Nonlinear Fault Recovery of a Quadrotor Using Progressive Accommodation

This paper proposes a nonlinear (NL) fault-tolerant control (FTC) strategy for stabilizing the attitude of a quadrotor affected by multiple rotor failures. The recovery process relies mainly on progressive accommodation (PA) strategy. The latter uses the Newton-Raphson (NR) algorithm in order to solve the state-dependent Riccati Equation (SDRE) in a recursive way. Simulations are performed using the NL model of the quadrotor in fault-free and post-fault cases. Both PA and the direct SDRE methods are employed so that the attitude control of the quadrotor can be stabilized. The results show that the PA strategy performs better than the classical method when it comes to convergence speed and to preserving the control objectives of the nominal system.