OPEN LOOP CONTROL OF MICRO-ELECTRO MECHANICAL SYSTEMS (MEMS)

Abstract

Micro-Electro-Mechanical Systems (MEMS) is an emerging field of new technology which has greatly drawn all the attention of researchers for last few decades. The superior performance ability of these devices in variety of applications can bring the revolution in micro-technology. The first chapter introduces us to this technology with its principle of working and advantages and also takes us to a journey of its major applications. The main concern of the presented work is regarding 'the electrostatic actuation' in these micro-devices which is very popular due to its distinct advantages. The peculiar phenomenon exhibited by these devices known as pull-in instability' is discussed in the subsequent chapter. Pull-in parameters of any actuator system are of immense importance while designing a device. Different approaches to determine pull-in parameters of electrostatically actuated microbeams have been proposed by many researchers. We have idealised the actual microbeam actuator into a parallel plate model with single degree of freedom (SDOF) and using energy approach, we have derived static and dynamic pull-in parameters for the same. Dynamic characteristics of the microbeam actuator can be exploited in applications like micro-switches, micro-sensors, microscanners, micro-resonators and many more. These characteristics for the actuator under consideration have been studied thoroughly in chapter 5. Some remarks about phase plane curve of the system have been presented. Some MEMS applications for example digital micromirror device (DMD) need controlled dynamic response. We have introduced an effective technique namely 'input shaping' which is used to suppress vibrations in macro and micro systems. We have proposed an algorithm based on this technique to achieve stable dynamic response of the actuator. This technique works excellently to reduce overshoot as well as settling time. Simulation results clearly indicate the successful working of the system.