U.S. patent application number 11/197063 was filed with the patent office on 2005-12-08 for apparatus and method for traversing compound curved and other surfaces.
This patent application is currently assigned to Skywalker Robotics, Inc.. Invention is credited to Cox, Cameron Raymond, Dailey, Frank, Jeswine, William W., Olsen, Eric.
Application Number | 20050269143 11/197063 |
Document ID | / |
Family ID | 26928550 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050269143 |
Kind Code |
A1 |
Jeswine, William W. ; et
al. |
December 8, 2005 |
Apparatus and method for traversing compound curved and other
surfaces
Abstract
A traction unit capable of traversing and turning on surfaces
that include compound curves like the surface of a sphere or are
inverted like a ceiling. The traction unit includes a plurality of
trucks operable to propel the unit across a surface and a plurality
of adherence members operable to releasably secure the unit to the
surface. In operation, the adherence members cyclically attach to
and release from the surface as the trucks propel the unit across
the surface. Within each cycle, after the unit has traveled a
predetermined distance relative to an attached member, the member
releases the surface and reattaches to the surface at a different
point.
Inventors: |
Jeswine, William W.;
(Seattle, WA) ; Dailey, Frank; (Seattle, WA)
; Olsen, Eric; (Lynnwood, WA) ; Cox, Cameron
Raymond; (Washougal, WA) |
Correspondence
Address: |
John M. Janeway
GRAYBEAL JACKSON HALEY LLP
Suite 350
155 - 108th Avenue NE
Bellevue
WA
98004-5973
US
|
Assignee: |
Skywalker Robotics, Inc.
|
Family ID: |
26928550 |
Appl. No.: |
11/197063 |
Filed: |
August 3, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11197063 |
Aug 3, 2005 |
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10823325 |
Apr 13, 2004 |
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10823325 |
Apr 13, 2004 |
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09946780 |
Sep 4, 2001 |
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6742617 |
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60235065 |
Sep 25, 2000 |
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Current U.S.
Class: |
180/164 |
Current CPC
Class: |
Y10S 180/901 20130101;
B62D 53/00 20130101; B62D 57/024 20130101; Y02P 70/585 20151101;
B62D 61/10 20130101; B64F 5/30 20170101; B62D 49/0621 20130101;
Y02P 70/50 20151101 |
Class at
Publication: |
180/164 |
International
Class: |
B60B 039/00; B60V
001/00 |
Claims
What is claimed is:
1. A system comprising: a traction unit operable to traverse a
surface; a tether attached to the traction unit and operable to
suspend the traction unit should the traction unit fall; and a boom
attached to the tether and operable to suspend the tether.
2. The system of claim 1 wherein the traction unit comprises: a
frame; a plurality of drive wheels attached to the frame and
operable to propel the frame across a surface; a plurality of
adherence members attached to and movable relative to the frame and
operable to releasably secure the frame to the surface, each
adherence member including an adherence foot attached to a body
that is operable to extend the adherence foot toward the surface
and retract the adherence foot from the surface; and a plurality of
return mechanisms attached to the frame and each operable to move a
respective adherence member to a respective return position when
the body retracts the adherence foot from the surface.
3. A system comprising: a first traction unit operable to traverse
a surface; a second traction unit operable to traverse a surface;
and a tether attached to the first and second traction units and
operable to suspend the first or second traction unit from the
second or first traction unit should the first or second traction
unit fall.
4. The system of claim 3 wherein the tether is rigid.
5. The system of claim 3 wherein each traction unit comprises: a
frame; a plurality of drive wheels attached to the frame and
operable to propel the frame across a surface; a plurality of
adherence members attached to and movable relative to the frame and
operable to releasably secure the frame to the surface, each
adherence member including an adherence foot attached to a body
that is operable to extend the adherence foot toward the surface
and retract the adherence foot from the surface; and a plurality of
return mechanisms attached to the frame and each operable to move a
respective adherence member to a respective return position when
the body retracts the adherence foot from the surface.
6. An adherence foot comprising: a backing plate; and a first
annular lip defining a first inner cavity and operable to form a
seal when the lip contacts a surface; a second annular lip defining
a second inner cavity that includes the first annular lip and first
inner cavity and operable to form a seal when the second annular
lip contacts a surface.
7. The adherence foot of claim 6 wherein the backing plate includes
a vacuum port operable to connect the first inner cavity with a
vacuum source.
8. The adherence foot of claim 6 further comprising a soft viscous
material disposed in a lip chamber located between the first
annular lip and the second annular lip and operable to protrude
from the lip chamber when the first and second lips are forced
towards the surface.
9. The adherence foot of claim 6 further comprising a third annular
lip defining a third inner cavity that includes the first and
second annular lips and the first and second inner cavities and
operable to form a seal when the third annular lip contacts a
surface.
10. The adherence foot of claim 6 further comprising: a third
annular lip defining a third inner cavity that includes the first
and second annular lips and the first and second inner cavities and
operable to form a seal when the third annular lip contacts a
surface; and a soft viscous material disposed in a lip chamber
located between the second annular lip and the third annular lip
and operable to protrude from the lip chamber when the second and
third lips are forced towards the surface.
11. A method of traversing a surface, comprising: attaching an
adherence foot to the surface; pulling a frame with a drive wheel
against the surface by pulling the adherence foot and frame toward
one another; moving the frame relative to the attached adherence
foot; releasing the adherence foot from the surface; and returning
the released adherence foot to a return position.
12. The method of claim 11 wherein attaching an adherence foot
includes generating a vacuum between the adherence foot and the
surface.
13. The method of claim 11 wherein releasing the adherence foot
from the surface includes generating air pressure greater than
atmospheric pressure between the adherence foot and the surface to
blow the adherence foot from the surface.
14. The method of claim 11 wherein moving the frame relative to the
attached adherence foot includes moving the frame relative to a
body of a respective adherence member.
15. The method of claim 11 wherein: moving the frame relative to
the attached adherence foot includes moving the frame relative to a
respective body; and releasing the adherence foot from the surface
occurs before the respective body contacts a hard limit that
prevents the frame from moving relative to the body.
16. The method of claim 11: wherein moving the frame relative to
the attached adherence foot includes moving the frame relative to a
respective body; and further comprising stopping the frame from
moving relative to the attached adherence foot when a respective
body contacts a hard limit and the adherence foot remains attached
to the surface.
17. The method of claim 11 wherein moving the frame relative to the
attached adherence foot includes: moving the frame relative to a
respective body; and crossing with the respective body a soft limit
that signals the location of the frame relative to the body before
the body contacts a hard limit.
18. The method of claim 11 wherein: moving the frame relative to
the attached adherence foot includes moving the frame relative to a
respective body; and releasing the adherence foot from the surface
includes releasing the adherence foot after the respective body
crosses a soft limit but before the adherence member contacts a
hard limit.
19. A method of attaching an adherence foot to the surface
comprising: contacting the surface with two or more annular lips of
an adherence foot; and generating an attachment force in the
adherence foot.
20. The method of claim 19 wherein contacting the surface with the
adherence foot includes contacting the surface with three annular
lips.
21. The method of claim 19 wherein generating an attachment force
between the adherence foot and the surface includes generating a
vacuum between a suction cup and the surface.
22. The method of claim 19 wherein generating an attachment force
in the adherence foot includes: pumping air out of an inner cavity
in a suction cup with a vacuum source connected to the suction cup;
and forming an air-tight or substantially air-tight seal between
one or more annular lips and the surface.
23. The method of claim 19 further comprising maintaining an
attachment force in the adherence foot that includes: forming an
air-tight or substantially air-tight seal between the surface and a
first annular lip that defines a first inner cavity; and forming an
air-tight or substantially air-tight seal between the surface and a
second annular lip that defines a second inner cavity including the
first annular lip and first inner cavity, wherein if the second
annular lip can not form or loses an air-tight or substantially
air-tight seal, a vacuum in the first inner cavity is not
destroyed.
