A Fault Tolerant Control strategy for an unmanned aerial vehicle based on a Sequential Quadratic Programming algorithm

In this paper a fault tolerant control strategy for the nonlinear model of an unmanned aerial vehicle (UAV) equipped with numerous redundant controls is proposed. Asymmetric actuator failures are considered and, in order to accommodate them, a sequential quadratic programming (SQP) algorithm which takes into account nonlinearities, aerodynamic and gyroscopic couplings, state and control limitations is implemented. This algorithm computes new trims such that around the new operating point, the faulty linearized model remains nearby from the fault free model. For the faulty linearized models, linear state feedback controllers based on an eigenstructure assignment method are designed to obtain soft transients during accommodation. Real time implementation of the SQP algorithm is also discussed.