Vibration minimized access control for disk drives

A new access control method called SMART (Structural Vibration Minimized Acceleration Trajectory) has been developed for hard disk drives. The access formula is derived from a minimum-jerk cost function. The closed loop of access mode is based on velocity control and the target velocity to keep minimum-jerk is easily calculated as a function of position by a DSP controller. With SMART control the high harmonics of the actuator acceleration are suppressed in comparison with conventional control. Residual vibration after the access operation and spacing fluctuation of the head slider are both greatly decreased.