Modeling and robust control of Blu-ray disc servo-mechanisms

This paper deals with the modeling and the robust control of the next generation of optical disc drives servo-mechanisms. While in many industrial servo-control implementations, the radial and focus loops are considered as decoupled, e.g. DVD drives, this is no longer true for HD-DVD and Blu-ray disc (BD) formats which are more sensitive to opto-mechanical interactions at high frequencies. The impact of such phenomena on the robustness of the servo is evaluated by using experimental data, and an H∞ controller is designed to reduce the coupling effect, by using a suitable disturbance model into the problem formulation. Simulations using experimental data illustrate the performance improvement of the compensated system despite the parametric uncertainties in mass-production optical disc drives.