A new damping scheduling proximate time optimal servomechanism

A proximate time-optimal servomechanism (PTOS) has been widely used in hard disk drives because of its simplicity and good performance. We propose a new damping scheduling PTOS (DSPTOS). Based on a PTOS, the proposed algorithm keeps the closed-loop damping coefficient a predetermined value. To obtain the constant closed-loop damping coefficient, the acceleration discount factor should be scheduled with regard to position error. Smaller damping in deceleration will boost up the rising speed, and larger damping in the settling phase reduces the overshoot and residual vibrations. Thus, the DSPTOS has faster settling time than the PTOS does. Moreover, the DSPTOS maintains the simplicity of the PTOS by introducing just a predetermined damping coefficient. We applied the proposed DSPTOS algorithm to a voice coil motor in a hard disk drive. Through simulations and real-time experiments, the effectiveness of the DSPTOS is verified. In particular, with respect to long stroke seeks, we improve the settling time by up to 15% with the DSPTOS