Control of linear motors for machine tool feed drives: Experimental investigation of optimal feedforward tracking control

This paper investigates the use of optimal l(1) and H-infinity model reference optimal feedforward control to enhance the tracking performance of a linear motor drive. Experimental work is presented which studies the effects of signal preview, tracking constraint, and reference model choice on tracking performance. Suboptimal l(1) control where the closed-loop system has a zero on the unit circle due to integral action in the feedback controller is given special attention, and is seen to give near optimal performance for the system under study here. For the specific trajectory employed here, the best performing feedforward controllers were experimentally seen to reduce by more than half the maximum and rms tracking errors of the H-infinity optimal feedback closed-loop systems.