GB2562735A

GB2562735A - Robotic end effector

Info

Publication number: GB2562735A
Application number: GB1708204.1A
Authority: GB
Inventors: Warburton Robert; Godden Matthew; Elias Hugo
Original assignee: Shadow Robot Co Ltd
Current assignee: Shadow Robot Co Ltd
Priority date: 2017-05-22
Filing date: 2017-05-22
Publication date: 2018-11-28
Anticipated expiration: 2037-05-22
Also published as: GB2562735B; GB201708204D0

Abstract

A robotic end effector safety device comprising first and second parts arranged for relative rotational movement around an axis at a joint, whereby areas of the joint are exposed by the relative rotational movement of the first and second parts; and a flexible strip of material 200; wherein the flexible strip of material is arranged to cover the areas of the joint which are exposed by the relative rotational movement of the first and second parts. The end effector may also comprise at least one recessed magnet, the flexible strip comprising magnetic material, wherein the flexible strip is retained by the at least one magnet. The end effector may also comprise a digit for a robotic hand or a robotic hand comprising a plurality of digits. The flexible strip of material may be constructed from stainless steel, an interconnected chain structure, Milanese chain or chainmail.

Description

(71) Applicant(s):

The Shadow Robot Company Limited (Incorporated in the United Kingdom) 251 Liverpool Road, LONDON, N1 1LX, United Kingdom (72) Inventor(s):

Robert Warburton

Matthew Godden

Hugo Elias (74) Agent and/or Address for Service:

CMS Cameron McKenna Nabarro Olswang LLP Cannon Place, 78 Cannon Street, London, EC4N 6AF, United Kingdom (51) INT CL:

B25J 15/00 (2006.01) B25J 17/00 (2006.01) (56) Documents Cited:

JP 2016054915 A JP 2012040666 A

KR20090122517

SUSHI ROBOT AND PATISSERIE ROBOT, (Published

June 2009), accessed at:

(58) Field of Search:

INT CL B25J

Other: WPI, EPODOC, INTERNET.

(54) Title of the Invention: Robotic end effector

Abstract Title: Robotic end effector safety device (57) A robotic end effector safety device comprising first and second parts arranged for relative rotational movement around an axis at a joint, whereby areas of the joint are exposed by the relative rotational movement of the first and second parts; and a flexible strip of material 200; wherein the flexible strip of material is arranged to cover the areas of the joint which are exposed by the relative rotational movement of the first and second parts. The end effector may also comprise at least one recessed magnet, the flexible strip comprising magnetic material, wherein the flexible strip is retained by the at least one magnet. The end effector may also comprise a digit for a robotic hand or a robotic hand comprising a plurality of digits. The flexible strip of material may be constructed from stainless steel, an interconnected chain structure, Milanese chain or chainmail.

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

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Robotic End Effector

Technical Field

The present invention relates to robotic end effectors. In particular, the invention relates to robotic end effectors having improved safety.

Background

It is a prime goal for designers and inventors in the technical field of robotic end effectors to provide an artificial hand approximating the human hand as regards to form, size, strength and weight and above all, a hand which is substantially indistinguishable from the human hand as regards to dexterity, i.e. its manipulative ability.

There have, over the years, been numerous attempts made by various individuals and organizations, to provide such an artifact, and whilst considerable progress has been achieved to date, the hand designs have invariably fallen short of the above-mentioned characteristics in one respect or another. Even where the designs have provided an effector which is sufficient (in terms of mechanical flexibility) to allow the end to grasp any object a human hand can grasp, thereby allowing it to use standard tools, these end effectors are less efficient and often hazardous.

In particular, the human fingers which incorporate distal phalange, intermediate phalanges, and proximal phalanges are particularly difficult to design. To obtain the range of motion provided by a finger, the artificial finger may be designed with joints approximating those found in the human hand with the use of drive arrangements, such as gears, which transmit high torques.

However, it has been found that robotic end effectors can be potentially hazardous to a user and any object to be handled because of the presence of pinch points between moving components of the end effector, particularly at the joints, and the possibility of users being able to access internal moving parts of the robotic end effectors, such as the drive arrangements, at the joints. These problems may be particularly severe for robotic hands, as a result of the large number of joints required, and their geometry.