24. The method of claim 19 further comprising releasing the
adherence foot from the surface that includes generating air
pressure greater than atmospheric pressure between a suction cup
and the surface to blow the suction cup away from the surface.
25. A method of attaching an adherence foot to the surface
comprising: determining the orientation of an adherence member
relative to the direction of gravity; generating an attachment
force in the adherence foot; and adjusting the attachment force in
the adherence foot based on the direction of gravity.
26. The method of claim 25 wherein generating an attachment force
includes generating a vacuum between a suction cup and the
surface.
27. The method of claim 25 wherein generating an attachment force
includes generating a vacuum between a suction cup and the surface
and adjusting the attachment force includes adjusting the vacuum
based on the direction of gravity.
28. A method of pulling the frame toward the surface comprising:
determining the orientation of an adherence member relative to the
direction of gravity; generating a retraction force in the
adherence member; and adjusting the retraction force in the
adherence member based on the direction of gravity.
29. The method of claim 28 wherein generating a retraction force
includes generating pressurized air in the adherence member.
30. The method of claim 28 wherein generating a retraction force
includes generating pressurized air in the adherence member and
adjusting the retraction force includes adjusting the air pressure
generated in the adherence member based on the direction of
gravity.
31. A method of releasing a plurality of adherence feet attached to
a surface comprising: selectively attaching one or more adherence
feet to a surface; and selectively releasing one or more attached
adherence feet from the surface while maintaining at least one
adherence foot attached to the surface at all times.
32. The method of claim 31 wherein selectively releasing one or
more attached adherence feet from the surface includes releasing
the adherence feet attached to respective adherence members that
contact respective hard limits established on the frame.
33. The method of claim 31 wherein selectively releasing one or
more attached adherence feet from the surface includes: releasing
the adherence foot attached to a respective adherence member that
is the first in time to cross a respective soft limit established
on the frame; and then releasing the adherence foot attached to a
respective adherence member that is the second in time to cross a
respective soft limit.
34. The method of claim 31 wherein selectively releasing one or
more attached adherence feet from the surface includes: releasing
all adherence feet attached to respective adherence members that
contact respective hard limits; then releasing the adherence foot
attached to a respective adherence member that is the first in time
to cross a respective soft limit; and then releasing the adherence
foot attached to a respective adherence member that is the second
in time to cross a respective soft limit.
35. The method of claim 31 further comprising determining whether
the release times of all the adherence feet are converging to one
point in time.
36. The method of claim 31 further comprising determining whether
the release times of all the adherence feet are converging to one
point in time and, wherein selectively attaching one or more
adherence feet to the surface includes selectively pausing
temporarily the attachment to the surface of at least one of the
one or more adherence feet.
37. A method of turning a wheel traversing on a surface comprising:
moving a wheel out of contact with the surface; turning the wheel
while the wheel is out of contact with the surface; and moving the
wheel into contact with the surface.
38. The method of claim 37 wherein moving the wheel away out of
contact with the surface includes pushing a frame away from the
surface.
39. A method of traversing an obstruction on a surface comprising:
sensing the obstruction; lifting a bogie of a bogie assembly higher
than the obstruction; contacting the obstruction with a belt of the
bogie assembly; and powering a drive wheel along the belt while the
belt contacts the obstruction.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The instant application is a divisional application of U.S.
patent application Ser. No. 10/823,325, titled "Apparatus And
Method For Traversing Compound Curved And Other Surfaces", filed 13
Apr. 2004 and presently pending, which is a divisional application
of U.S. patent application Ser. No. 09/946,780, titled "Apparatus
And Method For Traversing Compound Curved And Other Surfaces",
filed 4 Sep. 2001 and is now U.S. Pat. No. 6,742,617, and the
instant application claims priority from U.S. Provisional Patent
Application 60/235,065, titled "Robotic System for Traversing
Surface", filed 25 Sep. 2000, all of which are hereby incorporated
by reference in their entirety.
TECHNICAL FIELD
[0002] This invention relates generally to unmanned, self-propelled
vehicles and more particularly to a vehicle such as a robot and
methods for traveling across and turning on a surface with compound
curves.
BACKGROUND
[0003] People frequently use unmanned, self-propelled vehicles such
as robots to perform a variety of functions that would be difficult
or dangerous for a person to perform. For example many people
frequently use robots to retrieve or dispose an explosive device or
inspect or work in an environment that could kill or injure a
person. People also frequently use robots to inspect or work in
locations that typically are hard to access or are inaccessible by
a person such as inspecting a pipeline.
[0004] Unfortunately, because robots typically propel themselves to
a work site, use of most conventional unmanned, self-propelled
vehicles is typically significantly limited by the ability of the
robot to propel itself over a surface. For example, surfaces that
include compound curves or three dimensional curves, abrupt
inclinations or declinations, steps or gaps can cause conventional
robots to become significantly less stable, i.e., more likely to
lose their preferred orientation relative to the surface, as they
traverse the surface or turn on it. In addition, surfaces that are
slippery can cause conventional robots to easily lose a significant
portion, if not all, of their traction to the surface. If either
happens while traversing an incline or inverted surface such as a
ceiling, such a loss of traction could cause the robot to fall.
Such a fall could seriously damage the robot, its payload if it has
any, or the surface or other components of the structure the robot
is traversing.
[0005] Another problem with conventional robots is they tend to
scrub the surface as they traverse and turn on it. This can cause
undesirable scratches on the surface. For example, the skin or
windshield of a commercial airplane must remain free from scratches
because of the high stress imposed on it during flight. If a
scratch does occur, the skin or windshield is often replaced at
great expense in both time and money.
[0006] Yet another problem with conventional robots is they tend to
bounce or jerk as they propel themselves across a surface. This can
be a significant problem during inspection of, for example, a
commercial airplane's crown skin or structure--the top part of the
airplane's body--because most inexpensive non-destructive
inspection techniques require the inspection apparatus to remain a
substantially constant distance from the surface being inspected.
Because of this requirement, most inspections of an airplane
typically include erecting a scaffold, which can be time consuming,
for an inspector to stand on prior to inspecting the structure.
SUMMARY
[0007] In one aspect of the invention, a traction unit includes a
frame, a plurality of trucks attached to the frame and operable to
propel the frame across a surface, and a plurality of adherence
members attached to and movable relative to the frame and operable
to releasably secure the frame to the surface. Each adherence
member includes a foot attached to a body that is operable to
extend the foot toward the surface and retract the foot from the
surface. The traction unit also includes a plurality of
corresponding return mechanisms attached to the frame and operable
to move the adherence members to respective return positions. With
the adherence members merely attaching the unit to the surface and
the trucks merely propelling the unit across the surface, the unit
can traverse and turn on compound curved surfaces.
[0008] In another aspect of the invention, a control unit makes
sure that at least one adherence member is attached to the surface
while the unit traverses the surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of a traction unit system
according to an embodiment of the invention.
[0010] FIG. 2 is perspective view of a frame and adherence member
included in the traction unit in FIG. 1 according to an embodiment
of the invention.
[0011] FIG. 3 is a perspective view of a return mechanism and
adherence member included in the traction unit in FIG. 1.
[0012] FIG. 4 is cross-sectional view of an adherence member in
FIGS. 1-3 according to an embodiment of the invention.
[0013] FIG. 5 is a block diagram of a pneumatic system included in
the traction unit system of FIG. 1 according to an embodiment of
the invention.
[0014] FIG. 6 is a front cross-sectional view of a truck included
in the traction unit in FIG. 1 according to an embodiment of the
invention.
