Research On Finite-time Convergence Exact Terminal Guidance Law For Interceptor Missile

The high-speed and maneuvering target is the main adversary for the future air defense and anti-missile system.How to accurately intercept this kind of the target is one of the main problems in the terminal guidance law design.The target’s maneuver is a typical uncertain disturbance in the relative dynamic model of the interceptor and target.The traditional proportional navigation lacks the ability to suppress the target maneuver.The optimal guidance law and the differential game guidance law need much more informations in application,and rely on the estimation of the remaining flight time.The traditional sliding mode guidance law can effectively deal with the target maneuver,but is susceptible to the chattering problem.In recent years,the developments of high-order sliding mode control and disturbance observer-based control have made great progress,especially for the study of super-twisting algorithms and fixed-time convergence observers.Hence,the advanced control methods will provide new approaches to design guidance law for intercepting high-speed and maneuvering targets.Therefore,this paper combines the latest developments of high-order sliding mode control and observer-based control to carry out the design of finite time convergence precision terminal guidance law.Firstly,the relative kinematics model of interceptor and target is established.The modeling method of guidance information for simulation is given.The interceptor accurately kill the target within finite-time can be defined as the robust stablization problem of the line-of-sight(LOS)angular rate(or the LOS normal velocity)within finite time.The symbol definitions,system stability theory and judgment lemmas,and related concepts of weighted homogeneity are introduced.The mathematical model and theoretical knowledge are the foundation for the subsequent research of the thesis.Secondly,for the finite time convergence robust control problem of LOS angular rate(or LOS normal velocity),the generic super-twisting algorithm is applied to design the three-dimensional guidance law.Since the discontinuous control appears in the integral term of the guidance command,It can effectively attenuates the influence of the chattering phenomenon and ensures the guidance precision.Since the bound of the target maneuvering acceleration is easily to be overestimated,adaptive super-twisting algorithm with the gain adaption law is proposed.And the adaptive super-twisting three-dimensional guidance law is designed.The theoretical research and simulation analysis show that the proposed guidance law can guarantee the LOS normal velocity converge to the neighborhood of the origin within finite time.The guidance law is independ on the estimation of the target maneuver boundary.And,the chattering phenomenon can be further weakened.Thirdly,in order to realize the fast estimation of the target acceleration,the research on fixed time convergence observer and disturbance observer is carried out.Based on the time scale paradigm and the bi-limit weighted homogeneousity theory,the fixed-time convergence observers of double powers and high power are designed respectively.Through theoretical derivation and simulation analysis,it can be seen that the obtained observer parameters are simple to set,and the observation error can converge to the neighborhood of the origin within fixed time.The practical experiences for ultilization of the presented observers is summarized.The design of the switching observer is proposed by using the proposed observers and the robust exact observers.The noise suppression capability of the switching observer can be improved.Based on the idea of extended state,the fixed-time convergence extended state observer based on the proposed state observer is given,and a simple theoretical derivation is carried out.Finally,the fixed-time convergence disturbance observer and the fixed-time convergence extended state observer proposed in this paper is used to design the finite-time convergence guidance law.A generalized three-dimensional guidance law model is proposed.The fixed-time convergence robust precise disturbance observer,the fixed-time convergence extended state observer and the switched fixed-time convergence disturbance observer are used to design the finite-time convergence three-dimensional guidance law.The feasibility of the algorithm is verified,and the influence of the convergence accuracy of various observers on the guidance precision is analyzed.