Design and Experiment of an Observer-based Controller for a Three-DOF Four-wire Type Optical Pickup Head

• Main Authors: Chien-Yu Shen, 沈建佑
• Other Authors: Chang-Po Chao
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/32947830432622117555

碩士 === 中原大學 === 機械工程研究所 === 92 === This thesis considers a four-wire type optical pickup that is installed in CD/DVD of commercial data-reading systems. The optical pickup owns three degrees of freedoms, focusing, tracking and tilting, respectively. The virtual work and Lagrange's equation are used to derive the equations of motion. On the other hand, the action forces of voice coil motor (VCM) are formulated to derive the compact governing equation. The design of the controller is base on sliding mode control theory. The full-order high-gain observer is designed first to estimate the velocities of the pickup to provide feedback signals for sliding control. By using the dSpace real-time control interface to verify the theoretical mode which taking the combined observed signal from full-order high-gain observer as feedback signal of sliding mode controller to make experiments. Finally, experiments are conducted to test and verify effectiveness of the observing velocity from high-gain observer replacing digital derivatives of available, measured positions to be the feedback signals.