Computer assisted teaching arrangement for conveyor line operation

• US 4,086,522 A
• Filed: 09/08/1976
• Issued: 04/25/1978
• Est. Priority Date: 09/08/1976
• Status: Expired due to Term

• Current Assignee: Unimation, Inc. (Stäubli Holding AG)
• Original Assignee: Unimation, Inc. (Stäubli Holding AG)
• Inventors: Engelberger, Joseph F., Perzley, William, Dunne, Maurice J.
• Primary Examiner(s): Butz, Eugene G.
• Application Number:
  US05/721,805
• Time in Patent Office: 594 Days
• Field of Search: 219/80, 318/568, 29/430, 235/151.11, 235/151.1, 214/1 BB, 198/340
• US Class Current: 318/568.13
• CPC Class Codes: G05B 19/4086 Coordinate conversions; Other special calculations
• 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: G05B 19/4182 manipulators and conveyor only
• CPC Class Codes: G05B 19/42 Recording and playback systems, i.e. in which the programme is recorded from a cycle of operations, e.g. the cycle of operations being manually controlled, after which this record is played back on the same machine
• CPC Class Codes: G05B 2219/35534 Conversion input data
• CPC Class Codes: G05B 2219/36458 Teach only some points, for playback interpolation between points
• CPC Class Codes: G05B 2219/41481 Divide command, block in subcommands, subblocks
• CPC Class Codes: G05B 2219/45213 Integrated manufacturing system ims, transfer line, machining center
• 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 29/49829 Advancing work to successive stations [i.e., assembly line]
• CPC Class Codes: Y10T 29/53004 with means to regulate operation by use of templet, tape, card or other replaceable information supply

Abstract

A programmable manipulator having an arm which is movable in a plurality of axes and encoder apparatus for the axes operative to develop position signals corresponding to the actual position of the arm is provided adjacent a workpiece moving along a predetermined path, a conveyor for example, to perform a series of programmed operations on the workpiece.

The programmable manipulator is provided with teach-programming apparatus for moving the arm during an initial teaching operation to different positions of the stationary workpiece corresponding to the desired series of operations of the manipulator relative to the stationary workpiece. Further, apparatus is provided for calculating digital representations during the teaching operation representing the positions of the arm accounting for the projected workpiece movement during playback and corresponding to the initial teaching positions relative to the workpiece. The calculated digital representations are than stored for use in controlling movement of the arm during playback with a moving workpiece.

The manipulator control electronics is provided with an interpolation unit which is effective to maintain the manipulator in synchronism with the moving conveyor during playback. This interpolation unit achieves substantially constant velocity dividing the recorded conveyor position signals for successive steps into a predetermined number of increments and utilizing the interpolated increments as artificial command signals.

A velocity mode constant may also be calculated and recorded during the teach mode and utilized in playback to generate velocity command signals to control the manipulator.

Claims

1. In a programmable manipulator, the combination of, a manipulator arm movable in a plurality of axes, a continuously moving conveyor positioned adjacent said programmed manipulator, memory storage means having stored therein a plurality of digital command signals at least some of which correspond to the program step position to which said arm is to be moved, one of said plurality of digital command signals including a digital representation of said conveyor position, one of said command signals for at least one program step including a continuous path mode signal, encoder means for each of said axes and said moving conveyor operative to develop position signals corresponding to the actual position of said arm in said plurality of axes and the actual position of said moving conveyor, address means for causing said stored command signals to appear at the output of said memory means in a predetermined sequence, means operative in the absence of said continuous path mode signal for moving said arm to the position represented by said stored command signals, means responsive to said continuous path mode signal for developing a digital signal equal to the difference between a command signal for a program step which includes said continuous path mode signal and the preceding command signal, means for dividing said difference signal into a predetermined number of increments according to said stored digital command signals at a program step which includes said continuous path mode signal, means for producing a series of artificial interpolation command signals equal in number to said predetermined number of increments which differ from said preceding command signals by said increments, means utilizing said artificial interpolation command signals to move said arm in a substantially continuous path, means for detecting the occurrence of a predetermined state of equality between said conveyor positional signal and said artificial conveyor command signal, and means responsive to said detecting means for developing an advance signal operative to control said dividing means to generate said predetermined number of increments.

2. In a programmable manipulator, the combination of, a manipulator arm movable in a plurality of axes, a continuously moving conveyor positioned adjacent said programmed manipulator, memory storage means having stored therein a plurality of digital command signals at least some of which correspond to the program step position to which said arm is to be moved, one of said plurality of digital command signals including a digital representation of said conveyor position, one of said command signals for at least one program step including a mode signal, encoder means for each of said axes and said moving conveyor operative to develop position signals corresponding to the actual position of said arm in said plurality of axes and the actual position of said moving conveyor, address means for causing said stored command signals to appear at the output of said memory means in a predetermined sequence, means for moving said arm to the position represented by said stored command signals, means responsive to said mode signal for developing a digital signal equal to the difference between a command signal for a program step which includes said mode signal and the preceding command signal, means for dividing said difference signal into a predetermined number of increments according to said stored digital command signals at a program step which includes said mode signal, means for producing a series of artificial command signals equal in number to said predetermined number of increments which differ from said preceding command signal by said increments, means for detecting the occurrence of the equality of said conveyor positional signal and said artificial conveyor command signal, and programmable counter means responsive to said detecting means for controlling the rate at which said series of artificial command signals are produced.

