Design and implementation of a fault tolerant controller for EMS systems

Conventional EMS (electromagnetic suspension) systems are susceptible to instability problems, and could even break down upon failures of the air-gap sensor or the accelerometer. Therefore, in order to improve EMS performance, a fault tolerant controller and a fault detection and isolation (FDI) algorithm are presented in this work. The fault tolerant controller is an extended version of the linear fault tolerant controller designed for known actuator or sensor failures, and it adopts the LMI-based H ∞ control for a class of nonlinear systems. The fault detection algorithm employs fuzzy inference. The merits of the proposed control scheme have been verified by the experiments with a single-axis two-magnet suspension system subjected to failures of the actuator or the sensors.