Modified dual-stage controller for dealing with secondary-stage actuator saturation

This paper proposes a modified decoupled master-slave (DMS) dual-stage control scheme for hard disk drives that offers enhanced stability when the secondary-stage actuator is saturated. A nonlinear secondary-stage actuator model is used instead of a linear model in the controller. This modification allows microactuators with relatively smaller displacement range to be used in the servo system without causing stability problems in the DMS controller. Simulation and experimental results confirm the effectiveness and robustness of the scheme.