Design And Implementation Of Flight Controllers Based On Qball-X4 Quad-rotor UAV

Qball-X4 unmanned vehicle (UAV) system is a real-time control and experimental platform developed by the Quanser Inc. of Canada. Quad-rotor UAV is a multivariable system which is strongly coupled, and under-actuated. Quad-rotor flight control can be achieved by control strategy such as PID control, state feedback control, nonlinear control. The main purpose of this thesis is to design and implement Qball-X4 real-time trajectory tracking control. The main contents and innovation are summarized as follows:(1) The Qball-X4 UAV system, including Qball-X4 structure, stress analysis and moment are analyzed in the thesis. Based on the Newton-Euler modeling method, the nonlinear model of Qball-X4 with six degrees of freedom is established. According to the characteristics of indoor flight control, the linear model is obtained by approximation and simplification methods.(2) Based on linearized model for the plant, PID controller is designed to realize the real-time trajectory tracking control, the gains of the PID controller are obtained by LQR optimal method. The simulation system is established to verify the control effect, and the design of the controller is applied to the actual flight control system to verify that the design can achieve control objectives.(3) Since the gains of the traditional PID controller cannot be adjusted, some improvements are made and gain scheduling of PID controller is designed. The gain scheduling in fuzzy control algorithm based on T-S fuzzy inference is applied. Then, the improved control scheme is implimented in both simulation and the hardware-in-the-loop simulation experiment.(4) Based on a nonlinear model for the plant, the control system is divided into two sub systems:the position and attitude control. The outputs of the position controller modify the given inputs of attitude system. The integral sliding mode controller is designed and implemented in the simulation system, while the controller and the plant model are written by the S-function. The chattering phenomenon of the simulation process is improved using the exponential reaching law method. The simulation results show that the improved controller can achieve the desired control objectives.