Control system for manipulator apparatus

Abstract

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.