Invariant-set-based fault tolerant control using virtual sensors

In this study an invariant-set approach to sensor FDI is employed together with control system reconfiguration based on the use of a virtual sensor. In the proposed FDI approach, invariant sets are specified for each considered healthy/faulty situation in the system´s sensor structure. The detection mechanism is based on the separation between the computed invariant sets and ´transition´ sets where appropriate residual variables ´jump´ when faults occur. The closed-loop system is then reconfigured by means of a virtual sensor which is adapted to the detected fault. Furthermore, conditions are derived in terms of bounds on reference signals, noise and disturbances which guarantee the stability of the closed-loop system under the resulting fault tolerant control scheme for all considered fault situations. Simulation results of the proposed scheme on a longitudinal car following scenario and experimental results on a laboratory scale magnetic levitation system confirm the validity of the approach under realistic conditions.