3. In a programmable manipulator, the combination of:

a manipulator arm movable in a plurality of axis;

a continuously moving conveyor positioned adjacent said programmed manipulator;

memory storage means having stored therein a plurality of digital command signals corresponding to different positions of said arm in said axes and different positions of said moving conveyor, at least one of said command signals including a variable interpolation mode signal;

encoder means for each of said axes and operative to develop digital position signals corresponding to the actual position of said arm in said plurality of axes;

conveyor encoder means for said moving conveyor and operative to develop a digital position signal corresponding to the actual position of said conveyor;

address means for causing said stored command signals to appear at the output of said memory means in a predetermined sequence;

means operative in the absence of said variable interpolation mode signal for moving said arm to the position represented by said stored command signals;

means responsive to said variable interpolation mode signal for developing a digital signal equal to the difference between a command signal which includes said variable interpolation mode signal and the preceding command signals;

means for producing a predetermined number of artificial command signals comprising means for dividing said difference signal into a number of increments equal to said predetermined number of artificial command signals, means for multiplying each of said increments by a variable integer increasing by one with each successive one of said series of artificial command signals, means for combining said series of multiplied increment products with said preceding command signal to produce said series of artificial command signals; and

means utilizing said artificial command signals to move said arm at a substantially constant velocity.

4. The combination of claim 3 wherein said means for moving said arm further comprises means common to said axes for comparing said digital position signals of said arm in said axes and said conveyor with said artificial command signals in said variable interpolation mode and wherein said dividing means further includes counter means responsive to said comparing means and advanced by the coincidence of each of said artificial command signals and said moving conveyor encoder means for controlling the generation of successive artificial command signals.

5. The combination of claim 4 wherein said stored command signals include coded data representing a preselected number of effective interpolation intervals equal to said number of artificial command signals, said difference signal including a digital representation for each of said axes and said conveyor representative of a number of conveyor encoder basic positional displacement units greater than or equal to said number of artificial command signals.

6. The combination of claim 5 wherein said multiplied increment products each include one or more positional conveyor encoder displacement units for said conveyor portion of said command signal.

7. The combination of claim 6 wherein said counter means is reset to a predetermined state upon generation of said preselected number of artificial command signals.

8. The combination of claim 6 wherein said preselected number of effective interpolator intervals of said stored command signal is a binary multiple of 16.

9. The combination of claim 4 wherein said comparing means sequentially compares different artificial command and position signal combinations corresponding to different ones of said axes and said conveyor during different periods in a repetitive multiplex scanning cycle.

10. The combination of claim 3 wherein said difference signal developing means and said artificial command signal producing means sequentially produce signals corresponding to different ones of said axes and said conveyor during different periods in a repetitive multiplex scanning cycle.

11. The combination of claim 10 wherein said artificial command signal is maintained for more than one repetitive multiplex scanning cycle.

12. In a programmable manipulator, the combination of:

a manipulator arm movable in a plurality of axes;

memory storage means having stored therein a plurality of digital command signals at least some of which correspond to the program step position to which said arm is to be moved, one of said plurality of digital command signals corresponding to a digital representation of a reference point on a reference axis which is different from said plurality of manipulator arm axes;

encoder means for each of said arm axes operative to develop position signals corresponding to the actual position of said arm in said plurality of axes;

encoder means for said reference axis operative to develop position signals corresponding to a predetermined reference point along said reference axis;

address means for causing said stored command signals in playback to appear at the output of said memory means in a predetermined sequence;

means for moving said arm to the position represented by said stored command signals;

means for developing a digital signal equal to the difference between command signals of successive program steps; and

means responsive to said difference signal for generating artificial command signals equal in number to a predetermined number according to one of said stored digital command signals, said artificial command signals being generated with a variable duration period as defined by said predetermined number, said artificial command signal generating means including means for detecting the occurrence of a predetermined state of equality between said reference point positional signal and said artificial reference point command signal, said detecting means controlling the generation of said artificial command signals by said command signal generating means.

13. In a programmable manipulator the combination of, a manipulator arm, means for moving said arm in a plurality of different axes, a continously moving conveyor positioned adjacent said programmed manipulator, memory storage means for storing digital representations corresponding to different positions of said arm in said axes and different positions of said moving conveyor, encoder means for each of said axes and operative to develop position signals corresponding to the actual position of said arm in said plurality of axes, means for storing said position signals in said memory storage means during an initial teaching operation with a static conveyor, means controlled in part by said encoder means for calculating new digital representations which are different from said manipulator arm position signals and correspond to desired new positions of said arm representing said desired initial teaching positions relative to said static conveyor, said means for storing said calculated digital representations in said memory storage means so that said stored digital representations may also act as command signals to control movement of said arm during playback.

14. The method of programming a manipulator provided with an arm which is movable in a plurality of axes and having encoder means for said axes operative to develop position signals corresponding to the actual position of said arm in a plurality of axes to perform a series of operations on a workpiece while the workpiece is continuously moving along a predetermined path, which comprises the steps of:

moving said arm during an initial teaching operation to different positions of the static workpiece;

storing said developed position signals corresponding to said positions of said teaching operation;

calculating digital representations utilizing said position signals which are different from said positions in said teaching operation and correspond to desired new positions of said arm representing said initial teaching positions relative to said static workpiece; and

storing said calculated digital representations in a memory for use in controlling movement of said arm during playback with a continuously movable workpiece in accordance with said stored calculated digital representations.

