# Robust Tracking Guidance for Zero Propellant Maneuver

## TL;DR

This paper presents a robust, adaptive guidance strategy for the Zero Propellant Maneuver that adjusts the reference trajectory online to improve performance and mitigate disturbances, verified through simulation.

## Contribution

It introduces an innovative online trajectory adjustment method based on Lyapunov control and physical coupling, enhancing ZPM robustness against uncertainties.

## Key findings

- Robustness against initial errors and uncertainties demonstrated
- Trajectory adjustment effectively reduces disturbance effects
- Simulation results confirm improved maneuver accuracy

## Abstract

The Zero Propellant Maneuver (ZPM) maneuvers the space station by large angle, utilizing the Control Momentum Gyroscopes (CMGs) only. A robust tracking guidance strategy is proposed to enhance its performance. It is distinguished from the traditional trajectory tracking guidance in that the reference trajectory is adjusted on-line, under the inspiration of eliminating the discrepancy on the total angular momentum of the space station system. The Lyapunov controller is developed to adjust the attitude trajectory and further redesigned for a better performance based on an interesting physical phenomenon, which is taken advantage of by coupling the components of state vector. The adjusted trajectory is then tracked to reach the target states of maneuver. Simulations results show that the disturbance effects arising from initial state errors, parameter uncertainty and modeling errors are attenuated or even eliminated, which verifies the robustness of the guidance strategy.

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Source: https://tomesphere.com/paper/1706.03448