An iterative learning control method with application for CNCmachine tools

摘要

A PID (proportional, integral, and derivative) iterative learningcontroller is proposed for precise tracking control of industrial robotsand CNC (computer numerical control) machine tools performing repetitivetasks. The convergence of the output error by the proposed learningcontroller is guaranteed under a certain condition even when systemparameters are not known exactly and periodic disturbances exist. Inactual implementation, the distance difference between the desired pathand the actual machined path, which is one of the most significantfactors in the evaluation of control performance of industrial robotsand CNC machine tools, is reduced in machining a circle with depth onthe aluminum workpiece as the proposed learning algorithm repeats.Experimental results demonstrate that the proposed PID learningcontroller can improve machining accuracy when the CNC machine toolperforms repetitive tasks in machining