Reconfigurable flight control strategies using model predictive control

Abstract

Tracking control for large amplitude manoeuvres in the presence of damages to airframe and control surfaces is addressed. The control reconfiguration algorithm is based on model predictive control, a constrained receding horizon optimisation is solved under the constraints of hard limits of actuator position and rate saturations and critical aircraft state limits imposed by allowable structural loads. Changed stability and control derivatives of the damaged aircraft are identified online and used by the receding horizon controller as internal model for prediction. An emphasis is given to incorporate handling quality specifications according to MIL-STD-1797A. The results demonstrate the ability of the proposed scheme to maintain level flight after a failure, to track the pilot commands despite the loss of actuator effectiveness, and to coordinate the use of the remaining active control surfaces to provide the decoupling between the rotational axes. Finally, the issue of online (onboard) implementation of constrained optimisation is examined.