Attitude control experiment of a spinning spacecraft using only magnetic torquers

Abstract

Magnetic torquers are attitude control devices used in spacecraft systems, and extensive research has been conducted on the attitude control of such spacecraft systems equipped with magnetic torquers. In this paper, a control law for spin spacecraft systems is proposed. Unlike existing control laws that switch between the spin rate and spin axis orientation control, the proposed angular momentum control law (AMCL) simultaneously provides feedback control for the spin rate and spin axis orientation based on the angular momentum error from the target. The steady-state and asymptotic behaviors of the angular momentum error are analyzed. In the analysis, both the saturated and unsaturated magnetic moments are considered. A testbed with magnetic torquers and a geomagnetic field simulator are developed to experimentally evaluate the performance of the AMCL. The geomagnetic field simulator is constructed using three Helmholtz coils to generate a time-variant magnetic field similar to that in orbit. The AMCL is used to conduct two ground experiments on the spin rate and spin axis orientation control. The effectiveness of the AMCL and behavior of the testbed are experimentally evaluated by comparing and analyzing the experimental and numerical simulation results. Consequently, the AMCL is found to achieve the required states in the experiments, and the asymptotic and steady-state behaviors appear to be consistent with the estimations made by numerical simulations. In conclusion, the proposed AMCL can appropriately control the spin motion of a spacecraft.