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Robust control in the three-dimensional optical pickup head for optical disk drive

The servo control of the DVD optical head with tilt control is often difficult because of the coupled effect between the fine tracking servo and the tilt angle servo. Experiences show that the control system characteristics changes with different tilt angle. The controller may have to adapt for the characteristic change. This study presents a model to represent the changes in the system dynamics with respect to the different tilt angle. The variation in the dynamic behavior can than be lumped into a multiplicative system uncertainty. A µ-control synthesis procedure is then shown to be an effective servo design tool.