WO2018154424A1

WO2018154424A1 - Robotic limb arrangement and associated robot

Info

Publication number: WO2018154424A1
Application number: PCT/IB2018/050998
Authority: WO
Inventors: Andries Hermann Leuschner
Original assignee: Induna Robotics (Pty) Ltd
Priority date: 2017-02-21
Filing date: 2018-02-19
Publication date: 2018-08-30
Also published as: ZA201906101B

Abstract

A mobile robot(10) which includes a body(12) and a plurality of articulated limb arrangements(14) connected to the body at spaced- apart positions, each limb arrangement includes a plurality of links, each of which is connected to an adjacent link, at least one of the links(26) being angularly displaceable relative to the link to which is connected about an axis through at least 360°(32).

Description

ROBOTIC LIMB ARRANGEMENT AND ASSOCIATED ROBOT

FIELD OF THE INVENTION

This invention relates to a robot and to a robotic limb arrangement. BACKGROUND OF THE INVENTION

The field of robotics includes fixed robots and mobile robots. Fixed robots are fixed in position and include one or more displaceable limbs which are typically connected to a fixed mounting structure. The current technology relates to mobile robots which are displaceable and are commonly used to navigate and perform tasks in environments which are relatively spacious and have regular or smooth surfaces, e.g. in underground pipes or other tubular structures. The manner in which robots travel along such surfaces typically does not present a problem. An example of such a robot is described in EP 2099672.

On the other hand, effective and/or efficient robot movement may be challenging in cases where robots are required to travel through environments having irregular or obstacle-strewn surfaces and which do not provide much room for manoeuvring. Examples of such environments are deep level hard rock mines and caves.

A variety of mobility configurations have been developed to traverse difficult terrain. These include numerous forms of legs, wheels and tracks. Examples of these configurations are shown in EP 2657125, US 4977971, US 4565487, WO 2015080788, US 7793743, US 8374722, US 5857533, US 7654348 and US 7017687. I n the I nventor's experience, however, existing mobility configurations of which he is aware do not always permit robots to navigate difficult terrain and confined spaces effectively or efficiently. For instance, the Inventor has found that when existing mobility configurations are employed, a robot may be unable to climb to higher ground when facing a walled cul-de-sac, thereby becoming trapped.

In light of the above, the Inventor has identified a need for a robotic limb arrangement which provides a robot with enhanced manoeuvrability, specifically for climbing over obstacles, climbing from lower areas to higher areas (and vice versa), crawling through low and narrow openings, traversing gaps or holes in a surface and traversing uneven or slippery surfaces.

The present invention aims to address the abovementioned need, at least to some extent.

SUMMARY OF THE INVENTION

Broadly, according to one aspect of the invention there is provided a mobile robot which includes

a body; and

at least one articulated limb arrangement attached to the body, wherein the limb arrangement includes a plurality of links, each of which is connected to an adjacent link, at least one of the links being angularly displaceable relative to the link to which it is connected about an axis through at least 360°.

According to another aspect of the invention there is provided an articulated limb arrangement for a mobile robot, the limb arrangement including a plurality of links, each of which is connected to an adjacent link, at least one of the links being angularly displaceable relative to the link to which it is connected about an axis through at least 360°.

The articulated limb arrangement includes:

a first link which is secured to the body for angular displacement about a first axis; a second link which is secured to the first link for angular displacement about a second axis; and

a third link which is rotatably secured to the second link for rotation about a third axis, wherein the third link is rotatable about the third axis through at least 360°.

The third axis may be spaced from the second axis and the third link may be rotatable about the third axis beyond 360°. The third link may be continuously rotatable about the third axis.

The first link is angularly displaceable about the first axis through at least 270°.

The second link may be angularly displaceable about the second axis through at least 270°. In one embodiment, the second link may be angularly displaceable about the second axis through at least 300°.

The second axis may be perpendicular to the first axis.

The third axis may be perpendicular to the first axis.

The second axis and the third axis may be generally parallel.

The first link, the second link and the third link may be elongate and may each have a proximal end and a distal end with a longitudinal axis being defined between the proximal end and the distal end of each of the links.

