Method of controlling an intelligent assist device in a plurality of distinct workspaces

• US 6,313,595 B2
• Filed: 01/23/2001
• Issued: 11/06/2001
• Est. Priority Date: 12/10/1999
• Status: Expired due to Fees

• Current Assignee: Fanuc Robotics North America Inc (Fanuc Corporation)
• Original Assignee: Fanuc Robotics North America Inc (Fanuc Corporation)
• Inventors: McGee, H. Dean, Swanson, Peter
• Primary Examiner(s): Donels, Jeffrey
• Assistant Examiner(s): Leykin, Rita
• Application Number:
  US09/767,978
• Publication Number:
  US 20010005120A1
• Time in Patent Office: 287 Days
• Field of Search: 318/568.11, 318/568.21, 254/1, 701/301
• US Class Current: 318/568.11
• CPC Class Codes: B25J 9/1679 characterised by the tasks executed
• CPC Class Codes: G05B 2219/36429 Power assisted positioning
• CPC Class Codes: G05B 2219/36432 By putting some constraints on some DOF, move within limited volumes, areas, planes, limits motion in x, y or z planes, virtual reality constraints
• CPC Class Codes: G05B 2219/39439 Joystick, handle, lever controls manipulator directly, manually by operator
• CPC Class Codes: G05B 2219/40074 Move tip of arm or carried object on surface, wall, constraint
• CPC Class Codes: G05B 2219/40517 Constraint motion planning, variational dynamic programming

Abstract

A method of controlling a powered manipulator in a plurality of workspaces is disclosed. The manipulator includes a handle, a motor, a force sensor, and is in combination with a processor controlling the manipulator. The method includes the steps of imparting force on the control handle, sensing direction and magnitude of the force, and sending data of the force to the processor. The data is processed to establish movement commands for the manipulator. The processor is programmed to establish at least one virtual constraint in a first workspace for limiting movement of the manipulator to prevent an operator from moving the manipulator to a limit of this workspace. After the manipulator is moved in this workspace, the manipulator is relocated from the first workspace into a second workspace different from the first workspace where the manipulator is then moved again. To limit movement of the manipulator in the second workspace, the at least one virtual constraint established in the first workspace is repositioned to the second workspace.

Claims

1. A method of controlling a powered manipulator in a plurality of workspaces wherein the powered manipulator includes a control handle, at least one motor, and at least one force sensor, and is in combination with a processor that controls the powered manipulator, said method comprising the steps of:

imparting a force on the control handle;

sensing a direction and magnitude of the force on the control handle with the force sensor and sending data indicative of the direction and the magnitude to the processor;

processing the direction and magnitude data from the force sensor to establish movement commands for the powered manipulator;

programming the processor to establish at least one virtual constraint in a first workspace of the plurality of workspaces for limiting movement of the powered manipulator in the first workspace to prevent an operator from moving the powered manipulator to at least one physical limit of the first workspace;

moving the powered manipulator in the first workspace in response to the movement commands from the processor;

relocating the powered manipulator from the first workspace into a second workspace of the plurality of workspaces that is different from the first workspace;

moving the powered manipulator in the second workspace in response to the movement commands from the processor; and

said method characterized by repositioning the established at least one virtual constraint from the first workspace to the second workspace upon relocation of the powered manipulator such that movement of the powered manipulator in the second workspace is limited to prevent the operator from moving the powered manipulator to at least one physical limit of the second workspace.

2. A method as set forth in claim 1 further including the step of indicating to the processor that the powered manipulator has been relocated into the second workspace.

3. A method as set forth in claim 2 wherein the step of indicating to the processor that the powered manipulator has been relocated is further defined as manually indicating to the processor that the powered manipulator has been relocated into the second workspace.

4. A method as set forth in claim 3 wherein the step of manually indicating to the processor that the powered manipulator has been relocated is further defined as manually locating a second reference point in the second workspace to determine a position of the second reference point relative to a first reference point in the first workspace.

5. A method as set forth in claim 4 wherein the step of repositioning the established at least one virtual constraint is further defined as manually activating a switching device to reposition the established at least one virtual constraint from the first workspace to the second workspace according to the determined position of the second reference point relative to the first reference point.

6. A method as set forth in claim 2 wherein the step of indicating to the processor that the powered manipulator has been relocated is further defined as automatically indicating to the processor that the powered manipulator has been relocated into the second workspace.

7. A method as set forth in claim 6 wherein the step of automatically indicating to the processor that the powered manipulator has been relocated is further defined as automatically sensing that the powered manipulator has been relocated into the second workspace with a sensing device.

8. A method as set forth in claim 7 further including the step of determining a position of a second reference point in the second workspace relative to a first reference point in the first workspace.