The present invention therefore aims to provide a robotic end effector, such as a robotic hand with safety features to improve safety when in use.

Summary

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

There is provided a robotic end effector comprising first and second parts arranged for relative rotational movement around an axis at a joint, whereby areas of the joint are exposed by the relative rotational movement of the firstand second parts; and a flexible strip of material; wherein the flexible strip of material is arranged to cover the areas of the joint which are exposed by the relative rotational movement of the firstand second parts.

The flexible strip of material may be arranged to prevent objects from accessing the areas of the joint which are exposed by the relative rotational movement of the firstand second parts.

The flexible strip of material may be arranged to cover potential pinch points of the joint.

The flexible strip may have first and second ends which are attached to the first part.

The flexible strip may extend around at least a part of the second part between its first and second ends.

The robotic end effector may further comprise at least one guide member arranged to contact the flexible strip between its first and second ends to control the path of the flexible strip.

The at least one guide member may be a plain bearing.

The robotic end effector may further comprise at least one recessed magnet; and the flexible strip of material comprises magnetic material; whereby the flexible strip of material is retained against a surface of the robotic end effector by the at least one recessed magnet.

The flexible strip of material may comprise stainless steel.

The flexible strip of material may comprise an interconnected chain structure.

The flexible strip of material may comprise a Milanese chain or chainmail.

There is also provided a digit for a robot hand comprising an end effector according to any of the above disclosure, and a robotic hand comprising a plurality of such digits.

The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.

The features of each of the above aspects and/or embodiments may be combined as appropriate, as would be apparent to the skilled person, and may be combined with any of the aspects of the invention. Indeed, the order of the embodiments and the ordering and location of the preferable features is indicative only and has no bearing on the features themselves. It is intended for each of the preferable and/or optional features to be interchangeable and/or combinable with not only all of the aspect and embodiments, but also each of preferable features.

Additional advantages and novel features of the invention will be set forth in part in the description which follows and will become apparent to those skilled in the art upon examination of the following and the accompanying figures or may be learned by practice of the invention.

Brief Description of the Drawings

The invention is diagrammatically illustrated, by way of example, with reference to the following drawings, in which:

Figure 1 illustrates an exemplary robotic end effector where the palm region is upward facing, with digits of the end effector in first positions;

Figure 2 illustrates the exemplary robotic hand of Figure 1 with digits in second positions;

Figure 3 illustrates a robotic hand according to an embodiment where the palm region is upward facing, with digits of the end effector in first positions;

Figure 4 illustrates the robotic hand of Figure 3 with digits in second positions;

Figure 5a illustrates a digit of the robotic hand of Figure 3 from one direction;

Figure 5b illustrates the digit of Figure 5a from another direction;

Figure 6a illustrates a cut away view of the digit of Figure 5 from one direction;

Figure 6b illustrates a cutaway view of the digit of Figure 5 from another direction;

Figure 7 illustrates a further cut away view of the digit of Figure 5;

Figure 8 illustrates a cutaway view of the digit of Figure 5 moving in a first direction;

Figure 9 illustrates a cutaway view of the digit of Figure 5 moving in a second direction;

Figure 10a illustrates a view of a part of the digit of Figure 5 from one direction;

Figure 10b illustrates a view of a part of the digit of Figure 5 from another direction;

Figure 11a illustrates a further view of a part of the digit of Figure 5 from one direction;

Figure 11 b illustrates a further view of a part of the digit of Figure 5 from another direction;

Figure 12a illustrates a wire used to form a flexible strip;

Figure 12b to 12d illustrate different views of a flexible strip used in the digit of Figure 4; and

Figure 12e illustrates a view of the flexible strip of Figures 12b to 12d.

Common reference numerals are used throughout the figures to indicate similar features.

Detailed Description

Additional advantages and novel features of the invention will be set forth in part within the description which follows and will become apparent to those skilled in the art upon examination of the following and the accompanying figures, or may be learned by practice of the invention.