The first link may be secured to the body at the proximal end of the first link to define a first articulation. The first axis may be defined at the first articulation and extends perpendicular to the longitudinal axis of the first link.

The distal end of the first link may be secured to the proximal end of the second link to define a second articulation. The second axis may be defined at the second articulation and extend laterally to the longitudinal axes of the first link and the second link.

The distal end of the second link may be secured to the proximal end of the third link to define a third articulation. The third axis may be defined at the end of the third articulation and extend laterally to the longitudinal axes of the second link and the third link.

The second link may define at least part of a longitudinal opening shaped and dimensioned to allow the third link to pass through the opening, thereby to permit the third link to rotate beyond 360°. In a preferred embodiment the opening is a composite opening defined by the first link and the second link.

In another embodiment the longitudinal axes of the second link and the third link are off set to permit the third link to rotate past the second link.

The third link, particularly the distal end thereof, may be configured to grip terrain to be traversed. The third link may be provided with gripping elements, e.g. pods or spikes.

The third link is preferably longer than the second link.

Displacement of one or more of the links may be provided by at least one motor drivingly connected to the one or more links, e.g. an electric motor. The limb arrangement may thus include one or more electric motors. In one embodiment, a dedicated electric motor is drivingly connected to each link.

Displacement of one or more of the links may be provided by one or more crank mechanisms. The crank mechanism may include a linear actuator and a crank.

The limb arrangement may be powered by a pressurised fluid, e.g. hydraulically. One or more rotary actuators, e.g. hydraulic rotary actuators, may be used to permit angular displacement of the links. The limb arrangement may include a fourth link. The fourth link may be located between the first link and the body of the robot, i.e. the first link may be secured or securable to the body via the fourth link. The fourth link may be arranged for angular displacement about a fourth axis. The fourth link may have a proximal end secured or securable to the body to define a fourth articulation. The fourth link may have a distal end secured or securable to the proximal end of the first link to define the first articulation.

I n some embodiments, the limb arrangement may include more than four links.

The body may define an operative horizontal axis and an operative vertical axis. The first axis may be generally parallel to the vertical axis. The second axis and/or the third axis may be generally horizontal.

The robot may include a mounting formation by which the first link is secured to the body. The mounting formation may be a bracket extending or protruding from a side or end of the body. The bracket may be complementally shaped to a proximal end of the first link.

The robot may include four or more limb arrangements connected to the body at spaced-apart positions. The limb arrangements may be equidistant from a central axis of the body. The central axis may be the operative vertical axis of the body. Each limb arrangement may be a limb arrangement of the type described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying conceptual drawings.

I n the drawings:

FIG. 1 shows a first three-dimensional view of an embodiment of a robot according to the invention; FIG. 2 shows a second three-dimensional view of the robot of FIG. 1;

FIG. 3 shows a top view of the robot of FIG. 1;

FIG. 4 shows a side view of the robot of FIG. 1;

FIG. 5 shows a three-dimensional view of an embodiment of a limb arrangement according to the invention;

FIG. 6 shows a top view of the limb arrangement of FIG. 5;

FIG. 7 shows a side view of a further embodiment of a limb arrangement according to the invention;

FIG. 8 shows a three-dimensional view of the limb arrangement of FIG. 7;

FIG. 9 shows a first three-dimensional view of an embodiment of a robot according to the invention;

FIG. 10 shows a second three-dimensional view of the robot of FIG. 9; and

FIG. 11 shows a three-dimensional view, including hidden detail, of an example of a rotary actuator which can be used in embodiments of the invention.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT

The following description of the invention is provided as an enabling teaching of the invention. Those skilled in the relevant art will recognise that many changes can be made to the embodiment described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances, and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not a limitation thereof.

The terms "vertical", "vertically", "vertical axis", "horizontal", "horizontally" and "horizontal axis" used throughout this specification should be construed with reference to the body of the robot and not with reference to the ground surface which the robot traverses. FIGs 1 to 4 conceptually illustrate an embodiment of a robot 10 according to the invention. The robot 10 of this embodiment is a mobile robot configured to traverse relatively difficult terrain, e.g. a deep level hard rock mine.

The robot 10 includes a body 12 and four articulated limb arrangements 14A-14D attached to the body 12.