15. The method of claim 14 wherein said calculating step further comprises the steps of:

converting said position signals corresponding to different angular positions of said arm in said plurality of axes for successive taught steps to Cartesian coordinates of the free end of said arm;

translating said resulting Cartesian coordinates to account for the projected movement of said workpiece in terms of positional displacement units along said predetermined path of said workpiece during the projected elasped time for said arm to traverse the distance between successive taught positions on said workpiece while it is moving at a nominal rate, said translated coordinates corresponding to the new position of said arm and the same position relative to the static workpiece when said workpiece is moving; and

reconverting said translated Cartesian coordinates defining said new position into said desired new position signals corresponding to the angular position of said arm about said plurality of axes.

16. The method of claim 15 wherein said translating step is accomplished by the steps of:

calculating the projected time interval T_1-2 for the arm to traverse the distance between successive taught points P_1s and P_2s on the workpiece at a projected arm velocity of S when the workpiece is moving at a projected velocity of Z_L, and

modifying the Cartesian coordinates of P_2s by a quantity which is defined by a first factor equal to the accumulated program position, Σ

D₁, up to program step 1 corresponding to P_1s in terms of a number of basic displacement units of workpiece position and the distance D_1-2 traversed by the workpiece during movement of the arm between P_1s and P_2s in terms of a number of basic displacement units of workpiece position.

17. The method of claim 16 wherein said T_1-2 calculating step is accomplished by the steps of:

defining the positional vector Δ

S_1-2 representing the distance between taught point P_1M1 and point P_2M2, where P_1M1 is the projected position of P_1s at a first program step 1 position Σ

D₁ and P_2M2 is the projected position of P_2s at a second successive program step 2 position Σ

D₂, said vector Σ

S_1-2 defined by summing the positional vectors Δ

S_s which is the positional change between said points P_1s and P_2s and the positional vector Δ

Z_1-2 which is the distance traversed by the workpiece at the projected velocity Z_L where Δ

Z_1-2 equals the product of Z_L and T_1-2,

additionally defining the positional vector Δ

S_1-2 in a second manner by the product of projected arm velocity S and T_1-2, and

solving for T_1-2 by equating the first and second defined quantities.

18. The method of claim 15 wherein said translating step further comprises the steps of:

calculating the positional vector Δ

S_1-2 in Cartesian coordinates defining the distance between a first taught point P_1M1 which is the projected point of P_1s at a first program step 1 position relative to the workpiece position and a second point P_2M2 which is the projected position of the workpiece when said arm is moved between teach points P_1s and P_2s at a projected nominal velocity Z_L, said positional vector Δ

S_1-2 calculated by summing the positional vector Δ

S_s, defining the vectorial positional change between said P_1s and P_2s taught points and the positional vector Δ

Z_1-2 which is the distance traveled by the workpiece at the projected workpiece velocity Z_L, the term Δ

Z_1-2 defined by Z_L multiplied by the time T_1-2 to traverse the distance from points P₁ to P₂ with the workpiece moving, said positional vector Δ

S_1-2 also being defined by the projected velocity of the arm S multiplied by the time T_1-2 to traverse from points P₁ to P₂ with the workpiece moving, said quantity T_1-2 solved from this relationship to define the term Δ

S_1-2, and modifying the Cartesian coordinates of P_2s by a factor of Σ

D₂ which is equal to the sum of the factors Σ

D₁ and D_1-2, where Σ

D₁ is the accumulated projected position of the workpiece from a reference point and D_1-2 is the distance defined by the product T_1-2 and Z_L.

19. In a programmable manipulator, the combination of:

a manipulator arm movable in a plurality of axes;

a continously moving conveyor positioned adjacent said programmed manipulator;

memory storage means having stored therein a plurality of digital command signals corresponding to the program step position to which said arm is to be moved, one of said plurality of digital command signals including a digital representation of said conveyor position, at least one of said command signals including a variable interpolation mode signal;

encoder means for each of said axes and said moving conveyor operative to develop position signals corresponding to the actual position of said arm in said plurality of axes and the actual position of said moving conveyor;

address means for causing said stored command signals to appear at the output of said memory means in a predetermined sequence;

means operative in the absence of said variable interpolation mode signal for moving said arm to the position represented by said stored command signals;

means responsive to said variable interpolation mode signal for developing a digital signal equal to the difference between a command signal for a program step which includes said variable interpolation mode signal and the preceding command signal;

means for producing a predetermined number of interpolation command signals according to a code in said stored digital command signals, said interpolation command signal producing means comprising a multiplier responsive to a control input and arranged to multiply said difference signal by a series of fractions according to said control input, the denominator of said fraction being equal to said predetermined number of interpolation command signals, and the numerator being a variable integer increasing by one with each successive one of said series of interpolation command signals, and means for combining said series of products of multiplied difference signals and fractions with said preceding command signal to produce said series of interpolation command signals;

means for detecting the occurrence of a predetermined state of equality of said conveyor encoder positional signal and said interpolation command signal; and

means responsive to said detecting means for developing a control signal connected to said control input of said multiplier.

