Adaptive hybrid tracking-error control for DVD drives in vehicular systems

The paper presents the implementation and application of an adaptive hybrid controller for the servo system of a DVD drive in recreation vehicle, to suppress tracking disturbance with frequencies less than 100 Hz caused by environmental vibration and to improve the performance of tracking servo system. The adaptive hybrid servo control (AHSC) technique consists of both the active feedforward and feedback disturbance cancellation. In this paper, the controller is designed based on an adaptive digital filter with robust variable step-size filtered-x-least-mean-square (RVSS-FXLMS) algorithm. The applied RVSS-FXLMS filtering algorithm is a combination of the RVSS convergence and FXLMS algorithms. The control signal generated by the AHSC as an anti-error input can effectively suppress the tracking errors arising from vibration disturbance. The experimental results demonstrate that the AHSC can successfully improve the tracking performance on an existing architecture of the DVD drives in a vehicular system. More precisely, in severe disturbances the implemented hybrid system can still pick up data in high speed revolution, but not to decrease disk speed.