재사용 발사체의 연착륙을 위한 궤적 최적화 기반 유도 기법 연구

Abstract

This paper aims to propose a landing guidance algorithm for reusable launchers that require soft landing via retro-propulsion of the engine. The proposed method is based on the trajectory optimization technique that is capable of generating the fuel-optimal trajectory for reusable launch vehicles. To realize the practical and optimal landing guidance, the acceleration command of the proposed guidance is given as the combination of the feedforward and feedback term from the optimal trajectory attained at the initial phase of the landing burn. As the baseline command, the optimal thrust command obtained from the optimal trajectory is directly feedforwarded. Then, to mitigate the trajectory tracking error, the feedback term is computed utilizing the linear position tracking controller obtained by LQR. The proposed guidance is verified by landing simulation for the assumed test launch vehicle.