Interaction rejection of multiple microactuators in dual-stage servos for hard disk drives

Dual-stage servos with multiple microactuators are an effective way to increase the servo performance for higher track density of hard disk drives. The multiple microactuators can be used to perform simultaneous read/write on multiple disk platters so as to achieve a higher data rate using the parallel processing. Also, faster, independent access to data is possible with multiple actuators. However, the interactions among microactuators may degrade system performance or even cause instability. In this paper, we mainly deal with the interaction problem for piezoelectric microactuators to achieve higher positioning accuracy. The control scheme for the microactuators, designed to reduce the interaction impact, is obtained by applying the generalized Kalman-Yakubovic-Popov lemma in conjunction with the Youla parameterization approach. Our simulation and experiment results demonstrate that the proposed control strategy can improve the position accuracy due to microactuator interaction by 40%.