Developing Electromechanical Coupling Macro Models for Dynamic Responses of MEMS Structures With Command Shaping Techniques

Dynamic response and structural longevity of MEMS devices such as RF switches is an important issue. However, the process involves complicated electromechanical interaction and stress analysis. In this paper, a rational analysis flow is first proposed to address this problem. By using a macro modeling approach, it is possible to estimate the dynamic performance and yield a contact velocity as the input for solving the associate contact stress. Such a macro model can be easily implemented in a MATLAB/Simulink environment, and a command shaping scheme is used to demonstrate the possible advantage of using the scheme to optimize the device performance and structural integrity. To achieve this, the pull-in voltage is discussed first and the command shaping methods are reanalyzed for MEMS applications for fast positioning and for minimizing contact stress during operations. An online tuning scheme is proposed for ease of design. These issues are integrated into a lumped-element Simulink model to serve as the platform for examining the effectiveness of the developed shaping schemes and evaluating the performance of electrostatically driven MEMS. Finally, essentially experimental investigations are performed to demonstrate the possible advantage of using shaping schemes. Throughout these analyses, it is possible to optimize the integrated system dynamics for applications in performance enhancement or in improving the structural reliability of electrostatic actuated MEMS devices.