9. A method as set forth in claim 8 wherein the step of repositioning the established at least one virtual constraint is further defined as automatically repositioning the established at least one virtual constraint from the first workspace to the second workspace according to the determined position of the second reference point relative to the first reference point.

10. A method as set forth in claim 1 wherein the step of repositioning the established at least one virtual constraint is further defined as programming the processor to establish a first reference frame in the first workspace that is associated with the established at least one virtual constraint in the first workspace.

11. A method as set forth in claim 10 wherein the step repositioning the established at least one virtual constraint is further defined as programming the processor to establish a second reference frame in the second workspace after the powered manipulator has been relocated from the first workspace into the second workspace.

12. A method as set forth in claim 11 further including the step of comparing the first reference frame to the second reference frame to determine a position of the second workspace relative to the first workspace.

13. A method as set forth in claim 12 wherein the step of repositioning the established at least one virtual constraint is further defined as repositioning the established at least one virtual constraint from the first workspace to the second workspace according to the determined position of the second workspace relative to the first workspace.

14. A method as set forth in claim 1 further including the step of programming the processor to establish a first tracking frame for tracking a first assembly unit on an operating assembly line having an operating rate and an upstream limit and a downstream limit.

15. A method as set forth in claim 14 further including the step of moving the first tracking frame with the first workspace along the operating assembly line to track the first assembly unit.

16. A method as set forth in claim 15 wherein the step of repositioning the established at least one virtual constraint is further defined as virtually attaching the established at least one virtual constraint with the first tracking frame such that the established at least one virtual constraint moves with the first tracking frame and the first workspace along the operating assembly line.

17. A method as set forth in claim 16 further including the step of programming the processor to establish a second tracking frame for tracking, a second assembly unit on the operating assembly line.

18. A method as set forth in claim 17 further including the step of moving the second tracking frame with the second workspace along the operating assembly line to track the second assembly unit.

19. A method as set forth in claim 18 wherein the step of repositioning the established at least one virtual constraint is further defined as virtually attaching the established at least one virtual constraint with the second tracking frame such that the established at least one virtual constraint moves with the second tracking frame and the second workspace along the operating assembly line after the powered manipulator has been relocated from the first workspace into the second workspace.

20. A method as set forth in claim 15 wherein the step of moving the powered manipulator in the first workspace is further defined as increasing a velocity of the powered manipulator as the powered manipulator approaches the operating assembly line.

21. A method as set forth in claim 20 wherein the step of increasing the velocity of the powered manipulator is further defined as incrementally increasing the velocity of the powered manipulator until the velocity matches the operating rate of the operating assembly line.

22. A method as set forth in claim 16 further including the step of mounting a first workpiece to the first assembly unit on the operating assembly line within the physical limit of the first workspace as defined by the at least one established virtual constraint.

23. A method as set forth in claim 19 further including the step of mounting a second workpiece to the second assembly unit on the operating assembly line within the physical limit of the second workspace as defined by the at least one established virtual constraint.

24. A method as set forth in claim 14 wherein the step of moving the powered manipulator in the first workspace is further defined as moving the powered manipulator within a range of travel of the powered manipulator corresponding to and between the upstream and downstream limits of the operating assembly line.

25. A method as set forth in claim 24 further including the step of slowing the operating rate of the operating assembly line as the range of travel of the powered manipulator approaches the downstream limit of the operating assembly line.

26. A method as set forth in claim 24 further including the step of signaling the operator of the powered manipulator as the range of travel of the powered manipulator approaches the downstream limit of the operating assembly line.

27. A method as set forth in claim 24 further including the step of stopping operation of the operating assembly line when the range of travel of the powered manipulator exceeds the downstream limit of the operating assembly line.

28. A method as set forth in claim 1 further including the step of modifying the established movement commands in response to the relationship between a location of the powered manipulator in the first and second workspaces and the established at least one virtual constraint.

29. A method as set forth in claim 28 wherein the step of modifying the established movement commands if further defined as varying a speed of the powered manipulator in response to the relationship between a location of the powered manipulator in the first and second workspaces and the established at least one virtual constraint.

30. A method as set forth in claim 1 further including the step of grouping the established virtual constraints in the first workspace thereby establishing a first arrangement of virtual constraints for limiting movement of the powered manipulator in the first workspace.

31. A method as set forth in claim 30 wherein the step of repositioning the established virtual constraints is further defined as repositioning the first arrangement of virtual constraints from the first workspace to the second workspace.

32. A method as set forth in claim 1 wherein the established at least one virtual constraint is selected from the group of consisting of two-dimensional virtual walls, two-dimensional virtual parallelograms, three-dimensional virtual funnels, three-dimensional virtual tunnels, and three-dimensional virtual spheres, and combinations thereof.

33. A method as set forth in claim 1 further including the step of limiting available torque from the motor of the powered manipulator to limit and prevent movement of the powered manipulator.