Dual-Stage HDD Disturbance Cancellation based on an Efficient Adaptive Feedforward Compensation Algorithm

Abstract

This paper applies an efficient adaptive feedforward compensation (AFC) algorithm for periodic disturbance cancellation on a hard disk drive (HDD) servo system. Such an algorithm is shown to be equivalent to a linear time invariant (LTI) model. With the help of this equivalence, we can easily choose optimal phase advance parameters, precisely predict the upper bounds of the allowable adaptation gains and determine the appropriate coefficients of a feedthrough term. Additionally, in order to obtain higher servo bandwidth, a dual-stage actuated structure is put forward. This dual-stage actuator system consists of a Voice Coil Motor (VCM) as a primary actuator and a micro actuator as a secondary actuator. Such a configuration can further reject the disturbance and maximize the servo system performance. The simulation results in time domain and frequency domain show that this scheme is capable of achieving a satisfactory performance in dealing with disturbances.