20. The combination of claim 19 wherein said multiplier comprises a plurality of programmable dividers, each of said dividers having a dividend input connected to said digital difference signal and a divisor input equal to said predetermined number of interpolation command signals divided by a different power of two starting with 2⁰ and increasing by one for each successive divider, the number of said dividers being equal to the number of binary digits in said predetermined number of interpolation command signals, a combiner and an enabling means responsive to said control signal and being connected to each of said quotient outputs of said dividers for selectively connecting said quotient output of each of said dividers to an input of said combiner, the output of said combiner producing said series of products of multiplied difference signals and fractions connected to said artificial command signal combining means.

21. The combination of claim 20 wherein said control signal developing means comprises a digital counter which is advanced in count by said detecting means and wherein said control signal is the binary state output of said counter and said counter produces a number of output states equal to the number of interpolation command signals on a plurality of binary lines, each of said enabling means being respectively connected to the binary line which represents the binary state output of said counter equal to the power of two in the divisor of the divider being controlled by said respective enabling means.

22. In a programmable manipulator, the combination of:

a manipulator arm movable in a plurality of axes;

a continuously moving conveyor positioned adjacent said programmed manipulator;

memory storage means having stored therein a plurality of digital command signals at least some of which correspond to the program step position to which said arm is to be moved, one of said plurality of digital command signals including a digital representation of said conveyor position, one of said command signals for at least one program step including a velocity mode constant;

encoder means for each of said axes and said moving conveyor operative to develop position signals corresponding to the actual position of said arm in said plurality of axes and the actual position of said moving conveyor;

address means for causing said stored command signals to appear at the output of said memory in a predetermined sequence;

means for moving said arm to the position represented by applied command signals;

means responsive to said velocity mode constant for developing a digital signal equal to the difference between a command signal which includes said velocity mode constant and the preceding command signal;

means for dividing said difference signal into a predetermined number of increments according to said stored digital command signals;

means for producing a series of artificial interpolation command signals equal in number to said predetermined number of increments which differ from said preceding command signals by said increments;

means common to said plurality of axes and said conveyor for comparing said digital position signals of said arm in said plurality of axes and said conveyor with said artificial interpolation command signals;

means responsive to said stored velocity mode constant and said difference signal for producing a velocity control signal by multiplying said velocity mode constant and said difference signal; and

means for combining said velocity control signal and the output of said comparing means to produce an error loop control signal applied to said moving means.

23. The combination of claim 22 wherein said velocity control signal means further comprises means for adjusting said velocity control signal for changes in the velocity of said conveyor.

24. The combination of claim 22 wherein said velocity control means further comprises means for converting said velocity control constant and said difference signal to an analog velocity control signal, said converting means comprising a first multiplying digital to analog converter having said stored velocity mode constant as a digital input and a multiplying reference input that is proportional to said moving conveyor velocity and a second multiplying digital to analog converter having a signal proportional to said difference signal as a digital input and the analog output of said first digital to analog converter as a multiplying reference input, the output of said second digital to analog converter generating said velocity control signal.

25. The combination of claim 24 wherein said comparing means further comprises a third digital to analog converter to produce an analog positional error signal.

26. The combination of claim 25 wherein said velocity control signal is approximately an order of magnitude larger than said positional error signal, said velocity mode constant is calculated in a teach phase with a stationary conveyor and utilized in replay to drive said manipulator at a substantially constant velocity and in synchronism with said moving conveyor, and said positional error signal operating on a closed servo loop basis to provide correction to said manipulator arm position with respect to said moving conveyor.

27. The combination of claim 22 wherein said comparing means sequentially compares different artificial command and position signal combinations corresponding to different periods in a repetitive multiplex scanning cycle.

28. The combination of claim 22 wherein said difference signal developing means and said artificial interpolation command signal producing means sequentially produce signals corresponding to different ones of said axes and said conveyor during different periods in a repetitive multiplex scanning cycle.

29. The combination of claim 22 wherein said artificial interpolation command signal producing means further comprises means responsive to said comparing means for controlling the successive generation of said artificial interpolation command signals upon coincidence of each of said artificial interpolation command signals and said conveyor encoder means position signals.

30. The combination of claim 29 where said stored command signals include coded data representing a preselected number of effective interpolation intervals equal to said number of artificial interpolation command signals, said difference signal including a digital representation for each of said axes and said conveyor, said digital conveyor representation being representative of a number of basic positional displacement units greater than or equal to said number of artificial interpolation command signals.

31. The combination of claim 30 wherein said multiplied increment products each include one or more positional conveyor displacement units for said conveyor portion of said command signal.

32. The combination of claim 22 wherein said stored velocity mode constant is equal to the predetermined number of increments divided by the number of conveyor encoder basic displacement units in said difference signal.

33. The combination of claim 24 wherein said second multiplying digital to analog converter sequentially produces signals corresponding to different ones of said axes during different periods in a repetitive multiplex scanning cycle.

34. The combination of claim 22 wherein said stored velocity mode constant is equal to the reciprocal of the number of conveyor encoder basic displacement units in said difference signal.

35. The combination of claim 22 wherein said stored velocity mode constant is a digital representation of the relative velocity of said manipulator arm in said plurality of axes relative to the velocity of said moving conveyor.

36. The combination of claim 22 wherein said stored velocity mode constant is a digital representation of the inverse of the relative time to complete the respective step at nominal conveyor velocity.

37. The combination of claim 24 wherein said digital input to said second multiplying digital to analog converter is equal to said difference signal.

