A phase-stabilized servo controller for dual-stage actuators in hard disk drives

A phase-stabilized servo controller was developed based on a Nyquist plot for moving-suspension dual-stage actuators. The controller uses the suspension resonances of a PZT microactuator to compensate for the track misregistration (TMR) due to windage disturbance caused by suspension vibration. Experimental results obtained using a prototype 3.5-in hard disk drive show that the crossover frequency of the open loop is 2.0 kHz, and that the root mean square of the TMR due to windage disturbance is reduced by 23% compared to that of a conventional notch-based dual-stage controller. Index Terms--Decoupled feedback control, dual-stage actuator, hard disk drive, windage.