Method and apparatus for controlling manipulator and workpiece positioner

• US 4,598,380 A
• Filed: 08/13/1984
• Issued: 07/01/1986
• Est. Priority Date: 08/13/1984
• Status: Expired due to Fees

• Current Assignee: ABB Robotics Incorporated (ABB Limited)
• Original Assignee: Cincinnati Milacron Incorporated (Milacron Incorporated)
• Inventors: Resnick, Brian J., Teach, Charles C., Holmes, John G., Messina, Elena R.
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): MACDONALD, ALLEN R
• Application Number:
  US06/640,431
• Time in Patent Office: 687 Days
• Field of Search: 364/169, 364/474, 364/475, 364/513, 364/702, 364/720, 364/853, 364/167, 364/171, 364/174, 364/191, 364/192, 364/193, 318/573, 318/568, 318/571, 901/20
• US Class Current: 700/251
• CPC Class Codes: G05B 19/41815 characterised by the cooperation between machine tools, manipulators and conveyor or other workpiece supply system, workcell
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method and apparatus are provided for cooperatively controlling motion between a tool centerpoint associated with a function element carried by a manipulator and rotation of a workpiece carried by a positioner. The tool centerpoint follows a linear path interpolated between programmed locations at a velocity resulting in a relative velocity between the tool centerpoint and the workpiece surface equal to a programmed velocity. Differences in radial distance of the tool centerpoint from the axis of rotation of the workpiece at successive programmed locations result in incremental velocity modifications along the path to maintain the relative velocity at the programmed value.

Claims

1. Method for cooperatively controlling motion of a tool centerpoint associated with the function element carried by a manipulator and rotation of a workpiece carried by a positioner, the motion effected by the manipulator being along a linear path intersecting the axis of rotation of the workpiece, the motion being defined by input signals, the manipulator and positioner having movable members driven by actuators controlled by servomechanism circuits, the relative motion of the tool centerpoint and workpiece surface being effected at a velocity represented by an input signal, the method comprising the steps of:

a. iteratively producing incremental velocity signals in response to the input signals, each incremental velocity signal representing the velocity of the tool centerpoint during an iteration interval;

b. modifying the incremental velocity signals in proportion to the change in radial distance of the tool centerpoint from the axis of rotation of the workpiece between successive iterations;

c. producing intermediate location coordinate signals in response to the modified incremental velocity signals, the intermediate location coordinate signals representing coordinates relative to a rectangular coordinate system associated with the manipulator of an intermediate location along the linear path of the tool centerpoint and an intermediate rotation of the workpiece; and

d. applying the intermediate location coordinate signals to the servomechanism circuits to effect coordinated motion of the movable members of the manipulator and positioner.

2. The method of claim 1 wherein the input signals define coordinates of starting and ending locations of the tool centerpoint motion and the workpiece rotation and the relative velocity between the tool centerpoint and the workpiece surface and the method further comprises the steps of:

a. producing an effective linear distance signal representing the distance resulting from the combination of tool centerpoint motion and workpiece rotation; and

b. producing an adjusted programmed velocity signal in response to the effective linear distance signal, the adjusted programmed velocity signal representing the velocity of the tool centerpoint which results in a relative velocity between the tool centerpoint and the workpiece surface equal to the programmed velocity.

3. The method of claim 2 wherein the step of producing intermediate location coordinate signals further comprises the steps of:

a. producing a programmed distance signal representing the larger of the linear distance traversed by the tool centerpoint between two programmed locations and the arc length swept by the average radial distance of the tool centerpoint from the axis of rotation when rotated through the programmed angular change of the workpiece;

b. producing coordinate component ratio signals, each coordinate component ratio signal representing the quotient of the change in magnitude of a selected coordinate and the programmed distance signal;

c. producing an incremental distance signal in response to the increment velocity signal and an interation interval signal representing the period between iterations, the incremental distance signal representing an increment of motion occurring over the iteration period; and

d. producing coordinate component signals in response to the incremental distance signal and the coordinate component ratio signals, the coordinate component signals representing coordinate components of the incremental distance.

