Method and control system for controlling a plurality of robots

• US 6,804,580 B1
• Filed: 04/03/2003
• Issued: 10/12/2004
• Est. Priority Date: 04/03/2003
• Status: Expired due to Term

• Current Assignee: KUKA Roboter GmbH (Midea Group Co., Ltd)
• Original Assignee: KUKA Roboter GmbH (Midea Group Co., Ltd)
• Inventors: Martin, David M., Mirza, Khalid, Chaffee, Michael C., Hagenauer, Andreas, Kneifel, R. William II, Stoddard, Kenneth A., Graf, Stefan
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Marc, McDieunel, Marc, McDieunel
• Application Number:
  US10/406,521
• Publication Number:
  US 20040199290A1
• Time in Patent Office: 558 Days
• Field of Search: 700/245-251, 700/254, 700/256, 700/264, 701/23, 701/228, 701/47, 701/200, 701/213, 701/217, 701/220, 701/28, 318/568.1, 318/568.11, 318/568.13, 318/568.16, 318/573, 318/574, 901/6, 901/9, 901/46, 901/48, 901/47, 801/47, 744/900.1, 714/15, 714/23, 714/24
• US Class Current: 700/248
• CPC Class Codes: B25J 9/1669 characterised by special application, e.g. multi-arm co-operation, assembly, grasping
• CPC Class Codes: B25J 9/1682 Dual arm manipulator; Coordination of several manipulators
• CPC Class Codes: G05B 2219/31157 Star network, hub
• CPC Class Codes: G05B 2219/39109 Dual arm, multiarm manipulation, object handled in cooperation
• CPC Class Codes: G05B 2219/39124 Grasp common rigid object, no movement end effectors relative to object
• CPC Class Codes: G05B 2219/39131 Each of the manipulators holds one of the pieces to be welded together
• CPC Class Codes: G05B 2219/39132 Robot welds, operates on moving workpiece, moved by other robot
• CPC Class Codes: G05B 2219/39139 Produce program of slave from path of master and desired relative position
• CPC Class Codes: G05B 2219/39142 Moving time between positions in slave program coordinated online with master
• CPC Class Codes: G05B 2219/39144 Scale moving time of all robots, machines to match slowest, no waiting
• CPC Class Codes: G05B 2219/39145 Slave path is the same as master path and superposed desired relative movement
• CPC Class Codes: G05B 2219/40307 Two, dual arm robot, arm used synchronously, or each separately, asynchronously
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y10T 74/20305 Robotic arm

Abstract

A system for controlling a plurality of robots and a method for controlling said system. Said system comprises a plurality of controllers, each having an associated motion system adapted to control attached robots, with each motion controller being able to receive motion instructions from at least one motion instruction source and at least one of said motion instruction sources being a control program, as well as a computer network over which said controllers communicate. In this way, the invention can be applied to solve problems which are commonly encountered in coordination activities such as load sharing, mating of parts while processing, fixtureless transfer, teaching, manual motion of coordinated operations, and time coordinated motion.

Claims

1. A method for controlling a system of a plurality of robots, said system comprising:

a plurality of controllers, each having an associated motion system controlling attached robots and receiving motion instructions from at least one motion instruction source, and a computer network over which said controllers communicate;

wherein time coordinated motion instructions are define and executed by said control program, each such time coordinated motion instruction with unique label, such that information is communicated among said plurality of controllers; and

wherein robot motion produced by like labeled time coordinated motion instructions executed on any of said plurality of controllers executes in such a way that they jointly begin at a first time, follow a common relative velocity profile, and jointly end at a second time.

2. The method according to claim 1, wherein an associated clock in each controller produces timing information based on a temporal reference frame;

wherein a system for supplying a synchronizing signal to said controllers periodically aligns the temporal reference frames of said clocks; and

wherein said controllers use said clocks to control said associated motion systems such that said attached robots controlled by said motion systems operate with clock-alignment.

3. The method according to claim 2, wherein a signal with a first frequency and phase is used to adjust a phase of one of said clocks operating at a second higher frequency on each of the plurality of controllers to make the phases of said higher frequency clocks the same in all of said plurality of controllers;

and

wherein said first frequency signal is proportional to the out-of-phase-ness.