The body 12 has a flat top 16 and a flat bottom 18 and is generally square in top view, as shown in FIG. 3. The body 12 is shown primarily for exemplary purposes and it should be understood may have many different shapes, sizes and configurations, depending on the application.

FIG. 4 illustrates a central, operatively vertical axis Z which extends upwardly through a centre of the body 12 and a horizontal axis Y which is perpendicular to the axis Z. The horizontal axis Y is also shown in FIG. 3. It will be understood that the vertical axis Z defines a vertical plane associated with the body 12 and the horizontal axis Y defines a horizontal plane associated with the body 12.

A mounting bracket 20A-20D is provided at each of the four corners of the body 12. Each mounting bracket 20A-20D includes an upper and a lower mounting plate which are vertically spaced apart and which extend horizontally away from the corner of the body 12 associated with the particular mounting bracket 20A-20D. The limb arrangements 14A-14D are secured to the body 12 by the mounting brackets 20A-20D.

The limb arrangements 14A-14D are equidistant from a centre point C of the body 12 (as shown in FIG. 3), through which the vertical axis Z extends. The limb arrangements 14A-14D are identical and, for ease of illustration and reference, the limb arrangements 14A-14D will be described below only with reference to one of the limb arrangements 14D.

The limb arrangement 14D includes three elongate, articulated links: a first link 22, a second link 24 and a third link 26. Each link 22, 24, 26 is independently angularly displaceable about a particular axis to provide the limb arrangement 14D with three degrees of freedom, as will be described in greater detail in what follows.

In this exemplary embodiment, the first link 22 has a length of 310 mm, the second link 24 has a length of 500 mm and the third link 26 has a length of 610 mm. It will be understood that these lengths are included primarily to illustrate an exemplary implementation of the invention. It has been found that it is preferable for the third link 26 to be longer than the second link 24, as it ensures that the third link 26 can protrude downwardly beyond the second link 24 when the second link 24 is in a fully vertical, upright position, thereby ensuring that the robot 10 remains mobile.

Each of the links 22, 24, 26 has a proximal end and a distal end defining a longitudinal axis (not shown) between them. The term "proximal" is used to refer to an end usually closest to the body 12, while the term "distal" is used to refer to an end usually furthest from the body 12.

The first link 22 is secured to the body 12 by the mounting bracket 20D so as to define a first articulation of the limb arrangement 14D. The mounting bracket 20D is complementally shaped to the first link 22 and defines a cavity between its mounting plates in which the proximal end of the first link 22 is received.

The proximal end of the first link 22 is secured between the mounting plates of the mounting bracket 20D in such a manner that the first link 22 is angularly displaceable through up to 270 degrees about a first axis XI. The first axis XI is parallel to the vertical axis Z and vertical plane, and is perpendicular to the longitudinal axis of the first link 22. The first axis XI is shown in FIGs 1, 2 and 4. The angle of displacement of the first link 22 is illustrated by the arrows 28 in FIG. 3.

The second link 24 is secured to the first link 22 so as to define a second articulation of the limb arrangement 14D. The proximal end of the second link 24 is secured to the distal end of the first link 22 in such a manner that the second link 24 is angularly displaceable through 300 degrees about a second axis X2. The second axis X2 is located in a plane parallel to the horizontal plane and is shown in FIGs 1, 2 and 3. The angle of displacement of the second link 24 is illustrated by the arrows 30 in FIGs 1 and 4.

It is envisaged that the second link 24 may, in other embodiments, be provided with an articulation (e.g. for transverse rotation) in a central region thereof, thereby providing a fourth degree of freedom.

The third link 26 is secured to the second link 24 so as to define a third articulation of the limb arrangement 14D. The proximal end of the third link 26 is secured to the distal end of the second link 24 in such a manner that the second third link 26 is rotatable through 360 degrees, or more, about a third axis X3. The third axis X3 is located in a plane parallel to the horizontal plane and to the plane in which the second axis X2 is located, and is shown in FIGs 1, 2 and 3. The angle of rotation of the third link 26 is illustrated by the arrows 32 in FIGs 1 and 2.

The second axis X2 and the third axis X3 are both perpendicular to the first axis XI. The second axis X2 extends laterally to the longitudinal axis of the second link 24 and the third axis X3 extends laterally to the longitudinal axis of the third link 26.