4. The method of claim 3 wherein the axis of rotation of the workpiece is not parallel to any of the axes of the manipulator rectangular coordinate system and the step of modifying the incremental velocity signals further comprises the steps of:

a. producing transformed coordinate signals representing coordinates of programmed locations relative to a workpiece positioner coordinate system;

b. producing intermediate radial distance signals in response to the transformed coordinate signals, the intermediate radial distance signals representing the radial distance from the axis of rotation of the workpiece to the intermediate tool centerpoint location; and

c. producing a modified increment velocity signal in response to the intermediate radial distance signal, the incremental velocity signal, and the starting location radial distance signal, the modified increment velocity signal representing the velocity of the tool centerpoint which results in a relative velocity between the tool centerpoint and the workpiece surface at the programmed velocity at the intermediate location of the tool centerpoint.

5. A method for selectively, cooperatively controlling motion of a tool centerpoint associated with the function element carried by a manipulator and rotation of a workpiece carried by a positioner, the motion effected by the manipulator being along a linear path intersecting the axis of rotation of the workpiece, the motion being defined by input signals representing starting and ending locations of the tool centerpoint relative to a rectangular coordinate system associated with the manipulator and starting and ending angular locations of the workpiece relative to the axis of rotation of the workpiece, the manipulator and positioner having movable members driven by actuators controlled by servomechanism circuits, the relative motion of the tool centerpoint and workpiece surface being effected at a velocity represented by an input signal, and axial and radial limit distances relative to the workpiece positioner being defined by further input signals, the method comprising the steps of:

a. producing a velocity coordination status signal in response to the input signals, the velocity coordination status signal representing the presence of a starting location within an envelope defined by the axial and radial limit distance input signals;

b. producing an effective linear distance signal representing the distance resulting from the combination of tool centerpoint motion and workpiece rotation;

c. producing an adjusted programmed velocity signal in response to the effective linear distance signal and the programmed velocity signal, the adjusted programmed velocity signal representing the velocity of the tool centerpoint which results in a relative velocity between the tool centerpoint and the workpiece surface equal to the programmed velocity;

d. iteratively producing incremental velocity signals in response to the adjusted programmed velocity signal and the location coordinate and rotation input signals, each incremental velocity signal representing the velocity of the tool centerpoint during an iteration interval;

e. modifying the incremental velocity signals in proportion to the change in radial distance of the tool centerpoint from the axis of rotation of the workpiece between successive programmed locations;

f. producing intermediate location coordinate signals in response to the modified incremental velocity signals, the intermediate location coordinate signals representing coordinates relative to a rectangular coordinate system associated with the manipulator of the tool centerpoint and intermediate rotations of the workpiece; and

g. applying the intermediate location coordinate signals to the servomechanism circuits to effect coordinated motion of the tool centerpoint and the workpiece.

6. The method of claim 5 wherein the step of producing a velocity coordination status signal further comprises the steps of:

a. producing transformed location coordinate signals in response to the location coordinate input signals, the transformed location coordinate signals representing coordinates of the tool centerpoint relative to a rectangular coordinate system having its origin in the plane of the positioner to which the workpiece is mounted and having one axis substantially coincident with the axis of rotation of the workpiece;

b. producing a radial distance signal in response to the transformed location coordinate signals, the radial distance signal representing the radial distance from the axis of rotation of the workpiece to the starting location coordinates;

c. comparing the transformed location coordinate signals and the radial distance signal to the axial and radial limit distance input signals; and

d. producing the velocity coordination status signal in response to detecting the presence of a starting location within the envelope defined by the axial and radial limit distance signals.

7. The method of claim 6 wherein the axis of rotation of the workpiece is not parallel to any of the rectangular coordinate axes associated with the manipulator and further input signals define the rotations of the coordinate axes of the manipulator coordinate system with respect to the axes of the manipulator coordinate system and further define the location of the origin of the positioner coordinate system relative to the manipulator coordinate system and the step of transforming location coordinate signals further comprises the steps of:

a. producing a translational displacement signal representing the linear distance between the location and the origin of the positioner rectangular coordinate system; and

b. producing transformed location coordinate signals in response to the translational displacement signal and the positioner coordinate system rotation input signals, the transformed location coordinate signals representing coordinates of the location relative to the positioner rectangular coordinate system.