Figures 1 and 2 illustrate an exemplary robotic end effector 10 with the palm region 105 of the robotic end effector 10 being shown upwardly facing. In this example, the robotic hand or end effector 10 of Figures 1 and 2 comprises three digits 102-106, which substantially imitate the middle and index fingers and thumb of a human hand, respectively. The finger digits 102-106 are arranged on the palm region 105 substantially spaced around the palm region 150 such that the positioning of the finger digits 102-106 substantially emulate the positioning of the fingers and thumb on a human hand. In this example, the end actuator 10 provides a three fingered robotic hand emulating a human hand. However, it will be appreciated that an alternative arrangement can be provided to more closely emulate either the left or the right human hand. Although not depicted in the figures, the end effector 10 may be attached to a robot arm, such as a commercially available robot arms.

The digits 102-106 each comprise a proximal interphalangeal joint 120. The joints 120 each provide for rotation of a movable part 102a-106a of each digit 102-106 relative to a fixed part 102b-106c of the digit 102-106 about a respective axis 120a. The fixed part 102b-106c of each digit 102-106 contains a respective drive mechanism able to drive movement of the movable part 102a-106a of the digit 102-106. Each joint 120 comprise a cylindrical surface 120b extending in a partial circle circumferentially about the axis 120a. The joints 120 are each provided with a bevel gear mechanism 170 connecting the drive mechanism to the movable part 102a-106a of the digit 102-106, and so enabling the drive mechanism to carry out controlled movement of the respective digit 102 about the axis 120a with an angular range as required to emulate the action of a human proximal interphalangeal joint. In this example, two apertures 120c are provided in the cylindrical surface 120b of each digit 102-106 on the palm side of the proximal interphalangeal joint 120. The apertures 120c are provided to enable contact between gears attached to the movable part 102a-106a and fixed part 102b-106c of the respective digit 102-106 through the cylindrical surface 120b in order to drive the joint 120 to control movement of the digit 102-106 relative to the palm region 105 throughout the desired range of movement.

In Figure 1, the robotic end effector 10 is shown with the finger digits 102-106 rotated about their respective joints 120 into respective first positions where the three digits 102-106 are splayed apart so that they point outwardly away from one another. As can be seen in Figure 1, when each of the digits 102-106 is in this first position a large part of the respective circumferential surface 120b and its respective two apertures 120c are exposed on an inner side of the respective joint 120 on a surface of the digit 102-106 facing in an inward direction towards the palm 105.

In Figure 2, the robotic end effector 10 is shown with the finger digits 102-106 rotated about their respective joints 120 into respective second positions where the three digits 102-106 are directed together so that they point inwardly and their respective tips 102c-106c are moved towards one another. As can be seen in Figure 2, when each of the digits 102-106 is in this second position a large part of the respective circumferential surface 120b and its respective two apertures 120c are exposed on an outer side of the respective joint 120 on a surface of the digit 102-106 facing in an outward direction away from the palm 105

The apertures 120c each provide a possible entry point potentially permitting access to the respective bevel gear mechanism 170, which could allow a user body part, such as a finger, skin or hair, or an object being manipulated by the user or the robot end effector 10 itself, to contact and become caught in the bevel gear mechanism 170. This could result in injury to a user or damage to the object, and/or damage to the mechanism of the robot end effector 10.

Further, as the three digits 102-106 move and rotate around the axes 120a of the respective joints 120 the edges of the apertures 120c may potentially form pinch points as the respective circumferential surface 120b. As can be understood by comparing in Figures 1 and 2, as each circumferential surface 120b rotates around the respective axis 120a, the circumferential surface 120b and the respective two apertures 120c will move relative to the fixed part 102b-106b of the respective digit 102-106 and other parts of the robotic end effector 10.

For example, as a digit 102-106 moves from the first position shown in Figure 1 to the second position shown in Figure 2 the respective circumferential surface 120b and two apertures 120c on the inner side of the respective joint 120 will move relative to the fixed part 102b-106b of the digit 102-106 so that the ends of the two apertures 120c will form potential pinch points closing up against a surface of the fixed part 102b-106b. Similarly, as a digit 102-106 moves from the second position shown in Figure 2 to the first position shown in Figure 1 the respective circumferential surface 120b and two apertures 120c on the outer side of the respective joint 120 will move relative to the fixed part 102b-106b of the digit 102-106 so that the ends of the two apertures 120c will form potential pinch points closing up against a surface of the fixed part 102b106b.

