U.S. patent application number 11/985346 was filed with the patent office on 2008-06-12 for versatile endless track for lightweight mobile robots.
Invention is credited to Stephen C. Jacobsen.
Application Number | 20080136254 11/985346 |
Document ID | / |
Family ID | 39414961 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080136254 |
Kind Code |
A1 |
Jacobsen; Stephen C. |
June 12, 2008 |
Versatile endless track for lightweight mobile robots
Abstract
A versatile endless track system for a lightweight robotic
vehicle is disclosed. The versatile endless track system includes a
flexible track configured for threading about a plurality of track
supports of the lightweight robotic vehicle. A plurality of
traction pads including at least two different types of traction
pads is disposed along the endless track. The different types of
traction pads provide different ground-interfacing profiles
designed to provide traction with respect to ground surfaces having
different traction properties. Optionally, traction pads can be
removable, allowing the versatile endless track to be reconfigured.
A method of configuring a versatile endless track is also
disclosed.
Inventors: |
Jacobsen; Stephen C.; (Salt
Lake City, UT) |
Correspondence
Address: |
THORPE NORTH & WESTERN, LLP.
P.O. Box 1219
SANDY
UT
84091-1219
US
|
Family ID: |
39414961 |
Appl. No.: |
11/985346 |
Filed: |
November 13, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60858804 |
Nov 13, 2006 |
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Current U.S.
Class: |
305/165 |
Current CPC
Class: |
B62D 55/27 20130101;
Y10S 180/901 20130101; B62D 55/28 20130101 |
Class at
Publication: |
305/165 |
International
Class: |
B62D 55/24 20060101
B62D055/24 |
Claims
1. A versatile endless track usable by a lightweight mobile robot,
the track comprising: a flexible track configured for threading
about a plurality of track supports, a changing ground-engaging
portion of the flexible track exposed for engagement with a ground
surface as the flexible track is rotated around the plurality of
track supports; and a plurality of traction pads disposed along the
flexible track, wherein at least two different types of traction
pad are included, each type of traction pad having a different
ground-interfacing profile designed to provide traction with
respect to ground surfaces having different traction properties,
and wherein sufficient traction pads of each type are included so
that at least one traction pad of each type is present on the
ground-engaging portion of the flexible track at all times.
2. The track of claim 1, wherein the flexible track comprises an
elastic belt to which the plurality of traction pads are
affixed.
3. The track of claim 1, wherein the flexible track comprises a
plurality of cables on which the plurality of traction pads are
threaded.
4. The track of claim 1, wherein the flexible track is configured
to provide a friction drive interface to at least one of the
plurality of track supports.
5. The track of claim 1, wherein the plurality of traction pads are
removably attached to a corresponding plurality of receptacles
disposed on the flexible track.
6. The track of claim 5, wherein the traction pads snap into the
corresponding receptacles.
7. The track of claim 1, wherein at least three different traction
pad types are included.
8. The track of claim 1, wherein each traction pad type is
optimized to provide traction with respect to a ground surface
having different traction properties.
9. The track of claim 8, wherein the traction pad types are
optimized to provide traction when loaded by a lightweight mobile
robot weighing less than 100 pounds.
10. The track of claim 1, wherein a first traction pad type is
designed to provide traction on a soft, friable surface and a
second traction pad type is designed to provide traction on a hard,
slippery surface.
11. The track of claim 1, wherein a first traction pad type is
designed to provide traction on a firm surface and a second
traction pad type is designed to provide traction on a soft
surface.
12. The track of claim 1, wherein a first traction pad type is
designed to provide traction on a solid surface and a second
traction pad type is designed to provide traction on a liquid
surface.
13. The track of claim 1, wherein at least one traction pad type
comprises a substantially flat ground-interfacing portion having a
high coefficient of friction and a second traction pad type
comprises a projecting cleat.
14. The track of claim 1, wherein at least one traction pad type
comprises a projecting cleat and a second traction pad type
comprises a water paddle.
15. The track of claim 1, wherein each of the traction pad types
are chosen from the group of traction pad types consisting of: a
sticky pad, a bar cleat, a spike, a suction cup, and a water
paddle.
16. A method of configuring an endless track with traction pads
comprising providing an endless track suitable for mounting on a
lightweight robotic vehicle; mounting the endless track on the
lightweight robotic vehicle so that a portion of the endless track
is exposed for interfacing to a ground surface; and attaching a
plurality of traction pads to the endless track in an alternating
sequence of at least two different traction pad types so that at
least one of each type of traction pad is within the exposed
portion of the endless track when the lightweight robotic vehicle
is operated.
