portion of
signal channeler 402. For the purpose of illustration, FIG. 19
shows the signal channeler 402 without waste intake conduits 234
and without fan intake conduit 114 attached. Several aspects of the
omni-directional sensor 410 as well as its operation, especially as
it relates to the navigation and direction of the robot 10 are
specifically described in U.S. patent application Ser. No.
11/633,869, by Ozick et al., entitled "AUTONOMOUS COVERAGE ROBOT
NAVIGATION SYSTEM," the entire disclosure of which is herein
incorporated by reference in its entirety.
[0261] The omni-directional receiver 410 is positioned on the
signal channeler 402, substantially off-center from (e.g.,
substantially forward of) the central vertical axis 20 of the robot
10. The off-center positioning of omni-directional receiver 410 can
allow the control module 1000 to be more sensitive in one
direction. In some implementations, such sensitivity allows the
robot 10 to discern directionality during maneuvers. For example,
if the omni-directional receiver 410 receives a signal, the control
module 1000 can direct the robot 10 to turn in place until the
signal received by the omni-directional receiver 410 weakens and/or
disappears. In some implementations, the control module 1000
directs the robot 10 to drive in the direction in which a weakened
signal and/or no signal is detected (e.g., away from the source of
the signal) and, if the robot 10 turns 360 degrees and is still
stuck in the beam, the robot 10 will turn 180 degrees and drive
forward in a last attempt to get free.
[0262] As shown in FIG. 19, the omni-directional receiver 410 can
be disposed substantially along a bottom portion 403 of the signal
channeler 402, facing toward the chassis 100. As compared to a
configuration in which an omni-directional receiver extends from a
top surface of the signal channeler (e.g., forming the highest
point of the robot), disposing the omni-directional receiver 410
along the bottom portion 403 of the signal channeler 402 can lower
the overall height profile of the robot 10. Additionally or
alternatively, this configuration can protect the omni-directional
receiver 410 from damage as the robot 10 maneuvers through tight
spaces and/or bumps into an overhead obstruction.
[0263] In some implementations, the omni-directional receiver 410
can be configured to receive transmissions of infrared light (IR).
In such implementations, a guide (e.g. a light pipe) can guide
emissions reflected off a conical reflector and channel them to an
emission receiver.
[0264] The omni-directional receiver 410 is disposed substantially
within a cavity 414 defined by a housing 412. A cover 416 extends
over the cavity 414 and forms a substantially water-tight seal with
the housing 412 to enclose the omni-directional receiver 410. In
some implementations, the cover 416 is releasably attached to the
housing 412 to allow, for example, replacement and/or repair of the
omni-directional receiver 410. The substantially water-tight seal
between the housing 412 and the cover 414 can include any of
various different seals. Examples of seals include epoxy,
ultrasonic welding, potting wells, welded interfaces, plugs,
gaskets, and polymeric membranes.
[0265] During use, an active external device (e.g., a navigation
beacon) can send a signal toward the signal channeler 402. The
signal channeler 402 is configured for total internal reflection of
the incident signal such that the signal moves substantially
unattenuated within the signal channeler 402 (e.g., within the
material forming the signal channeler). In some implementations,
the signal channeler 402 is a substantially uniform layer of
polished polycarbonate resin thermoplastic. The signal moving
through the signal channeler 402 is internally reflected through
the signal channeler 402. The omni-directional receiver 410 is
arranged to detect signal reflected through the signal channeler.
The omni-directional receiver 416 is in communication (e.g.,
electrical communication) with the control module 1000. Upon
detecting a signal traveling through the signal channeler 402, the
omni-directional receiver 416 sends a signal to the control module
1000.
[0266] In some implementations, the control module 1000 responds to
the signal from the omni-directional receiver 416 by controlling
the wheel modules 500, 501 to navigate the robot 10 away from the
source of the signal. For example, as an initial escape procedure,
the control module 1000 can direct the wheel modules 500, 501 to
move the robot 10 in a rearward direction. Such movement in the
rearward direction, can position the robot 10 further away from the
beam such that robot 10 can determine directionality (e.g., spin
out of the beam) by rotating substantially in place. In a
subsequent escape procedure, the controller 1000 can direct the
robot 10 in a direction away from the signal.
[0267] In some implementations, the robot 10 is configured to
detect the virtual wall pattern and is programmed to treat the
virtual wall pattern as a room wall so that the robot does not pass
through the virtual wall pattern.
[0268] In some implementations, the robot 10 includes a radio to
control the state of the navigation beams through commands
transmitted over a packet radio network.
