# Research on Head Pursuit Interception Strategy for Hypersonic Target
## 4 Simulation and Analysis  
The guidance strategy designed in this paper is verified and analyzed using digital simulation. Two forms of target maneuvering and non-maneuvering flight are adopted. For the non-linear missile model, the simulation is carried out according to the designed control scheme. The simulation conditions are as follows. a. The hypersonic target flies at an altitude of 30 km at flight speed. The allowable overload is 15 g.  
b. Initial conditions of the initial guidance phase: The interceptor is launched from the ground launcher at the initial speed \(V_{M0}\) = 100 m/s. The initial launch flight-path inclination is 45 degrees and the azimuth angle is \(-\)45 degrees. The engine starts for 10 s and then shuts down. The interceptor is guided near the preset turning point by the initial guidance law. c. Initial conditions of the midcourse guidance phase: The initial flight-path inclination and azimuth angle of the midcourse guidance phase are the same as the terminal trajectory inclination and deflection angle of the initial guidance phase. The interceptor is guided near the predicted impact point by the midcourse guidance law. d. Initial conditions of the terminal guidance phase: The initial flight-path inclination and azimuth angle of the terminal guidance phase are the same as the terminal trajectory inclination and deflection angle of the midcourse guidance phase. The interceptor is guided by the terminal guidance law to the interception point, and the intercept accuracy should be less than 10 m.  
The simulation results are shown in Figures 7-15. Figures 7 and 8 show the interceptor and target interceptor interception trajectory. When the target is non-maneuvering, the interception trajectory is ideal, and the interceptor intercepts the target successfully at 171.45 s. When the target is maneuvering, the interceptor is maneuvering with the target maneuvering. The interceptor gradually coincides with the target track in the end guidance. Finally, the target is successfully intercepted at 171.46 s. The terminal velocity of the interceptor in the initial guidance phase is 2.2 Ma, the flight-path inclination angle is 56.4 degrees, and the azimuth angle is 2.8 degrees, which is also the initial condition of the interceptor in the midcourse guidance phase. The terminal velocity of the interceptor in the midcourse guidance phase is 2.0 Ma, the flight-path inclination angle is 0.1 degrees, and the azimuth angle is \(-\)179.3 degrees, which is also the initial condition of the interceptor in the terminal guidance phase. Under the condition of target maneuvering, the terminal velocity of the interceptor in the initial guidance phase is 2.2 Ma, the trajectory tilt is 56.4 degrees, and the trajectory deflection angle is 2.8 degrees, which is also the initial condition of the interceptor in the midcourse guidance phase. The terminal velocity of the interceptor in the midcourse guidance phase is 2.0 Ma, the flight-path inclination angle is 0.1 degrees, and the azimuth angle is \(-\)179.4 degrees, which is also the initial condition of the interceptor in the terminal guidance phase. Figures 9 and 10 show the overload of the interceptor. The maximum overload is 15 g, which is not more than the allowable overload. Figure 8: Interception trajectory (target maneuvering). Figure 10: Overload of interceptor (target maneuvering). Figure 7: Interception trajectory (target non-maneuvering). Figure 9: Overload of interceptor (target non-maneuvering). when the target is maneuvering. To some extent, this solves the problem of high control difficulty and low guidance precision in the proportional navigation method. Using this guidance strategy, the interceptor has great robustness to acceleration interference, and the correctness of the guidance strategy is verified. The object is a hypersonic interceptor, which proves that the guidance strategy is suitable for the interception of hypersonic targets.