38. The combination of claim 24 wherein said velocity control signal means further comprises second means for dividing said difference signal by a divisor equal to said predetermined number of increments divided by 16 and the digital input to said second multiplying digital to analog converter is equal to the output of said second dividing means.

54. The combination of claim 22 further comprising means for sensing the velocity of each of said plurality of axes and wherein said combining means is responsive to said velocity sensing means and further comprises means for comparing said combined velocity control signal and the output of said positional comparing means with the velocity of said axes, said moving means being responsive to said velocity comparing means.

39. A digital multiplier responsive to a control input and arranged to multiply a first digital number by a series of fractions according to said control input, said multiplier comprising:

a plurality of programmable dividers, each of said dividers having a dividend input connected to said first digital number and a divisor input connected to a predetermined digital number divided by a different power of two starting with 2⁰ and increasing by one for each successive divider, the number of said dividers being equal to the number of binary digits in said predetermined number,

a combiner, and

an enabling means responsive to said control signal and being connected to each of said quotient outputs of said dividers for selectively connecting said quotient output of each of said dividers to an input of said combiner, the denominator of said series of fractions being equal to said predetermined number and the numerator being a variable integer increasing by one with each successive one of said series of integers in said predetermined number, each of said enabling means having an input representing a binary digit in said predetermined number.

40. The multiplier of claim 39 wherein the input of each of said enabling means is respectively connected to the binary state of said predetermined number equal to the power of two in the divisor of the divider being controlled by said respective enabling means.

41. In a programmable manipulator arranged adjacent a workpiece moving along a predetermined path to perform a series of predetermined operations relative to the workpiece the combination of:

a manipulator arm movable in a plurality of axes;

memory storage means having stored therein a plurality of digital command signals corresponding to the program step position to which said arm is to be moved, at least one of said plurality of digital command signals including a velocity mode constant comprising a digital representation proportional to the reciprocal of the distance to be traversed between successive program steps by the workpiece;

address means for causing said stored command signals to appear at the output of said memory means in a predetermined sequence;

means for developing a digital signal equal to the difference between command signals of successive program steps;

means responsive to said stored velocity mode constant, the workpiece velocity and said difference signal for producing a velocity control signal, said velocity control signal producing means comprising means for multiplying said velocity mode constant and said difference signal; and

means responsive to said velocity control signal for moving said arm.

42. The combination of claim 41 wherein said velocity control signal producing means further comprises means for adjusting said velocity control signal for changes in the velocity of said workpiece relative to a nominal velocity.

43. The combination of claim 41 wherein said multiplying means comprises a first multiplying digital to analog converter having said stored velocity mode constant as a digital input and a multiplying reference input that is proportional to said moving workpiece velocity and a second multiplying digital to analog converter having a signal proportional to said difference signal as a digital input and the analog output of said first digital to analog converter as a multiplying reference input, the output of said second digital to analog converter generating said velocity control signal.

44. The combination of claim 41 wherein said difference signal developing means and said velocity control signal producing means sequentially product signals corresponding to different ones of said axes during different periods in a repetitive multiplex scanning cycle.

45. The combination of claim 43 wherein said second multiplying digital to analog converter sequentially produces signals corresponding to different ones of said axes during different periods in a repetitive multiplex scanning cycle.

46. In a programmable manipulator arranged adjacent a workpiece moving along a predetermined path to perform a series of predetermined operations relative to the workpiece, the combination of:

a manipulator arm movable in a plurality of axes;

memory storage means having stored therein a plurality of command signals corresponding to the program step position to which said arm is to be moved, at least one of said plurality of digital command signals including a velocity mode constant comprising a digital representation proportional to the reciprocal of the relative time for the workpiece to traverse a predetermined distance at a projected nominal velocity;

address means for causing said stored command signals to appear at the output of said memory means in a predetermined sequence;

means for developing a digital signal equal to the difference between command signals of successive program steps;

means responsive to said stored velocity mode constant, said workpiece velocity and said difference signal for producing a velocity control signal, said velocity control signal producing means comprising means for multiplying said velocity mode constant and said difference signal; and

means responsive to said velocity control signal for moving said arm.

47. The combination of claim 46 wherein said velocity control signal producing means further comprises means for adjusting said velocity control signal for changes in the velocity of said workpiece along said reference axis relative to said projected nominal velocity.

48. The combination of claim 46 wherein said multiplying means comprises a first multiplying digital to analog converter having said stored velocity mode constant as a digital input and a multiplying reference input that is proportional to said moving workpiece velocity and a second multiplying digital to analog converter having a signal proportional to said difference signal as a digital input and the analog output of said first digital to analog converter as a multiplying reference input, the output of said second digital to analog converter generating said velocity control signal.

49. The combination of claim 46 wherein said difference signal developing means and said velocity control signal producing means sequentially produce signals corresponding to different ones of said axes during different periods in a repetitive multiplex scanning cycle.

50. The combination of claim 48 wherein said second multiplying digital to analog converter sequentially produces signals corresponding to different ones of said axes during different periods in a repetitive multiplex scanning cycle.

