A controller design method for constructing a robust track-following system

This paper provides a robust tracking controller design method for the track-following system of an optical disk drive. A tracking loop gain adjustment algorithm is introduced to accurately estimate the tracking vibration quantity in spite of the uncertainties of the actuator. A minimum tracking open-loop gain is calculated by the estimated tracking vibration quantity and a tolerable limit of tracking error. A weighting function is selected to have a slightly larger gain than the calculated minimum tracking open-loop gain. A robust tracking controller is designed by considering a robust H_infin control problem with the reasonable weighting function. The proposed tracking controller design method is applied to the track-following system of a DVD rewritable drive and is evaluated through the experimental results .