Compliant End Of Arm Tooling For A Robot

• US 20110211938A1
• Filed: 08/29/2008
• Published: 09/01/2011
• Est. Priority Date: 08/29/2008
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Research Ltd. (ABB Ltd.)
• Inventors: Martinez, Carlos, Eakins, William, Fuhlbrigge, Thomas A., Chen, Heping, Rossano, Gregory
• Granted Patent: US 8,606,398 B2
• Time in Patent Office: Days
• US Class Current: 414/738
• CPC Class Codes: B25J 13/085 Force or torque sensors B25J13/082, B25J13/084 take precedence
• CPC Class Codes: B25J 15/0019 End effectors other than grippers
• CPC Class Codes: B25J 15/0052 multiple gripper units or multiple end effectors
• CPC Class Codes: B25J 15/04 with provision for the remote detachment or exchange of the head or parts thereof
• CPC Class Codes: B25J 17/0208 Compliance devices
• CPC Class Codes: B25J 9/1687 Assembly, peg and hole, palletising, straight line, weaving pattern movement
• CPC Class Codes: B25J 9/1694 characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
• CPC Class Codes: G05B 2219/39574 Passive compliant hand, wrist
• CPC Class Codes: G05B 2219/40035 Shake grasped parts for dropping excess entangled parts back into pin
• CPC Class Codes: G05B 2219/40053 Pick 3-D object from pile of objects
• CPC Class Codes: G05B 2219/40537 Detect if robot has picked up more than one piece from bin; interlocked parts
• CPC Class Codes: Y10T 74/20329 Joint between elements

Abstract

A robot (12) is used to pick parts from a bin (40 in FIG. 1). The robot has a compliant apparatus (42) and one or more tools are connected to the apparatus to perform the picking. The compliant apparatus has mechanisms for monitoring and/or controlling its compliance. The compliant apparatus can have various embodiments. Force sensing can be used during removal of grasped parts from the bin to determine the force exerted on the picking tool (s). The signal indicative of the exerted force can be used by the robot controller to determine the weight of the parts that may be held by the picking tool(s). The robot has one or more devices (FIG. 16, 17) which can be the picking tool to stir the parts in the bin.

Claims

1. A compliant apparatus for use by a robot to pick a part from a bin having one or more of said parts therein, said compliant part picking apparatus comprising:

at least one rigid component;

at least one compliant component having at least one degree of freedom connected to said at least one rigid component; and

means mounted on said compliant part picking apparatus for monitoring and/or controlling the compliance of said compliant component.

2. The compliant part picking apparatus of claim 1 further comprising a tool connected to said rigid component, said tool for picking said part from said bin.

3. The compliant part picking apparatus of claim 1 further comprising two or more rigid components, a tool for picking said part from said bin connected to one of said two or more rigid components, said at least one compliant component connected directly to said rigid component connected to said tool or through another of said two or more rigid components to said rigid component connected to said tool.

4. The compliant part picking apparatus of claim 1 wherein said compliant component comprises either a gas filled device whose compliance depends on the pressure of said gas in said gas filled device or a compressible device whose compliance depends on its compressibility.

5. The compliant part picking apparatus of claim 4 wherein said gas filled device further comprises means for sensing said gas pressure in said gas filled device.

6. The compliant part picking apparatus of claim 4 wherein said compressible device further comprises means for detecting compliant motion of said compliant part picking device.

7. A robot for picking one or more parts randomly distributed in a bin comprising:

a moveable arm;

a computing device connected to said robot for controlling motion of said moveable arm; and

a compliant part picking apparatus connected to said moveable arm comprising;

at least one rigid component connected to said moveable arm;

at least one compliant component having at least one degree of freedom connected to said at least one rigid component; and

means for monitoring and/or controlling the compliance of said compliant component;

said robot further comprising a tool connected to said rigid component, said tool for picking one or more of said parts from said bin.

8. The robot of claim 7 wherein said compliant component comprises a gas filled device whose compliance depends on the pressure of said gas in said gas filled device and means for monitoring and/or controlling said gas pressure.

9. The robot of claim 8 wherein said computing device upon determining that one or more of said randomly distributed parts in said bin can be picked by said tool causes said robot moveable arm to move said tool to grasp said one or more pickable parts.

