ABSTRACT
Increasing demands on the dynamical behavior of MEMS devices are reaching a point where mechanical design and simple-signal, open-loop driving cannot provide further improvements. Alternative approaches based on control theory, such as open-loop or closed-loop driving strategies, must be used instead to provide further enhancements in device performance. Simple input signals can be made more complex to fit MEMS dynamics better, therefore yielding better dynamic performance. Such control techniques are commonly referred to as preshaped open-loop driving and control. The ultimate step in improving precision and speed of response is use of feedback or closed-loop control. Unlike macromechanical systems, where the implementation of the feedback is relatively simple, in the MEMS case the feedback design may be quite problematic. Limited availability of sensor data, presence of sensor dynamics and noise, and the typically fast actuator dynamics all pose challenge in MEMS feedback design. The purpose of this chapter is to explore both open-and closed-loop strategies and to address the comparative issues of driving and control for MEMS devices. An optical MEMS switching device is used as an example in this study. On the basis of both experimental results and computer simulations, advantages and disadvantages of the different control strategies are discussed.
