# Correction Strategy of Online Midcourse Guidance for High-Speed Gliding Target Interceptor
## 4 Simulation Verification
### Simulation Scenario 1: Online Correction Algorithm for Single PIP
Due to the update of PIPs, the change process of the velocity gain in Figure 12 converges globally and fluctuates locally. The main reason is that the update of the PIPs leads to the change in the velocity gain, but it can eventually converge to a small value. Although the final accuracy is degraded, it can still meet the requirements of midcourse guidance, which shows that the online correction algorithm can satisfy the interceptor correction when the PIPs are updated multiple times. Simulation Scenario 3: Verify the Effectiveness of Online Correction of Interceptor When Setting the Switch Threshold in Stages  
Set a fixed threshold \(\epsilon=50\) m/s, to achieve the interceptor as far as possible not to start before stage the switching point, set the first phased threshold \(\epsilon_{1}=0\) m/s, and set the second phased \(\epsilon_{2}=70\) m/s \(>50\) m/s. In the simulation, the update period of the PIP is 5 s. With the interceptor flying, the PIP finally converges to the real PIP \([641572,50000,50000]\). To verify the correction effect under the phase-setting threshold method and fixed threshold method when the 3-fold variance of the PIP distribution at  
Figure 11: Trajectory at different inclination angles for multiple PIP updates. Figure 12: Trend of speed gain at different inclination angles for multiple PIP updates. switching threshold method can effectively save fuel when the threshold of the first stage is \(\varepsilon_{1}=0\) m/s and the threshold of the second stage is \(\varepsilon_{2}=70\) m/s. Compared with the methods of regenerating optimal trajectories based on the target's maneuver in documents [6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17], the method in this paper does not need to regenerate the optimal trajectory based on the updated PIP of the target, which avoids the huge computational cost brought by re-optimization. In addition, compared with the methods in documents [18; 19; 20; 21; 22; 23; 24; 25; 26; 27], the correction algorithm in this paper is not limited to the original trajectory. If the trajectory needs to be changed, the engine start direction can be determined by the required speed, which is more suitable for the application scenario where PIP updates occur in a wide space and for intercepting high-speed gliding targets. Although the correction method proposed in this paper can achieve rapid interceptor correction based on the randomly updated PIP during flight, thus achieving the purpose of fuel saving, this fuel-saving method is not the optimal solution, and the problem of fuel optimization requires further research. The next research direction for the authors will be how to develop an optimal fuel-saving correction method based on the constantly updated target PIP. Conceptualization, W.L., L.S. and T.Z. ; methodology and other work, W.C. All authors have read and agreed to the published version of the manuscript. This work was supported by the National Natural Science Foundation of China (Grant no. 62173339). All data generated or analyzed during this study are included in this published article. The authors declare no conflict of interest.