[0015] FIG. 7A is a side view of the truck in the FIGS. 1 and 6
including a bogie assembly according to an embodiment of the
invention.
[0016] FIG. 7B is a side view of the truck in FIGS. 1 and 6
including a bogie assembly according to another embodiment of the
invention.
[0017] FIG. 8 is a block diagram of a control system included in
the traction unit system of FIG. 1 according to an embodiment of
the invention.
[0018] FIGS. 9A-9F are views of a traction unit included in the
traction unit system of FIG. 1 performing three types of turns
according to an embodiment of the invention.
[0019] FIG. 10 is a side view of a train including three traction
units in FIG. 1 traversing up an incline according to an embodiment
of the invention.
[0020] FIG. 11 is a side view of a train including three traction
units in FIG. 1 traversing up around a corner and down a decline
according to an embodiment of the invention.
[0021] FIG. 12 is a top view of a traction unit including six
adherence members according to another embodiment of the
invention.
[0022] FIG. 13 is a top view of a train of traction units including
two rows of traction units linked side by side according to another
embodiment of the invention.
[0023] FIG. 14 is a perspective view of a traction unit in FIG. 1
tethered to a boom and traversing an airplane.
[0024] FIG. 15 is a perspective view of two traction units in FIG.
1 tethered to the top of a building and cooperatively working.
DETAILED DESCRIPTION
[0025] FIG. 1 is a perspective view of a traction unit system
according to an embodiment of the invention. The traction unit
system is capable of turning on and traversing across compound
curved surfaces--surfaces curved in three dimensions such as the
surface of a sphere or the like--with little or no surface
scrubbing or abrasion.
[0026] Referring to FIG. 1, the system 20 includes a traction unit
22 operable to traverse a surface 23, a pneumatic system 24
including a source of pressured air 26 for powering some or all of
the components of the traction unit 22, a control system 28
including a micro-processor (not shown) for instructing and
coordinating the operation of some or all of the components of the
traction unit 22, a vacuum source 30 and an umbilical cord 32 that
includes pneumatic 34, vacuum 36 and electrical lines 38 connecting
the appropriate components to the source of pressurized air 26,
vacuum source 30 and control system 28, and a tether 40 operable to
suspend the traction unit 22 above a surface 23.
[0027] The traction unit 22 includes a frame 42 having a lead
portion 44 that typically indicates the direction of travel when
the unit 22 is traversing a surface 23, adherence members 46a-46d
(46d not shown) attachable and moveable relative to the frame 42
for releasably securing the frame 42 to the surface 23 or lifting
the frame 42 away from the surface 23, return mechanisms 48a-48d
attachable to the adherence members 46a-46d for moving the members
46a-46d to a return position, and trucks 50a-50d (50d not shown)
rotatably or fixedly attachable to the frame 42 for propelling the
unit 22 over and maintaining the frame 42 a constant or
approximately constant distance away from the surface 23.
[0028] The adherence members 46a-46d attach the traction unit 22 to
the surface 23 and include an adherence foot 52a-52d (52d not
shown) that each member 46a-46d extends to and retracts from the
surface 23 for this purpose. The adherence feet 52a-52d include a
suction cup 54a-54d (54d not shown) that is connected to the vacuum
source 30 by the vacuum lines 36. Although the feet 52a-52d are
shown and discussed as including suction cups 54a-54d, the feet may
include magnets or other conventional mechanisms that can attach to
and release from a surface. The adherence members 46a-46d can
extend their adherence feet 52a-52d below a plane (not shown)
defined by the points on the surface 23 where the trucks 50a-50d
contact the surface 23 or retract the adherence feet 52a-52d above
the same plane. This allows the adherence members 46a-46d to secure
the traction unit 22 to surfaces that undulate within the area
covered by the frame 42 of the traction unit 22. This also allows
the traction unit 22 to suspend the trucks 50a-50d off the surface
23 to change direction quickly and without scrubbing the surface
23. Although the system 20 includes four adherence members 46a-46d,
the traction unit 22 may include more or fewer adherence
members.
[0029] The trucks 50a-50d propel the traction unit 22 across the
surface 23 and include wheels 56a-56d (56d not shown). The trucks
50a-50d typically do not attach the traction unit 22 to the surface
23. The trucks 50a-50d are typically located at the corners of the
traction unit 22 while the adherence members 46a-46d are typically
located within the corners for greater stability. Although, the
trucks 50a-50d and adherence members 46a-46d can be arranged
differently.
[0030] The traction unit 22 also includes steering mechanisms
58a-58d that can steer each truck 50a-50d independently or steer
two or more trucks together, and obstruction sensors 59a-59d.
[0031] Still referring to FIG. 1, in operation, the adherence
members 46a-46d repeatedly attach to and release from the surface
23 as the wheels 56a-56d of the trucks 50a-50d propel the frame 42
across the surface 23. Although the operation of one adherence
member 46a is discussed, the other adherence members 46b-46d
operate in a similar manner. At a first moment in the movement
cycle (the first moment is not necessarily first but simply picked
as an arbitrary first moment for discussion purposes) the adherence
member 46a hangs from the frame 42 above the surface 23 and extends
the adherence foot 52a to the surface 23. This is the return
position and typically occurs when the return mechanism 48a has
stopped moving the adherence member 46a. With the adherence member
46a attached to the surface 23, the frame 42 moves relative to the
adherence member 46a as the wheels 56a-56d accelerate the frame 42
across the surface 23, propel the frame 42 at a constant or
substantially constant speed, or otherwise move the frame. After,
the frame 42 moves a predetermined distance relative to the member
46a, the adherence foot 52a releases its hold on the surface 23 and
is retracted away from the surface 23. Next, the return mechanism
48a moves the released member 46a back to the return position where
the member 46a extends the adherence foot 52a to once again attach
to the surface 23 and repeat the cycle. In one embodiment, to help
ensure that the frame 42 is secured to the surface 23 while it
traverses the surface 23, the control system 28 coordinates the
attachment and release of each member 46a-46d so that at least one
of the members 46a-46d is attached to the surface 23 at all
times.
[0032] The traction unit 22 can be combined with another traction
unit/units 22 to form a train, as discussed with FIGS. 10 and 11.
Such a train of units is capable of traversing obstructions on a
surface like gaps or steps, or traversing abrupt changes in the
contour of a surface like a corner between a wall and a floor or
the location where a wing of an airplane meets the body. In
addition, the units 22 can be tethered to each other or to a boom
to prevent the units from damaging the surface should they happen
to fall or fail to work cooperatively. For example, an area of a
surface can be scanned by a scanning tool (not shown) mounted to a
beam (not shown) that two units 22 support, or one unit 22 can
carry a container of cleaning solution while another unit 22
carries a sprayer.
[0033] FIG. 2 is perspective view of the traction unit 22 of FIG. 1
including the frame 42 and one adherence member 46a according to an
embodiment of the invention. The remaining adherence members
46b-46d, trucks 50a-50d, return mechanisms 48a-48d and steering
mechanisms 58a-58d have been omitted for clarity. But, it is
understood that this illustration can also apply to the omitted
adherence members 46b-46d.
[0034] Referring to FIG. 2, in one embodiment, the frame 42
includes two portions 60 and 62 that are pivotable about a center
point 64 to promote stability of the traction unit 22 as it
traverses a compound curved surface. A bolt 66 loosely threaded to
a nut (not shown) after being inserted through both portions 60 and
62 fastens the portions 60 and 62 together. In other embodiments,
conventional bearings (not shown) can be used to permit rotation
between the portions. In one embodiment, each portion 60 and 62 is
made from a conventional metal plate having a high strength to
weight ratio such as aluminum. Each portion 60 and 62 includes two
sections 68b-68d that divide the portions 60 and 62 into two equal
or approximately equal areas. When the traction unit 22 traverses
compound curved surfaces, the distance from the surface at each
wheel (not shown) to the frame 42 is typically not the same for all
four trucks (not shown) at any given instant in time. If the frame
42 did not have the additional flexibility provided by pivoting
about the center point 64, the wheels on the trucks might lose
contact with the surface and hinder the progress of the unit 22
across the surface.
