A safe-parking and safe-switching framework for fault-tolerant control of switched nonlinear systems

This work considers the problem of handling actuator faults in switched nonlinear systems that transit between multiple modes subject to input constraints. The faults considered preclude the possibility of operation at the nominal equilibrium point in the active mode. For the case where the switching schedule is fixed, a safe-parking scheme is designed, which accounts for the switched nature, to operate the system at temporary equilibrium points during fault-repair time and allow resumption of nominal operation after fault repair. For the case where the switching schedule is adjustable, a safe-switching scheme is designed, which exploits the switched nature, to switch the system to a mode (if exists and available) where nominal operation can be preserved (through control structure reconfiguration when necessary) to continue nominal operation. The proposed framework is demonstrated via a switched process example, as well as application to a polymerisation process of methyl methacrylate.