The first link 22 has a forked distal region and the second link 24 consists of two parallel, spaced apart arms which are connected at the second articulation and the third articulation. The first and second links 22, 24 together define a longitudinal central opening 34 shaped and dimensioned to permit the third link 26 to rotate through the opening 34. The opening 34 is best shown in FIGs 1 and 3. The third link 26 is thus continuously or freely rotatable (i.e. indefinitely rotatable) and can be rotated through angles greater than 360 degrees from a particular starting point.

The distal end of the third link 26 provides a gripping region 36. The gripping region 36 is used by the robot 12 to traverse terrain, in use.

Although not shown in the drawings, it will be understood that displacement and rotation of the links 22, 24, 26 can be driven in any suitable manner. For instance, in the configuration of the exemplary embodiment, a dedicated motor (e.g. electric motor) may be drivingly connected to each link 22, 24, 26 to permit the links 22, 24, 26 to be angularly displaced or to rotate.

FIGs 5 and 6 illustrate a further embodiment of a limb arrangement 40 according to the invention. The limb arrangement 40 includes three elongate, articulated links: a first link 42, a second link 44 and a third link 46. Each link 42, 44, 46 is independently angularly displaceable about a particular axis to provide the limb arrangement 40 with three degrees of freedom.

The structure and functioning of the limb arrangement 40 are substantially similar to the structure and functioning of the limb arrangements 14A-14D described with reference to FIGs 1 to 4. However, in this embodiment, the third link 46 is laterally offset relative to the first link 42 and the second link 44. In other words, a longitudinal axis F extending through the lengths of the first link 42 and the second link 44 and a longitudinal axis G of the third link 46 are laterally spaced apart from each other, as shown in FIG. 6.

The distal end 50 of the second link 44 and the proximal end 52 of the third link 46 are rotatably secured to each other in a side-by-side manner. The third link 46 is thus continuously or freely rotatable past a side 54 of the second link 44 (as opposed to through the second link 44) and can be rotated through angles greater than 360 degrees from a particular starting point.

FIGs 7 and 8 illustrate a further embodiment of a limb arrangement 60 according to the invention. The limb arrangement 60 of FIGs 7 and 8 also includes three elongate, articulated links: a first link 62, a second link 64 and a third link 66. Each link 62, 64, 66 is independently angularly displaceable about a particular axis to provide the limb arrangement 60 with three degrees of freedom.

The structure and functioning of the limb arrangement 60 are similar to the structure and functioning of the limb arrangements 14A-14D described with reference to FIGs 1 to 4. However, in this embodiment, a crank arrangement is included for driving rotation of the third link 66. The crank arrangement includes two crank mechanisms 68A and 68B respectively provided on either side 70A, 70B of the second link 64.

Each of the crank mechanisms 68A, 68B includes a mounting block 72A, 72B, an elongate linear actuator 74A, 74B and a crank 76A, 76B. The mounting block 72A, 72B is secured to an outer surface of the side 70A, 70B of the second link 64, in the region of the proximal end 80 of the second link 64.

The linear actuator 74A, 74B is hingedly connected to the mounting block 72A, 72B at one end and is pivotably connected to the crank 76A, 76B at its other end. The linear actuator 74A, 74B is hydraulically powered and is configured to provide telescopic, linear motion by which the length of the linear actuator 74A, 74B can be increased or reduced to rotate the crank 76A, 76B. The length of the linear actuator 74A, 74B is increased in the direction of the crank 76A, 76B.

The crank 76A, 76B has a generally planar, oblong shape. One end of the crank 76A, 76B is secured to the linear actuator 74A, 74B, as described above, while the other end of the crank 76A, 76B is drivingly secured to a rotatable shaft 82 which connects the crank 76A, 76B to the proximal end of the third link 66. The rotatable shaft 82 extends laterally through a slot (not shown) in the distal end of the second link 64 and also connects the cranks 76A, 76B to each other for simultaneous rotation. The cranks 76A, 76B are arranged in an out of phase manner such that a 90 degree angle exists between the lengths of the cranks 76A, 76B when the limb arrangement 60 is viewed from the side. This angle (a) is shown in FIG. 7.

