# Intelligent Trajectory Prediction Algorithm for Reentry Glide Target Based on Intention Inference
###### Abstract  
Aimed at the problem of the insufficient utilization of intention information and flight data for the trajectory prediction of a reentry glide target, an intelligent trajectory prediction algorithm based on intention inference was proposed. Firstly, a control parameter prediction network was developed to predict the variation of the control parameter values. Secondly, based on the Gaussian mixture model and Dubins circle, the importance of strategic places was modeled, the functional relationship between the strategic places and trajectories was established, and the influence factors of target threat were analyzed. Subsequently, an intention inference network was designed, which can accurately identify the key point the target intends to attack and realize the nonlinear calculation of the target's threat value. Finally, according to the common guidance law of reentry glide target, the lateral sign-variation rule was designed to carry out the target trajectory prediction based on intention inference. Simulation revealed that the parameter prediction network designed in this paper can realize the modification of filtering control parameters and effectively predict the value of these parameters. Moreover, taking the result of intention inference network, trajectory prediction in different prediction cases was accomplished. The maximal error of spatial distance (MESD) of the proposed method was less than 9 km when the prediction time was 100 s, and the best result was obtained in the long-term prediction. Compared with other mainstream prediction methods, the proposed method obtained the best prediction accuracy. reentry glide target; trajectory prediction; intention inference; importance of strategic places; temporal sequence prediction network Article Intelligent Trajectory Prediction Algorithm for Reentry Glide Target Based on Intention Inference  
[PERSON], M.  
The first type of method entails obtaining the prediction trajectory by selecting the suitable control parameters and iterative integration. Based on the aerodynamic model of the reentry glide target, [PERSON] et al. [5] proposed a group of control parameters with a simple variation law through simulation analysis, which has a good prediction effect for the HTV-2 target. [PERSON] et al. [6] introduced a new control parameter for the problem that the variation law of control parameters is not easy to predict in the literature [5]. The simulation showed that the variation law of this new control parameter was easier to estimate. [PERSON] et al. [7] simplified the aerodynamic force on a reentry glide target and obtained the simplified dynamic model. On this basis, the dynamic equation was deduced, and the trajectory prediction method was proposed. The above methods can effectively analyze the model, estimate the variation of control parameters, and predict the trajectory; however, the correlation between the prediction method and the flight data are not strong, as the prediction accuracy is limited by fitting the variation law of the control parameter with a simple function. Experiments in this paper have shown that it can lead to hundreds of kilometers of errors in long-term predictions. The second type of method to predict trajectories involves identifying the maneuvering mode of the target. [PERSON] et al. [8] and [PERSON] et al. [9] analyzed the long-period motion of equilibrium glide, fitted skip glide into the oscillation curve by Liouville transformation and the multi-scale theory method, and provided the formula of skip times. [PERSON] et al. [10; 11] analyzed the second-order approximate solutions of skip glide and equilibrium glide of targets with the constant attack angle, but the solutions were fairly complex. [PERSON] et al. [12] regarded the quasi-equilibrium glide state of lift vehicles as a regular perturbation problem, decomposed the longitudinal trajectory of quasi-equilibrium glide into the combination of equilibrium glide and high-order terms, and analyzed the error between the real solution and the low-order solution.