Joint sensor based backstepping for fault-tolerant flight control

The sensor based backstepping control law, based on the singular perturbation theory and Tikhonov's theorem, is a novel nonlinear incremental control approach. This Lyapunov function based method is not susceptible to model uncertainties since it uses measured state derivatives instead of an onboard model. Considering these merits, the sensor based backstepping method is extended to handle sudden structural changes in the fault-tolerant flight control of an overactuated Boeing 747-200 aircraft with the control allocation being considered. Because of the application of the backstepping technique, this double-loop joint sensor based backstepping attitude controller allows more interaction between its outer and inner loops compared to a standard nonlinear dynamic inversion angular control approach. The benchmark with engine separation and rudder runaway failure scenarios is employed to evaluate the new controller. The simulation results show that the new joint sensor based backstepping attitude controller can lead to an unbiased tracking error performance in the nominal condition and more consistent sideslip angles than those produced by the hybrid sensor based backstepping approach when the aircraft is under failures.