Study Of Attitude Control Algorithm For Quad-rotors

With the opening up of the low altitude areas, rotor aircraft as a kind of relying on the dc motor speed regulating control a non-traditional unmanned aerial vehicle(UAV) flight directly, because of its simple, flexible control, and the ability to adapt to the complex geographical environment and weather, has been widely used in military and civil field. Secondly, as a typical under-actuated(output more than input),strong coupling nonlinear system, as the object of scientific research is also very meaningful. This article selects four rotor as the input of the rotor unmanned aerial vehicle(UAV) as the research object, the set up and analyzed the four rotor aircraft,on the basis of the mathematical model for aircraft attitude stability control problem,using the linear and nonlinear control method, designed the three kinds of attitude control algorithm, and is verified by simulation experiments. The main research work of this paper is as follows:1. By studying the structure and control principle of the four rotor aircraft,modeling method based on the theoretical derivation modeling method(mechanism),according to the Newton’s second law and the Euler equation, a mathematical model of the system stability and for spacecraft attitude control problem, in the relevant conditions of the model was simplified, which laid a foundation for attitude control algorithm research.2. According to the mathematical model of four rotor aircraft, the cascade PID control algorithm was adopted to design the height of the aircraft system attitude controller. The simulation platform was built by Matlab/simulink. The simulation experiment results show the effectiveness of the proposed controller.3. In view of the under-actuated system characteristics and the influence of system dynamic characteristics, in order to improve the control efficiency and precision of the aircraft, in this paper, based on the footwork of four rotor aircraft attitude controller was designed by the sliding mode control, and through the simulation experiments verify the effectiveness and feasibility of the controller. The simulation results show that the control effect of sliding mode control algorithm issuperior to the cascade PID control, has some robustness.4. In order to simulate the actual flight environment, consider the many interference factors, is presented based on the adaptive gait of the sliding mode control, the simulation results show that the designed controller has good control effect, and anti-jamming capability is strong, have stronger robustness.