Design and implementation of a hard disk drive servo system using robust and perfect tracking approach

This paper deals with the problem of a servo system design for a conventional hard disk drive with a single voice-coil-motor (VCM) actuator using a so-called robust and perfect tracking (RPT) approach. We will first model the physical system and then formulate it into a robust and perfect tracking problem, in which a measurement feedback controller can be obtained to achieve a robust and perfect tracking for any step reference, i.e., the -norm of the resulting tracking error with 1 can be made arbitrarily small in the presence of external disturbances and initial conditions. Some tradeoffs are then made in order for the RPT controller to be implementable using the existing hardware setup. The implementation results of the RPT controller are compared with those of a proportional integral derivative (PID) controller. The results show that the servo system with our RPT controller has much better performance than the PID one has. Our servo system has faster settling time, lower overshoot and higher accuracy.