A user body part, such as a finger, skin or hair, or an object being manipulated by the user or the robotic end effector 10, could become caught in, and be crushed by, these pinch points as the digits 102-106 move. This could also result in injury to a user or damage to the object, and/or damage to the mechanism of the robot end effector 10.

Figures 3 and 4 illustrate a robotic end effector 20 according to an embodiment of the present invention.

In this embodiment, the general structure of the robotic end effector 20 shown in Figures 3 and 4 is similar to the robotic end effector 10 of Figures 1 and 2, and comprises three finger digits 102106 arranged similarly to the example of Figures 1 and 2.

In this embodiment, the finger digits 102-106 each comprise a proximal interphalangeal joint 120 for rotation about an axis 120a comprising a circumferential surface 120b with apertures 120c, and driven by a bevel gear mechanism 170, similarly to the example of Figures 1 and 2.

In the illustrated embodiment of Figures 3 and 4, each of the joints 120 is covered by a respective flexible shielding member 200. A respective flexible shielding member 200 is provided on each the digits 102-106. Each flexible shielding member 200 extends across the exposed parts of the circumferential surface 120b on the inner and outer sides of the respective joint 120 and covers the respective apertures 120c of the proximal interphalangeal joint 120 formed in the circumferential surface 120b.

It should be understood that the apertures 120c are not visible in Figures 3 and 4 because the apertures 120c are covered by the flexible shielding members 200.

In the illustrated embodiment of Figures 3 and 4, the flexible shielding members 200 cover the apertures 120c, and so close off the possible access/entry points to the bevel gear mechanisms 170, so preventing user body parts, or objects being manipulated by a user, or by the robotic end effector 20 itself, from contacting or becoming caught in the bevel gear mechanisms 170. Further, the flexible shielding member 200 prevent user body parts, or objects, accessing and being caught in any pinch points formed by the edges of the apertures 120c.

Although Figures 1 to 4 illustrate palm region 105 attached to three finger digits 102-106, it will be appreciated that alternative arrangements and component shapes are possible. In fact, any shape or configuration suitable for use as means for emulating a palm region or similar in an end effector, or at least means suitable for connecting the members in a particular arrangement, may be provided. Furthermore, the number of finger digits can vary according to the use of the end effector.

Figures 5a and 5b illustrate more detailed views of the finger digit 102 in isolation from the other parts of the robotic end effector 20. Figure 5a is a view showing the inner side of the finger digit 102 and its respective joint 120, and Figure 5b is a view showing the outer side of the finger digit 102 and its respective joint 120. Figure 5a shows the finger digit 102 in the first position of Figures 1 and 3, while Figure 5b shows the finger digit 102 in a straight position where the movable part 102a and the fixed part 102b of the finger digit 102 are aligned.

Figures 6a and 6b show cut-away views of the finger digit 102 in isolation from the other parts of the robotic end effector 20, and showing the internal structure of the finger digit 102. Figure 6a is a view showing the inner side of the finger digit 102 and its respective joint 120, and Figure 6b is a view showing the outer side of the finger digit 102 and its respective joint 120. Figures 6a and 6b both show the finger digit 102 arranged in the straight position of Figure 5b.

The other finger digits 104 and 106 of the robotic end effector 20 will be the same as the finger digit 102 illustrated in Figures 5a to 6b.

In the illustrated embodiment the flexible shielding member 200 comprises a pair of adjacent rectangular flexible strips 200a, 200b each having first and second ends 200c and 200d. The flexible shielding member 200 is secured at the first ends 200c of the strips 200a, 200b to the inner side of the movable part 102a of the finger digit 102 at an inner fixing point 201 adjacent to the joint 120, extends around the joint 120, and is secured at the second ends 200d of the strips 200a, 200b to the outer side of the movable part 102a of the finger digit 102 at an outer fixing point 202 adjacent to the joint 120. The two strips 200a, 200b each have a constant width along their length and have the same width, so that the width of the flexible shielding member is twice the width of each of the rectangular flexible strips 200a, 200b.

