Design of resonant controller for hard disk drive servo system using a mixed passivity and small-gain approach

Effective compensation of mechanical resonant modes is one of the design challenges in read/write head-positioning servomechanism of hard disk drive (HDD) servo. Resonant modes create oscillation in the system response and may lead to instability if not compensated properly. This paper presents a resonant controller designed in a simple and yet efficient way to suppress the effects of resonant modes of Voice Coil Motor (VCM) actuator used in HDD. The design is based on a mixed passivity and small gain approach to an unstable plant model. Since the original theorem is for stable systems, therefore a stabilizable controller is used for the design. Experimental results substantiate the effectiveness of the controller.