Design Of UAV Controller Based On Fractional Sliding Mode Control

Quadrotor UAV can take off and land vertically,autonomous hovering,with small size,light weight,flexible control and other advantages,has been widely used in agriculture,industry,national defense and other fields.However,the quadrotor UAV system itself is very complex and sensitive to disturbance,so it is very difficult to control the UAV.In this paper,the fractional calculus operator is introduced into the traditional sliding mode control theory because it has a certain memory of the historical information of the function,and the fractional sliding mode control theory formed is studied.Taking the modern quadrotor UAV trajectory tracking control problem as the background,considering the model underdrive,nonlinear and external disturbance in the quadrotor UAV trajectory tracking control to design has high control accuracy,strong robustness and good anti-jamming of fractional order sliding mode control law.The main work of this paper is as follows:Firstly,the flight principle of the quadrotor UAV and the conversion relationship of the double coordinate system are analyzed in detail,and then the dynamics model of quadrotor UAV under the small Angle flight is established according to Newton-Euler method.And through the analysis of its dynamic model characteristics to determine the quadrotor UAV flight control system control target and control principle block diagram,which makes preparation for the subsequent control system design of UAV.Secondly,comprehensive fractional method has good robustness and control flexibility and advantages of the integral sliding mode surface,the fractional calculus operator is introduced in the approach law design part of sliding mode control,and the improved fractional exponential approach law is constructed,and then a new fractional integral sliding mode controller is designed by combining it with the traditional integral sliding mode surface.It is applied to the flight control system of quadrotor uav.In order to achieve better control effect,particle swarm optimization algorithm was used to optimize the controller parameters,and the method was compared with PID and integer order sliding mode controller through several groups of different experiments to verify the feasibility and superiority of the method.Finally,considering the disturbance of unmanned aerial vehicle(uav)in the natural environment,design the fractional order sliding mode controller based on ADRC.The main idea is to use the state observer in the active disturbance rejection control algorithm to estimate the disturbance of the system,including internal disturbance and external disturbance,and then compensate the estimated disturbance to the control system,so as to improve the disturbance rejection ability of the control system.Finally,the stability,robustness and immunity of the proposed method are verified by several different experiments.