In addition to extending around the joint 120, the flexible shielding member 200 also extends around a drive mechanism 210 inside the finger digit 102, as shown in Figures 6a and 6b. As discussed above with reference to Figures 1 and 2, the drive mechanism 210 is connected to the bevel gear mechanism 170 and arranged to be able to drive rotation of the movable part 102a of the finger digit 102 around the joint 120 relative to the fixed part 102b of the finger digit 102.

An inner slot 212 is provided in an outer surface of the inner side of the fixed part 102b of the finger digit 102 adjacent the joint 120, and the flexible shielding member 200 passes through this slot between the circumferential surface 120a at the inner side of the joint 120 and the interior of the fixed part102b of the finger digit 102. An outer slot 214 is provided in an outer surface of the outer side of the fixed part 102b of the finger digit 102 adjacent the joint 120, and the flexible shielding member 200 passes through this slot between the circumferential surface 120a at the outer side of the joint 120 and the interior of the fixed part 102b of the finger digit 102.

As can be seen in particular in Figure 5a, on the inner side of the joint 120 the flexible shielding member 200 extends circumferentially around the cylindrical surface 120b and extends tangentially away from the cylindrical surface 120b to the inner slot 212. S imilarly, as can be seen in particular in Figure 5b, on the outer side of the joint 120 the flexible shielding member 200 extends circumferentially around the cylindrical surface 120b and extends tangentially away from the cylindrical surface 120b to the outer slot 214,

Inside the fixed part 102b of the finger digit 102 a number of guide members 216 are provided to guide the flexible shielding member 200 in a desired stable path between the inner slot 212 and outer slot 214 and around the drive mechanism 210. The guide members 216 are fixed, so that the path of the flexible shielding member 200 between the inner slot 212 and outer slot 214 has a fixed length.

Figure 7 illustrates a cut-away side view of the finger digit 102 showing a more detailed view of the arrangement of the guide members 216. In the illustrated embodiment five guide members 216 are used. Each guide member 216 comprises a cylinder 216a arranged for rotation about a central axis 216b to act as a plain bearing.

The operation of the finger digit 102 and flexible shielding member 200 during movement of the finger digit 102 will now be explained with reference to Figures 8 and 9. Figures 8 and 9 illustrate cut-away side views of the finger digit 102.

Figure 8 illustrates the finger digit 102 rotating about the joint 120 and moving outwardly in the direction of the arrow 800, away from the second position of Figures 2 and 4, and towards the first position of Figures 1 and 3. As the finger digit 102 rotates the angular and areal extent of the part of the cylindrical surface 120b exposed on the inner side of the joint 120 increases and the extent of the part of the cylindrical surface 120b exposed on the outer side of the joint 120 decreases. In order to accommodate this change in the exposed extents of the cylindrical surface 120b on the inner and outer sides of the joint 120 the flexible shielding member 200 moves from the outerside of the joint 120 through the outer slot 214, overthe guide members 216around the drive mechanism 210, and through the inner slot 212 to the inner side of the joint 120, as indicated by the arrows 810.

Figure 9 illustrates the finger digit 102 rotating anti-clockwise about the joint 120 and moving inwardly in the direction of the arrow 900, away from the first position of Figures 1 and 3, and towards the second position of Figures 2 and 4. As the finger digit 102 rotates the angular and areal extent of the part of the cylindrical surface 120b exposed on the inner side of the joint 120 decreases and the extent of the part of the cylindrical surface 120b exposed on the outer side of the joint 120 increases. In order to accommodate this change in the exposed extents of the cylindrical surface 120b on the inner and outer sides of the joint 120 the flexible shielding member 200 moves from the inner side of the joint 120 through the inner slot 212, over the guide members 216 around the drive mechanism 210, and through the outer slot 214 to the outer side of the joint 120, as indicated by the arrows 910.

Figures 10a and 10b illustrate detailed views of a part of the finger digit 102. Figure 10a is a view showing the outer side of the finger digit 102 and its respective joint 120, and Figure 10b is a view showing the inner side of the finger digit 102 and its respective joint 120. Figures 10a and 10b show the finger digit 102 in a straight position where the movable part 102a and the fixed part 102b of the finger digit 102 are aligned.

