Control System Design and Experimanetal Verification of an Equivalent MEMS Electrostatic Actuator

• Main Authors: Cheng-Chung Ho, 何正中
• Other Authors: Kuo-Shen Chen
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/624u33

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 90 === Electrostatic actuators are important driving elements for microelectromechanical systems (MEMS). However, their working range is usually limited by pull-in instability. In addition, the uncertainties and nonlinearity from fabrication and structural characteristics also make it difficulty to achieve uniform performance and therefore, increase the cost of packaging and calibration. As a result, it is important to incorporate a robust controller to increase both the dynamical range and the robustness of electrostatic actuators. This thesis focused on the development of feedback controller for a double-clamped beam, a common MEMS structure. In addition to the parametric uncertainty and pull-in instability, this structure also exhibits considerable Duffing nonlinearity. Therefore, increase the difficulty for control. However, it is not flexible to develop controllers in MEMS scale due to the difficulty of extra high bandwidth requirement and sensing available schemes. As a result, based on the analogy of system dynamics, we develop a macroscale equivalent system and utilizing electromagnetic actuators as the equivalent driving elements. A novel calibration scheme utilizing pull-in phenomenon is used to calibrate eletromagnets. Both feedback linearization and sliding controllers are designed to extend the operation range of actuators. The computer simulation indicates that with proper design, electrostatic actuators can achieve stable behavior beyond the pull-in linit. However, it is also found that the feedback linearization controller can achieve this goal only under small parametric uncertainty. On the other hand, sliding control shows more robust performance. The result of this thesis can be applied in two fields. First, it can be used as a basis of rapid prototyping of controller for MEMS. Second, the calibration and control schemes proposed in this thesis can be directly applied in marcoscale mechatronics applications such as magnetic suspension and precision positioning.