###### Abstract  
This paper presents an effective method for the fast prediction of the target reachable zone of a boosting gliding vehicle in the gliding phase. Firstly, a six-point method is proposed for the rapid determination of the reachable zone and the feasible discrimination of the target. The method chooses six boundary points with notable features to characterize the reachable zone and considerably reduces the computational consumption. Furthermore, taking into account the need for a rapid launch and safety against unexpected events during the gliding phase, a database method for the prediction of the reachable zone is presented, which builds the database with time nodes and six boundary points and employs interpolation methods to calculate the reachable zone. The results suggest that online planning by the database method has significant potential for predicting the target reachable zone. The accuracy error is less than 1%, and the computational efficiency is increased by 90% when compared to the six-point approach. boosting gliding vehicle; target reachable zone; D-V profile method; fast prediction method +
Footnote †: journal: Medical  
model according to the current state. However, due to the complex coupling relationship, only first- or second-order approximate solutions can be obtained by reasonable simplification. [PERSON] et al. [3] developed high-precision analytical solutions for 3-dimensional (3-D) hypersonic gliding trajectory over the rotating and spherical Earth using the regular perturbation method. Aiming at the special gliding problem where the gliding speed is close to the first cosmic speed, [PERSON] et al. [4] planned a drag acceleration profile and derived the analytical solution of a three-dimensional special gliding trajectory by properly simplifying the nonlinear equations of motion. The numerical method firstly creates the control input and then predicts the trajectory by using the integral method. The designed control input can be a bank angle or a generalized flight profile characterizing the vehicle's motion, such as a drag acceleration-velocity (D-V) profile [11] or a drag acceleration-lateral lift-to-drag ratio-energy (\(D-(L/D)\sin{\
u}-E\)) profile [12]. More enticingly, the numerical method can be employed for the trajectory planning of complicated flight missions that take multiple waypoints and no-fly zone constraints into consideration because of its algorithmic robustness and adaptability to path constraints and terminal constraints. [PERSON] et al. [13] proposed a new entry trajectory generation method for hypersonic glide vehicles based on a three-dimensional acceleration profile which meets range requirements while considering waypoint and no-fly zone constraints. The reachable zone [16; 17] is an important indicator for evaluating the coverage range and flight capability of a boosting gliding vehicle. The results of the reachable zone calculation and the perception of the current vehicle status can also be used by the vehicle to decide whether to switch to a new target location or a new tracking profile, as well as whether to implement a new safe disposal plan autonomously or with the help of ground commanders. This can increase the autonomy and safety of the vehicle. The methods for the calculation of the reachable zone have been extensively studied by many scholars at present, mainly the constant bank angle method [18; 19], the optimization method [20; 21; 22; 23], and the profile design method [24; 25]. The constant bank angle method, which is frequently employed in engineering, is simple, reliable, and rapid, although it contains certain errors when compared to the actual reachable zone. The optimization approach is the most precise solution method now accessible, but the pace of the solution is very slow, necessitating additional study to fulfil the requirements of online planning. [PERSON] et al. [20] proposed an algorithm for the approximation of nonconvex reachable sets by using optimal control.