51. In a programmable manipulator for operation adjacent a reference axis, the combination of:

a manipulator arm movable in a plurality of axes;

memory storage means having stored therein a plurality of digital command signals corresponding to the program step position to which said arm is to be moved, at least one of said plurality of digital command signals including a velocity mode constant representing the reciprocal of the distance to be traversed between successive program steps by a reference point moving along said reference axis;

address means for causing said stored command signals to appear at the output of said memory means in a predetermined sequence;

means common to said plurality of axes for developing position signals corresponding to the actual position of said arm in said plurality of axes and for comparing said digital position signals with said command signals;

means responsive to said stored velocity mode constant and said digital command signals for producing a velocity mode control signal;

means for combining said velocity mode control signal and the output of said comparing and position signal developing means to produce an error loop control signal; and

means responsive to said combining means for moving said arm to the position represented by said digital command signals.

52. The combination of claim 51 wherein said plurality of stored digital command signals include a digital representation of positions along said reference axis, said comparing and position signal developing means further comprising means for developing reference axis position signals and for comparing said reference axis position signals with said stored digital reference axis representations, and further comprising means responsive to said reference axis comparing and position signal developing means for controlling said address means.

53. The combination of claim 51 further comprising means for sensing the velocity of each of said plurality of axes and wherein said combining means is responsive to said velocity sensing means and further comprises means for comparing said combined velocity mode control signal and said output of said positional comparing and signal developing means with the velocity of said axes, said moving means being responsive to said velocity comparing means.

55. In a programmable manipulator provided with a manipulator arm which is movable in a plurality of axes, having encoder means for said axes operative to develop position signals corresponding to the actual position of said arm and being arranged adjacent a reference axis to perform a series of operations on a workpiece moving along said reference axis, the combination of:

means for positioning said arm during an initial teaching operation with a stationary workpiece to different positions corresponding to the desired operations of the manipulator relative to the stationary workpiece;

means for calculating signals representing positions of said arm accounting for projected workpiece movement and corresponding to said initial teaching positions relative to said workpiece; and

means for storing said calculated arm position signals for use as command signals in controlling movement of said arm in a playback cycle with a moving workpiece.

56. The combination of claim 55 wherein a first series of operations corresponding to different positions of said manipulator arm is performed during said initial teaching operation at a first workpiece location and a second series of operations corresponding to different positions of said manipulator arm is performed during said initial teaching operation at a second workpiece location.

59. The combination of claim 55 further comprising means responsive to said storing means and said calculating means for selectively advancing said workpiece during the initial teaching operation to the approximate position corresponding to the position of the workpiece accounting for projected workpiece movement.

60. The combination of claim 55 further comprising means responsive to said command signals for controlling movement of said arm in correlation with a moving workpiece during a playback cycle.

61. The combination of claim 60 further comprising workpiece encoder means for developing position signals corresponding to workpiece movement along said reference axis, said movement controlling means including means for dividing the resultant difference between successive stored command signals into a number of increments equal to a predetermined number of artificial command signals, means for multiplying each of said increments by a variable integer increasing by one with each successive one of said artificial command signals, and means for combining said series of multiplied increment products with the preceding stored command signal to produce said series of artificial command signals.

62. The combination of claim 61 wherein said means for controlling movement of said arm further comprises means for comparing said position signals corresponding to workpiece movement with said artificial command signals, and said dividing means further comprises counter means responsive to said comparing means and advanced by the coincidence of said artificial command signals and said position signals corresponding to workpiece movement for controlling the generation of successive artificial command signals.

63. The combination of claim 60 further comprising workpiece reference axis encoder means for developing position signals corresponding to workpiece movement along said reference axis, said stored command signals including a workpiece reference axis positional signal corresponding to projected workpiece movement, said movement controlling means including means for detecting a predetermined state of equality between said positional signals of said workpiece encoder means and said artificial workpiece reference axis command signals, and means controlled by said detecting means for generating a predetermined number of artificial command signals for controlling movement of said arm in correlation with said moving workpiece.

64. The combination of claim 63 wherein said artificial command signal generating means further comprises:

a multiplier responsive to a control input and arranged to multiply the resultant difference between successive command signals by a series of fractions according to said control input, the denominator of each of said fractions being equal to said predetermined number of artificial command signals, the numerator being a variable integer increasing by one with each successive one of said artificial command signals; and

means for combining said series of products of multiplied difference signals and fractions with the preceding command signal to produce said series of artificial command signals, said control input being generated by said detecting means.

65. The combination of claim 64 wherein said multiplier comprises a plurality of programmable dividers, each of said dividers having a dividend input connected to said resultant difference signal and a divisor input equal to said predetermined number of artificial command signals divided by a different power of two starting with 2°

and increasing by one for each successive divider, the number of said dividers being equal to the number of binary digits in said predetermined number of artificial command signals and means for selectively supplying the quotient outputs of said dividers to said combining means in accordance with said control input, said detecting means including a digital counter which is advanced in count upon each detected predetermined state of equality.

66. The combination of claim 60 further comprising workpiece reference axis encoder means for developing position signals corresponding to workpiece movement along said reference axis, said calculating means comprising means responsive to said workpiece reference axis encoder means for calculating projected workpiece position signals for each of said initial teaching positions of said manipulator arm, and means for calculating a velocity mode constant, and means for storing said projected workpiece position signals and said velocity mode constant.

67. The combination of claim 66 wherein said velocity mode constant comprises a digital representation proportional to the reciprocal of the relative time for the workpiece to traverse a predetermined distance at a predetermined velocity along said reference axis.

68. The combination of claim 66 wherein said velocity mode constant comprises a digital representation proportional to the reciprocal of the distance to be traversed between successive command signals by the workpiece along said reference axis.

