Fault Detection using Set Membership Identification for Micro-Electrostatic Actuators

Fault detection in micro-electrostatic actuators caused primarily by their mechanical components (combs, thin air-damping) is investigated in this article. The system is assumed to be linearly parameterizable and the parameter vector contains the quantities that are susceptible to faults. While the system is operating in a closed-loop configuration, a set-membership identifier monitors the feasible region within which the nominal parameters should reside. The hyper-volume of this region is a measure of the uncertainty of the system parameters and decreases in a monotonic manner with time. A fault is detected when: a) there is a sudden increase in this volume, or b) when the identified centroid of the parameter vector resides out of the feasible region, or c) when the system´s output is out of its allowable predicted bounds. Simulation studies are offered to test the efficiency of the suggested fault-detection method.