17. The method of claim 16 further comprising selecting the at
least two different traction pad types from a predefined assortment
of traction pad types, wherein the at least two traction pad types
are selected to correspond to a planned operating environment.
18. The method of claim 16 further comprising replacing at least
one of the plurality of traction pads with a traction pad of a
different type.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/858,804, filed Nov. 13, 2006 in the United
States Patent and Trademark Office, and entitled, "Versatile
Endless Track for Lightweight Mobile Robots," which application is
incorporated by reference in its entirety herein.
FIELD OF THE INVENTION
[0002] The present invention relates to small, unmanned ground
robotic vehicles. More particularly, the present invention relates
to a versatile endless track for a lightweight robotic vehicle.
BACKGROUND OF THE INVENTION AND RELATED ART
[0003] Unmanned robotic vehicles can be deployed in a variety of
applications and environments, including for example, search and
rescue, military operations, and industrial operations. Unmanned
robotic vehicles can help to avoid the need to expose humans to
hazardous environments, such as unstable buildings, military
conflict situations, and chemically, biologically, or nuclear
contaminated environments.
[0004] Unmanned robotic vehicles face many challenges when
attempting mobility. Terrain can vary widely, including for
example, bumpy or smooth surfaces, firm or soft ground, loose and
shifting materials, etc. For small robotic vehicles, the challenges
become even greater. A vehicle optimized for operation in one
environment may perform poorly in other environments.
[0005] The use of endless tracks are known to provide a good
compromise which allows a robotic vehicle to accommodate a large
variation in terrain types while maintaining relatively good
traction and maneuverability. For example, tank-like vehicles using
a pair of parallel endless tracks can provide high stability in
some environments.
[0006] For small robotic vehicles, however, the traction
performance of endless tracks can be less than desired. In part,
traction performance for small robotic vehicles can be poor because
the robotic vehicle is relatively lightweight. Little downward
force is applied to the endless track, resulting in reduced
frictional forces between the endless track and the ground
surface.
SUMMARY OF THE INVENTION
[0007] The present invention includes a versatile endless track
system for a lightweight robotic vehicle that helps to overcome
problems and deficiencies inherent in the prior art. In one
embodiment, the versatile endless track system includes a flexible
track on which a plurality of traction pads are disposed. At least
two different traction pad types are included, where each type of
traction pad has a different ground-interfacing profile designed to
provide traction with respect to ground surfaces having different
traction properties.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will become more fully apparent from
the following description and appended claims, taken in conjunction
with the accompanying drawings. Understanding that these drawings
merely depict exemplary embodiments of the present invention, they
are, therefore, not to be considered limiting of its scope. It will
be readily appreciated that the components of the present
invention, as generally described and illustrated in the figures
herein, can be arranged and designed in a wide variety of different
configurations. Nonetheless, the invention will be described and
explained with additional specificity and detail through the use of
the accompanying drawings in which:
[0009] FIG. 1 illustrates a perspective view of a versatile endless
track mounted on a lightweight robotic vehicle according to an
embodiment of the present invention;
[0010] FIG. 2 illustrates a perspective view of a versatile endless
track in accordance with another embodiment of the present
invention;
[0011] FIG. 3 illustrates a perspective view of a versatile endless
track according to another embodiment of the present invention;
[0012] FIG. 4 illustrates a perspective view of a versatile endless
track according to yet another embodiment of the present
invention;
[0013] FIG. 5 illustrates a perspective view of one type of
traction pad according to an embodiment of the present
invention;
[0014] FIG. 6 illustrates a perspective view of another type of
traction pad according to an embodiment of the present invention;
and
[0015] FIG. 7 illustrates a flow diagram of a method for
configuring an endless track with traction pads according to an
embodiment of the present invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0016] The following detailed description of exemplary embodiments
of the invention makes reference to the accompanying drawings,
which form a part hereof and in which are shown, by way of
illustration, exemplary embodiments in which the invention may be
practiced. While these exemplary embodiments are described in
sufficient detail to enable those skilled in the art practice the
invention, it should be understood that other embodiments may be
realized and that various changes to the invention may be made
without departing from the spirit and scope of the present
invention. Thus, the following more detailed description of the
embodiments of the present invention is not intended to limit the
scope of the invention, as claimed, but is presented for purposes
of illustration only and not limitation to describe the features
and characteristics of the present invention, to set forth the best
mode of operation of the invention, and to sufficiently enable one
skilled in the art to practice the invention. Accordingly, the
scope of the present invention is to be defined solely by the
appended claims.
