SE2051357A1 - Gripping tool, gripping system, and robot - Google Patents

Abstract

A gripping tool (26) comprising a base structure (38); a first member (40) rotatable about a first axis (48) relative to the base structure (38), the first member (40) comprising a first gripping element (50); a second member (42) linearly movable along a second axis (54), substantially perpendicular to the first axis (48), relative to the base structure (38), the second member (42) comprising a second gripping element (56) for gripping a handle (28) together with the first gripping element (50) when the first member (40) adopts a first gripping position (64) and the second member (42) adopts a second gripping position (66); a linear actuator (44) arranged to move the second member (42) between a second free position (62) and the second gripping position (66); and a transmission (46) arranged to transmit a linear movement of the second member (42) towards the second free position (62) to a rotation of the first member (40) towards the first free position (60).

Description

1O GRIPPING TOOL, GRIPPING SYSTEM, AND ROBOT Technical Field The present disclosure generally relates to a gripping tool. In particular, agripping tool for a robot, a gripping system comprising one or more suchgripping tools, and a robot comprising one or more such gripping tools or such gripping system, are provided.Background People are spending time to move carts, trolleys, beds or other such carriersbetween two points in many different situations. This is a simple task thattoday can be carried out by a robot. The human time can thereby be betterspent. However, today it is still only a very small part of these situations thatuse robotic solutions. Robotic solutions are usually employed where logisticsflows are very controlled and where logistics requirements are very static (does not vary over time).

To replace carriers, such as carts, trolleys or beds, with mobile robots istypically too costly. Factories, warehouses, hospitals, etc. can have hundredsor thousands of such carriers. In addition, these carriers often stand still mostof time. Thus, if such carriers are replaced with mobile robots, the mobile robots would be poorly utilized.

Traditional solutions with fewer-than-carts AGVs (Automated GuidedVehicle) that can pick up a cart by lifting it from below and move it between locations have several maj or disadvantages, for example: An AGV cannot pick up all kinds of carriers, i.e. it requires a special design ofcarrier that fits with the AGV. It would typically require a significant cost to replace or rebuild existing carriers made for manual transport. 1O Many such AGVs must be designed to carry the complete weight/ size of thecarrier and its content in a stable and safe way. The AGV might for examplehave to lift the carrier high in order to be able to create a clear sight for its sensors.Summary One object of the present disclosure is to provide a gripping tool for a robot, which gripping tool has a less complicated and a more robust design.

A further object of the present disclosure is to provide a gripping tool for a robot, which gripping tool has a cost-effective design.

A still further object of the present disclosure is to provide a gripping tool for a robot, which gripping tool enables reliable gripping of a handle for humans.

A still further object of the present disclosure is to provide a gripping tool fora robot, which gripping tool solves several or all of the foregoing objects in combination.

A still further object of the present disclosure is to provide a gripping systemcomprising a gripping tool, which gripping system solves one, several or all of the foregoing objects.

A still further object of the present disclosure is to provide a robot comprisinga gripping tool or a gripping system, which robot solves one, several or all of the foregoing objects.

According to one aspect, there is provided a gripping tool for a robot, thegripping tool comprising a base structure; a first member rotatable about afirst axis relative to the base structure between a first free position and a firstgripping position, the first member comprising a first gripping element; asecond member linearly movable along a second axis, substantiallyperpendicular to, or perpendicular to, the first axis, relative to the basestructure between a second free position and a second gripping position, the second member comprising a second gripping element for gripping a handle 1O together with the first gripping element when the first member adopts thefirst gripping position and the second member adopts the second grippingposition; a linear actuator arranged to move the second member between thesecond free position and the second gripping position; and a transmissionarranged to transmit a linear movement of the second member towards thesecond free position to a rotation of the first member towards the first free position.

The gripping tool enables firm gripping of handles for humans to move a cart,a trolley, a bed or other similar carrier. The gripping tool can be engaged witha variety of such carriers without requiring any modification of the carriers.The gripping tool has a simple and robust design since it enables a firm grip on the handle with a single linear actuator.

The gripping tool utilizes the fact that the majority of carrier handles forhumans have similar cross-sectional shape (to give comfortable grip for"average" human) and that there is usually a free space above the handle forhorizontal handles and next to the handle for vertically oriented handles. The linear actuator may for example be electric or pneumatic.

The gripping tool may further comprise a force device arranged to force thefirst member from the first free position towards the first gripping position.In this case, the gripping tool can be oriented arbitrarily in space. The forcedevice may be a spring. However, in case the gripping tool is used with thefirst second axis in a horizontal direction and the first member above thesecond member, a force device may not be needed. Instead, the first membermay be forced from the first free position towards the first gripping position by gravity.

