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.