Research On Flight Control Of Fixed-wing UAV Based On Singular Perturbation Decompositio

With the development of automatic control theory,fixed wing UAV is more and more widely used.The control of speed and attitude is the basic problem of fixed wing UAV.Unmanned fixed wing aircraft is a type of typical body with nonholonomic linear constraints,which also has the characteristics of strong coupling and nonlinearity.In addition,it is greatly affected by external disturbances like wind speed.The control strategies of flight attitude and speed are also different for different forms of fixed wing aircraft.Therefore,compared with other kind of UAVs such as rotor,the design of controller for fixed wing UAV is more complex and difficult.The singular perturbation method is essentially a time scale decomposition method,which decomposes the coupled system in different time scales,reduces the complexity of controller design and the numerical ill conditioned problems caused by the rigidity of the system.In order to improve the response speed and reduce the risk of flight control failure caused by internal and external disturbances of the system,this paper focus on the study of flight attitude control of fixed wing UAV based on singular perturbation method.The follows are the main research contents of this paper:The mathematical model of fixed wing UAV is established according to the momentum theorem and the momentum moment theorem.Aiming at the problems of strong coupling and nonlinearity of the fixed wing UAV model,the established mathematical model of fixed wing UAV is decomposed into fast subsystem and slow subsystem according to the singular perturbation theory,so as to realize dynamic decoupling,and the control inputs are designed for fast subsystem and slow subsystem respectively.Aiming at the high requirements of flight control accuracy and safety of fixed wing UAV.This paper also designed a kind of PID controller and adaptive sliding mode controller based on nonlinear disturbance observer for the established fixed wing singular perturbation model.The Lyapunov function is used to analyze the stability of the control system designed in this paper to verify the theoretical feasibility of the algorithm.In order to obtain the simulation parameters under limited conditions,the fixed wing model is drawn by MATLAB software,and the aerodynamic coefficients are obtained by wind tunnel simulation experiments.By building the experimental platform and physical simulation platform of fixed wing UAV,the effectiveness of the algorithm is verified in the physical simulation and actual environment.The analysis of flight data shows that the control method designed by this paper is feasible in the physical control of fixed wing UAV.