Missile Integrated Guidance Law Design Based On Sliding Mode Control Theory

In recent decades,sliding mode control has been studied by a large number of scholars as a nonlinear control method with high robustness.Sliding mode control theory has many advantages,such as simple controller design,short control time,strong anti-interference ability and easy physical realization,it makes the system more effective in dealing with uncertainties and external disturbances from the system.The sliding mode control is widely applied in the guidance law design because of the high stability,fast and precise strike ability and attack angle restriction of the terminal process.In order to further improve the performance of the missile,the missile guidance and control system must be considered integrally to achieve the integrated design of the missile's attitude control and guidance(Integrated Guidance and Control).Based on the background of missile attacking maneuvering target in terminal guidance and control,based on sliding mode control theory and considering the first order dynamic characteristics of missile autopilot,an approximate integrated guidance law is designed.A novel integrated guidance law is designed with dynamic surface control and nonlinear state observer.The main contents are as follows:First of all,the coordinate system commonly used in the missile guidance model and the transformation relations among the various coordinate systems is introduced in this paper.Introduces the basic control principle of sliding mode control,introduces several common sliding mode control terminal sliding mode control,detailed description of the reaching phase of sliding mode control and sliding stage in mathematics,the robustness of sliding mode control are analyzed,introduces the causes of the chattering phenomenon,the harm of the chattering phenomenon,as well as several methods of eliminating chattering.The idea of dynamic surface control and its advantages over backstepping control are introduced with several examples.Secondly,the missile is regarded as a particle,and the dynamic and kinematic equations of the centroid of the missile are given.Ignoring the coupling between the pitching plane and the yaw plane.The kinematics equation of missile guidance and control in the pitching plane,and the interception equation between two missiles in the two-dimensional plane are presented.Thirdly,combined with two dimensional missile's target interception equation and the first order dynamic delay characteristic of autopilot,a quasi integrated guidance model in two-dimensional plane is given.In this model,a fast terminal sliding mode guidance law is designed based on the fast terminal sliding surface and fast approaching law.Lyapunov stability principle is applied to prove the guidance law in any state to meet the rapid global convergence in finite time.The simulation analysis shows that the guidance law can effectively compensate for the delay of autopilot,meet the restriction of attack angle,and have shorter guidance time.Finally,based on the kinematic equation of missile's pitching plane and the missile intercept equation in two-dimensional plane,the integrated guidance model of pitch plane is constructed.In view of the model,an integrated guidance law,which considers attack angle constraints,is designed based on dynamic surface control and nonsingular fast terminal sliding surface.In addition,considering the disturbance caused by the switching function and the unknown acceleration of the nonsingular fast sliding mode controller,the chattering of the system will be increased,and the uncertainty of the system will be increased.A new nonlinear extended state observer is designed,and the estimated value of the observer is used to counteract the uncertainty in the integrated control,and an observer based low chatting integrated guidance law is formed.Finally,the two integrated guidance laws are simulated and compared by a simulation scene of tracking the sinusoidal acceleration target.