8. A method for cooperatively controlling motion of the tool centerpoint associated with the function element carried by a manipulator and rotation of a workpiece carried by a positioner, the motion effected by the manipulator being along a linear path intersecting the axis of rotation of the workpiece, the motion being defined by input signals representing coordinates of starting and ending locations of the tool centerpoint motion relative to a rectangular coordinate system associated with the manipulator, starting and ending orientations of the function element through the tool centerpoint at the programmed locations and starting and ending angular locations of the workpiece, the manipulator and positioner having movable members driven by actuators controlled by servomechanism circuits, the relative motion of the tool centerpoint and workpiece surface being effected at a velocity represented by an input signal, the method comprising the step of:

a. producing an effective linear distance signal representing the distance resulting from the combination of tool centerpoint motion and workpiece rotation;

b. producing an adjusted programmed velocity signal in response to the effective linear distance signal and the programmed velocity signal, the adjusted programmed velocity signal representing the velocity of the tool centerpoint which results in a relative velocity between the tool centerpoint and the workpiece surface equal to the programmed velocity;

c. iteratively producing incremental velocity signals in response to the location coordinate input signals and the adjusted programmed velocity signal, each incremental velocity signal representing the velocity of the tool centerpoint during an iteration interval;

d. modifying the incremental velocity signals in proportion to the change in radial distance of the tool centerpoint from the axis of rotation of the workpiece between successive programmed locations;

e. producing intermediate location coordinate signals in response to the modified incremental velocity signal, the intermediate location coordinate signals representing coordinates relative to the manipulator rectangular coordinate system of intermediate locations of the tool centerpoint and intermediate orientations of the function element and intermediate angular locations of the workpiece; and

f. applying the intermediate location coordinate signals to the servo mechanism circuits to effect coordinated motion between the tool centerpoint and the workpiece.

9. The method of claim 8 wherein the step of producing intermediate location coordinate signals further comprises the step of:

a. producing a programmed distance signal representing the largest of the linear distance traversed by the tool centerpoint, the effective arc length swept by the function element through the programmed orientation changes, and the arc length swept by the average radial distance of the tool centerpoint from the axis of rotation of the workpiece between the start and finish rotations of the workpiece;

b. producing coordinate component ratio signals, each coordinate component ratio signal representing the quotient of the change in magnitude of a coordinate and the programmed distance signal;

c. producing an incremental distance signal in response to the incremental velocity signal and an iteration interval signal representing the period between iterations, the incremental distance signal representing an increment of motion occurring over the iteration period; and

d. producing coordinate component signals in response to the incremental distance signal and the coordinate component ratios, the coordinate component signals representing coordinate components of the incremental distance.

10. The method of claim 9 wherein the axis of rotation of the workpiece is not parallel to any of the coordinate axes of the rectangular coordinate system associated with the manipulator and the step of modifying the incremental velocity signals further comprises the steps of:

a. producing transformed coordinate signals representing coordinates of programmed locations relative to a workpiece positioner rectangular coordinate system having its origin in the plane of the positioner to which the workpiece is mounted and one axis substantially coincident with the axis of rotation of the workpiece.

b. producing intermediate radial distance signals in response to the transformed location coordinate signals, the intermediate radial distance signals representing the radial distance from the axis of rotation of the workpiece to the intermediate tool centerpoint location; and

c. producing a modified increment velocity signal in response to the intermediate radial distance signal, the increment velocity signal and the starting location radial distance, the modified incremental velocity signal representing the velocity of the tool centerpoint resulting in a relative velocity between the tool centerpoint and the workpiece surface equal to the programmed velocity at the intermediate location.

11. Apparatus for cooperatively controlling motion of a tool centerpoint associated with a function element carried by a manipulator and rotation of a workpiece carried by a positioner, the motion effected by the manipulator being along a linear path intersecting the axis of rotation of the workpiece, the motion being defined by input signals, the manipulator and positioning device having movable members driven by actuators controlled by servomechanism circuits, the relative motion of the tool centerpoint and workpiece surface being effected at a velocity represented by an input signal, the apparatus comprising:

a. means for storing input signals;

b. means responsive to the input signals for iteratively producing incremental velocity signals, each incremental velocity signal representing the velocity of the tool centerpoint during an iteration interval;

c. means for modifying the incremental velocity signal in proportion to the change in radial distance of the tool centerpoint from the axis of rotation of the workpiece between successive iterations;

d. means responsive to the modified incremental velocity signal for producing intermediate location coordinate signals representing coordinates of an intermediate location along the linear path of the tool centerpoint relative to a rectangular coordinate system associated with the manipulator and an intermediate angular coordinate of the workpiece rotation relative to the axis of rotation of the workpiece;

e. means for applying the intermediate location coordinate signals to the servomechanism circuits to effect coordinated motion of the tool centerpoint and the workpiece at a relative velocity defined by the velocity input signal.

