An entry guidance algorithm based on trajectories database

This paper presents an entry guidance algorithm for lunar capsule based on trajectories database for improving the robustness of the reference trajectory entry guidance. A trajectories database under the dispersion is established to evaluate the influence of the various errors exerted on entry dynamics. The reference entry trajectory is generated based on trajectories database according to the dispersion at the entry interface obtained through navigation system. The reference trajectory has taken the dispersion into account so that the reference entry guidance performs better. A linear feedback tracking law is presented to track the reference trajectory and meet the terminal criteria. Additional Monte-Carlo simulations results have been provided to demonstrate the validation and robustness of the entry guidance algorithm.