Linear quadratic controller with fault detection in compact disk players

The design of the positioning controllers in optical disk drives are today subjected to a trade off between an acceptable suppression of external disturbances and an acceptable immunity against surfaces defects. In this paper an algorithm is suggested to detect defects of the disk surface combined with an observer and a linear quadratic regulator. As a result, the mentioned trade off is minimized and the playability of the tested compact disk player is considerably enhanced.