Fault Isolation and Fault Tolerant Control for the Uncertain Quadrotor UAV System

In this paper, the fault isolation and fault diagnosis for the attitude control system of the quadrotor unmanned aerial vehicle (UAV) are shown, based on which the successive fault tolerant control (FTC) is also carried out. In most of modern literatures about the quadrotor UAV, the employed system dynamical models are established under ideal assumption conditions. However, system uncertainties of the quadrotor UAV system originating from modeling and other aspects, are seldom taken into account, which is deviated from the actual consequence. In this paper, a general dynamical model of the attitude control system of the quadrotor UAV is given, then for the aim to be more approximate to actual consequences, system uncertainties of state and input are considered. For the uncertain quadrotor UAV system, firstly, an observer method is employed to detect the fault location. Secondly, to diagnose the fault precisely, an adaptive observer with fault estimation term is employed. Lastly, on the basis of accurate fault estimation information, a sliding mode controller is employed to compensate the fault. Ultimately, the validity of the above mentioned methods is confirmed by numerical simulations.