The force device may comprise a spring. The spring may for example be a coilspring or a flat spring. The flat spring may lie over a hinge between the first member and the base structure.

The first gripping element may comprise a first gripping surface and the second gripping element comprises a second gripping surface. In this case, 1O the first gripping surface and the second gripping surface may each lie in a plane substantially parallel with, or parallel with, the first axis.

The second gripping surface may lie in a plane that is angled 20 degrees to 60 degrees to a plane perpendicular to the second axis.

The first gripping surface and the second gripping surface may besubstantially parallel, or parallel, when the first member adopts the first gripping position.

The first gripping element and/ or the second gripping element may beresilient. Each of the first gripping element and the second gripping element may for example be made of rubber.

The first member may be arranged to reach the first gripping position beforethe second member reaches the second gripping position during movementof the second member from the second free position to the second gripping position.

A movement of the second member from the second free position to thesecond gripping position may comprise a first stroke and a second stroke,following the first stroke. In this case, the first stroke may allow the firstmember to move from the first free position to the first gripping position, andthe second stroke may lock the first member in the first gripping position.The gripping tool thus enables both a gripping of the handle and a locking of this grip with a simple design and operation.

The transmission may comprise a cam profile and a cam follower arranged tofollow the cam profile. The cam profile may be arranged on the first memberand the cam follower may be arranged on the second member. In this case,the cam profile may comprise a hook, and the cam follower may be arrangedto engage the hook when the second member adopts the second gripping position to thereby lock the first member to the second member.

According to a further aspect, there is provided a gripping system comprising one or more gripping tools according to the present disclosure. 1O The gripping system may be configured to rotate each gripping tool about anaxis substantially parallel with, or parallel with, the second axis. By means ofthis feature, the gripping tool can grip both horizontal handles and verticalhandles. This rotation axis will not be carrying any load in the direction of thedegree of freedom other than when rotating the gripping tool unloaded. Thegripping tool can thus be actuated about the rotation axis with a smallactuator (e.g. electric or pneumatic). The rotation axis can be set to "floating" when the gripping tool is engaged with the handle.

The gripping system may comprise two gripping tools. In this case, thegripping system may be configured to adjust a distance between the twogripping tools in a direction substantially parallel with, or parallel with, thefirst axis. This feature is particularly valuable when the gripping tools shouldgrip two parallel vertical handles of carriers with different designs, e.g. when a distance between two vertical handles varies between different carriers.

The gripping system may be configured to adjust a height of each grippingtool. Despite that most carrier handles are positioned at a similar heightabove the ground, small differences in height between different carriers mayexist. Therefore, for one gripping system to handle a variety of carriers, such height degree of freedom may be used, e.g. with a relatively short stroke.

According to a further aspect, there is provided a robot comprising a grippingtool according to the present disclosure or a gripping system according to thepresent disclosure. The robot may comprise an automated guided vehicle(AGV). By means of the robot, carts or trolleys having standard handles for humans can be moved easily. The robot may be omni-directional.Brief Description of the Drawings Further details, advantages and aspects of the present disclosure will becomeapparent from the following description taken in conjunction with the drawings, wherein: 1O Fig. 1: schematically represents a side view of a trolley and a robotcomprising two gripping tools; Fig. 2: schematically represents a top view of the trolley and the robot; Fig. 3: schematically represents a perspective view of the trolley; Fig. 4: schematically represents a perspective view of a further example ofa trolley; Fig. 5: schematically represents a perspective view of a hospital bed; Fig. 6: schematically represents a perspective view of a shopping cart; Fig. 7: schematically represents a perspective view of one of the grippingtools; Fig. 8: schematically represents a side view of the gripping tool in an openposition; Fig. 9: schematically represents the gripping tool in a closed position; Fig. 10: schematically represents the gripping tool in a closed and lockedposition; and Fig. 11: schematically represents a further example of a gripping tool.

Detailed Description In the following, a gripping tool for a robot, a gripping system comprising oneor more such gripping tools, and a robot comprising one or more suchgripping tools or such gripping system, will be described. The same or similarreference numerals will be used to denote the same or similar structural features.

Fig. 1 schematically represents a side view of a robot 10 and a trolley 12, andFig. 2 schematically represents a top view of the robot 10 and the trolley 12.With collective reference to Figs. 1 and 2, the robot 10 is positioned on a floor14. The robot 10 comprises an AGV (Automated Guided Vehicle) 16. The AGV16 is omni-directional, i.e. it can move in any direction along the floor 14 andit can rotate in a controlled manner and independently from its translationalong its path. The trolley 12 comprises a plurality of wheels, such as caster wheels. 1O The robot 10 further comprises a base member 18. The base member 18 ispositioned on the AGV 16.

