An integrated control/diagnostic system for a hard disk drive

This paper describes the implementation of an integrated control/diagnostic system for an advanced hard disk drive (HDD) servo system. An observer-based state feedback control design with the pole placement technique has been successfully applied to achieve a bandwidth of 688 Hz, which is quite satisfactory at a 4.5 kHz sampling frequency. Experimental results indicate, however, that the performance of this high precision, high-order control system deteriorates seriously when faults occur. Therefore, a fault identification filter (FIDF) was adopted for fault detection of sensor and actuator failures and accommodation of the actuator failure. In cases where either sensor or actuator fault occurs, experimental results indicate that to maintain high precision and control performance for the HDD system, DSP implementation of the high-order integrated control/diagnostic system is necessary