Design and experimental study of an observer-based controller for a three-DOF four-wire type optical pickup head. - Paul C.-P. Chao 001; Jeng-Sheng Huang; C.-W. Chiu; Chien-Yu Shen (ACC, 2005)

Sensorless Tilt Compensation for a Three-Axis Optical Pickup Using a Sliding-Mode Controller Equipped With a Sliding-Mode Observer. - Paul C.-P. Chao 001; Chien-Yu Shen (IEEE Trans. Control. Syst. Technol., 2009)