12. The apparatus of claim 11 wherein the means for producing intermediate location signals further comprises:

a. means for producing a programmed distance signal representing the larger of the linear distance traversed by the tool centerpoint and the arc length swept by the average radial distance of the tool centerpoint from the axis of rotation of the workpiece through the angular change of location of the workpiece;

b. means for producing coordinate component ratio signals, each coordinate component ratio signal representing the quotient of the change in magnitude of a selected coordinate and the programmed distance signal;

c. means responsive to the modified incremental velocity signal and an iteration interval signal representing the period between iterations for producing an incremental distance signal representing an increment of motion occurring during an iteration; and

d. means responsive to the incremental distance signal and the coordinate component ratio signals for producing the coordinate component signals representing coordinate components of the incremental distance.

13. The apparatus of claim 12 wherein the input signals define coordinates of starting and ending locations of the tool centerpoint motion relative to the manipulator rectangular coordinate system and the workpiece rotation and the apparatus further comprises:

a. means for producing an effective linear distance signal representing the distance resulting from the combination of tool centerpoint motion and workpiece rotation; and

b. means responsive to the effective linear distance signal for producing an adjusted programmed velocity signal representing the velocity of the tool centerpoint which results in a relative velocity between the tool centerpoint and the workpiece surface equal to the programmed velocity.

14. The apparatus of claim 13 wherein the axis of rotation of the workpiece is not parallel to any of the coordinate axes defining locations of the tool centerpoint and the apparatus further comprises means for producing transformed coordinate signals representing coordinates of tool centerpoint locations relative to a workpiece positioner rectangular coordinate system having its origin in the plane upon which the workpiece is mounted and having one axis substantially coincident with the axis of rotation of the workpiece.

15. The apparatus of claim 14 wherein the means for modifying the incremental velocity signals further comprises:

a. means responsive to the transformed coordinate signals for producing an intermediate radial distance signal representing the radial distance from the axis of rotation of the workpiece to the intermediate tool centerpoint location; and

b. means responsive to the intermediate radial distance signal, the increment velocity signal and the radial distance signal of the starting location for producing a modified increment velocity signal.

16. Appratus for cooperatively controlling motion of a tool centerpoint associated with a function element carried by a manipulator and rotation of a workpiece carried by a positioner, the motion effected by the manipulator being along a linear path oblique to the axis of rotation of the workpiece and having a component tangent to an arc swept by a radius from the axis of rotation of the workpiece to the tool centerpoint, the motion being defined by input signals representing starting and ending locations of the tool centerpoint relative to a rectangular coordinate system associated with the manipulator and the starting and ending angular locations of the workpiece, the manipulator and positioner having movable members driven by actuators controlled by servomechanism circuits, the relative motion of the tool centerpoint and workpiece surface being effected at a velocity represented by an input signal, the apparatus comprising:

a. means for storing input signals;

b. means responsive to the input signals for producing an effective linear distance signal representing the distance resulting from the combination of tool centerpoint motion and workpiece rotation;

c. means responsive to the effective linear distance signal for producing an adjusted programmed velocity signal representing the velocity of the tool centerpoint which results in a relative velocity between the tool centerpoint and the workpiece surface equal to the program velocity;

d. means responsive to the input signals and the adjusted velocity signal for iteratively producing incremental velocity signals, each incremental velocity signal representing the velocity of the tool centerpoint during an iteration interval;

e. means for modifying the incremental velocity signals in proportion to the change in radial distance of the tool centerpoint from the axis of rotation of the workpiece between successive iterations;

f. means responsive to the modified incremental velocity signal for producing intermediate location coordinate signals representing coordinates relative to the manipulator coordinate system of an intermediate location along the linear path of the tool centerpoint and further representing intermediate rotations of the workpiece; and

g. means for applying the intermediate location coordinate signals to the servo mechanism circuits to effect coordinated motions between the tool centerpoint and the workpiece.

