Optimal Reset Control for a Dual-Stage Actuator System in HDDs

This paper presents an optimal reset control method for a dual-stage actuator servo system in hard disk drives. The dual-actuator system consists of a voice coil motor (VCM) as a first stage actuator and a push-pull-type piezoelectric transducer (PZT) as a second-stage actuator. It is considered as dual-input single-output (DISO) problem. We designed two optimal reset controllers for VCM and PZT, and combined the two components with a decoupled master-slave structure. With a base linear system designed conventionally, the discrete-time reset law design aims at improving the system transient responses. The design method can guarantee the system stability and the solution of the controller is obtained by solving Riccati equations. Track seeking performance is investigated and simulation results and experiment results show that the proposed method is able to achieve short settling time and low overshoot.