69. The combination of claim 68 further comprising means responsive to said stored veocity mode constant and the resultant difference between successive command signals for producing a velocity control signal.

70. The combination of claim 69 wherein said velocity control signal producing means further comprises means for adjusting said velocity control signal for changes in the velocity of said workpiece along said reference axis relative to said predetermined velocity.

71. The combination of claim 69 wherein said velocity control signal producing means further comprises means for converting said velocity control constant and said resultant difference signal between successive command signals to an analog velocity control signal.

72. The combination of claim 71, wherein said converting means comprises a multiplying digital to analog converter having said stored velocity mode constant as a digital input and a multiplying reference input that is proportional to said moving workpiece velocity, and a second multiplying digital to analog converter having a signal proportional to said resultant difference signal as a digital input and the analog output of said first digital to analog converter as a multiplying reference input, the output of said second digital to analog converter generating said analog velocity control signal.

73. The combination of claim 72 wherein said second multiplying digital to analog converter sequentially produces signals corresponding to different ones of said axes during different periods in a repetitive multiplex scanning cycle.

74. The combination of claim 66 wherein said movement controlling means comprises means for comparing said encoder position signals for said axes with respective ones of said command signals, and means for combining said velocity mode constant and the output of said comparing means to produce an error loop control signal.

75. The combination of claim 74 which includes means for sensing the velocity of each of said plurality of axes, and means for controlling said combining means in accordance with said sensing means.

76. The combination of claim 66 further comprising means for sensing the velocity of each of said plurality of axes, and means for comparing said sensed velocity and said velocity mode constant to produce an error loop control signal.

77. The combination of claim 55 wherein said calculating means further comprises:

means for converting said position signals corresponding to different angular positions of said arm in said plurality of axes for successive taught steps to Cartesian coordinates of the free end of said arm;

means for translating said resulting Cartesian coordinates to account for the projected movement of said workpiece in terms of positional displacement units along said reference axis during the projected elapsed time for said arm to traverse the distance between successive taught positions on said workpiece, and

means for reconverting said translated Cartesian coordinates into new position signals corresponding to different angular positions of said arm in said plurality of axes.

83. The combination of claim 77 wherein said translating means comprises:

means for determining the projected time interval T_1-2 for the arm to traverse the distance between successive taught points P_1s and P_2s on the stationary workpiece at a projected arm velocity of S, and

means for modifying the Cartesian coordinates of P_2s by a quantity which is defined by a first factor equal to the accumulated program position, Σ

D₁, up to program step 1 corresponding to P_1s in terms of a number of basic displacement units of workpiece position and the distance D_1-2 traversed by the workpiece during movement of the arm between P_1s and P_2s in terms of a number of basic displacement units of workpiece position.

84. The combination of claim 83 wherein said T_1-2 determining means comprises:

means for defining the positional vector Δ

S_1-2 representing the distance between taught point P_1m1 and point P_2m2, where P_1m1 is the projected position of P_1s at a first program step 1 position Σ

D₁ and P_2m2 is the projected position of P_2s at a second successive program step 2 position D₂,

first means for defining said vector S_1-2 by summing the positional vectors Δ

S_s and Δ

Z_1-2 where Δ

S_s is the positional change between said points P_1s and P_2s and the positional vector Δ

Z_1-2 is the distance traversed by the workpiece at the projected velocity Z_L and is defined by the product of Z_L and T_1-2,

second means for defining said positional vector Δ

S_1-2 in a second manner by the product of the projected arm velocity S and T_1-2, and

means for obtaining T_1-2 by equating said first and second defined quantities Δ

S_1-2.

85. The combination of claim 77 wherein said translating means comprises:

means for determining the positional vector Δ

S_1-2 in Cartesian coordinates defining the distance between a first taught point P_1m1 which is the projected point of P_1s at a first programm step 1 position relative to the workpiece position and a second point P_2m2 which is the projected position of the workpiece when said arm is moved between teach points P_1s and P_2s at a projected nominal velocity S, said positional vector Δ

S_1-2 calculated by summing the positional vector Δ

S_s defining the vectorial positional change between said P_1s and P_2s taught point and the positional vector Δ

Z_1-2 which is the distance traversed by the workpiece at the projected workpiece velocity Z_L, the term Δ

Z_1-2 being defined by Z_L multiplied by the time T_1-2 to traverse the distance from points P₁ to P₂ with the workpiece moving, said predetermined quantity T_1-2 defining the term Δ

S_1-2, and

means for modifying the Cartesian coordinates of P_2s by a factor of Σ

D₂ which is equal to the sum of the factors Σ

D₁ and D_1-2, where Σ

D₁ is the accumulated projected position of the workpiece from a reference point and D_1-2 is the distance defined by the product of T_1-2 and Z_L.

57. In a programmable manipulator the combination of, a manipulator arm which is movable in a plurality of axes, said arm being located adjacent a reference axis to perform a series of operations on a workpiece moving along said reference axis;

means for positioning said arm at a desired location relative to a stationary workpiece during an initial teaching operation;

means for calculating the new position in space which said arm should occupy in order to be positioned at said desired location relative to the workpiece assuming a predetermined velocity of said workpiece during a subsequent playback cycle; and

means for storing digital representations corresponding to said calculated new position for use as a command signal in controlling movement of said arm during said subsequent playback cycle.