The robot 10 further comprises a first link 2oa. The first link 2oa istranslationally movable in a vertical direction relative to the base member 18 at a first joint 22a.

The robot 10 of this example further comprises two manipulators. The firstlink 2oa and the manipulators form one example of a gripping system 24according to the present disclosure. Each manipulator comprises a secondlink 2ob rotatable in a horizontal plane relative to the first link 2oa at asecond joint 22b, a third link 2oc rotatable in a horizontal plane relative tothe second link 2ob at a third joint 22c, a fourth link 2od rotatable in ahorizontal plane relative to the third link 2oc at a fourth joint 22d, and a fifthlink 2oe rotatable in a vertical plane relative to the fourth link 2od at a fifth joint 22e.

The robot 10 further comprises two gripping tools 26. The gripping tools 26 are connected to a respective fifth link 2oe of the robot 1o.

The trolley 12 comprises a gripping handle 28 for being gripped by a human.As shown in Figs. 1 and 2, the handle 28 is horizontally oriented. The robot 10 can grip the handle 28 by means of the gripping tools 26.

The two gripping tools 26 provide two geometrically separated points ofconnection such that the overall connection can transfer completely all forcesand moments (three forces and three moments) between the trolley 12 andthe robot 1o. This has the advantage that an increased maneuverability of asystem comprising the robot 10 and the trolley 12 is provided. At the sametime, the stability of the system is increased when the gripping tools 26 gripthe handle 28. Due to the kinematics of the manipulators, a horizontal distance 30 between the gripping tools 26 can be changed.

By driving the first joint 22a, a height 32 of the gripping tools 26 above the floor 14 can be adjusted. Since the majorities of horizontal handles 28 for 1O being gripped by humans are positioned at a similar height 32, the stroke of this linear motion can be relatively short, e.g. approximately 150 mm.

By driving the fifth joint 22e, the gripping tools 26 can be reoriented to grip vertical handles instead of the illustrated horizontal handle 28.

In addition to the above five joints 22a-22e, each gripping tool 26 has onedegree of freedom. The design, kinematics and number of degrees of freedomof the robot 10 may be greatly varied. According to one example, the robot 10comprises only one degree of freedom, namely inside each gripping tool 26.According to an alternative example, the robot 10 comprises the first joint 22a but not the fifth joint 22e.

Fig. 3 schematically represents a perspective view of the trolley 12 in Figs. 1and 2. The trolley 12 is one example of a carrier according to the present disclosure.

Fig. 4 schematically represents a perspective view of a further example of atrolley 12. The trolley 12 in Fig. 4 comprises four vertical handles 28. Asshown, the vertical handles 28 are "outstretched" to fit humans of differentheights. Ergonomics suggest that humans should be able to have their armsalong the body and a close to 90 degree elbow angle when moving suchtrolley 12. Also the trolley 12 in Fig. 4 can be moved by means of the robot 10.

Clothes on hangers may be suspended in the trolley 12.

Fig. 5 schematically represents a perspective view of a hospital bed 34. Thehospital bed 34 is a further example of a carrier according to the presentdisclosure. As shown in Fig. 5, the hospital bed 34 comprises a horizontal handle 28. Also the hospital bed 34 can be moved by means of the robot 10.

Fig. 6 schematically represents a perspective view of a shopping cart 36. Theshopping cart 36 is a further example of a carrier according to the presentdisclosure. As shown in Fig. 6, the shopping cart 36 comprises a horizontal handle 28. Also the shopping cart 36 can be moved by means of the robot 10. 1O As can be gathered from Figs. 3-6, most carriers have in common that theyare made for humans to push or pull. To this end, most carriers havesimilarly looking handles 28 present at a similar height 32 above the floor 14,for example approximately 1 m above the floor 14. Each handle 28 in Figs. 3- 6 has a circular cross-sectional shape.

Fig. 7 schematically represents a perspective view of one of the gripping tools26 in Figs. 1 and 2 in an open position, and Fig. 8 schematically represents aside view of the gripping tool 26 in the open position. Each of the twogripping tools 26 has the same design. With collective reference to Figs. 7 and8, the gripping tool 26 comprises a base structure 38, a first member 40, a second member 42, a linear actuator 44 and a transmission 46.

