Research On The Attitude Control Of Quad-rotor Unmanned Aerial Vehicles Based On Adaptive Control

Four-rotor unmanned vehicle is a simple body structure, manipulation and strong, non-coaxial rotor vertical takeoff and landing UAV. Due to the recent geology survey, weather detection, air traffic control, and military application are occupied widely, scholars pay more attention to this research field. In this paper, OS4-type four-rotor unmanned helicopter as research subjects, the dynamic model is established on the basis of analysis of the kinematics and dynamics characteristics of the flight. The nonlinear control algorithm of the four-rotor UAV model are researched and designed on the basis of PID model linearization.Firstly, dynamical model of a small disturbance is linearized through the small perturbation, then the whole system is divided into vertical, horizontal two subsystems, and they are used for PID controller design. Feasibility of the controller is tested by simulating two motion modes: sentinel hovering and trajectory tracking. Simulation results show that aircraft can accurately reach the target position under the role of the PID controller. But some performance parameters such as rise time, settling time, response overshoot should be improved.Secondly, since the performance of PID controller is not satisfied enough to solve nonlinear control system, the nonlinear backstepping controller is designed according to four-rotor unmanned helicopter model “strict feedback” feature. The advanced control system is divided into the attitude control loop(inner loop) and position control loop(outer loop), corresponding to the inner(attitude) controller and the outer(position) controller in order to avoid higher grade complexity and long computation time. The attitude output performance parameters of backstepping algorithm with Matlab Simulink simulation is improved comparing with that based on small perturbation linearization PID controller,.Thirdly, In this paper backstepping controller to Z axis direction of aircraft body based on the self-adaptive is designed on account of the outside uncertain interference in real flight, its simulation results show that the controller possess the certain anti-interference ability and robustness.Finally, real flight test results for PID controller and backstepping controller shows that it is consistent with the simulation and conclusion verified the reasonableness of the design.