Control of a dual stage actuator system for noncircular cam turning process

This paper presents a robust repetitive controller design for a dual stage actuator system for the noncircular cam turning process. The secondary actuator in this dual stage system is a piezoelectric actuator which is installed inside of the hollow piston of an electrohydraulic actuator. The controller is designed through a sequence of two SISO designs under the assumption that there is little interaction between two actuator systems. The error from the first stage electrohydraulic actuator is fed to the second stage piezoelectric actuator as reference. Therefore, the overall sensitivity function is effectively squared through two actuators and the total error is the same as the error coming from the piezoelectric actuator. Experimental results show the tracking performance improvement in noncircular cam turning application.