The first member 40 is rotatable relative to the base structure 38 about a firstaxis 48. In the orientation of the gripping tool 26 in Figs. 7 and 8, the firstaxis 48 is horizontal. The first member 40 comprises a first gripping element50, here exemplified as a piece of resilient rubber. The first gripping element 50 in turn comprises a first gripping surface 52.

The second member 42 is linearly movable relative to the base structure 38along a second axis 54 by means of the linear actuator 44. In the orientationof the gripping tool 26 in Figs. 7 and 8, the second axis 54 is horizontal andperpendicular to the first axis 48. The first axis 48 and the second axis 54 arehowever offset in that the first axis 48 is oriented vertically above the firstaxis 48 in the orientation of the gripping tool 26 in Figs. 7 and 8. The secondmember 42 comprises a second gripping element 56, here exemplified as apiece of resilient rubber. The second gripping element 56 in turn comprises a second gripping surface 58.

As shown in Figs. 7 and 8, each of the first gripping surface 52 and the secondgripping surface 58 lies in a respective plane parallel with the first axis 48.The circular cross-sectional shape of the handle 28 can be seen in Figs. 7 and8. 1O The linear actuator 44 may for example have a maximum stroke of 100 mm.The linear actuator 44 provides one degree of freedom. The linear actuator 44 may be electric or pneumatic.

In Figs. 7 and 8, the gripping tool 26 is in an open position where the firstmember 40 is positioned in a first free position 60 and the second member42 is positioned in a second free position 62. The first member 40 is rotatableabout the first axis 48 from the first free position 60 to a first grippingposition 64 (Figs. 9 and 10) and the second member 42 is linearly movablealong the first axis 48 from the second free position 62 to a second gripping position 66 (Fig. 10).

The transmission 46 is arranged to transmit a linear movement of the secondmember 42 along the second axis 54 towards the second free position 62 to arotation of the first member 40 about the first axis 48 towards the first free position 60.

In this example, the transmission 46 comprises a cam profile 68 and a camfollower 70 arranged to follow the cam profile 68. Alternative types oftransmissions, such as gear trains or linkages, may however be used instead.In this example, the cam profile 68 is provided on the first member 40 andthe cam follower 70 is provided on the second member 42. The cam profile 68 comprises a straight inclined edge and a hook 72.

As particularly shown in Fig. 8, the second gripping surface 58 is angled approximately 35 degrees to a plane perpendicular to the second axis 54.

Fig. 9 schematically represents the gripping tool 26 in a closed position. Bydriving the second member 42 along the second axis 54 away from the secondfree position 62 by means of the linear actuator 44, the cam follower 70travels along the inclined edge of the cam profile 68. In Fig. 9, the secondmember 42 has made a first stroke 74 away from the second free position 62.The first stroke 74 allows the first member 40 to move from the first freeposition 60 to the first gripping position 64, e.g. by means of gravity or by means of a force device, such as a spring (Fig. 11). The handle 28 is now 1O 11 contacted on opposite sides by the first gripping element 50 and the second gripping element 56.

As shown in Fig. 9, there is a gap both above and below the handle 28between the first gripping surface 52 and the second gripping surface 58. Thegripping tool 26 does therefore not have to be perfectly aligned with thehandle 28 in the vertical direction in order to successfully grip the handle 28.In case a larger gap is desired, the first member 40 may be replaced with a first member having a cam surface 68 with a different inclination or profile.

Fig. 9 further shows that the first gripping surface 52 and the second grippingsurface 58 are parallel when the first member 40 adopts the first grippingposition 64.

Fig. 10 schematically represents the gripping tool 26 in a closed and lockedposition. By driving the second member 42 further along the second axis 54away from the second free position 62 and into the second gripping position66 by means of the linear actuator 44, the second member 42 makes a secondstroke 76 away from the second free position 62. During the second stroke 76,the cam follower 70 engages the hook 72. The first member 40 is therebylocked to the second member 42. During the second stroke 76, the firstgripping element 50 and the second gripping element 56 are compressedfurther. The first member 40 is thus arranged to reach the first grippingposition 64 before the second member 42 reaches the second grippingposition 66 during movement of the second member 42 from the second free position 62 to the second gripping position 66.

The gripping tool 26 enables both a gripping of the handle 28 and a locking ofthis grip with a simple design and operation. The gripping tool 26 is nowlocked in this state during transport of the trolley 12. The linear actuator 44 maintains its position even if power is lost.

Fig. 11 schematically represents a further example of a gripping tool 26. Thegripping tool 26 in Fig. 11 comprises a spring 78, here exemplified as a coil spring. The spring 78 is one example of a force device according to the 1O 12 present disclosure. One end of the spring 78 is fixed to the first member 40and one end of the spring 78 is fixed to the base structure 38. The spring 78exerts a force on the first member 40 towards the first gripping position 64.