[0269] Control module 1000 can be configured to maneuver the robot
10 about a first area while the robot 10 is in a cleaning mode. In
the cleaning mode, the robot 10 can be redirected in response to
detecting a gateway marking emission (e.g., from a beacon). In
addition, the control module 1000 can be configured to maneuver the
robot 10 through a gateway into the second bounded area while in a
migration mode.
[0270] In some implementations, the control module 1000 is
configured to move the robot 10 in a first bounded area in the
cleaning mode for a preset time interval. When the present time
interval elapses, the control module 1000 can move the robot 10 in
a migration mode. While in migration mode, the controller 1000 can
direct the wheel modules 500, 501 to maneuver the robot while
substantially suspending the wet cleaning process. In some
implementations, the migration mode can be initiated when the
omni-directional receiver 410 encounters the gateway marking
emission a preset number of times.
[0271] Wall Follower
[0272] Dust and dirt tend to accumulate at room edges. To improve
cleaning thoroughness and navigation, the robot 10 can follow
walls. Additionally or alternatively, the robot 10 can follow walls
as part of a navigation strategy (e.g., a strategy to promote full
coverage). Using such a strategy, the robot can be less prone to
becoming trapped in small areas. Such entrapments could otherwise
cause the robot to neglect other, possibly larger, areas.
[0273] Using a wall follower, the distance between the robot and
the wall is substantially independent of the reflectivity of the
wall. Such consistent positioning can allow the robot 10 to clean
with substantially equal effectiveness near dark and light colored
walls alike. The wall follower includes a dual collimination system
including an infrared emitter and detector. In such a collimination
system, the field of view of the infrared emitter and detector can
be restricted such that there is a limited, selectable volume where
the cones of visibility intersect. Geometrically, the sensor can be
arranged so that it can detect both diffuse and specular
reflection. This arrangement can allow the wall following distance
of the robot 10 to be precisely controlled, substantially
independently of the reflectivity of the wall. The distance that
the robot 10 maintains between the robot and the wall is
independent of the reflectivity of the wall.
[0274] Referring to FIG. 4, the robot 10 includes a wall follower
sensor 310 disposed substantially along the right side of the
bumper 300. The wall follower sensor 310 includes an optical
emitter 312 substantially forward of a photon detector 314. In some
implementations, the position of the wall follower sensor 310 and
the optical emitter 312 can be reversed such that the wall follower
sensor 310 is substantially forward of the optical emitter 312.
Details of the wall follower sensor 310 are disclosed in U.S.
patent application Ser. No. 12/118,250, entitled "Autonomous
Coverage Robot Sensing," the entire contents of which are
incorporated herein by reference.
[0275] Bump Sensors
[0276] Bump sensors can be used to detect if the robot physically
encounters an obstacle. Bump sensors can use a physical property
such as capacitance or physical displacement within the robot to
determine the robot has encountered an obstacle.
[0277] Referring to FIG. 7, the chassis 100 carries at least one
bump sensor 330 along a forward portion of the chassis 100. In some
implementations, bump sensors 330 are substantially uniformly
positioned on either side of the fore-aft axis 22 and are
positioned at substantially the same height along the center
vertical axis 20. As described above, bumper 300 is attached to
chassis 100 by hinges 110 such that the bumper 300 can move a
distance rearward along the fore-aft axis 22 if the bumper 300
encounters an obstacle. In the absence of a bump, the bumper 300 is
hingedly supported on the chassis 100 at a short distance
substantially forward of the at least one bump sensor 330. If the
bumper 300 is moved rearward (e.g., through an encounter with an
obstacle), the bumper 300 can press on one or more of the at least
one bump sensors 330 to create a bump signal detectable by the
control module 1000.
[0278] Details of the at least one bump sensor 330 are disclosed in
U.S. patent application Ser. No. 12/118,250, entitled "Autonomous
Coverage Robot Sensing," the entire contents of which are
incorporated herein by reference.
[0279] Cliff Sensor
[0280] Cliff sensors can be used to detect if a portion (e.g., a
forward portion) of the robot has encountered an edge (e.g., a
cliff). Cliff sensors can use an optical emitter and photon
detector pair to detect the presence of a cliff. In response to a
signal from a cliff detector, the robot can initiate any of various
different cliff avoidance behaviors. Details of cliff sensors
carried on bumper 300 are disclosed in U.S. patent application Ser.
No. 12/118,250, entitled "Autonomous Coverage Robot Sensing," the
entire contents of which are incorporated herein by reference.
