  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.