58. The combination of claim 57, which includes means responsive to said command signal for moving said arm to said desired location relative to a moving workpiece during a subsequent playback cycle, and means for adjusting said arm moving means for variations in the actual velocity of said moving workpiece from said predetermined velocity during said subsequent playback cycle.

90. The combination of claim 57, which includes means responsive to said command signal for moving said arm to said desired location relative to a workpiece which is moving at a velocity which is different from said assumed velocity during a subsequent playback cycle.

91. The combination of claim 57, which includes means for positioning a workpiece at two different locations relative to said manipulator during said initial teaching operation, means for positioning said arm at a series of desired locations relative to said workpiece when said workpiece is at each of said two different locations, said two series of desired locations collectively comprising a desired path of movement of said arm relative to a moving workpiece during a subsequent playback cycle.

92. The combination of claim 91 wherein said calculating means calculates new positions of said arm corresponding to said two series of desired locations while correcting for the positioning of said workpiece at said two different locations during said initial teaching operation.

78. In a programmable manipulator provided with a manipulator arm which is movable in a plurality of axes, having means for developing position signals corresponding to the actual position of said arm in said plurality of axes and arranged adjacent a reference axis to perform a series of operations on a workpiece moving along said reference axis, the combination of:

means for positioning said arm at different locations relative to a stationary workpiece during an initial teaching operation;

means for converting said position signals corresponding to different angular positions of said arm in said plurality of axes for successive taught steps into corresponding Cartesian coordinates; and

means for translating said resulting Cartesian coordinates to account for the projected movement of said workpiece in terms of positional displacement units along said reference axis during the projected elapsed time for said arm to traverse the distance between successive taught positions on said workpiece.

79. In a programmable manipulator provided with a manipulator arm which is movable in a plurality of axes, having means for developing position signals corresponding to the actual position of said arm in said plurality of axes, and arranged adjacent a reference axis to perform a series of operations on a workpiece moving along said reference axis, the combination of:

means for positioning said arm at different locations relative to a stationary workpiece during an initial teaching operation;

means for converting said position signals corresponding to different angular positions of said arm in said plurality of axes for successive taught steps into corresponding Cartesian coordinates;

means for calculating the time interval required for said arm to traverse the distance between successive taught positions when the workpiece is moving at a predetermined velocity; and

means controlled by said calculating means for translating said resulting Cartesian coordinates to account for movement of said workpiece along said refenece axis during said calculated time interval.

82. The combination of claim 79 wherein said predetermined velocity of said workpiece is the maximum allowable velocity of said workpiece when said arm is moving at its maximum velocity.

80. In a programmable manipulator provided with a manipulator arm which is movable in a plurality of axes, having means for developing position signals corresponding to the actual position of said arm in said plurality of axes and arranged adjacent a reference axis to perform a series of operations on a workpiece moving along said reference axis, the combination of:

means for positioning said arm at different locations relative to a stationary workpiece during an initial teaching operation;

means for converting said position signals corresponding to different angular positions of said arm in said plurality of axes for successive taught steps into corresponding Cartesian coordinates;

means for calculating the time interval required for said arm to traverse the distance between successive taught locations when said arm is moving at a first predetermined velocity and said workpiece is moving along said reference axis at a second predetermined velocity; and

means controlled by said calculating means for translating said resulting Cartesian coordinates to account for movement of said workpiece along said reference axis during said calculated time interval.

81. In a programmable manipulator provided with a manipulator arm which is movable in a plurality of axes, having means for developing position signals corresponding to the actual position of said arm in said plurality of axes and arranged adjacent a reference axis to perform a series of operations on a workpiece moving along said reference axis, the combination of:

means for positioning said arm at different locations relative to a stationary workpiece during an initial teaching operation;

means for converting said position signals corresponding to different angular positions of said arm in said plurality of axes for successive taught steps into corresponding Cartesian coordinates;

means for calculating the path of movement which is required for said arm when moving at a first predetermined velocity in order to position said arm at the taught location relative to the workpiece when the workpiece is moving at a second predetermined velocity; and

means controlled by said calculating means for translating said resulting Cartesian coordinates to values corresponding to said taught location relative to a moving workpiece.

86. The method of programming a manipulator to perform a series of operations on a workpiece while the workpiece is moving along a predetermined path, the manipulator having an arm which is movable in a plurality of axes and encoder means for said axes operative to develop position signals corresponding to the actual position of said arm, the method comprising the steps of:

moving said arm to different positions relative to a stationary workpiece during an initial teaching operation, said positions corresponding to desired operations of the manipulator relative to the stationary workpiece;

calculating signals representing manipulator arm positions different from the positions to which said arm is moved during said teaching operation and corresponding to positions of said arm accounting for projected workpiece movement; and

storing said calculated signals for use in controlling movement of said arm during playback with a moving workpiece.

87. The method of claim 86 wherein said initial teaching operation step comprises the steps of moving said arm through a first series of operations corresponding to different positions of said manipulator arm at a first workpiece location and moving said arm through a second series of operations corresponding to different positions of said manipulator arm at a second workpiece location.

88. The method of claim 87 wherein said first and second series of operations correspond to the same pattern of operations relative to said workpiece.

89. The method of claim 86 further comprising the step of selectively advancing the workpiece during the initial teaching operation to the approximate position corresponding to the position of the workpiece accounting for projected workpiece movement.