In use, linear motion of the linear actuators 74A, 74B cause the cranks 76A, 76B to rotate, thereby resulting in rotation of the third link 66. As is the case in the embodiment described with reference to FIGs 1 to 4, the third link 66 is continuously or freely rotatable through a longitudinal, central opening 78 in the first link 62 and second link 64. It has been found that the out-of-phase arrangement of the cranks 76A, 76B eliminates the occurrence of so-called "dead spots", or power voids, when the third link 66 is rotated.

FIGs 9 and 10 conceptually illustrate a further embodiment of a robot 90 according to the invention. The robot 90 of this embodiment is similar to the robot 10 described with reference to FIGs 1 to 4, and like reference numerals refer to like components, axes and directions.

The robot 90 differs from the robot 10 in that the mounting plates 20A-20D are rotatably secured to the body 16 for rotation about a fourth axis X4 as indicated by the arrows 92, thereby providing a fourth articulation 90A-90D (i.e. a fourth degree of freedom).

The limb arrangements 14A-14D thus each include a fourth link in the form of the mounting plates 20A-20D. Taking the limb arrangement 14D as an example, the mounting plate 20D has a proximal end which is rotatably secured to the body 16 and a distal end which is secured to the proximal end of the first link 22.

FIG. 11 conceptually illustrates a hydraulic rotary actuator 100 which can be used in embodiments of the invention in order to permit angular displacement of one or more of the links as described above. In this example, the actuator 100 is a vane-type actuator.

The actuator 100 includes a cylindrical housing 102 which is fixedly attachable to a portion of a robot, e.g. the body, by way of two pairs of mounting studs 104 protruding from a mounting plate 105 which is secured to the exterior of the housing 102.

The interior of the housing 102 is divided into a first chamber 106 and a second chamber 108 by a fixed divider 110 and a rotary vane 112. The divider 110 and the vane 112 are both generally planar and prevent fluid from flowing between the first chamber 106 and the second chamber 108 in the interior of the housing 102. The divider 110 is attached to a sidewall of the housing 102 and the vane 112 is attached to a rotary shaft 114 which extends axially through the housing 102.

The first chamber 106 is defined between a first side of the divider 110 and a first side of the vane 112, while the second chamber 108 is defined between a second side of the divider 110 and a second side of the vane 112. Two fluid inlets 116 and 118 are provided at a top of the housing, on opposite sides of the divider 110. The inlet 116 is configured to permit hydraulic fluid to enter and egress the first chamber 106 and the inlet 118 is configured permit hydraulic fluid to enter and egress the second chamber 108.

In use, pressure differentials between the chambers 106, 108 are created using hydraulic fluid, thereby causing the vane 112 and the shaft 114 to rotate about a longitudinal axis L of the shaft 114 relative to the housing 102 and the divider 110. In this example, the actuator 100 permits rotation of about 280 degrees.

The Inventor believes that the robot and robotic limb arrangement of the present invention provides numerous advantages. The Inventor has found that a robot equipped with limb arrangements as described herein may provide enhanced manoeuvrability for climbing over obstacles, climbing from lower areas to higher areas (and vice versa), crawling through low and narrow openings, traversing gaps or holes in a surface and traversing uneven or slippery surfaces.

More specifically, as described with reference to the drawings, the third link 26, 46, 66 of the articulated limb arrangement 14D, 40, 60 may be capable of rotating substantially continuously, e.g. through a full rotation of 360 or more, e.g. 540 degrees, from a starting point. For instance, the freedom of motion of the third link 26, 46, 66 permits a robot, when in a tight space, to rotate the third link 26, 46, 66 inwardly towards its body and up over the axis about which it rotates instead of only being able to swing outwards. As a result, the third link 26, 46, 66 is capable of pulling or urging the robot upwards and out of a tight position.

Claims

1. A mobile robot which includes

a body; and

2. A robot as claimed in claim 1, in which the articulated limb arrangement includes:

a first link which is secured to the body for angular displacement about a first axis;

a second link which is secured to the first link for angular displacement about a second axis; and

3. A robot as claimed in claim 2, in which the third axis is spaced from the second axis and the third link is rotatable about the third axis beyond 360°.

