On the improvement of tracking servo performance of HDD using accelerometer

In the track following problem of HDD, there are many disturbances such as windage, pivot friction, bias torque from flex cable, RRO, and noise. Especially, the windage is one of the major sources, and its magnitude increases drastically as the disk rotation speed increases. In this paper, a method to attenuate the influence of input torque disturbances is proposed by the use of an accelerometer. The disturbances are estimated from the accelerometer attached at the carriage of VCM actuator, and are feedbacked into the control input in order to attenuate its effect to PES in the multi-rate control framework. Experiment shows that the proposed method effectively decreases the influence of the windage in the low frequency range without increasing the control bandwidth