Study on Autonomous Gravity-assists with a Path-following Control

TL;DR

This paper presents a robust path-following control law based on sliding mode control theory for autonomous gravity-assist maneuvers, demonstrating effectiveness in simulations of flybys around moons and planets with significant insertion errors.

Contribution

It introduces a novel control strategy for autonomous gravity-assist trajectories that is robust to disturbances and applicable to complex N-body environments.

Findings

Successfully stabilizes orbital geometry during flybys.

Enables close approach within 10 km of Enceladus surface.

Effective in complex Jovian tour scenarios.

Abstract

We investigate the autonomous control of gravity-assist hyperbolic trajectories using a path following control law based on sliding mode control theory. This control strategy ensures robustness to bounded disturbances. Monte Carlo simulations in the environments of Titan and Enceladus, considering significant insertion errors on the order of 50 km, demonstrate the effectiveness of the proposed approach. The Enceladus example showcases the applicability of the control strategy for close flybys of asteroids and small moons during scientific observations. It successfully stabilizes the orbital geometry within a short time span, avoiding collisions and enabling a close approach to Enceladus' surface with a separation distance of 10 km. Furthermore, we explore its application in a Jovian tour, considering a more complex N-body problem. Results indicate that the control system, while unable to guarantee a complete tour, plays a crucial role in ensuring precise trajectory control during flybys. In such cases, the vehicle guidance system requires higher precision than what can be achieved with a patched conics model. These findings demonstrate the effectiveness of the proposed control strategy for gravity-assist maneuvers and highlight its potential for various space exploration missions involving close encounters with celestial bodies.