17. The apparatus of claim 16 wherein the means for producing an effective linear distance signal further comprises:

a. means for producing a tangential deviation signal representing the tangential distance between two successive programmed locations of the tool centerpoint;

b. means for producing an arc distance signal representing the arc length swept by the average radial distance of the tool centerpoint from the axis of rotation of the workpiece when rotated through the programmed angular change of the workpiece;

c. means responsive to the tangential deviation signal and the arc distance signal for comparing the magnitudes thereof; and

d. means responsive to the comparing means for producing an effective linear distance signal irrespective of the relative magnitudes of the tangential deviation signal and arc length signal.

18. The apparatus of claim 17 wherein the means for producing intermediate location signals further comprises:

a. means for producing a programmed distance signal representing the larger of the linear distance between two successive programmed locations of the tool centerpoint and the arc length represented by the arc distance signal;

b. means for producing coordinate component ratio signals representing the quotient of the change in magnitude of the coordinate component and the programmed distance signal;

c. means responsive to the increment velocity signal and an iteration interval signal representing the period between iterations for producing an incremental distance signal representing an increment of motion occurring over the iteration period; and

d. means responsive to the incremental distance signal and the coordinate component ratios for producing coordinate component signals representing coordinate components of the incremental distance.

19. The apparatus of claim 18 wherein the axis of rotation of the workpiece is not parallel to any of the coordinate axes defining programmed locations and the apparatus further comprises means for producing transformed coordinate signals representing coordinates of programmed locations relative to a rectangular coordinate system having its origin in the plane of the positioner to which the workpiece is mounted and having one axis substantially coincident with the axis of rotation of the workpiece.

20. The apparatus of claim 19 wherein the means for modifying the incremental velocity signals further comprises:

a. means responsive to the transformed coordinate signals for producing an intermediate radial distance signal representing the radial distance from the axis of rotation of the workpiece to the intermediate tool centerpoint location; and

b. means responsive to the intermediate radial distance signal, the increment velocity signal and the starting location radial distance signal for producing a modified increment velocity signal.

21. Apparatus for selectively, cooperatively controlling motion of a tool centerpoint associated with a function element carried by a manipulator and rotation of a workpiece carried by a positioner, the motion effected by the manipulator being along a linear path intersecting the axis of rotation of the workpiece, the motion being defined by input signals representing starting and ending locations of the tool centerpoint relative to a rectangular coordinate system associated with the manipulator and the starting and ending angular coordinates of the workpiece relative to the axis of rotation thereof, the manipulator and positioner having movable members driven by actuators controlled by servomechanism circuits, the relative motion of the tool centerpoint and workpiece surface being effected at a velocity represented by input signals, further input signals defining axial and radial limit distances relative to the axis of rotation of the workpiece, the apparatus comprising:

a. means for storing input signals;

b. means responsive to the input signals for producing a velocity coordination status signal representing the presence of a starting location within an envelope defined by the axial and radial limit distance signals;

c. means responsive to the velocity coordination status signal for producing an adjusted velocity signal representing the velocity of the tool centerpoint resulting in a velocity thereof relative to the workpiece surface equal to the programmed velocity;

d. means responsive to the location defining input signals and the adjusted velocity signals for iteratively producing incremental velocity signals, each incremental velocity signal representing the velocity of the tool centerpoint during an iteration interval;

e. means for modifying the incremental velocity signals in proportions to the change in radial distance of the tool centerpoint from the axis of rotation of the workpiece between successive iterations;

f. means responsive to the modified incremental velocity signals for producing intermediate location coordinate signals representing coordinates relative to a rectangular coordinate system associated with the manipulator of an intermediate location along the linear path of the tool centerpoint and an intermediate angular coordinate of the workpiece rotation relative to the axis of rotation thereof; and

g. means for applying the intermediate coordinate signals to the servo mechanism circuits to effect coordinated motion of the movable members.