In the illustrated embodiment, as is shown in Figure 10a, five permanent magnets 920a are recessed into the surface of the finger digit 102a on the outer side of the finger digit 102 and its respective joint 120. The permanent magnets 920a are recessed into a section 120d of the surface of the outer side of the finger digit 102a extending between the outer fixing point 202 and the circumferential surface 120a. Further, as is shown in Figure 10b, four permanent magnets 920b are recessed into the surface of the finger digit 102a on the inner side of the finger digit 102 and its respective joint 120. The permanent magnets 920b are recessed into a section 120e of the surface of the innerside of the finger digit 102a extending between the inner fixing point 201 and the circumferential surface 120a.

The flexible shielding member 200 comprises magnetic material so that the flexible shielding member 200 is magnetically attracted towards the permanent magnets 920a and 920b, and so tends to be held against the sections 120d and 120e respectively of the surface of the finger digit 102a.

Figure 11a illustrates a detailed view of the outer side of the finger digit 102 and its respective joint 120. Figure 11a shows the finger digit 102 rotated about the joint 120 into the first position where the finger digit 102 is directed outwardly from the other finger digits 104-106, and the palm 105. When the finger digit 102 is in this position, the flexible shielding member 200 is retained in contact with the section 120d of the surface of the finger digit 102a by the magnetic attraction between the permanent magnets 920a and the flexible shielding member 200, as indicated by the cross-hatched line 1000a.

In the absence of the permanent magnets 920a, when the finger digit 102 rotates outwardly about the joint 120 the flexible shielding member 200 might tend to be pulled away from the section 120d of the surface of the finger digit 102a by tensile forces acting along the length of the flexible shielding member 200 and towards a position extending directly between the outer fixing point 202 and the outer slot 214, as indicated by the solid line 1000b.

Similarly, Figure 11b illustrates a detailed view of the inner side of the finger digit 102 and its respective joint 120, showing the finger digit 102 rotated about the joint 120 into the second position where the finger digit 102 is directed inwardly towards the other finger digits 104-106, and the palm 105. When the finger digit 102 is in this position, the flexible shielding member 200 is retained in contact with the section 120e of the surface of the finger digit 102a by the magnetic attraction between the permanent magnets 920b and the flexible shielding member 200, as indicated by the cross-hatched line 1001a.

In the absence of the permanent magnets 920b, when the finger digit 102 rotates outwardly about the joint 120 the flexible shielding member 200 might tend to be pulled away from the section 120e of the surface of the finger digit 102a by tensile forces acting along the length of the flexible shielding member 200 and towards a position extending directly between the inner fixing point 201 and the inner slot 212, as indicated by the solid line 1001b.

It will be understood that the flexible shielding member 200 should be retained against the surface of the finger digit 102a in the sections 120d and 120e in order to block access to the apertures 120c and any pinch points, and further to prevent any potential pinch points being formed between the flexible shielding member 200 and the other parts of the finger digit 102a.

Figures 12a to 12d illustrate a structure for the rectangular flexible strips 200a, 200b making up the flexible shielding member 200 according to an embodiment.

In the illustrated embodiment, each flexible strip 200a, 200b may be formed by a strip of stainless steel Milanese chain material. Milanese chain, which is also referred to as Milanese loop, is a flexible sheet material formed from a plurality of spiral wires which are linked by being braided together. The spiral wires are arranged so that the axes of the different spirals, that is, the axes about which the different spirals are wound, are coplanar and parallel. The resulting sheet material is flexible about axes parallel to the spirals and relatively inflexible in other directions. Further, because the flexible strips 200a and 200b forming the flexible shielding member 200 are formed of stainless steel, which is a magnetic material, the flexible shielding member 200 is magnetically attracted to the permanent magnets 920a and 920b.

Figure 12a shows a single spiral wire 300. The spiral wire 300 is formed of stainless steel and has a diameter of 0.5 mm, and is wound into a helical spiral having an external diameter of 1.5 mm and a length of 41.5 mm.

