Spacecraft Spin Stabilization Using a Transverse Wheel for Any Inertia Ratio

Abstract

Hughes Space and Communications Company recently launched the e rst of a series of satellites featuring a patented control strategy capable of stabilizing spin about a given spacecraft axis, regardless of spin-to-transverse inertia ratio. The control system, which functions during the ascent phase of the mission, makes use of on-station control hardware, a gyro and a transverse reaction wheel, to stabilize spin. This is believed to be the e rst instance of stabilization of spin with arbitrary inertia ratio using a single transverse wheel. For stability reasons, these satellites are the e rst Hughes satellites to spin negatively in transfer orbit. It is paradoxical that, for some inertia ratios, negative spin can be stabilized when positive spin cannot. Note that, in such cases, even the negative spin, though stable, may be technically uncontrollable at one point in the mission. The history of active spin control is discussed, and some global principles for spin stabilization using a single wheel are established. Theory, design, and e ight experience of the Hughes active spin controller are presented and contrasted to prior solutions. Finally, ground simulations and e ight telemetry are presented and compared.