Design and control of a rotary dual-stage actuator positioning system

This paper presents the design and control of a rotary dual-stage actuator (DSA) positioning system, which has a flexure-based beam driven by a voice coil motor (VCM) and a piezoelectric (PZT) actuator simultaneously. The design goal is to enable the two actuators complementary to each other for the combined ability of high positioning accuracy and a large tangential displacement range. To achieve a high tracking speed, the flexure beam is designed via finite element method (FEM) analysis to have sufficiently high open-loop bandwidth. System identification and measurements on the DSA prototype are also presented to verify the FEM analysis. Finally, the composite nonlinear control (CNC) method is applied to the DSA system. Experimental results demonstrate that the DSA servo system significantly outperforms the single-stage servo system in both step tracking and disturbance rejection.