Research On Attitude Control And Anti-interference Of Quadrotor UAV

The four-rotor UAV is a kind of unmanned aerial vehicle with small size,high flight maneuverability,strong endurance and high stability.It has a good development prospect.With the development of technology,hardware and software technology and control technology are becoming more and more mature,the four-rotor UAV has gradually developed towards multi-functionality,and has been widely used in civil,commercial and military fields.In this paper,the four-rotor UAV is taken as the research object,and its development status and research status are analyzed.Based on the previous conclusions,the attitude control algorithm is designed and verified by simulation experiments under the condition of external disturbance.The main contents of the research include:(1)Firstly,the system structure and flight principle of the quadrotor UAV are analyzed.The physical coordinate system and the ground coordinate system are established according to the principle.The Euler angle is selected as the description of the attitude angle,and the coordinate transformation matrix of carrier coordinate system to the ground coordinate system is derived.Finally,based on the aerodynamic characteristics and flight principle,the dynamic model of the four-rotor UAV is established.In view of the disturbance of air disturbance and measurement noise in the attitude control of quadrotor UAV,this paper adds the external interference part to the established dynamic attitude model of the four-rotor UAV,and uses this system to design the proportional integral observer to estimate the system state.At the same time,the stability of the estimated state error is proved.The stability of the estimation error of the system is verified by simulation experiments.The design of the method can estimate the state of the system through feedback of partial states,and can also estimate the interference of the unknown input of the system,thereby improving the steady-state tracking accuracy of the state observer,and the design and calculation of the whole system is simple and easy to implement in engineering.(2)For the sensitive characteristics of the dynamic model of the quadrotor UAV,which is unstable and susceptible to interference,it is only necessary to carry out the necessary simplified analysis of its complex theoretical model.Based on the dynamic attitude model of quad-rotor UAV with external disturbance,this paper introduces the sliding mode control algorithm to enhance the anti-interference ability of the system and solve the problem of system robustness.It is proved that the method is effective by derivation proof and simulation experiments.Then,the anti-step slidingmode attitude controller is designed according to the jitter problem existing in the traditional sliding mode,and the stability proof is proved.The simulation experiment proves that the anti-step sliding mode suppresses the jitter phenomenon to some extent.(3)In the design of the sliding mode controller,sometimes in order to suppress the disturbance of large amplitude,when setting the controller to adjust the speed parameter,too high and too low will cause large oscillation error and the anti-disturbance amplitude range of the four-rotor system is reduced.To solve this problem,this paper refers to the observer-based controller design method,and designs the sliding mode controller based on the proportional integral observer designed in Chapter 3.Combining the proportional-integral observer with the sliding mode attitude controller can not only estimate the state of the system and the unknown input interference of the system through the proportional-integral observer,but also enhance the robustness and anti-disturbance performance of the system through the sliding mode controller.Finally,the effectiveness is verified by proof of stability and simulation experiments.