4. A method for controlling a system of a plurality of robots, said system further comprising:

a plurality of controllers, each having an associated motion system controlling attached robots;

at least one of said controllers having at least one motion instruction source; and

a computer network over which said controllers communicate;

wherein at least one first controller of said plurality of controllers sends a commanded position of its a attached robot over said network;

wherein at least one second controller of said plurality of controllers receives said commanded position over said network from said first controller;

wherein said second controller defines at least one first robot reference frame with a fixed position relative to some point on said attached robot of said first controller (independent reference frame) and at least one second robot reference frame with a fixed position relative to some point on said attached robot of said so controller;

wherein said second controller by using said commanded position maintains a spatial transformation relationship (dependency relationship) between said second robot reference frame (dependent reference frame) and said independent reference frame by moving its an attached robot to maintain said transformation relationship; and

wherein said dependency relationship is defined by a motion instruction source of said second controller.

5. The method according to claim 4, wherein said spatial transformation relationship is a Cartesian transformation relationship.

6. The method according to claim 4, wherein a teaching system of said second controller, using said commanded position, records a taught position defined relative to said independent reference frame for later use, such that upon later use said second controller causes said second robot reference frame to follow a path prescribed by a motion instruction source of said second controller to said taught position.

7. The method according to claim 4, wherein said dependency is created by a motion of said second robot reference frame to a position defined relative to said independent reference frame from a position defined relative to a reference frame different from said independent reference frame.

8. The method according to claim 4, wherein said second controller maintains said transformation dependency relationship between said dependent reference frame and said independent reference frame while there is no command from any of said motion instruction sources of said second controller and/or when said second controller is changing from one of said motion instruction sources to another.

9. The method according to claim 4, wherein said dependent reference frame defined with respect to a robot attached to a first controller is defined as an independent reference frame with respect to said robot by a different controller.

32. The method according to claim 4, wherein the spatial transformation relationship (dependency relationship) of the at least one second controller is a motion of a second robot reference frame defined relative to an independent reference frame, said relative motion instruction issued by a motion instruction source of said at least one second controller.

10. A method for controlling a system of a plurality of robots, said system farther comprising:

a plurality of controllers, each having an associated moon system controlling attached robots;

at least one of said controllers having at least one motion instruction source; and

a computer network over which said controllers communicate;

wherein at least one first controller of said plurality of controllers sends a commanded position of its A attached robot over said network;

wherein at least one second controller of said plurality of controllers receives said commanded position over said network from said first controller;

wherein said second controller defines at least one first robot reference frame with a fixed position relative to some point on said attached robot of said first controller (independent reference frame) and at least one second robot reference frame with a fixed position relative to some point on said attached robot of said second controller;

wherein said second controller by using said commanded position maintains a spatial transformation relationship (dependency relationship) between said second robot reference frame (dependent reference frame) and said independent reference frame by moving an attached robot to maintain said transformation relationship;

wherein said dependency relationship is defined by a motion instruction source of said second controller;

wherein further an associated clock in each controller produces timing information based on a temporal reference frame;

wherein a system for supplying a synchronizing signal to said controllers periodically aligns said temporal reference frames of said clocks; and

wherein said controllers use said clocks to control said associated motion systems such that said attached robots controlled by said motion systems operate with clock-alignment.

11. The method according to claim 10, wherein a teaching system of said second controller, using said commanded position, records a taught position defined relative to said independent reference frame for later use, such that upon later use said second controller causes said second robot reference frame to follow a path prescribed by a motion instruction source of said second controller to said taught position.

12. The method according to claim 10, wherein said dependency is created by a motion of said second robot reference frame to a position defined relative to said independent reference frame from a position defined relative to a reference frame different from said independent reference frame.

13. The method according to claim 10, wherein said second controller maintains said fixed transformation dependency relationship between said dependent reference frame and said independent reference frame while there is no command from any of said motion instruction sources of said second controller and/or when said second controller is changing from one of said motion instruction sources to another.

14. The method according to claim 10, wherein said dependent reference frame defined with respect to a robot attached to a first controller is defined as an independent reference frame with respect to said robot by a different controller.

15. A system for controlling a plurality of robots, said system comprising:

a plurality of motion controllers, each of said plurality of motion controllers having an associated motion system controlling an attached robot, with each of said motion controllers receiving motion instructions from at least one motion instruction source; and

a computer network over which said controllers communicate;

wherein said control program is arranged for defining and executing a uniquely labeled time coordinated motion instruction for communicating information among said plurality of controllers;

.and

wherein said controllers are arranged for synchronized execution of like labeled time coordinated motion instructions such that said instructions execute in such a way that they jointly begin at a first time, follow a common relative velocity profile, and jointly end at a second time.