[0017] The following detailed description and exemplary embodiments
of the invention will be best understood by reference to the
accompanying drawings, wherein the elements and features of the
invention are designated by numerals throughout.
[0018] In general, the environments faced by lightweight robotic
vehicle can be highly variable, as lightweight robotic vehicles may
be used indoors or outdoors, on land or water. The term "ground" is
thus used broadly within the present application to refer generally
to the surface on which the lightweight robotic vehicle is
operating, which can include ground, vegetation, road surface,
flooring, carpet, liquid surfaces, and the like. The highly
variable environment encountered by lightweight robotic vehicles
differs from that of traditional tracked vehicles, such as tanks or
earth working equipment, which typically operate in very limited
environments (e.g., outdoors on unprepared surfaces).
[0019] For example, earth working equipment often includes cleat
bars on the tracks to help provide traction in soft or slippery
conditions, such as mud or soft ground. The cleat bars sink into
and engage with the ground, helping to reduce slippage of the
tracks. Good performance is also obtained on hard ground, because
the weight of the equipment is sufficiently large to develop large
downward forces which translate into high friction (and thus
traction) for portions of the track in contact with the ground.
[0020] In contrast, a lightweight robotic vehicle is less able to
develop large downward force, and thus different approaches to
developing traction are required. Although one approach is to use
cleat profiles adapted for developing traction when lightly loaded,
such a solution is likely to only perform well over a relatively
narrow range of environmental conditions. For example, cleats might
perform well when the robotic vehicle is operated over a very soft
surface (e.g., sand or soil), but provide very little traction when
operated over a very hard, smooth surface (e.g., glass or polished
stone). Accordingly, a particular cleat or other traction device
configuration is often a compromise solution that performs well
over a relatively narrow range of surface conditions.
[0021] It has been recognized by the inventors of the present
invention that a versatile endless track can provide traction over
a wide range of conditions by including a number of different
traction pads of different ground-interfacing profiles on the
endless track. With reference to FIG. 1, shown is an illustration
of a versatile endless track, according to a first exemplary
embodiment of the present invention. The versatile endless track,
shown generally at 10, is mounted on a lightweight robotic vehicle
14, threaded about a plurality of track supports 12. The track
includes a flexible track 16. Disposed along the flexible track 16
are a plurality of traction pads 18. Different types 20, 22 of
traction pads are included, each traction pad type having a
different exposed ground-interfacing profile designed to provide
traction with respect to ground surfaces having different traction
properties.
[0022] An exposed portion 26 of the flexible track 16 engages with
the ground when the lightweight robotic vehicle is in operation. It
will be appreciated that the exposed portion is constantly changing
as the flexible track is rotated around the plurality of track
supports. Sufficient traction pads 18 of each type 20, 22 can be
included so that at least one traction pad of each type is present
on the exposed ground-engaging portion of the flexible track at all
times.
[0023] The flexible track 16 can be constructed in various ways.
For example, the flexible track can be a loop which is slid
laterally over the track supports 12. Alternately, the track can be
a long assembly which is threaded through the track supports after
which ends of the flexible track are attached together to form a
loop. The flexible track can be an elastic belt, for example of
rubber or other elastomeric material. As another example, the
flexible track can be two or more cables 19 on which the traction
pads are threaded as shown in FIG. 2 in accordance with another
embodiment of the present invention.
[0024] Generally, the lightweight robotic vehicle 14 includes a
drive unit which causes the versatile endless track 16 to rotate
about the track supports 12 providing propulsion of the lightweight
robotic. For example, one of the track supports can provide a
friction drive interface to the flexible track. Friction drive
interfaces provide a benefit in that the flexible track need not
include gear-like protrusions on the internal surface in order to
interface to the drive unit. Friction drive interface is possible
for lightweight robotic vehicles because the forces involved are
relatively low (as compared, for example, to large heavy vehicles
such as a tank or snowmobile).
