Robust resonant controller for compensation of resonance in voice coil motor actuator of hard disk drive servo system

Abstract

In hard disk drive (HDD) servo system and in many other precision servomechanism, one of the design challenges is effective compensation of mechanical resonant modes. System response becomes oscillatory because of these modes. If not compensated properly, excessive or unbounded oscillation may even lead to instability. This paper presents a robust resonant controller designed in a simple and yet efficient way to suppress the resonant modes of voice coil motor (VCM) actuator used in HDD servomechanism. The design is based on mixed passivity, negative-imaginary and small gain approach. Results of the design are verified using a benchmark problem, as well as by experiments carried out using a VCM actuator extracted from a HDD bought off-the-shelf. Simulation and experimental results substantiate the effectiveness of the proposed design methodology.