Experimental study on direct adaptive control of a PUMA 560 industrial robot

摘要

Abstract The article describes the implementation and experimental validation of a new direct adaptive control scheme on a PUMA 560 industrial robot. The testbed facility consists of a Unimation PUMA 560 six‐jointed robot and controller, and a DEC Micro VAX II computer which hosts the RCCL (Robot Control “C” Library) software. The control algorithm is implemented on the Micro VAX which acts as a digital controller for the PUMA robot, and the Unimation controller is effectively bypassed and used merely as an I/O device to interface the Micro VAX to the joint motors. The control algorithm for each robot joint consists of an auxiliary signal generated by a constant‐gain PID controller, and an adaptive position‐velocity (PD) feedback controller with adjustable gains. The adaptive independent joint controllers compensate for the interjoint couplings and achieve accurate trajectory tracking without the need for the complex dynamic model and parameter values of the robot. Extensive experimental results on PUMA joint control are presented to confirm the feasibility of the proposed scheme, in spite of strong interactions between joint motions. The scheme is also implemented for control of the end‐effector motion in Cartesian space. Experimental results validate the capabilities of the proposed control scheme. The control scheme is extremely simple and computationally very fast for concurrent processing with high sampling rates.