Research On Head Pursuit Interception Guidance Law Based On Sliding Mode Control

In the wake of countries competing to develop the high-efficiency offensive weapons,the high-precision systems have also developed.Compared with ordinary targets,hypersonic targets have higher speed(more than Mach 5),higher penetration ability and greater destructive power.There are many problems in the interception of hypersonic targets by traditional methods,such as the great difficulty in control and difficulty in reaching the required precision.In order to overcome these problems,the head pursuit interception method is used,which place the interceptor in the front of the target by maneuvering,the interceptor gradually approach the predicted flight trajectory of the target at a lower speed,and the flight direction is consistent with it.This interception mode converts the interceptor speed greater than the target speed into the interceptor speed less than the target speed,reduces the control difficulty,so then improves the precision and reduces the energy demand of the interceptor.The interception becomes more reasonable and efficient.The main tasks are described as following:According to the principle of head pursuit interception and classical mechanics theory,the kinematics and dynamics models of interceptor and target are established,and then the equations of relevant parameters are obtained.According to the guidance conditions of head pursuit interception,utilizing the merits of proportional navigation and the adaptive characteristics of variable structure control to jamming,a sliding mode variable structure guidance law is designed.This guidance law adopts the idea of controlling the interceptor to be proportional to the altitude angle of the target.The low-speed interceptor is controlled before the high-speed target from the beginning to end,it has good robustness.Meanwhile,aiming at the chattering problems in sliding mode control,the guidance law is optimized.The saturation function is used to replace the original switching function to restrain the chattering.In reality,the interceptor is generally affected by air resistance,which changes its velocity.To solve this problem,an appearance model of the interceptor is established.Based on this model,mesh processing and numerical calculation of some aerodynamic characteristics are carried out.The resistance values of the interceptor at different Mach numbers and heights are analyzed and obtained.The results of the analysis are added to the guidance law to simulate.Based on the MATLAB platform,the air-to-airinterception process is simulated under the conditions of uniform and variable speed of interceptor,which are in two cases of target non-maneuvering and maneuvering.The simulation results verify the feasibility and robustness of this guidance law,and it has the actual value of popularization.This work have practical significance for the design of head pursuit interception guidance law and the promotion of ground-to-air interception for hypersonic targets.