Dual-stage actuator servo control for high density disk drives

Four servo loop designs for disk drive dual-stage actuator systems are studied. The characteristics and benefits of each design are discussed. A parallel loop structure has been designed for a dual loop system with suspension based piezoelectric microactuators. Simulations in both frequency and time domains show dramatic performance improvements of the dual-actuator system over the conventional single loop servo system. The design was also implemented on a floating point DSP based experimental setup to show significant reduction of head motion achieved by using the dual-loop servo.