Adaptive control for focusing of optical drive read/write heads

This paper presents an adaptive control scheme and experimental results for the focusing of an optical read-write head for optical data storage drives. The adaptive control applies recursive least squares (RLS) algorithm to predict output disturbance and dynamically computes control commands to minimize the output focusing error. The adaptive control could become unstable when significant modeling errors and uncertainties exist. An extension is made to the existent adaptive control scheme to achieve robust stability while sacrificing minimally the control performance. Simulation and experiment conducted on the optical focusing of a digital video recording drive´s read-write head are presented to demonstrate the effects of the proposed adaptive control scheme on stability and performance.