Phase Lead Reset Control Design with an Application to HDD Servo Systems

This paper investigates a time-dependent phase lead reset control (PLRC) scheme which resets the sub-set of states of the systems at a predefined time. A phase lead reset compensator that has a flat gain characteristic is proposed to be used together with the common feedback control design to enlarge the servo bandwidth by increasing the phase stability margin. We also propose to have a reset time slightly earlier than the instants of input zero-crossing in the usual reset control to solve the impulsive effect in the control signal that leads to control signal saturation. Sinusoidal describing function analysis of the proposed control scheme shows that it can relax the Bode´s gain-phase constraint. The application of the proposed PLRC to the hard disk drive (HDD) servo system shows that the performance improvement. Our results also show that the large sharp peaks in the control voltage which may lead to track following controller saturation is also avoided