Improvement on a hard disk drive servo system using friction and disturbance compensation

This paper deals with compensation of torque disturbances in a hard disk drive (HDD) to improve its head positioning performance. The torque disturbances from the data flex cable and friction in the actuator rotary pivot bearing yield a significant bias and large residual error, which deteriorate performance of the overall system. Reducing effect of these torque disturbances has been one of challenges in designing head positioning servo systems. In this paper, a comprehension physical model of the voice coil motor (VCM) will be derived through analysis of physical effects and the parameters will be determined with the Monte Carlo method to match those responses measured in the perturbation method. A modified integral is added into a linear control law to reduce the disturbances and improve performance of head positioning servo systems. The simulation and experimental results show significant improvement on performance of the head positioning servo systems.