Design of hybrid closed loop control systems for a MEMS accelerometer using nonlinear control principles

This paper presents and compares two novel hybrid control algorithms applicable to the conventional capacitive MEMS accelerometer. These schemes are realized by separately adding a sliding-mode and a backstepping controller to a conventional PID closed loop system to achieve higher stability and higher dynamic range and to prevent pull-in phenomena by preventing finger displacement from passing a maximum preset value, a criteria which is necessary for a shock resistance system. The analysis of convergence and resolution show that while the proposed control schemes satisfy these criteria they also keep resolution performance better than what is normally obtained in conventional PID controllers. The performance of the two proposed hybrid controllers investigated here is compared and validated by computer simulation.