16. The system according to claim 15, wherein said motion instruction source is local to said controller.

17. The system according to claim 15, wherein said motion instruction source is remote from said controller.

18. The system according to claim 15 further comprising:

an associated clock for each controller that produce timing information based on a temporal reference frame; and

a system for supplying a synchronization signal to said controllers that periodically aligns the temporal reference frames of said clocks;

said controllers being arranged for using said clocks to control said associated motion systems such that said attached robots controlled by said motion systems operate with clock-alignment.

19. The system according to claim 18, wherein said clocks are hardwired to said controllers.

20. The system according to claim 18, wherein said clocks are connected to said controllers via phase locking means, said phase locking means comprising a serial synchronizing connection and/or an Ethernet connection.

21. A system for controlling a plurality of robots, said system comprising:

a plurality of controllers, each having an associated motion system attached robots;

at least one of said controllers, having at least one motion instruction source;

a computer network over which said controllers communicate;

at least one first controller of said plurality of controllers having a position sending system for sending a commanded position of said attached robots over said network;

at least one second controller of said plurality of controllers having a position receiving system for receiving said commanded position over said network from at least one of said first controllers;

said second controller arranged for defining at least one first robot reference frame with a fixed position relative to some point on said robot attached to said first controller (independent reference frame) and at least one second robot reference frame with a fixed position relative to some point on said robots attached to said second controller;

said second controller arranged for maintaining a certain spatial transformation relationship (dependency relationship) between said second robot reference frame (dependent reference frame) and said independent reference frame;

said relationship specified by sad motion instruction source of said second controller.

22. The system according to claim 21, wherein said spatial relationship is a Cartesian transformation relationship.

23. The system according to claim 21, wherein a teaching system of said second controller is arranged for recording taught positions defined relative to an independent reference frame for later.

24. The system according to claim 21, wherein said notion instruction source of said second controller is arranged for creating said dependency relationship between a second robot reference frame and said independent reference frame.

25. The system according to claim 21, wherein said motion instruction source of said second controller is arranged for issuing a relative motion instruction such that said dependency relationship of said second controller is a motion of said dependent reference frame defined relative to said independent reference frame.

26. The system according to claim 21, wherein said second controller is arranged for maintaining said transformation dependency relationship between said dependent reference frame and said independent reference fire while there is no command from any one of said motion instruction sources of said second controller and/or when said second controller changes from one of said instruction sources to another.

27. A system for controlling a plurality of robots, said system comprising:

plurality of controllers, each having an associated motion system controlling attached robots;

at least one of said controllers having at least one motion instruction source;

a computer network over which said controllers communicate;

at least one first controller of said plurality of controllers having a position sending system for sending a commanded position of said attached robot over said network;

at least one second controller of said plurality of controllers having a position receiving system for receiving said commanded position over said network from at least one of said first controllers;

said second controller arranged for defining at least one first robot reference frame with a fixed position relative to some point on said robot attached to said first controller (independent reference frame) and at least one second robot reference frame with a fixed position relative to some point on said robot attached to said second controller,

said second controller arranged for maintaining a certain spatial transformation relationship (dependency relationship) between said second robot reference frame (dependent reference frame) and said independent reference frame,

said relationship specified by said motion instruction source of said second controller;

said system further comprising;

an associated clock or each controller that produces timing information based on a temporal reference frame; and

a system for supplying a synchronization signal to said controllers that periodically aligns the temporal reference frames of said clocks;

said controllers being arranged for using said clocks to control said associated motion systems such that said attached robots controlled by said notion systems operate with clock-alignment.

28. The system according to claim 27, wherein a teaching system of said second controller is arranged for recording taught positions defined relative to an independent reference fine for later use.

29. The system according to claim 27, wherein said motion instruction source of said second controller is arranged for creating said dependency relationship between a second robot reference frame and said independent reference free.

30. The system according to claim 27, wherein said motion instruction source of said second controller is arranged for issuing a relative motion instruction such that said dependency relationship of said second controller is a motion of said dependent reference frame defined relative to said independent reference frame.

31. The system according to claim 27, wherein said second controller is arranged for maintaining said transformation dependency relationship between said dependent reference frame and said independent reference frame while there is no command from any one of said motion instruction sources of said second controller and/or when said second controller changes from one of said instruction sources to another.