Supervisory fault tolerant control of the NASA AirStar aircraft

A multi-level reconfiguration framework is proposed for fault tolerant control of overactuated aerial vehicles, where the levels indicate how much authority is given to the reconfiguration task. On the lowest, first level the fault is accommodated by modifying only the actuator/sensor configuration, so the fault remains hidden from the baseline controller. A dynamic reallocation scheme is applied on this level. The allocation mechanism exploits the actuator/sensor redundancy available on the aircraft. In case the fault cannot be managed at the actuator/sensor level the reconfiguration process has access the baseline controller. Based on the LPV control framework, this is done by introducing fault-specific scheduling parameters. The baseline controller is designed to provide acceptable performance level along all fault scenarios coded in these scheduling variables. The decision of which reconfiguration level has to be initiated in response to a fault is determined by a supervisor unit. The method is demonstrated on the full six degrees of freedom nonlinear simulation model of the GTM UAV.