[0035] Although, the portions 60 and 62 are shown and described as
pivotable relative to each other about a center point 64, the
portions may pivot about a point located elsewhere on the portions
60 and 62.
[0036] Still referring to FIG. 2, the frame 42 maintains the
adherence member's alignment between the frame 42 and surface (not
shown) underneath the frame 42 and supports the adherence member
46a as the member 46a moves within a translation zone 70. In one
embodiment the frame 42 includes linear frame bearings 72
attachable to the frame 42 that movably support linear member-mount
bearings 74 attachable to the adherence member 46a. Each bearing 72
and 74 includes a bearing guide 76 and 78 having first 80 and 84
and second 82 and 86 ends. The frame bearing guides 76 are
attachable to the frame 42 and typically extend the width of a
portion 60 or 62 of the frame 42. The member-mount bearing guides
78 are attachable to the frame bearing carriages 88 which are
slidable relative to the frame bearing guides 76. The member-mount
bearing carriage 90 is slidable relative to the member-mount guides
78 and is attachable to the adherence member 46a. By mounting the
member-mount carriage 90 on both member-mount bearing guides 78,
the adherence member 46a does not swing out of alignment between
the frame 42 and surface when the traction unit 22 ascends or
descends an incline or traverses a ceiling or inverted wall upside
down.
[0037] The frame section 68a includes the translation zone 70 that
defines the area in which the adherence member 46a moves relative
to the frame 42 when the traction unit 22 traverses a surface (as
previously discussed, the frame 42 actually moves while the
adherence member 46a remains stationary). In one embodiment the
translation zone 70 includes a hard limit 92 that defines the zone
70 and a soft limit 94 disposed within the hard limit 92 of the
zone 70 and defined by limit switches 96 which may be magnetic reed
switches, micro-switches or other conventional switches. The hard
limit 92 is the adherence member's travel limit imposed by the
frame carriages 88 contacting either end 80 or 82 of the frame
guides 76, and the member-mount carriage 90 contacting the frame
carriages 88 at either end 84 or 86 of the member-mount guides 78.
The hard limit 92 prevents the adherence member 46a from moving
relative to the frame 42 once it encounters the hard limit 92.
[0038] Still referring to FIG. 2, tripping one or both of the limit
switches 96 warns the micro-processor in the control system 28
(FIG. 1) (not shown) that the adherence member 46a is close to a
hard limit 92. Typically, the soft limit 94 is approximately half
the distance from a center of the translation zone 70 and the hard
limit 92, but may be any distance between the these two locations
within the zone 70. In one embodiment, a switch 96 is attached to a
frame carriage 88 and another switch 96 is attached to the
member-mount carriage 90. Both switches 96 operate by riding a
switch rail 98. Once the adherence member 46a encounters the soft
limit 94, the switch rail 98 depresses the switch contact 100; but
when the adherence member 46a is within the soft limit 94, the
switch contact 100 remains extended.
[0039] FIG. 3 is a perspective view of the return mechanism 48a in
FIG. 1 including a return bushing and cord. Although FIG. 3
illustrates one return mechanism 48a, one adherence member 46a,
frame bearings 72 and member-mount bearings 74, it is understood
that this illustration can also apply to the other return
mechanisms 48b-48d, corresponding to the other adherence members
46b-46d in FIG. 1.
[0040] The return mechanism 48a moves the adherence member 46a
relative to the frame 42 after the adherence member 46a releases
the surface (not shown). In one embodiment, the return mechanism
48a is mounted to the frame by conventional fasteners and includes
an actuator 102 selectively operable to move the adherence member
46a, a return bushing 104 attachable to a frame section (not shown)
and having a hole 106 defining a return position typically in the
center of the translation zone 70 (FIG. 2), and a return cord 108
attached to the actuator 102 at a first end 110, insertable through
the hole 106 and attached to the member-mount carriage 90 at a
second end 112. To move the adherence member 46a, the return
mechanism 48a pushes the cord 108 away from the return bushing 104
by extending its ram 114. With the first end 110 of the cord 108
attached to the actuator 102, the second end 112 of the cord 108 is
pulled toward the return bushing 104. To prevent the cord 108 from
slipping off the ram 114, the ram 114 includes a cord guide 116 in
which the cord 108 is disposed.
[0041] In operation, the control system's micro-processor typically
commands the return mechanism 48a to move the adherence member 46a
for a predetermined length of time. This length of time is
typically three quarters (3/4) of a second but may be more or less
depending on the speed of the traction unit 22 as it traverses a
surface (not shown) and the pressure of the air used to power the
mechanism 48a. During this length of time, the pneumatic system 24
(FIG. 1) supplies high pressure air to the actuator 102 as
discussed in greater detail in conjunction with FIG. 5. Although,
the micro-processor keeps track of the length of time the actuator
102 operates, conventional sensors (not shown) such as
micro-switches, magnetic reed switches or optical sensors may
signal the micro-processor of the return of the adherence member
46a to the return position. If the return mechanism 48a does not
finish returning the adherence member 46a to the return position
before the mechanism 48a stops, the adherence member 46a merely
stops moving relative to the frame 42 and commences extending its
suction cup 54a to the surface.
[0042] Although the return position is discussed located in the
center of the translation zone 70, the return position can be
anywhere within the translation zone 70. In addition, although the
cord guide 116 moves with the ram 114, the cord guide 116 can
remain stationary while the ram 114 moves within it. Also, the ram
114 can include a tube through which the cord 108 runs to prevent
the cord 108 from slipping off the ram 114.
[0043] FIG. 4 is cross-sectional view of the adherence member 46a
in FIGS. 1-3 according to an embodiment of the invention. It is
understood that this illustration can also apply to the other
adherence members 46b-46d.
[0044] The adherence member 46a includes the suction cup 54a for
attaching the adherence member 46a to a surface 118 and includes a
body 120 operable to extend and retract the suction cup 54a to and
from the surface 118. The suction cup 54a is pivotally attachable
to the body 120 to allow the suction cup 54a to form a seal with a
curved or canted surface (not shown). Thus, when the suction cup
54a initially touches a curved or canted surface a portion of the
cup 54a touches the surface and, by continuing to extend the cup
54a, the body 120 causes the remaining portion of the cup 54a to
contact the surface.
[0045] Still referring to FIG. 4, in one embodiment, the suction
cup 54a includes three concentric lips 122a-122c and a soft viscous
material 124 such as silicone or other conventional rubber with a
very low durometer value to promote the formation and maintenance
of a seal with rough or grooved surfaces. The lips 122a-122c extend
from a backing plate 126 away from the body 120 and define an inner
cavity 128 and lip chambers 130 that contain the soft viscous
material 124. The inner cavity 128 includes a vacuum port 132
connected to the vacuum source 30 (FIG. 1) by the vacuum line 36.
When the lips 122a-122c of the cup 54a contact the surface 118 they
form a seal and create a vacuum in the inner cavity 128. This
vacuum attaches the cup 54a to the surface 118 and squeezes the
soft viscous material 124 into contact with the surface 118. As
long as at least one of the lips 122a-122c forms a seal with the
surface 118, the cup 54a can generate a vacuum and attach to the
surface 118.
