Research On Fault-Tolerant Control Methods For Quadrotor UAV

Quadrotor UAV is adapted to the multi-platform, multi-space environment for its feature of small size, simple structure, light weight, low cost, and good concealment. UAV flying at low altitudes and its good mobility can make it take off and land on a small flexible platform, without ejection mechanism, launchers mechanism and other auxiliary equipment. Due to its many advantages, both in military and civilian fields it has a very broad application prospects. In this paper, quadrotor UAV model is researched in this dissertation and its mathematical model is established. Then prediction filtering method is adopted to estimate faults and finally adaptive backstepping fault-tolerant controller is designed. The main contents are as follows:First, the definitions of the inertial coordinate system and the body coordinate system are carried out for flight control, which leads to the establishment of kinematic equation for qudarotor UAV; Using the Newton- Euler method rigid body dynamics equation for the model is derived. Forces and moments acting on quadrotor UAV are analysed specifically, which helps to build the full expression of the mathematical model.Secondly, according to the mathematical model the position controller and attitude controller are designed for the basic control of quadrotor UAV. The basic algorithm and the general step of non-linear predictive filtering method is explained. And use this non-linear method to estimate the faults of actuator and design the active fault-tolerant controller.Finally, the basic theory and algorithm of backstepping control method widely used in the nonlinear system is introduced. According to the double loop control structure of quadrotor UAV backstepping position and attitude controllers are designed separately. The simulations are carried out to show the good perforamance of the designed basic backstepping controller. Based on the backstepping controller and with the adaptive law for estimation of faults, we designd the adaptive backstepping fault-tolerant controller for quadrotor UAV. We also proved the effectiveness of this controller.