[0281] Stasis Sensor
[0282] A stasis sensor can be used to detect whether or not the
robot is in fact moving. For example, a stasis sensor can be used
to detect if the robot is jammed against an obstacle or if the
drive wheels are disengaged from the floor, as when the robot is
tilted or becomes stranded on an object. In a wet cleaning
application, a stasis sensor can detect whether the wheels are
slipping on a cleaning liquid applied to the surface. In such
circumstances, the drive wheels may spin when the mobile robot
applies power to them, but the robot is not moving. Details of
stasis sensors for detecting whether the robot is moving are
disclosed in U.S. patent application Ser. No. 12/118,250, entitled
"Autonomous Coverage Robot Sensing," the entire contents of which
are incorporated herein by reference.
[0283] Power Module/Interface Module
[0284] Referring to FIGS. 1-7, the power module 1200 delivers
electrical power to all of the major robot subsystems. The power
module 1200 includes a self-contained power source releasably
attached to the chassis 100, e.g., a rechargeable battery, such as
a nickel metal hydride battery, or the like. In addition, the power
source is configured to be recharged by any of various different
recharging elements and/or recharging modes. In some
implementations, the battery can be replaced by a user when the
battery becomes discharged or unusable. The controller 1000 can
also interface with the power module 1200 to control the
distribution of power, to monitor power use and to initiate power
conservation modes as required.
[0285] The robot 10 can include one or more interface modules 1700.
Each interface module 1700 is attached to the chassis 100 and can
provide an interconnecting element or port for interconnecting with
one or more external devices. Interconnecting elements are ports
can be accessible on an external surface of the robot 10. The
controller 1000 can also interface with the interface modules 1700
to control the interaction of the robot 10 with an external device.
In particular, one interface module element can be provide for
charging the rechargeable battery via an external power supply or
power source such as a conventional AC or DC power outlet. The
interface module for charging the rechargeable battery can include
a short-circuit loop that will prevent the rechargeable battery
from taking charge if there is water in the charge port of the
robot 10. In some implementations, the rechargeable battery
includes a fuse that will trip if there is water in the battery
recharging path.
[0286] Another interface module element can be configured for one
or two way communications over a wireless network and further
interface module elements can be configured to interface with one
or more mechanical devices to exchange liquids and loose particles
therewith, e.g., for filling a cleaning fluid reservoir.
[0287] Active external devices for interfacing with the robot 10
can include, but are not limited to, a floor standing docking
station, a hand held remote control device, a local or remote
computer, a modem, a portable memory device for exchanging code
and/or date with the robot 10 and a network interface for
interfacing the robot 10 with any device connected to the network.
In addition, the interface modules 1700 can include passive
elements such as hooks or latching mechanisms for attaching the
robot 100 to a wall for storage or for attaching the robot to a
carrying case or the like.
[0288] In some implementations, an active external device can
confine the robot 10 in a cleaning space such as a room by emitting
a signal in a virtual wall pattern. The robot 10 can be configured
to detect the virtual wall pattern (e.g., using an omni-directional
receiver as described above) and is programmed to treat the virtual
wall pattern as a room wall so that the robot does not pass through
the virtual wall pattern. Such a configuration is described in U.S.
Pat. No. 6,690,134 by Jones et al., entitled Method and System for
Robot Localization and Confinement, the entire disclosure of which
is herein incorporated in its entirety.
[0289] In some implementations, an active external device includes
a base station used to interface with the robot 10. The base
station can include a fixed unit connected with a household power
supply, e.g., an AC power wall outlet and/or other household
facilities such as a water supply pipe, a waste drain pipe and a
network interface. The robot 10 and the base station can each be
configured for autonomous docking and the base station can be
further configured to charge the robot power module 1200 and to
service the robot in other ways. A base station and autonomous
robot configured for autonomous docking and for recharging the
robot power module are described in U.S. patent application Ser.
No. 10/762,219, by Cohen, et al., filed on Jan. 21, 2004, entitled
Autonomous Robot Auto-Docking and Energy Management Systems and
Methods, the entire disclosure of which is herein incorporated by
reference in its entirety.
[0290] Other robot details and features combinable with those
described herein may be found in U.S. patent application Ser. No.
12/118,117, entitled "COMPACT AUTONOMOUS COVERAGE ROBOT", U.S.
Pre-grant Publications 2008/00652565, 2007/0244610, and
2007/0016328, 2006/0200281, and 2003/0192144, and also U.S. Pat.
Nos. 6,748,297 and 6,883,201. The disclosures of these prior
applications, publications, and patents are considered part of the
disclosure of this application and are hereby incorporated by
reference in their entireties.
* * * * *