Glide guidance for reusable launch vehicles using analytical dynamics

Abstract

This paper proposes a novel glide guidance law for the reusable launch vehicle (RLV), in which longitudinal and lateral paths are separately designed to quickly derive guidance commands. First, an altitude profile is designed in the longitudinal plane. Using this profile, the terminal altitude, flight path angle, and position are naturally met and the quasi-equilibrium glide condition (QEGC) is easily satisfied. Second, analytical solutions of altitude, velocity, and flight path angle are deduced in the glide phase; so the values of path constraints and performance index can also be analytical calculated. Third, a new concept of virtual target is proposed to design the lateral motion. By analytically determining the virtual target with the solutions in the glide phase, the cross-range is online adjusted to control the dissipation in velocity. Finally, the guidance law is proposed based on these analytical solutions. In the guidance law, longitudinal and lateral motions are controlled by online updating the profile and revising the virtual target, respectively. Integration-based predictors are unnecessary in comparison with conventional guidance laws, so a short guidance period can be used to improve the robustness. The effectiveness and the robustness of the proposed method are demonstrated with various scenarios and Monte Carlo simulation, respectively.