Fault-tolerant control of a magnetic levitation system using virtual-sensor-based reconfiguration

In this paper, a fault tolerant control strategy, which combines a fault detection and identification (FDI) method based on an invariant-set approach with controller reconfiguration based on the use of a virtual sensor, is implemented on a magnetic levitation (MAGLEV) system. The MAGLEV system includes two sensors which, together with a nominal observer-based feedback controller with integral action, are used to stabilise a steel ball at a desired position in the air. The FDI unit employs two observers that can detect the faulty and healthy situations based on a “set-separation” approach. The closed-loop system is reconfigured by means of a virtual sensor which is adapted to the fault situation detected by the FDI unit. Experimental results on a laboratory apparatus confirm the effectiveness of the proposed strategy.