[0046] In other embodiments the suction cup 54a may include more or
fewer lips that may or may not be concentric. In addition, the soft
viscous material 124 may include fibrous material to increase the
material's tensile strength.
[0047] The suction cup 54a can be made from any conventional
resilient material such as rubber or plastic depending on the
environment and type of surface the cup 54a will contact.
[0048] Still referring to FIG. 4, in one embodiment, the body 120
includes a conventional actuator 134 that reciprocates a rod 136 to
extend and retract the suction cup 54a from the surface 118. The
rod 136 has a first end 138 that pivotally attaches to the backing
plate 126 of the suction cup 54a and a second end 140 attached to a
piston 142. Conventional universal joints or ball-and-socket joints
143 typically attach the first end 138 to the suction cup 54a. By
supplying the actuator 134 with pressured air via the lines 34a and
34b, as discussed below in conjunction with FIG. 5, the actuator
134 moves the suction cup 54a toward or away from the body 120.
[0049] In other embodiments the body 120 may include a conventional
rotary actuator or some other conventional mechanism operable to
move the suction cup 54a to and from the body 120.
[0050] FIG. 5 is a block diagram of the pneumatic system 24 in FIG.
1 according to an embodiment of the invention. The system 24 powers
the suction cup 54a, the return mechanism 48a, and adherence member
46a by distributing negative, low-positive, or high-positive
pressurized air to these components. Although FIG. 5 illustrates
the pneumatic system 24 powering one return mechanism 48a, one
adherence member 46a and one suction cup 54a, it is understood that
this illustration can also apply to the other return mechanisms
48b-48d, adherence members 46b-46d and suction cups 54b-54d.
[0051] Referring now to FIG. 5, the system provides air at three
different pressures, negative or vacuum, low, and high, to the
return mechanism 48a, adherence member 46a and suction cup 54a as
directed by the micro-processor of the control system 28 (FIG. 1).
The system 24 includes a return mechanism valve 144 for selectively
supplying high pressure air to power the return mechanism 48a, a
high/low pressure control valve 146 for selectively supplying low
or high pressure air to an adherence-member control valve 148 that
powers the piston 142 (FIG. 4) of the adherence member 46a to
extend or retract the suction cup 54a, and a suction cup valve 150
for supplying a vacuum or high pressure air to the suction cup 54a.
The system 24 also includes the vacuum source 30 (FIG. 1) connected
to the suction cup valve 150 by the line 152 and is typically
mounted apart from the traction unit 22 and a vacuum sensor 154
connected to the suction cup valve 150 and suction cup 54a by the
line 156. The vacuum sensor 154 monitors the air pressure in the
suction cup 54a and relays this information to the micro-processor
via line 158. Line 160 connects the high/low-pressure control valve
146, return-mechanism valve 144, and suction-cup valve 150 to the
source of pressurized air 26 typically mounted apart from the
traction unit 22. Line 161 connects the high/low-pressure control
valve to the source of pressurized air 26. Line 162 connects the
high/low pressure control valve 146 to the adherence member control
valve 148, which lines 164 and 166 connect to the adherence member
46a. Line 168 exhausts the system to the atmosphere.
[0052] In one embodiment, the high pressure is approximately 125
pounds per square inch (psi) above atmospheric pressure; the low
pressure is approximately 10 psi, and the vacuum is approximately
11-12 psi below atmospheric pressure. However other pressure values
may be used depending on the weight of the payload and/or type of
surface traversed. The valves 144-150 are attached to the frame 42
(FIG. 1) and are separate from their respective mechanism 48a,
member 46a or cup 54a. But, these valves 144-150 may be formed as a
part of their respective mechanism 48a, member 46a or cup 54a or
located apart from the traction unit 22.
[0053] Still referring to FIG. 5, as the traction unit 22 traverses
the surface (not shown) the system 24 cycles the extension and
retraction of the suction cup 54a, the return of the adherence
member 46a as well as the attachment and release of the suction cup
54a to and from the surface. At a first moment in the cycle (the
first moment is not necessarily first but simply picked as an
arbitrary first moment for discussion purposes) the adherence
member 46a hangs above the surface in its return position and the
suction cup valve 150 connects the vacuum source 30 to the suction
cup 54a via lines 152 and 36. With the suction cup 54a suspended
above the surface, the vacuum draws in air from the atmosphere and
the vacuum sensor 154 senses a small negative pressure in line 36.
The micro-processor then connects the air pressure source 26 to the
adherence member 46a by directing the high/low pressure control
valve 146 to connect the line 161 supplying low pressure air to the
line 162 and directing the adherence-member control valve 148 to
connect the line 162 to the line 34a. Thus, the adherence member
46a extends the suction cup 54a to the surface. Once the suction
cup 54a touches the surface, the cup 54a forms a seal with the
surface and the vacuum sensor 154 senses an increase in negative
pressure. Based on this information, the micro-processor connects
the air pressure source 26 to the adherence member 46a by directing
the high/low pressure control valve 146 to connect the line 160
supplying high pressure air to the line 162 and directing the
adherence member control valve 148 to connect line 162 to line 34b.
If, however the suction cup 54a fails to form a seal with the
surface the adherence member 46a will continue to extend the
suction cup 54a under low pressure and the adherence member 46a
will simply remain stationary relative to the surface until it
trips a limit switch 96 (FIG. 2). In other embodiments, the
micro-processor instructs the adherence member 46a to retract the
suction cup 54a, and the return mechanism 48a to move the adherence
member 46a after a predetermined length of time lapses without the
vacuum sensor 154 sensing an increase in negative pressure. With
the suction cup 54a attached to the surface, the adherence member
46a can not retract the suction cup 54a, and thus instead secures
the traction unit 22 to the surface by pulling the traction unit 22
toward the surface. With the adherence member 46a attached to the
surface, the traction unit 22 moves relative to the member 46a
until the member 46a trips a limit switch 96. Once tripped, the
micro-processor connects the air pressure source 26 to the suction
cup 54a with lines 36 and 160 to generate positive pressure in the
suction cup 54a and blow the suction cup 54a off the surface. With
the suction cup 54a blown from the surface and the adherence member
46a exerting a retraction force on the cup 54a, surface abrasion by
the cup 54a during release is minimized. When a limit switch 96 is
tripped, the micro-processor also connects the air pressure source
26 to the return mechanism 48a by directing the return mechanism
valve 144 to connect the line 160 to the line 170 which causes the
return mechanism 48a to extend its ram 114. After the return
mechanism 48a runs for approximately three quarters (3/4) of a
second, the micro-processor directs the return mechanism valve 144
to connect line 160 to line 172 which causes the return mechanism
48a to retract its ram 114. The adherence member 46a is now back in
a position similar to the first moment and the cycle can
repeat.
[0054] In other embodiments, the system 24 may include an
orientation sensor such as a conventional inclinometer or
accelerometer to monitor the orientation of the traction unit 22
relative to the direction of gravity and a regulator to increase or
decrease the vacuum and/or high air pressure. This allows one to
adjust the amount of suction the cups 54a-54d forms with the
surface and the retraction force in the adherence members 46a-46d
when the traction unit 22 is traversing a ceiling or steeply
inclined wall. For example, the traction unit 22 may be upside down
as it traverses the underside of an airplane's aft body section. In
addition, the vacuum generated at the suction cup 54a may be
generated by blowing air through a venturi and connecting the
vacuum port 132 (FIG. 4) of the suction cup 54a to an orifice in
the side wall of the venturi.
[0055] FIG. 6 is a front view of the truck 50a in FIG. 1 including
a motor, a body, two wheels and a drive shaft according to an
embodiment of the invention. Although FIG. 6 illustrates one truck
50a, it is understood that this illustration can also apply to the
other trucks 50b-50d (FIG. 1).
