Fault-tolerant switching control of a magnetic levitation system

In this paper, a fault tolerant switching control strategy is implemented on a magnetic levitation (MAGLEV) system. Two sensors are embedded in the MAGLEV system and their measurements used by two independent estimators. Each sensors-estimator combination, together with a feedback controller can levitate and stabilise a one-inch steel ball at a desired position in the air. The paper focuses on the design and testing of a switching scheme which, at each instant of time, selects the sensors-estimator combination that provides the best closed loop performance based on a chosen criterion. Theoretical results on the system linearisation around an operating point ensure local closed-loop stability and good performance under the occurrence of an abrupt fault in one of the plant sensors. Experimental results are provided which confirm the fault tolerant capabilities of the strategy.