Unimation, Inc.

William Perzley

Maurice J Dunne

Joseph F Engelberger

Torsten H Lindbom

Wilbur N Roberts

Horace L Gardner

Rajan C Penkar

Stanley J Blanchard

Brian W Pollard

Yung-Ming Yen-Chen

Jeffrey R Davis

A coordinate conversion system is provided for moving the manipulator arm and hand in repsonse to an input command signal of the 3.times.4 matrix type. The manipulator is provided with a fixed offset between two of the secondary wrist axes so that a stronger wrist configuration is provided which can handle heavier payloads.

Coordinate conversion system and method for controlling an industrial

A control system for manipulator apparatus having a manipulator arm movable in a plurality of axes utilizes resolved compliant motion control to improve servo response characteristics. The position and velocity of the manipulator arm are controlled using load modeling to account for compliance in the arm and to synthesize feedback signals representing movement of a remote point of the arm to provide a loop bandwidth greater than is possible using feedback signals from inner less remote points of the manipulator that are closer to the drive points. The feedback signals are derived using predetermined combinations of force related feedback signals from the axis drive arrangements and position and velocity feedback signals of the manipulator apparatus at points closer to the main drive and support structure of the manipulator and before certain compliant portions of the manipulator arm. To further enhance response and control of the manipulator arm, load modeling is also used to provide controlled deceleration before the manipulator arm is brought to a stop during work operation.

Control system for manipulator apparatus with resolved compliant motion

A control system is provided for a programmable manipulator having an arm movable in a plurality of axes that results in improved dynamic performance and control of a manipulator arm over a wide range of arm loads, dynamic operating parameters of the arm, and over the full range of arm operating positions. The control system for one or more of the controlled axes includes several servo control loops utilizing force or pressure feedback from the axis actuators and variable inertia scaling of selected loop command signals and loop parameters. The variable inertia scaling in accordance with the inertia of the arm provides improved dynamic performance of the manipulator arm while maintaining stable servo-loop operation over a wide range of operating parameters. In a preferred arrangement, the variable inertia scaling is accomplished by the use of a look up table with appropriate interpolation of the table entries. The look up table is stored in a digital axis processor with the appropriate variable inertia scaling factors being determined by the axis processor for use by the respective axis servo-loop. The look up table in accordance with various predetermined operating requirements of the manipulator apparatus includes data entries representing inertia scaling factors according to the mass of the arm load, the commanded velocity in a particular axis, and the operating positions of one or more of the major control axes of the arm.

Control system for manipulator apparatus

Teach assist apparatus is provided for a programmable manipulator arm to precompute a projected fixed path solution during an initial teaching operation. The projected fixed path solution represents a desired series of manipulator arm work operations to be performed with respect to a workpiece in the minimum execution time while the workpiece is moving at a projected velocity. During the teaching operation, the manipulator arm is moved to various teach positions corresponding to the desired series of work operations relative to the workpiece. The teach assist apparatus computes the minimum execution time on the basis of the maximum dynamic capabilities of the manipulator arm being taught. The precomputed path data is stored and control apparatus is provided to reconstruct the precomputed fixed path solution in a playback work cycle in accordance with dynamic movement of the workpiece. The precomputation performed by the teach-assist apparatus is also useful to perform work operations on a stationary workpiece. In a preferred arrangement, the teach-assist apparatus determines the minimum execution time for each controlled manipulator axis for each step; the axis requiring the largest execution time being utilized to determine the minimum execution time.

Off-line teach assist apparatus and on-line control apparatus

A programmable automatic assembly system is provided which may be employed to assemble small parts. Each assembly station includes cooperating manipulator arms which are programmable to assemble parts on a centrally located work table. Improved facilities are provided for teaching the manipulator arms at each station, these facilities including a computer which assists the teaching operator in setting up the programs required for assembly of small parts to close tolerances. Each manipulator arm includes closed loop teach facilities for maintaining the arm at a previously located position during the teaching mode of operation. The computer is employed as a teach assist facility in performing a number of tasks during the teaching operation which are extremely difficult for the operator to perform manually. All of the assembly stations may be controlled during playback from a common disc storage facility so that the control circuitry and memory storage facilities at each manipulator are minimized.

Programmable automatic assembly system

A programmable automatic assembly system is provided which may be employed to assemble small parts. Each assembly station includes cooperating manipulator arms which are programmable to assemble parts on a centrally located work table. Improved facilities are provided for teaching the manipulator arms at each station, these facilities including a computer which assista the teaching operator in setting up the programs required for assembly of small parts to close tolerances. Each manipulator arm includes closed loop teach facilities for maintaining the arm at a previously located position during the teaching mode of operation. The computer is employed as a teach assist facility in performing a number of tasks during the teaching operation which are extremely difficult for the operator to perform manually. All of the assembly stations may be controlled during playback from a common disc storage facility so that the control circuitry and memory storage facilities at each manipulator are minimized.

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.

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Weston, CT, United States of America

William Perzley