22. The apparatus of claim 21 wherein the means for producing the velocity coordination status signal further comprises:

a. means responsive to the programmed location input signals for producing transformed programmed location coordinate signals representing coordinates of the tool centerpoint relative to a rectangular coordinate system having its origin in the plane of the positioner to which the workpiece is affixed and having an axis substantially coincident with the axis of rotation of the workpiece;

b. means responsive to the transformed programmed location coordinate signals for producing a starting location radial distance signal representing the radial distance from the axis of rotation of the workpiece to a starting location of the tool centerpoint;

c. means for comparing the transformed programmed location coordinate signals to the axial and radial limit distance input signals; and

d. means responsive to the comparing means for producing a velocity coordination status signal in response to detecting the presence of the starting location within the envelope defined by the axial and radial limit distance signals.

23. The apparatus of claim 22 wherein the axis of rotation of the workpiece is not parallel to any of the coordinate axis defining programmed locations, and further input signals define rotations of the workpiece positioner coordinate system with respect to the manipulator rectangular coordinate system and the means for producing transformed coordinate signals further comprises:

a. means for producing translational displacement signals representing the linear distance between the location defined by the manipulator coordinates and the origin of the positioner rectangular coordinate system; and

b. means responsive to the translational displacement signals and the positioner coordinate system rotation input signals for producing the transformed coordinate signals.

24. An apparatus for cooperatively controlling motion of the tool centerpoint associated with the function element carried by a manipulator and rotation of a workpiece carried by a positioner, the motion effected by the manipulator being along a linear path intersecting the axis of rotation of the workpiece, the motion being defined by input signals representing starting and ending locations of the tool centerpoint motion and starting and ending orientations of the function element through the tool centerpoint and starting and ending angular positions of the workpiece, the manipulator and positioner having movable members driven by actuators controlled by servomechanisms circuits, the relative motion of the tool centerpoint and workpiece surface being effected at a velocity represented by input signals, the apparatus comprising:

a. means for storing input signals;

b. means responsive to the input signals for iteratively producing incremental velocity signals, each incremental velocity signal representing the velocity of the tool centerpoint during an iteration interval;

c. means for modifying the incremental velocity signals in proportion to the change in radial distance of the tool centerpoint from the axis of rotation of the workpiece between successive iterations;

d. means responsive to the modified incremental velocity signals for producing intermediate location coordinate signals representing coordinates relative to a rectangular coordinate system associated with the manipulator of an intermediate location along the linear path of the tool centerpoint and intermediate changes of orientation of the function element through the tool centerpoint and intermediate rotations of the workpiece; and

e. means for applying the intermediate location, orientation and rotation coordinate signals to the servomechanism circuits to effect coordinated motion between the tool centerpoint and the workpiece.

25. The apparatus of claim 24 wherein the means for producing intermediate location signals further comprises:

a. means for producing a program distance signal representing the largest of;

the linear distance between two programmed locations; and

the effective arc length swept by the function element between two programmed orientation; and

the arc length swept by the average radial distance of the tool centerpoint from the axis of rotation of the workpiece through the programmed rotation of the workpiece;

b. means for producing coordinate component ratio signals representing the quotient of the change in magnitude of the coordinate component and the programmed distance signal;

c. means responsive to the increment velocity signal and an iteration interval signal representing the period between iterations for producing an incremental distance signal representing an increment of motion occurring over the iteration period; and

d. means responsive to the incremental distance signal and the coordinate component ratios for producing coordinate component signals representing coordinate components of the incremental distance.

26. The apparatus of claim 25 wherein the axis of rotation of the workpiece is not parallel to any of the coordinate axes defining programmed locations of the tool centerpoint relative to the manipulator and the apparatus further comprises means for producing transformed coordinate signals representing coordinates of programmed locations relative to a rectangular coordinate system associated with the workpiece positioner having its origin in the plane of the positioner to which the workpiece is mounted and having an axis coincident with the axis of rotation of the workpiece.

27. The apparatus of claim 26 wherein the means for modifying the incremental velocity signals further comprises:

a. means responsive to the transformed coordinate signals for producing an intermediate radial distance signal representing the radial distance from the axis of rotation of the workpiece to the intermediate tool centerpoint location; and

b. means responsive to the intermediate radial distance signal, the incremental velocity signal, and the starting location radial distance signal for producing a modified increment velocity signal.