Each of the flexible strips 200a, 200b comprises a large number of spiral wires 300 arranged in parallel and side by side, with adjacent spiral wires 300 intertwined with one another to interlink them and form a strip of Milanese chain material.

Figures 12b to 12d illustrate the flexible strip 200a Milanese chain material in plan view, side view, and perspective view, respectively. The strip 200a has a thickness of 1.5 mm, determined by and corresponding to the external diameter of each of the helical spiral wires 300, a width of 41.5 mm, determined by and corresponding to the length of each of the helical spirals of the helical spiral wires 300, and a length of 261 mm, determined by the number of helical spiral wires 300 making up the strip 200a.

The intertwining of the adjacent spiral wires 300 allows relative rotational movement of the adjacent spiral wires 300, which renders the strip 200a flexible about axes parallel to the axes of the helical spirals of the spiral wires 300, so that the strip 200a can bend readily in the direction perpendicular to its width and length, being able to be formed into loops having a minimum internal radius of 1.2 mm. However, the individual spiral wires 300 are relatively stiff, so that the strip 200a is stiff and inflexible about axes perpendicular to the axes of the helical spirals of the spiral wires 300.

Figure 12e illustrates a perspective view of the strip 200a of Milanese chain arranged in a series of loops 320 to illustrating the flexibility of the Milanese chain.

The strip 200b is identical to the strip 200a. Since the strips 200a and 200b each have a length of 261 mm and a width of 41.5 mm, the flexible shielding member 200 has a length of 261 mm and a width of 83 mm.

The length and width of the flexible shielding member 200 are selected to match the dimensions of the joint 120, with the width of the flexible shielding member 200 substantially corresponding to the width of the circumferential surface 120a, and the length of the flexible shielding member 200 substantially corresponding to the distance between the inner fixing point 201 and the outer fixing point 202 along the path defined by the guide members 216. Accordingly, in alternative examples having different dimensions of the joint, the flexible shielding member would have different matching dimensions.

As discussed above, for each of the joints 120 the flexible shielding member 200 comprising the flexible strips 200a and 200b covers the apertures 120c, preventing access to the internal parts of the joint 120, such as the bevel gear mechanisms 170, and any pinch points. Accordingly, the flexible shielding member 200 provides a significant improvement over known robotic hands, as the flexible shielding member 200 provides a protective covering over the apertures, hence avoiding direct and accidental access to the bevel gear mechanism and possible pinch points.

As is explained above, the Milanese chain material making up the flexible strips 200a and 200b is relatively inflexible about axes perpendicular to the axes of the helical spirals of the spiral wires 300, and as a result the flexible shielding member 200 cannot be bent to lift its edges away from the circumferential surface 120a to allow access to the apertures 120c.

In some examples raised flanges may be provided at the sides of the circumferential surface 120a to provide a further obstacle to access to the apertures 120c. In some examples such flanges may be formed by parts of an outer surface of the fixed part 102b of the finger digit 102. In other examples such flanges may be formed by raised parts of the circumferential surface 120a.

In the illustrated embodiment the flexible shielding member 200 is formed by two flexible strips 200a and 200b arranged side by side. In other examples the flexible shielding member may be formed by a single, unitary, flexible strip, or may be formed by three or more flexible strips.

In the illustrated embodiment Milanese chain is used to form the flexible shielding member. In other examples alternative flexible sheet materials may be used. Such flexible sheets may be formed by linked chains or by sheets of interconnected links or rings forming a flexible mesh or chainmail like structure. A number of suitable sheet material structures are known.

In the illustrated embodiment the flexible shielding member 200 is formed from stainless steel. Stainless steel has desirable properties of resistance to accidental damage or interference, and resistance to corrosion, which make it suitable for this purpose. However, in other examples different materials, or mixtures of materials, may be used.

The illustrated embodiment shows the use of the flexible shielding member applied to a proximal interphalangeal joint of a digit of a robotic hand emulating a human hand. In other examples the flexible shielding member may be applied in a similar manner to other joints of digits of a robotic hand emulating a human hand, or to joints of digits of robotic end effectors which do not emulate a human hand.

