Time-coordination entry guidance using a range-determined strategy

A time-coordination entry guidance method based on a range-determined strategy is developed for hypersonic glide vehicles. This method is composed of two components: a time-constrained entry guidance algorithm and a coordinated flight time generation approach. Different from the previous work, the proposed strategy provides a novel scheme to solve the coordinated entry guidance problem, significantly reducing the computational load and the coupling between flight time control and the motion form. Firstly, the longitudinal guidance algorithm generates the flight profile based on the flight time constraint while considering adaptability to external disturbance. The magnitude of the bank angle and the range-to-go command can be derived from the profile. The command is used to plan the lateral trajectory represented by the Bézier curve in lateral guidance. Then, the heading error corridor can be established according to the line-of-sight between the vehicle and the reference point on the lateral trajectory, which controls the bank angle reversal time. The profile and the lateral trajectory are updated to guide the vehicle to the terminal point while meeting terminal and path constraints. This paper discusses how to estimate the adjustable range of a single vehicle's flight time and illustrates an approach for multi-vehicle coordinated flight time generation. Numerical simulations are conducted in nominal and dispersed conditions, and the results demonstrate the method's efficiency and robustness.