Research On Hover Control Of Quadrotor Aircraft

Quadrotor is one of multi-rotors aerial vehicles which possess the ability of vertical take-off and landing and spot hover. It has a simple structure with a small size, light weight, flexbility. It can be achieved various attitudes by changing the speed of four rotors, which make it suitable for military reconnaissance, ground environment inspection, aerial photography in low altitude and transmission line inspection. It can be applied in both military and civil fields.However, the dynamics model of quadrotor is nonlinear, underactuated, strong coupling, and it is susceptible to external disturbances of the airstream and noise and so on in flight process, which increase the difficulty of the controller design. The research emphasis of this thesis is to design control algorithms for quadrotor. Firstly, the basic motion of quadrotor and its working principle are introduced, after accomplishing force analysis according to Newton’s laws and Euler Theory, we achieve dynamic models of quadrotor. Then two controllers are designed in this thesis based backstepping algorithm and sliding mode algorithm, compared with the traditional PID control algorithm, and corresponding experiments are did respectively.Backstepping contoller is designed by using backstepping for Uncertain Systems(disturbance or uncertainty does not satisfy matching condition) showed strong robustness and self adaptability, MATLAB / Simulink simulation is showed that backstepping contoller realize the stability of quadrotor. The sliding mode control has the advantages of fast response, the insensitive of corresponding parameter variation and disturbance, and no need for on-line identification, simple physical implementation. In this paper, the controller is designed by sliding mode algorithm, and exponential approach law is used for weakening the dithering and having a fast response, which realized the stability control of quadrotor.In summary, the controllers of quadrotor by using PID algorithm, backstepping algorithm and sliding mode algorithm are designed, and MATLAB simulation is carried out. The results show that three kinds of control strategies realize stability control for quadrotor. When certain interference signal is added to the systems, PID control system is unable to keep stability, however, backstepping and sliding mode control achieve stabilize in a certain period of time, It is showed that the backstepping and sliding mode control has good anti-interference performance.