Terminal Guidance Law Design Of Homing Missiles

With the quick development of weapon technology,warfare has entered the era that is marked by high-tech confrontation.Missiles are one of the most widely used precision-guided munitions among others.The requirements for navigation guidance law used in missiles have been growing tougher and tougher with the development of military industries and warfares.Traditional classical guidance laws have been failing to meet the more and more complicated interception requirements.For example,in the traditional design scheme,the guidance law doesn’t consider the dynamics of missile autopilot,however,when faced with high-speed and large maneuvering targets,the performance of such kind of guidance law will significantly decrease,even fail to intercept the target.For the targets with ultrasonic speed,traditional tail-pursuit guidance law requires that the missile should possess a even higher speed,which is unrealistic.The head-on interception guidance laws are also challenged since there exists only a rather small interception window due to the high relative speed.All those arising challenges and requirements demand novel navigation guidance laws with better performance.This paper mainly discusses the current development and the trend of terminal guidance law,and the achievements obtained are as follows:First,this paper proposes an H2 optimal proportional navigation guidance law.Based on the Line-of-sight rate design method,we deduce the upper limit of LOS rate for successful interception.Traditional design procedure designs the navigation law and the missile’s autopilot system separately,which will decrease the performance of the guidance law.In our design,we comprehensively analyze the homing loop’s diagram,in which the dynamics of missile autopilot is taken into consideration.Finally,based on H2 optimal control theory,an analytic optimal guidance law in a form of a time-variant transfer function is proposed,which is also easy to implement.Simulation under various conditions are carried out to validate the proposed design,which shows that it’s able to nullify the LOS rate quickly and has better interception performance than the traditional proportional navigation guidance law.Second,this paper presents a guidance law with terminal angle constraints based on sliding mode control.Relationship between terminal impact angle and terminal LOS angle is analysed,showing that it’s equivalent to design a terminal LOS angle constrained guidance law.A nonsingular terminal sliding mode control approach is applied to achieve a new guidance law.Lyapunov function is used to prove the stability of the proposed guidance law.Finally,simulation results show that the proposed guidance law can successfully intercept the target with the required angle in spite of the target maneuver.Third,the head pursuit guidance that emerges recently is studied.This paper focuses on the terminal term of head pursuit.Necessary and sufficient conditions about the guidance coefficient and terminal angle for successful interception are presented.Finally,we presents a adaptive-reaching law based sliding mode head pursuit guidance approach.Simulation has validated the effectiveness of the derived guidance scheme,and demonstrated that the maximal overload it requires during the engagement is smaller than traditional sliding mode head pursuit guidance.