[0025] Various ways of attaching the traction pads 18 to the
flexible track 16 are possible. For example, as shown in FIG. 2,
the traction pads can be threaded onto flexible track which is
formed from a plurality of cables 19. As another option, as shown
in FIG. 3 the traction pads may be integrally formed with the
flexible track, for example by molding the flexible track as single
assembly, in accordance with an embodiment of the present
invention. As another option, the traction pads may be formed of
different materials and attached to the flexible track by glue,
fasteners, and similar techniques. The traction pads may be
removable, allowing for easy replacement or changing of the types
of traction pads.
[0026] FIG. 4 illustrates a particular example of a technique for
attaching the traction pads 28, 29 to the flexible track 16 in
accordance with an embodiment of the present invention. The
flexible track includes a plurality of receptacles 30 into which
the traction pads can be inserted. For example, the traction pads
can slide or snap into the receptacles. The traction pads can have
a friction fit interface to the receptacle, allowing for manual
insertion and removal of the traction pads by a person. A friction
fit can be appropriate for the lightweight loading conditions of
small robotic vehicles because the forces placed on the traction
pad are relatively small. For example, lightweight robotic vehicles
generally weigh less than 100 pounds, and typically under 50
pounds, although some lightweight robotic vehicles can weight less
than 20 or even 10 pounds.
[0027] The traction pads 18 can be arranged in a sequential order,
for example as illustrated in FIG. 2, although this is not
essential. In other words, for three traction pad types A, B, and
C, the traction pads can be arranged in sequence A-B-C-A-B-C . . .
all the way around the flexible track. Alternately, the traction
pads can be arranged in different orders. For example, it may be
desirable to include more of one traction pad type than other
traction pad types due to differences in the traction provided.
Accordingly, the traction pads may be arranged in a sequence such
as A-A-A-B-C-A-A-A-B-C . . . where three traction pads of type A
are provided for each traction pad of type B and type C. For
example, FIG. 3 illustrates an alternate arrangement of different
types of traction pads. Of course, many other arrangements are
possible as will occur to one of skill in the art.
[0028] It is desirable that sufficient traction pads of each type
are included so that at least one traction pad of each type is
present on the ground-engaging portion of the flexible endless
track at all times. This can help to ensure that adequate traction
is provided at all times.
[0029] A versatile endless track 10 having two or more types of
traction pads 18 can provide improved traction for a lightweight
robotic vehicle 14 in a variety of conditions. Previously, endless
track configurations have generally presented a uniform
ground-interface profile that is a compromise design for a range of
surface conditions. In contrast, the versatile endless track can
include multiple traction pads, each traction pad type designed for
good performance under specific conditions. For example, different
types of traction pads can be defined by their differing
ground-interfacing profiles. The flexible track 16 can have two,
three, or more differing types of traction pads.
[0030] Various examples of traction pads will now be described,
although various other traction pads will occur to one of skill in
the art having possession of this disclosure. A first traction pad
type can be designed to provide traction on a soft, friable
surface. For example, FIG. 5 illustrates a traction pad 40 designed
to help spread the weight of the lightweight robotic vehicle over
an area to help avoid breaking the surface which could allow
slippage of the track. The traction pad includes a low-profile
projecting bar cleat 42 mounted on a substantially flat
ground-interfacing surface 44.
[0031] A second traction pad type can be designed to provide
traction on a hard, slippery surface. For example, FIG. 6
illustrates a sticky-pad 50 designed to provide a large, high
coefficient of friction surface. The sticky-pad has a substantially
flat ground-interfacing surface 52 which can include grit,
non-drying adhesive, or similar high coefficient of friction
material. Alternately, a traction pad design for use on a hard,
slippery surface can include one or more suction cups.
[0032] Various other traction pad types and profiles can be used,
including for example, flat pads (e.g., 20), cleats (e.g., 22),
spikes (e.g., 24), tread patterns (e.g., 25), saw tooth profiles
(e.g., 28) and water paddles (e.g., 29).
[0033] Because different traction pads are included on the
versatile endless track to accommodate different conditions, in one
embodiment the individual traction pad types may each be optimized
to provide traction with respect to a ground surface having
different traction properties. In other words, the individual
traction pad types need not be compromise designs designed for more
than one surface type. Thus, when designing a traction pad type for
operation in sand, as an example, the performance of the traction
pad in mud or hard ground may be ignored. This is possible because
multiple traction pad types are included on the versatile endless
track. When conditions are encountered for which one traction pad
type provides poor performance, other traction pad types are likely
to perform well. Thus, depending on the ground surface conditions,
one type of traction pads may provide most of the traction while
other types provide relatively little traction. Of course, the
individual traction pads can also be designed to accommodate a
range of surface conditions as well. Hence, great flexibility in
the versatile endless track is obtained.
