Method and device for controlling manipulators

• US 20050273198A1
• Filed: 06/01/2005
• Published: 12/08/2005
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: KUKA Roboter GmbH (Midea Group Co., Ltd)
• Original Assignee: KUKA Roboter GmbH (Midea Group Co., Ltd)
• Inventors: Bischoff, Rainer
• Granted Patent: US 7,571,025 B2
• Time in Patent Office: Days
• US Class Current: 700/248
• CPC Class Codes: B25J 9/1682 Dual arm manipulator; Coordination of several manipulators
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G05B 2219/39008 Fixed camera detects reference pattern held by end effector
• CPC Class Codes: G05B 2219/39045 Camera on end effector detects reference pattern
• CPC Class Codes: G05B 2219/39046 Compare image of plate on robot with reference, move till coincidence, camera
• CPC Class Codes: G05B 2219/39051 Calibration cooperating manipulators, closed kinematic chain by alignment
• CPC Class Codes: G05B 2219/39114 Hand eye cooperation, active camera on first arm follows movement of second arm
• CPC Class Codes: G05B 2219/39397 Map image error directly to robot movement, position with relation to world, base not needed, image based visual servoing
• CPC Class Codes: Y10T 74/20207 Multiple controlling elements for single controlled element
• CPC Class Codes: Y10T 74/20305 Robotic arm
• CPC Class Codes: Y10T 74/20311 including power cable or connector
• CPC Class Codes: Y10T 74/20329 Joint between elements
• CPC Class Codes: Y10T 74/20335 Wrist

Abstract

The invention relates to a method for controlling a plurality of manipulators, such as multiaxial or multiaxle industrial robots. At least one manipulator functions as the reference manipulator and is moved in a plurality of preset poses within its working area at which internal position values are determined as first desired poses. For each desired pose, subsequently a first actual pose of the reference manipulator is determined by an external measuring system. Subsequently at least one further manipulator moves up to specific poses of the reference manipulator as second desired poses and for each of these poses an actual pose of the further manipulator is determined by an external measuring system. On the basis of actual-desired deviations between the thus determined desired and actual poses of the two manipulators, subsequently a parameter model for the further manipulator is established and with it it is possible to compensate simultaneously both its own errors and those of the reference manipulator. The method according to the invention can be used in conjunction with a simplified, improved cooperation between manipulators.

Claims

1. Method for controlling a plurality of manipulators, such as multiaxial industrial robots, whereof at least one functions as a reference manipulator and at least one other as a copying manipulator, in which:

a) the reference manipulator is moved into a plurality of predetermined poses within its working area and for determining internal position values of the reference manipulator in the same as first desired poses,

b) for each desired pose from step a), an associated pose of the reference manipulator is determined as the first actual pose by an external measuring system,

c) the copying manipulator advances to the poses determined by the reference manipulator as second desired poses,

d) for each pose advanced to in step c), one pose of the copying manipulator is determined as the second actual pose by an external measuring system and

e) a parameter model for the copying manipulator is determined from actual-desired deviations between the first desired and actual poses (of the reference manipulator) and second desired and actual poses (of the copying manipulator) for the simultaneous compensation of errors of both the copying manipulator and errors of the reference manipulator.

2. Method according to claim 1, wherein in step c) the copying manipulator advances to the first desired poses of the reference manipulator preset in step a).

3. Method according to claim 1, wherein in step c) the copying manipulator advances to the first actual poses of the reference manipulator determined in step b).

4. Method according to claim 3, wherein the copying manipulator is moved until a pose thereof and the actual pose of the reference manipulator coincide within the framework of the preset deviation tolerances and/or a preset displacement or offset.

5. Method according to claim 4, wherein the movement of the copying manipulator in step c) takes place as a function of the external measuring system.

6. Method according to claim 1, wherein the operation of the reference manipulator and the copying manipulator takes place substantially simultaneously, the desired and/or actual pose of the reference manipulator being transmitted to the copying manipulator by means of a suitably constructed link, particularly a data link.

7. Method according to claim 1, wherein the copying manipulator carries the external measuring system, so that the latter is jointly moved by the copying manipulator.

8. Method according to claim 7, wherein there is a mechanical forced coupling by means of the external measuring system between the reference manipulator and the copying manipulator.

9. Method according to claim 1, wherein that pose determination by the external measuring system takes place optically.

10. Method according to claim 1, wherein the reference manipulator and copying manipulator are operated in a common working cell.

11. Method according to claim 1, wherein the copying manipulator is operated in a further working cell identical to the reference manipulator working cell.

12. Method according to claim 1, wherein the first desired and actual poses of the reference manipulator are stored following their determination.

13. Method according to claim 12, wherein the reference manipulator and copying manipulator are operated in time-staggered manner, the desired and/or actual poses of the reference manipulator being transmitted in stored form to the copying manipulator.

14. Method according to claim 12, wherein the reference manipulator and copying manipulator are operated successively in one working cell on the same control device.

15. Method according to one of the preceding claims, wherein initially a first manipulator is selected as the reference manipulator and a second manipulator as the copying manipulator, that subsequently the second manipulator functions as the reference manipulator and a further manipulator as the copying manipulator, etc.

16. Device for improving accuracy characteristics of manipulators, such as multiaxial industrial robots, having:

at least two manipulators,

at least one control device for moving the manipulators into predetermined desired poses,

at least one external measuring system for determining actual poses of the manipulators corresponding to the given desired poses,

a comparator device for determining a deviation (Δ

) between the desired and actual poses of a manipulator and

a model forming device for determining a parameter model of at least one of the manipulators from the combined actual-desired deviations (A) of the manipulators.

17. Device according to claim 16, wherein at least one external measuring system is arranged in stationary manner and operatively connected to a working area of a manipulator.

18. Device according to claim 16, wherein an external measuring system is located on a manipulator and is movable therewith.

19. Device according to claim 16, wherein an external measuring system is constructed as an optically measuring measuring system.

20. Device according to claim 19, wherein the optical measuring system is constructed for determining all the degrees of freedom of a pose of the manipulators.

21. Device according to claim 19, wherein the external measuring system is a stereo image processing system.

22. Device according to claim 18, wherein the jointly moved measuring system is constructed as a measuring system measuring by means of a mechanical forced coupling between the manipulators.

23. Device according to claim 22, wherein the measuring system is a force-moment sensor.

24. Device according to claim 16, wherein the measuring system is constructed as a filament or wire measuring system.

25. Device according to claim 16, characterized by a common working cell for the simultaneous operation of at least two manipulators.

26. Device according to claim 16, characterized by separate working cells for a plurality of manipulators.

27. Device according to claim 16, characterized by transmission means for transmitting data between manipulators, particularly for the transmission of desired and/or actual poses, as well as internal position values.

28. Device according to claim 16, characterized by storage means at least for desired and/or actual poses of a manipulator.

29. Device according to claim 28, characterized by a working cell for the sequential operation of the manipulators, particularly on the same control device.