[0056] Referring to FIG. 6, the truck 50a propels and steers the
traction unit 22 across a surface and includes a wheel motor 174
connected to two wheels 56a and 56b by a drive shaft 176 disposed
within a truck body 178. In one embodiment, the wheel motor 174 is
mounted to the frame 42 with conventional fasteners such as screws
or bolts. A steering bearing mount 180 retains the steering bearing
182 and is attached to the frame 42 below the wheel motor 174. The
steering bearing 182 supports a steering tube 184 mounted to the
truck body 178 and permits the steering tube 184 to rotate relative
to the bearing mount 180 and frame 42. Secured to the outer surface
186 of the steering tube 184, the steering sprocket 188 is
attachable to the steering motor (not shown) via a conventional
belt or chained links (not shown) that convey the power of the
steering motor to the truck body 178 when a turn is desired.
Extending downward from the wheel motor 174, an upper drive shaft
190 couples a lower drive shaft 192 to the wheel motor 174 via a
conventional universal joint 193. A worm gear 194 attachable to the
bottom of the lower drive shaft 196 engages a spur gear 198
attachable to an axle 200 to transmit the power from the motor 174
to the wheels 56a and 56b. The truck body 178 supports the axle 200
with conventional wheel bearings 201 that allow the axle 200 to
rotate relative to the truck body 178. Conventional techniques (not
shown) such as a castle nut and cotter pin, or bolts attach the
wheels 56a to the axle 200 and transmit the rotation of the axle
200 to the wheels 56a.
[0057] In one embodiment the motor 174 is conventional electrical
motor sized to provide enough power to the wheels 56a to propel the
traction unit 22 up a 90 degree incline, and the wheels 56a are
typically made of any material, such as Tygon.RTM., that is
chemically resistant to aviation hydraulic fluid. In other
embodiments, the motor 174 may be a stepping motor or a pneumatic
actuator whose power output can be varied, and the wheels can be
made of any conventional material depending on the conditions of
the environment and surface the traction unit 22 operates on.
[0058] FIG. 7A is a side view of the truck 50a in FIGS. 1 and 6
including a bogie assembly according to an embodiment of the
invention. FIG. 7B is a side view of the truck 50a in FIGS. 1 and 6
including two bogie actuators according to another embodiment of
the invention. In FIGS. 7A and 7B the truck motor, body and drive
shaft in FIG. 6 have been omitted.
[0059] Referring to FIGS. 7A and 7B, the bogie assembly 202
typically provides more traction than the wheels 56a (FIG. 6) or
other conventional wheels and typically allows the traction unit 22
to traverse obstacles that the wheels 56a (FIG. 6) or other
conventional wheels normally could not. In one embodiment, the
bogie assembly 202 includes a drive wheel 204 connected to the
wheel motor 174 (FIG. 6) (not shown) that propels the truck 50a and
thus the frame 42 (FIG. 1) (not shown) across a surface 206, a
first and second bogie 208 and 210 pivotable about the drive wheel
204, and a belt 212 connected to the drive wheel 204 and bogies 208
and 210. One or more actuators 214 connected to bogie links 216a
and 216b move the bogies 208 and 210 toward or away from the
surface 206. Depending on the surface being traversed, the belt 212
can be any conventional resilient material such as rubber or
plastic, or the belt 212 can be linked metal chain. With the bogies
208 and 210 extended such that they compress the belt 212 between
themselves and the surface 206, the area of the belt 212 that
contacts the surface 206 typically extends from one bogie 208 to
the other 210 and at a minimum includes the area contacting each
bogie 208 and 210, drive wheel 204 and the surface 206. With more
contact area, the traction unit 22 has more traction. The bogie
assembly 202 overcomes obstacles conventional wheels normally can
not by placing a portion of the belt 212 on the obstacle and
allowing the drive wheel 204 to climb up the belt 212 much like a
tank going over a fallen tree whose diameter is greater than any of
the tanks wheels.
[0060] Referring to FIG. 7A, in one embodiment, a wishbone link 218
connects the actuator 214 to the two bogie links 216a and 216b. In
this arrangement the bogies 208 and 210 do not pivot about the
drive wheel 204 independently of each other. Referring to FIG. 7B,
in another embodiment, each bogie link 216a and 216b has an
actuator 214 connected to it, which allows each bogie 208 and 210
to pivot independently about the drive wheel 204. This allows an
operator to place a bogie 208 or 210 against the surface 206 and
create additional traction without placing the other bogie against
the surface such as when the other bogie is damaged or prevented
from contacting the surface.
[0061] FIG. 8 is a block diagram of the control system 28 in FIG. 1
according to an embodiment of the invention. The control system 28
automatically controls the various components on the traction unit
22 (FIG. 1) and also allows an operator to control the unit 22. The
blocks identified by a name ending with the same number refer to
components associated with each other in a common frame section
68a-68d (FIG. 2). For example, the extension or retraction of an
adherence member in one frame section is controlled by the
adherence member control valve (AMCV1) and the return mechanism
that moves the same adherence member is controlled by the return
mechanism control valve (RMCV1). Although, the following discusses
the control system by referring to the components common to a
single frame section, the discussion applies to the other
components common to the other frame sections.
[0062] Referring to FIG. 8, in one embodiment the control system 28
includes a micro-processor (MP) 220 that receives signals from an
operator (OP), obstruction and vacuum sensors (OS1 and VS1) 222a
and 224a, a limit switch (LS1) 226a and an encoder (EN1) 228a
directly and via a controller (CON) 230, and instructs the valves
(suction-cup valve, SCV1, adherence-member control valve, AMCV1,
high/low-pressure control valve, HLPCV1, return-mechanism control
valve, RMCV1, and lift control valves, LCVA and LCVB, if
applicable) 126a-150a and 232 and 234, wheel-motor and
steering-motor drivers (WMD1 and SMD1) 236a and 238a and wheel and
steering motors (WM1 and SM1) 240a and 242a in response to signals
it receives. In one embodiment, the system 28 may automatically
control the components of the traction unit 22 without receiving
instructions from an operator. In other embodiments, the control
unit 28 may control some or all of the components of the traction
unit 22 from instructions it receives from an operator.
[0063] Still referring to FIG. 8, the MP directs the operation of
an adherence member 46a (FIG. 1) as follows. At a first moment in
the cycle (the first moment is not necessarily first but simply
picked as an arbitrary first moment for discussion purposes) the
adherence member 46a hangs above the surface in its return position
and the MP 220 instructs the AMCV1 148a and the HLPCV1 146a to
pressurize the adherence member 46a to extend the cup 54a (FIG. 1).
Next, the MP 220 waits for the VS1 154a to signal the suction cup's
attachment to the surface by signaling an increase in negative
pressure. Once this signal is received, the MP 220 instructs the
AMCV1 148a and HLPCV1 146a to pressurize the adherence member to
retract the cup 54a and thus pull the wheels 56a-56d (FIG. 1)
against the surface. The frame 42 (FIG. 1) now moves relative to
the adherence member 46a, which eventually trips a LS1 226a that
defines the soft limit 94 (FIG. 2). The MP 220 records this event
and compares the timing of this event against other current similar
events by the other adherence members 46b-46d in the traction unit
22. If another event occurred prior to this one, the MP 220 will
release the other adherence member 46b-46d that caused the event
from the surface before releasing the adherence member 46a.
Otherwise, the MP 220 instructs the SCV1 150a to pressurize the
suction cup 54a to a pressure greater than atmospheric pressure to
release the adherence member 46a. Immediately after this, typically
a fraction of a second later, the MP 220 instructs the RMCV1 144a
to pressurize the return mechanism 48a (FIG. 1) to move the
adherence member 46a to the return position. As previously
discussed, in one embodiment the return mechanism 48a operates for
approximately 3/4 of second at which time the MP instructs the
RMCV1 144a to pressurize the mechanism 48a to stop moving the
member 46a.
