Building a Better B-Dot: Fast Detumbling with Non-Monotonic Lyapunov Functions

TL;DR

This paper introduces a novel magnetic detumbling controller for spacecraft that uses non-monotonic Lyapunov functions to predict future magnetic fields, avoiding uncontrollable states and significantly reducing detumbling time.

Contribution

The paper presents a new control method based on non-monotonic Lyapunov functions that improves detumbling speed and efficiency over existing methods by predicting future magnetic field states.

Findings

Detumbles spacecraft faster than existing controllers.

Achieves lower overall angular momentum during detumbling.

Proven convergence through theoretical analysis and simulations.

Abstract

Spacecraft detumbling with magnetic torque coils is an inherently underactuated control problem. Contemporary and classical magnetorquer detumbling methods do not adequately consider this underactuation, and suffer from poor performance as a result. These controllers can get stuck on an uncontrollable manifold, resulting in long detumbling times and high power consumption. This work presents a novel detumble controller based on a non-monotonic Lyapunov function that predicts the future magnetic field along the satellite's orbit and avoids uncontrollable configurations. In comparison to other controllers in the literature, our controller detumbles a satellite in significantly less time while also converging to lower overall angular momentum. We provide a derivation and proof of convergence for our controller as well as Monte-Carlo simulation results demonstrating its performance in representative use cases.