Intelligent robust controller design for a micro-actuator

In this article the design of an intelligent robust controller for a Micro-Actuator (μ - A) is presented. The μ - A is composed of a micro-capacitor, whose one plate is clamped while its other flexible plate's motion is constrained by hinges acting as a combination of springs and dashpots. The distance of the plates is varied by the applied voltage between them. The dynamics of the plate's rigid-body motion results in an unstable, nonlinear system. The control structure is constructed from: a) a feedforward controller which stabilizes the micro-actuator around its nominal operating point, b) a robust PID controller whose gains are initially tuned via the utilization of Linear Matrix Inequalities (LMIs) and subsequently are switched according to the position of the upper plate, and c) an intelligent prefilter which appropriately shapes the reference signal. The resulting overall control scheme is applied to the non-linear model of the μ-A where simulation results are presented to prove the efficacy of the suggested scheme.