[0064] Still referring to FIG. 8, in one embodiment the MP 220
coordinates the attachment and release of the adherence members
46a-46d to the surface such that the traction unit 22 has at least
one adherence member 46a-46d attached to the surface at any give
time while it traverses the surface. If the MP 220 determines that
the release times of all the adherence members 46a-46d are
converging to one point in time, the MP 220 will pause the suction
cup extension of one two or three adherence members 46a-46d as the
traction unit 22 continues to move across the surface.
Alternatively, the MP 220 can halt the movement of the traction
unit 22 across the surface and move the timing of one, two or three
adherence members 46a-46d to various positions within their
attachment and release cycle.
[0065] Still referring to FIG. 8, in one embodiment, the MP 220
also directs the operation of the trucks 50a-50d as follows. The MP
220 receives and analyzes information from the controller (CON) 230
and operator, and instructs the CON 230 accordingly. The CON 230
then locally directs the wheel motor driver (WMD1) 236a and
steering motor driver (SMD1) 238a from signals received from the
encoder (EN1) 228a. The WMD1 236a controls the operational
parameters of the wheel motor (WM1) 240a such as power and speed.
The SMD1 238a controls the operational parameters of the steering
motor (SM1) 242a such as turning the wheels 56 a(FIG. 1). The EN1
228a communicates positional data of the traction unit 22 to the
CON 230, which the CON 230 then compares with the instructions
received from the MP 220 and instructs the motor drivers 236a and
238a accordingly. In addition, if an adherence member 46a-46d
contacts a hard limit 92 (FIG. 2), the MP 220 can stop the WM1 240a
to prevent scrubbing and then move the adherence member 46a to a
return position.
[0066] Still referring to FIG. 8, if multiple traction units 22 are
combined to form a train (discussed in conjunction with FIGS. 10,
11 and 13), the control system will typically include a master
micro-processor (MSTRMP) 240 to coordinate the operation of the MPs
220 of each traction unit 22. Alternatively, the MSTRMP 240 may
replace the individual MPs 220 and the operator would then control
the train via the MSTRMP 240. In response to the obstruction sensor
(OS1) 222a notifying the MP 220 of an obstruction, inclination or
declination, either the MSTRMP 240 or MP 220 instructs the link
control valve (LCVA) 232 to pressurize the link actuator
accordingly (discussed in greater detail in conjunction with FIGS.
10 and 11). In addition, and as previously discussed herein, the MP
220 may also monitor the orientation of the adherence member 46a
relative to gravity with a conventional inclinometer or
accelerometer, and adjust the vacuum within the suction cup 54a
accordingly.
[0067] FIGS. 9A-9F are views of the traction unit 22 of FIG. 1
performing three types of turns according to an embodiment of the
invention. FIGS. 9A and 9B show the traction unit 22 performing a
standing turn. FIGS. 9C and 9D show the traction unit 22 performing
a pivot turn. FIGS. 9E and 9F show the traction unit 22 performing
a radius turn.
[0068] Referring to FIGS. 9A and 9B, the standing turn allows an
operator to change the direction of the traction unit 22 without
the wheels 56a-56d of the trucks 50a-50d touching the surface 242.
This type of turn allows the traction unit 22 to change directions
without scrubbing--abrading the surface 242 as the wheels 56a-56d
attempt to change the unit's direction of travel--the surface 242
and without changing its alignment relative to the surface 242.
Scrubbing often produces scratches on a surface, which can
cosmetically or structurally damage a surface, and becomes more
prevalent the slipperier a surface becomes. Maintaining the same
alignment is important for some types of work or inspection
applications.
[0069] Still referring to FIGS. 9A and 9B, to perform a standing
turn, the MP 220 (FIG. 8) or operator instructs the adherence
members 46a-46d (46c and 46d not shown) to attach their suction
cups 54a-54d (54c and 54d not shown) if the cups 546-54d are not
already attached to the surface 242. Once the cups 54a-54d are
attached, the adherence members 46a-46d further extend their cups
54a-54d against the surface 242. This causes the wheels 56a-56d
(56c and 56d not shown) of the trucks 50a-50d (50c and 50d not
shown) to lift away from the surface 242. Next, the operator or MP
220 turns the wheels 56a-56d of the trucks 50a-50d, and then
retracts the suction cups 54a-54d causing the traction unit's
turned wheels 56a-56d to again contact the surface 242.
[0070] Although the standing turn is described and shown as turning
all the wheels 56a-56d of the traction unit 22 to point in the same
direction, the wheels 56a-56d may be turned to point in different
directions.
[0071] Referring to FIGS. 9C and 9D, the pivot turn allows the
traction unit 22 to rotate about any point within the traction unit
22 without traversing the surface (not shown). To accomplish this
turn the operator or MP 220 can instruct two adjacent wheel motors
240a and 240b to drive their corresponding wheels 56a and 56b
forward while instructing the remaining wheel motors 240c and 240d
to drive their corresponding wheels 56c and 56d in the opposite
direction, as shown in FIG. 9C. Alternatively, the operator or MP
220 can instruct all the steering motors (not shown) to turn their
corresponding wheels 56a-56d as shown in FIG. 9D and instruct the
wheel motors 240a-240d to drive the wheels 56a-56d in the
appropriate direction.
[0072] Referring to FIGS. 9E and 9F, the radius turn allows the
traction unit 22 to rotate about a point outside the traction unit
22 as the unit 22 traverses a surface (not shown). The turn shown
in FIG. 9E is similar to a conventional car turning right around a
corner and causes the turned wheels 56a and 56c to scrub the
surface. The turn shown in FIG. 9F typically does not cause the
wheels 56a-56d to scrub the surface. However, to perform this
radius turn without scrubbing any of the wheels 56a-56d on the
surface, the turn radius and speed of the outside wheels 56a and
56c must be greater than the turn radius and speed of the inside
wheels 56b and 56d.
[0073] FIGS. 10 and 11 are side views of three traction units
22a-22c of FIG. 1 linked together to form a train 250 according to
an embodiment of the invention. FIG. 10 shows the train 250
including two link assemblies 252a and 252b and traversing up an
incline. FIG. 11 shows the train of FIG. 10 traversing a
decline.
[0074] Referring to FIGS. 10 and 11, in one embodiment, the train
250 includes a first link assembly 252a operable to pivot the a
first or lead traction unit 22a up or down relative to a second or
middle traction unit 22b, and a second link assembly 252b operable
to pivot a third or trail traction unit 22c up or down relative to
the middle traction unit 22b. The train 250 also includes
obstruction sensors 254a-254h mountable to each unit 22a-22c and
operable to sense obstructions on the surface 256 such as gaps,
steps or protrusions, and any substantial inclination or
declination in the surface 256 about to be traversed. The first
link assembly 252a includes a pivot link 258a pivotally attached at
one end to the rear 260a of the lead unit 22a and pivotally
attached at the other end to the front 262b of the middle unit 22b.
The link assembly 252a also includes two actuator links 264a and
264b that are pivotally attached to each other at one of their ends
and attached to either the rear 260a of the lead unit 22a or front
262b of the middle unit 22b, and a link actuator 266a that is also
pivotally linked to the middle unit 22b and the actuator link 264b.
Conventional techniques such as bolts insertable through bushings
or ball, needle or journal bearings, can be used to pivotally
attach the links 258a, 264a and 264b and the actuator 266 to each
other as well as corresponding traction units 22a-22c. The second
link assembly 252b is configured similar to the first link assembly
252a. The obstruction sensors are typically conventional proximity
sensors using sound or light to sense impending obstructions and
notify the micro-processor 220 (FIG. 8).
