Unimation, Inc.

Stanley J Blanchard

William Perzley

Brian W Pollard

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

The disclosed forms of shaft-position encoder employ 'fast' and 'slow' rotary selectors coupled by gearing to each other and to the shaft whose position is to be encoded. The selectors cooperate selectively with elements in respective 'fast' and 'slow' circular series of elements. Two counters register the number of pulses in respective pulse trains, the number of pulses in a train varying in accordance with the number of elements in each of the 'fast' and the 'slow' series between one end of the series and an element in cooperation with a related selector. The combined values registered in the counters represents the shaft position code. The inherent uncertainty in recognizing when the 'slow' counter should register any particular value represented by the position of its selector along its series of elements could create significant ambiguity, which is here resolved through use of the value registered in the counter of the 'fast' series of elements.

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Danbury, CT, United States of America

Stanley J Blanchard