In the illustrated embodiment the flexible shielding member prevents access to a bevel gear mechanism through apertures, and to pinch points formed by the apertures. In other examples the flexible shielding member may prevent access to other types of exposed or accessible mechanisms and/or access to pinch points formed in other ways.

In the illustrated embodiment the joint comprises a cylindrical surface. In other examples the joint may have other geometries.

In the illustrated embodiment the flexible shielding member is guided along a path having a fixed length by five fixed guide members. In other examples a different number of guide members may be used, as required by the path to be followed by the flexible shielding member. In some examples some, or all, of the guide members may be arranged for movement. In some examples this may be desirable in order to compensate for changes in the length of the path between the points where the flexible shielding member is connected to the digit as the joint rotates, as a result of the geometry of the joint. In some examples one or more of the guide members may be arranged to tension the flexible shielding member.

In the illustrated embodiment five permanent magnets 920a are used on the outer side of the finger digit 102 and four permanent magnets 920b are used on the inner side of the finger digit 102. In other examples different numbers of permanent magnets may be used, an dthe same, or different, numbers of permanent magnets may be used on the outer and inner sides of the finger digit. In general one or more permanent magnets may be used on each side of the finger digit.

In the illustrated embodiment, the finger digits 102-106 are attached to the palm 105 so as to emulate the human hand. However, it will be appreciated that the finger digits 102-106 need not be so attached and in fact can be attached at a multitude of positions on the palm 105, wherein each achieve different dexterity and results. It will also be appreciated that in some examples, one or more of the finger digits 102-106 may be releasable connectable to a plurality of locations on the palm 105 to allow for alternative configurations and functionalities to be made.

In the illustrated embodiment three identical digits 102 to 106 are used. In some examples a different number of digits may be used. In some examples the different digits may be different to one another.

Those skilled in the art will appreciate that while the foregoing has described what is considered to be the best mode and, where appropriate, other modes of performing the invention, the invention should not be limited to the specific configurations and methods disclosed in this description of the preferred embodiment. Those skilled in the art will recognize that the invention has a broad range of applications in many different types of robotics and that the embodiments may take a wide range of modifications without departing from the inventive concept as defined in the appended claims.

Claims

1. A robotic end effector comprising:

first and second parts arranged for relative rotational movement around an axis at a joint, whereby areas of the joint are exposed by the relative rotational movement of the first and second parts; and a flexible strip of material;

wherein the flexible strip of material is arranged to cover the areas of the joint which are exposed by the relative rotational movement of the firstand second parts.

2. The robotic end effector of claim 1, wherein the flexible strip of material is arranged to prevent objects from accessing the areas of the joint which are exposed by the relative rotational movement of the firstand second parts.

3. The robotic end effector of claim 1 or claim 2, wherein the flexible strip of material is arranged to cover potential pinch points of the joint.

4. The robotic end effector of any preceding claim, wherein the flexible strip has first and second ends which are attached to the first part.

5. The robotic end effector of claim 4, wherein the flexible strip extends around at least a part of the second part between its firstand second ends.

6. The robotic end effector of claim 5, further comprising at least one guide member arranged to contact the flexible strip between its first and second ends to control the path of the flexible strip.

7. The robotic end effector of claim 6, wherein the at least one guide member is a plain bearing.

8. The robotic end effector of any preceding claim wherein the robotic end effector further comprises at least one recessed magnet; and the flexible strip of material comprises magnetic material;

whereby the flexible strip of material is retained against a surface of the robotic end effector by the at least one recessed magnet.

9. The robotic end effector of claim 8, wherein the flexible strip of material comprises stainless steel.

10. The robotic end effector of any preceding claim, wherein the flexible strip of material comprises an interconnected chain structure.

11. The robotic end effector of claim 8, wherein the flexible strip of material comprises a Milanese chain.

12. The robotic end effector of claim 8, wherein the flexible strip of material comprises chainmail.

13. A digit for a robot hand comprising an end effector according to any preceding claim.

14. A robotic hand comprising a plurality of digits according to claim 11.

Intellectual

Property Office

Application No: GB 1708204.1 Examiner: Mr Gary Clements