# Research on Head Pursuit Interception Strategy for Hypersonic Target
###### Abstract  
In the wake of countries competing to develop high-efficiency offensive weapons, high-precision systems have also developed. Due to the high speed and high maneuverability of hypersonic targets, it is always difficult to meet the accuracy and rapidity requirements by using the traditional interception mode. In order to improve the accuracy of the hypersonic target interception, a head pursuit guidance strategy is developed for hypersonic target interception in this study. Firstly, a dynamic model is established by analyzing the relative motion between the interceptor and the target, which needs to place the low-speed interceptor before the high-speed target. Subsequently, a head pursuit interception guidance strategy is presented, which controls the interceptor flight trajectory by controlling its normal acceleration to achieve a successful interception target. Finally, for the maneuvering and non-maneuvering targets, the dynamic characteristics of interceptor are analyzed, respectively, and full trajectory dynamic simulations under different conditions for the hypersonic target interception are worked out to illustrate the feasibility and robustness of the proposed guidance strategy. hypersonic target; maneuvering; head pursuit; full trajectory; guidance strategy +
Footnote †: journal:  
In order to overcome these difficulties, [PERSON] put forward a head pursuit interception idea, that is, the interceptor is placed on the predicted flight trajectory in front of the target by maneuvering, and the flight direction is consistent with it [1; 2]. Because the interceptor has a lower flight speed, the target approaches the interceptor, thus achieving the interception. This interception mode converts an interceptor speed greater than the target speed into an interceptor speed less than the target speed and reduces the energy demand of the interceptor and thus reduces the control difficulty and interception cost. To research the quality of the air-to-air interceptor guidance strategy, it is necessary to research the head pursuit interception mode guidance strategy. For the proportional navigation (PN) guidance law and its derived modified guidance law and three-dimensional guidance law, their basic ideas are to apply the control force in the direction of reducing the line-of-sight angular rate. The proportional navigation guidance methods have some theoretical defects when dealing with such objects. They cannot guarantee the stability of line-of-sight in the terminal guidance phase, which is equivalent to simple proportional feedback. Therefore, the line-of-sight angle at the end may diverge, and the miss distance will be too large. [PERSON] established a three-dimensional model of face-to-face interception in which the interceptor and the target move in opposite directions, which is quite different from head pursuit interception [3]. [PERSON] designed a three-dimensional guidance law based on proportional navigation, but its guidance law is based on ballistic linearization, and the limitation of proportional navigation is great [4]. [PERSON] designed the guidance law based on the quasiparallel approach principle [5; 6]. His guidance law only needed to keep the line-of-sight angle as a constant and did not require the interceptor to be in the same direction as the target velocity. Therefore, the guidance law was not only applicable to head pursuit interception. However, the guidance law needed a large overload to intercept maneuvering targets, and the angular velocity of the line of sight at the end of the guidance easily diverged. [PERSON] used the auxiliary circle design guidance law algorithm to make the interceptor intercept along the auxiliary circle [7], and [PERSON] applied the neural network PID control to the hypersonic vehicle [8]. These two methods were simple and effective but did not have good adaptability to target maneuvering.