4. A robot as claimed in claim 3, in which the third link is continuously rotatable about the third axis.

5. A robot as claimed in any one of claims 2 to 4, in which the first link is angularly displaceable about the first axis through at least 270°.

6. A robot as claimed in any one of claims 2 to 5, in which the second link is angularly displaceable about the second axis through at least 270°.

7. A robot as claimed in claim 6, in which the second link is angularly displaceable about the second axis through at least 300°.

8. A robot as claimed in any one of claims 2 to 7, in which the second axis is perpendicular to the first axis.

9. A robot as claimed in any one of claims 2 to 8, in which the third axis is perpendicular to the first axis.

10. A robot as claimed in any one of claims 2 to 9, in which the second axis and the third axis are generally parallel.

11. A robot as claimed in any one of claims 2 to 10, in which the first link, the second link and the third link are elongate and each has a proximal end and a distal end.

12. A robot as claimed in claim 11, in which a longitudinal axis is defined between the proximal end and the distal end of each of the links.

13. A robot as claimed in any claim 11 or claim 12, in which the first link is secured to the body at the proximal end of the first link to define a first articulation.

14. A robot as claimed in claim 13, in which the first axis is defined at the first articulation and extends perpendicular to the longitudinal axis of the first link.

15. A robot as claimed in claim 13 or claim 14, in which the distal end of the first link is secured to the proximal end of the second link to define a second articulation.

16. A robot as claimed in claim 15, in which the second axis is defined at the second articulation and extends laterally to the longitudinal axes of the first link and the second link

17. A robot as claimed in claim 15 or claim 16, in which the distal end of the second link is secured to the proximal end of the third link to define a third articulation.

18. A robot as claimed in claim 17, in which the third axis is defined at the end of the third articulation and extends laterally to the longitudinal axes of the second link and the third link.

19. A robot as claimed in claim 17 or claim 18, in which the second link defines at least part of a longitudinal opening shaped and dimensioned to allow the third link to pass through the opening, thereby to permit the third link to rotate beyond 360°.

20. A robot as claimed in claim 19, in which the opening is a composite opening defined by the first link and the second link.

21. A robot as claimed in claim 17 or claim 18, in which the longitudinal axes of the second link and the third link are off set to permit the third link to rotate past the second link.

22. A robot as claimed in any one of claims 2 to 21, in which the third link is provided with gripping formations in order to grip a surface over which the robot is moving.

23. A robot as claimed in any one of claims 2 to 22, in which the third link is longer than the second link.

24. A robot as claimed in any one of claims 2 to 23, in which at least one of the links is driven by an electric motor.

25. A robot as claimed in any one of claims 2 to 24, in which at least one of the links is driven by a crank mechanism.

26. A robot as claimed in any one of claims 2 to 25, in which at least one of the links is driven by a rotary actuator.

27. A robot as claimed in any one of claims 2 to 26, which includes a fourth link.

28. A robot as claimed in claim 27, in which the fourth link is located between the first link and the body of the robot.

29. A robot as claimed in claim 28, in which the fourth link is angularly displaceable about a fourth axis.

30. A robot as claimed in claim 29, in which the fourth link has a proximal end secured to the body and defining a fourth articulation and a distal end to which the proximal end of the first link is connected to define the first articulation.

31. A robot as claimed in any one of claims 2 to 30, in which the body defines an operative horizontal axis and an operative vertical axis, the first axis being generally parallel to the vertical axis and the second axis and/or the third axis being generally horizontal.

32. A robot as claimed in any one of the preceding claims, which includes at least four limb arrangements which are connected to the body at spaced-apart positions which are equidistant from a central axis of the body.

33. An articulated limb arrangement for a mobile robot, the limb arrangement including a plurality of links, each of which is connected to an adjacent link, at least one of the links being angularly displaceable relative to the link to which it is connected about an axis through at least 360°.

34. An articulated limb arrangement as claimed in claim 33, which includes: a first link which is secured or securable to a body of the robot for angular displacement about a first axis;

a second link which is secured or securable to the first link for angular displacement about a second axis; and

a third link which is rotatably secured or securable to the second link for rotation about a third axis, wherein the third link is rotatable about the third axis through at least 360°.