[0075] Still referring to FIGS. 10 and 11, In one embodiment, the
train 250 also includes tools 267a and 267b mounted to traction
units 22a and 22c. The tools 267a and 267b can be any conventional
tool such as an inspection probe 267c or arm with a claw 267a as
desired.
[0076] Still referring to FIG. 10, when obstruction sensor 254a
senses a substantial inclination, the sensor 254a notifies the MP
220. The MP 220 then instructs the adherence members 46a-46d of the
lead unit 22a to release the surface 256 as previously discussed in
conjunction with FIG. 5. Next, the MP 220 instructs the pneumatic
system 24 of FIG. 5 to supply pressurized air to the link actuator
266 to pivot the lead unit 22a above the inclined surface 252. Next
the MP 220 extends the suction cups 54a-54d of the adherence
members 46a-46d of the lead unit 22a and instructs the middle and
trail units 22b and 22c to propel the lead unit 22a to the inclined
surface 252. Once the suction cups 54a-54d contact the surface 252
and establish a seal, the MP 220 instructs the lead unit 22a to
propel the train 250 up the incline.
[0077] Referring to FIG. 11, the same operational sequence
previously discussed is used to propel the train around and down a
90 degree decline. But, when the traction unit 22a descends the
decline the middle and trail units 22b and 22c retard the speed of
the train 250 as it moves down the decline.
[0078] Still referring to FIG. 11 the sensors 254a-254h can also be
made to sense a gap (not shown) deep and wide enough to typically
prevent the train 250 from traversing the surface 256. When such a
gap is encountered the operational sequence previously described is
used, but in this instance the link actuator 266a suspends the lead
traction unit 22a over the gap as the middle and trail units 22b
and 22c propel the train 250. Then, once the obstruction sensor
254a notifies the MP 220 (FIG. 8) that the lead unit 22a has passed
the gap, the MP 220 instructs the link actuator 266a to lower the
lead unit 22a back to the surface 256. To suspend and propel the
middle unit 22b over the gap, the adherence members 46a-46d of the
middle unit 22b are released from the surface and both link
actuators 266a and 266b suspend the middle unit 22b over the gap by
preventing one or more of the middle unit's trucks 50a-50d from
dropping into the gap. In other embodiments the link actuators 266a
and 266b may include locks operable to prevent the middle unit 22b
from dropping into the gap.
[0079] Although, the train 250 is shown and described as formed by
linking the traction units 22a-22c front to rear with respect to
each other, the train 250 can be formed by linking the units
22a-22c side to side with respect to each other. Furthermore the
link assemblies 252a and 252b may attach to one or more of the
wheel axles 200 (FIG. 6) of the different traction units 22a-22c or
a combination of the wheel axles 200 and frame 42 (FIG. 1). Also,
two or more link assemblies 252a and 252b may attach one of the
units 22a-22c to another unit 22a-22c instead of merely one as
shown and discussed above.
[0080] FIG. 12 is a top view of a traction unit 270 including six
adherence members 46a-46f according to an embodiment of the
invention. In one embodiment, the additional adherence members
46e-46f may be operable to secure the traction unit 270 to the
surface as the unit 270 traverses the surface (not shown). In such
an arrangement, the additional adherence members 46e-46f cycle
through an attachment, release and return operation similar to
operations previously discussed in conjunction with FIGS. 1, 5 and
8. Furthermore, in this arrangement the cycling of the additional
adherence members 46e-46f are typically monitored by the MP 220
(FIG. 8) with respect to the other adherence members 46a-46d to
help ensure at least one adherence member 46a-46f is attached to
the surface while the unit 270 traverses the surface.
[0081] In another embodiment, the additional adherence members
46e-46f may be operable to merely help attach the traction unit 270
to the surface while the unit 270 is stationary. For example, if
the unit 270 is suspended upside down or carries a payload
including a drill to work on a specific location of the surface,
the unit 270 may require more force to secure it to the surface
than the other adherence members 46a-46d can provide alone. In such
a situation, the additional adherence members 46e-46f may be
attached to the frame 42 such that they do not move relative to the
frame as the unit 270 traverses a surface. In such an arrangement,
the additional adherence members 46e-46f are typically suspended
above the surface as the unit 270 moves to the work location. Once
at the location the operator or MP 220 typically instructs the
additional adherence members 46e-46f to extend their suction cups
54a-54f to the surface and form a seal similar to the other
adherence members 46a-46d. Thus, the unit 270 is more securely
attached to the surface. Furthermore, on inclines where the trucks
50a-50d are not able to prevent the unit 270 from unwanted movement
down the incline, the additional adherence members 46e-46f can help
prevent the unit 270 from moving.
[0082] Although two additional adherence members 46e-46f are shown,
more may be added to further secure the traction unit 270 to the
surface.
[0083] FIG. 13 is a top view of two trains of traction units linked
side by side according to another embodiment of the invention.
Train 272 and train 274 are similar to the train 250 discussed in
conjunction with FIGS. 10 and 11 except each traction unit 270
includes six adherence members 46a-46f like the unit 270 discussed
in conjunction with FIG. 12. Link assemblies 274 are similar to the
link assemblies 252a and 252b discussed in conjunction with FIGS.
10 and 11 and attach train 272 to train 274. By linking two trains
272 and 274 side by side, a large and heavy payload can be easily
moved across a surface and/or secured to a work location on the
surface.
[0084] FIG. 14 is a perspective view of the traction unit 22 of
FIG. 1 tethered to a boom 276 as it traverses an airplane fuselage
278. Tethering the unit 22 to the boom 276 allows the operator of
the unit 22 to place the unit 22 near a desired location on the
airplane fuselage 278 or other surface as applicable and have the
unit 22 traverse a short distance to the desired location instead
of placing the unit 22 on the wing 280 or bottom 282 of the
fuselage 278--typical locations on the airplane within easy,
unassisted reach of the operator--and waiting for the unit 22 to
travel a long distance to the desired location. In addition,
tethering the unit 22 to the boom 276 allows the operator to
prevent costly damage to other structures of the airplane like the
wing 280, window 284, or fuselage 278 if the traction unit 22
should happen to fall from the fuselage 278.
[0085] The umbilical cord 32 connects the traction unit 22 to the
pneumatic system 24 (FIG. 1) and control system 28 (FIG. 1) as
previously discussed in conjunction with FIG. 1 and includes a
tether 40 (FIG. 1) which can be any conventional material strong
enough to catch the unit 22 in free fall and can be attached to the
boom 276 and traction unit 22 using conventional techniques such as
a bolt or a hook. The anti-swing rope 286 prevents the unit 22 from
swinging back into the fuselage 278 by automatically retracting
should the traction unit 22 happen to fall. The boom 276 can be any
conventional boom or similar to the boom discussed in U.S. Pat. No.
4,417,424, which is incorporated by reference.
[0086] FIG. 15 is a perspective view of two traction units 22a and
22b of FIG. 1 tethered to the top of a building and working
cooperatively. The tethers 40 (FIG. 1) in the umbilical cords 32
prevent costly damage to the building and people below the traction
units 22a and 22b should the traction units 22a and 22b happen to
fall. The traction units 22a and 22b support the beam 288 which in
turn supports a window washing tool 290 that can be moved along the
beam 288 in the direction of either unit 22a and 22b. In this
arrangement the traction units 22a and 22b can wash more than one
window 292 without moving to each window 290. In other embodiments,
the beam 288 may support other tools such as an inspection probe or
drill.
[0087] From the foregoing it will be appreciated that, although
specific embodiments of the invention have been described herein
for purposes of illustration, various modifications may be made
without deviating from the spirit and scope of the invention.
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