Acceleration feedforward control against rotational disturbance in hard disk drives

We have developed a hard disk drive (HDD) free of rotational disturbance using dual piezoelectric accelerometers. The dual accelerometers detect angular acceleration in the HDD and compensate for its negative effects. For optimum compensation we introduced the use of an optimal phase compensation filter (PCF). Using this controller, HDD performance does not decrease even under the severest conditions: for example, in a disk array system that has the severest mechanical interaction between HDDs.