Westinghouse Electric Corporation

Staubli International Ag.

Roy E Lancraft

Richard J Casler, Jr

Eimei M Onaga

Kenneth E Daggett

Norman J Bergman

Rajan C Penkar

Barrett L Booth

Marcus D Nuncy

Chi Sha

A digital control provides adaptive feedforward torque control for a robot having a plurality of arm joints. An electric motor drives each of the robot arm joints and a power amplifier supplies drive current to each motor under controlled operation. Each joint motor has feedback control loop means including position and velocity control loops driving a torque control loop in accordance with position commands to generate motor commands for controlling the associated power amplifier. The motion of said joint motor generates position and velocity feedback signals respectively for combination with the position and velocity commands to generate an error signal as a torque command for each of the torque control loops from the corresponding position and velocity control loops. Load force is sensed at the endmost robot joint. The actual load moment for each robot joint on the basis of the load force and the dynamic/kinematic data moment is computed for each robot joint on the basis of stored dynamic and kinematic data for the robot arm. The data and load moments are combined for each joint and applied as a feedforward torque for combination with the position and velocity errors in generating the torque command for each of the torque control loops. A feedback signal representative of the joint motor drive current is combined with the torque command to generate a torque error signal in each torque control loop.

Robot control system having adaptive feedforward torque control for

A digital robot control is provided with position/velocity and torque control loops with microprocessor servo controllers in each. The position/velocity servo controller includes two microprocessors that operate as a servo engine in providing position/velocity control for six robot axes. One microprocessor operates as a manager to perform data processing and coordination tasks supportive to position/velocity control. The other microprocessor performs position and velocity servo calculation tasks and operates as a slave processor to the position/velocity control manager. The programming for the position/velocity control sends manager position and other commands and position and velocity feedback from other control levels to the position/velocity calculator and sends torque commands received from the calculator to the next lower control level. The calculator employs position/velocity control algorithms in making torque command calculations.

Multiprocessor position/velocity servo control for multiaxis digital

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Southbury, CT, United States of America

Roy E Lancraft