10. The robot of claim 8 wherein said computing device upon determining that said tool has a collision with said bin or said pickable parts while attempting to grasp said one or more pickable parts cause said means for controlling said gas pressure in said gas filled device to release said gas pressure and said moveable arm to move said tool away from away from the location of said collision.

11. The robot of claim 7 further comprising a tool mounted on said robot for stirring one or more of said one or more randomly distributed parts in said bin when said computing device determines that a predetermined event has occurred.

12. The robot of claim 7 wherein said computing device causes said picking tool to stir one or more of said one or more randomly distributed parts in said bin upon the occurrence of a predetermined event.

13. The robot of claim 7 further comprising means for monitoring the force exerted during removal of one or more parts grasped by said picking tool from said bin and sending a signal to said computing device indicative of said exerted force.

14. The robot of claim 13 wherein said computing device causes said robot to search for a direction to remove said one or more picked parts that has an exerted force that is less than said predetermined limit when said computing device has determined that said exerted force exceeds a predetermined limit.

15. The robot of claim 14 wherein said computer device causes said picking tool to release said one or more picked parts after said computing device determines that a predetermined search limit has been reached in searching for a direction to remove said one or more picked parts from said bin without exceeding said predetermined limit for said exerted force.

16. The robot of claim 14 wherein said computing device causes said robot to release said one or more picked parts when said robot cannot find a direction to remove said picked parts that has an exerted force that is less than said predetermined limit.

17. The robot of claim 7 wherein said compliant component comprises a compressible device whose compliance depends on its compressibility and means for detecting compliant motion.

18. The robot of claim 13 wherein said computing device determines from said signal from said force exerted monitoring means if the weight held by said tool is more than the weight of one part.

19. The robot of claim 18 wherein after said computing device has determined that the weight held by said tool is more than the weight of one part said computing device causes said tool to be moved over said bin in a manner designed to encourage all but one of said picked parts to be freed from said tool and dropped back into said bin.

20. The robot of claim 19 wherein after said computing device has determined that the weight held by said tool is more than the weight of one part said computing device determines if a predetermined limit of attempts for said tool to drop parts picked by said tool has been reached.

21. The robot of claim 18 wherein after said computing device has determined that the weight held by said tool is more than the weight of one part said computing device causes said tool to release all of said picked parts into said bin.

22. The robot of claim 20 wherein after said predetermined limit is reached said computing device causes said tool to release all of said picked parts into said bin.

23. The robot of claim 11 further comprising force sensing means for sending a signal to said computing device indicative of said stirring tool contacting one or more of said randomly distributed parts in said bin when stirring is performed.

24. The robot of claim 12 further comprising force sensing means for sending a signal to said computing device indicative of said picking tool contacting one or more of said randomly distributed parts in said bin when stirring is performed.

25. A compliant apparatus for use by a robot for picking of randomly distributed objects, said apparatus comprising:

one or more rigid components in a predetermined arrangement with more than one compliant device, each of said more than one compliant devices providing compliance in one or more degrees of freedom to facilitate extraction of one or more of said objects from said bin.

26. The compliant apparatus of claim 25 further comprising one or more end points, each of said end points capable of picking up one of said objects.

27. The compliant apparatus of claim 25 wherein each of one said more than one compliant device can have different amounts of compliance along different axes to provide more compliance in one or more degrees of freedom than in others.

28. The compliant apparatus of claim 26 wherein each of said more than one compliant device can have different amounts of compliance along different axes to provide more compliance in one or more degrees of freedom than in others.

29. A tool for a robot comprising:

a compliant component;

two rigid bodies, said compliant component between said rigid bodies; and

one or more flexible tethers holding said compliant component and said rigid bodies in a predetermined relationship to each other,

said compliant component and said one or more flexible tethers allowing said rigid bodies to move in relation to one another and change said predetermined relationship to each other after said tool is subjected to forces and/or torques that exceed a predetermined amount of said forces and/or torques.

30. The tool of claim 29 wherein said compliant component and said rigid bodies return to said predetermined relationship after said forces and/or torques are reduced to be below said predetermined amount of said forces and/or torques.