Accelerometer feedforward servo for disk drives

Summary form only given. This paper discusses the design and verification of a new direct adaptive control scheme to attenuate the effect of external disturbances on a disk drive. The adaptive controller acts as an add-on compensator to the existing fixed compensator. An accelerometer which is mounted on the base of the disk drive generates the input signal for the controller. The control objective is to minimize the variance of the position error signal in the presence of external random vibrations. In this paper, only vibrational disturbances parallel to the spindle axis of the disk drive are considered. The stationary modes of a disk platter is split into two modes which are shifted by the disk rotational frequency. A model of the IBM Winchester Lightning 3.5" disk drive was used in simulations. Additionally, a method to frequency weight the solution to a Wiener filtering problem was developed when there is no unique solution. Simulation results show that a 7 dB attenuation at high frequencies can be achieved if frequency weighting method is used.