Terminal Soft Landing Guidance Law Using Analytic Gravity Turn Trajectory

TL;DR

This paper introduces a novel terminal landing guidance law based on an analytic gravity turn trajectory, improving landing precision, robustness, and fuel efficiency through a nonlinear control approach and ground collision avoidance.

Contribution

It develops an analytic solution for gravity turn trajectories to enhance terminal landing guidance, including collision avoidance and robustness analysis.

Findings

Demonstrates improved fuel efficiency over existing methods

Shows robustness against disturbances in numerical simulations

Incorporates ground collision avoidance into guidance law

Abstract

This paper presents an innovative terminal landing guidance law that utilizes an analytic solution derived from the gravity turn trajectory. The characteristics of the derived solution are thoroughly investigated, and the solution is employed to generate a reference velocity vector that satisfies terminal landing conditions. A nonlinear control law is applied to effectively track the reference velocity vector within a finite time, and its robustness against disturbances is studied. Furthermore, the guidance law is expanded to incorporate ground collision avoidance by considering the shape of the gravity turn trajectory. The proposed method's fuel efficiency, robustness, and practicality are demonstrated through comprehensive numerical simulations, and its performance is compared with existing methods.