[0034] Versatile endless tracks as described above can be helpful
in adapting the configuration of a lightweight robotic vehicle for
a particular task. For example, different types of traction pads
can be installed on a lightweight robotic vehicle depending on the
environmental conditions expected for a planned operating
environment of the lightweight robotic vehicle. A lightweight
robotic vehicle, which is expected to operate on both solid land
and on water, can include a mixture of paddle-type traction pads
and cleat-type traction pads. As another example, a lightweight
robotic vehicle that is expected to operate over a wide variety of
surface conditions might include three or more different traction
pad types, including for example, sticky-pads, short spikes, long
spikes, bar cleats, suction cups, and water paddles. With a
reconfigurable versatile endless track, where the traction pads are
easily removed and replaced, a virtually unlimited number of
different arrangements are possible.
[0035] FIG. 7 illustrates a method for configuring an endless track
with traction pads in accordance with an embodiment of the present
invention. The method, shown generally at 70, includes the step of
providing 72 an endless track suitable for mounting a lightweight
robotic vehicle. Various materials and configurations of endless
tracks are described above. A next step of the method is mounting
74 the endless track on the lightweight robotic vehicle so that a
portion of the endless track is exposed for interfacing to a ground
surface. Various techniques for mounting the endless track on the
lightweight robotic vehicle are described above. The method also
includes the step of attaching 76 a plurality of traction pads to
the endless track so that at least one of each type of traction pad
is included within the exposed portion of the endless track when
the lightweight robotic vehicle is operated. For example, the
traction pads may be placed in a sequential order as described
above.
[0036] The method can include replacing at least one of the
plurality of traction pads with a traction pad of a different type.
For example, the lightweight robotic vehicle can be reconfigured
for a different operating environment by replacing one type of
traction pads with a different type of traction pads. As a
particular example, consider a first configuration where the
traction pads types consist of alternating suction cups and spikes,
designed to provide good traction on both a smooth, hard surface
and a soft, penetrable surface. The spikes might be removed and
replaced with sticky pads to provide good traction on both smooth,
hard surfaces and rough, hard surfaces. As another example, a first
configuration having two traction pad types might be rearranged to
include a third traction pad type to provide increased
versatility.
[0037] Summarizing and reiterating to some extent, a versatile
endless track system in accordance with embodiments of the present
invention provides flexibility in the configuration of an endless
track for a lightweight robotic vehicle. A mix of different
traction pad types can be included which correspond to a range of
expected environments, where individual traction pads provide good
traction properties under different conditions. Traction pads can
be removed and replaced with different traction pad types to adapt
the lightweight robotic vehicle to different conditions.
[0038] The foregoing detailed description describes the invention
with reference to specific exemplary embodiments. However, it will
be appreciated that various modifications and changes can be made
without departing from the scope of the present invention as set
forth in the appended claims. The detailed description and
accompanying drawings are to be regarded as merely illustrative,
rather than as restrictive, and all such modifications or changes,
if any, are intended to fall within the scope of the present
invention as described and set forth herein.
[0039] More specifically, while illustrative exemplary embodiments
of the invention have been described herein, the present invention
is not limited to these embodiments, but includes any and all
embodiments having modifications, omissions, combinations (e.g., of
aspects across various embodiments), adaptations and/or alterations
as would be appreciated by those in the art based on the foregoing
detailed description. The limitations in the claims are to be
interpreted broadly based the language employed in the claims and
not limited to examples described in the foregoing detailed
description or during the prosecution of the application, which
examples are to be construed as non-exclusive. For example, in the
present disclosure, the term "preferably" is non-exclusive where it
is intended to mean "preferably, but not limited to." Any steps
recited in any method or process claims may be executed in any
order and are not limited to the order presented in the claims.
Means-plus-function or step-plus-function limitations will only be
employed where for a specific claim limitation all of the following
conditions are present: a) "means for" or "step for" is expressly
recited in that limitation; b) a corresponding function is
expressly recited in that limitation; and c) structure, material or
acts that support that function are described within the
specification. Accordingly, the scope of the invention should be
determined solely by the appended claims and their legal
equivalents, rather than by the descriptions and examples given
above.
* * * * *