The spring 78 thereby ensures closing of the gripping tool 26.

While the present disclosure has been described with reference to exemplaryembodiments, it will be appreciated that the present invention is not limitedto what has been described above. For example, it will be appreciated that thedimensions of the parts may be varied as needed. Accordingly, it is intendedthat the present invention may be limited only by the scope of the claims appended hereto.

Claims (17)

1. A gripping tool (26) for a robot (10), the gripping tool (26) comprising:- a base structure (38); - a first member (40) rotatable about a first axis (48) relative to the basestructure (38) between a first free position (60) and a first grippingposition (64), the first member (40) comprising a first gripping element(50): - a second member (42) linearly movable along a second axis (54),substantially perpendicular to the first axis (48), relative to the basestructure (38) between a second free position (62) and a secondgripping position (66), the second member (42) comprising a secondgripping element (56) for gripping a handle (28) together with the firstgripping element (50) when the first member (40) adopts the firstgripping position (64) and the second member (42) adopts the secondgripping position (66); - a linear actuator (44) arranged to move the second member (42)between the second free position (62) and the second gripping position(66); and - a transmission (46) arranged to transmit a linear movement of thesecond member (42) towards the second free position (62) to a rotation of the first member (40) towards the first free position (60).

2. The gripping tool (26) according to claim 1, further comprising a forcedevice (78) arranged to force the first member (40) from the first free position (60) towards the first gripping position (64).

3. The gripping tool (26) according to claim 2, wherein the force device (78) comprises a spring.

4. The gripping tool (26) according to any of the preceding claims, whereinthe first gripping element (50) comprises a first gripping surface (52)and the second gripping element (56) comprises a second gripping surface (58), and wherein the first gripping surface (52) and the second 1O 14 gripping surface (58) each lies in a plane substantially parallel with thefirst axis (48).

5. The gripping tool (26) according to claim 4, wherein the secondgripping surface (58) lies in a plane that is angled 20 degrees to 60 degrees to a plane perpendicular to the second axis (54).

6. The gripping tool (26) according to any of the preceding claims, whereinthe first gripping element (50) comprises a first gripping surface (52)and the second gripping element (56) comprises a second grippingsurface (58), and wherein the first gripping surface (52) and the secondgripping surface (58) are substantially parallel when the first member (40) adopts the first gripping position (64).

7. The gripping tool (26) according to any of the preceding claims, whereinthe first gripping element (50) and/ or the second gripping element (56) is resilient.

8. The gripping tool (26) according to any of the preceding claims, whereinthe first member (40) is arranged to reach the first gripping position(64) before the second member (42) reaches the second grippingposition (66) during movement of the second member (42) from the second free position (62) to the second gripping position (66).

9. The gripping tool (26) according to any of the preceding claims, whereina movement of the second member (42) from the second free position(62) to the second gripping position (66) comprises a first stroke (74)and a second stroke (76), following the first stroke (74), wherein thefirst stroke (74) allows the first member (40) to move from the first freeposition (60) to the first gripping position (64), and wherein the secondstroke (76) locks the first member (40) in the first gripping position (64)- 1O

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17. The gripping tool (26) according to any of the preceding claims, whereinthe transmission (46) comprises a cam profile (68) and a cam follower (70) arranged to follow the cam profile (68). The gripping tool (26) according to claims 9 and 10, wherein the camprofile (68) is arranged on the first member (40) and the cam follower(70) is arranged on the second member (42), wherein the cam profile(68) comprises a hook (72), and wherein the cam follower (70) isarranged to engage the hook (72) when the second member (42) adoptsthe second gripping position (66) to thereby lock the first member (40) to the second member (42). A gripping system (24) comprising one or more gripping tools (26) according to any of the preceding claims. The gripping system (24) according to claim 12, wherein the grippingsystem (24) is configured to rotate each gripping tool (26) about an axis substantially parallel with the second axis (54). The gripping system (24) according to claim 12 or 13, wherein thegripping system (24) comprises two gripping tools (26), and whereinthe gripping system (24) is configured to adjust a distance (30) betweenthe two gripping tools (26) in a direction substantially parallel with thefirst axis (48). The gripping system (24) according to any of claims 12 to 14, whereinthe gripping system (24) is configured to adjust a height (32) of eachgripping tool (26). A robot (10) comprising a gripping tool (26) according to any of claims 1 to 11 or a gripping system (24) according to any of claims 12 to 15. The robot (10) according to claim 16, wherein the robot (10) comprises an automated guided vehicle (16).