Stable Equilibria of Satellites Containing a Momentum Wheel in a Controlled Gimbal

摘要

The report presents all stable equilibrium states of rotation of a rigid body satellite containing a single gimbaled momentum wheel in a zero gravity field. For an arbitrary but fixed speed of the wheel relative to the satellite body it is shown that there may be one, two or three stable rotational equilibrium states of the satellite depending on the value of the total angular momentum. In each of these states the satellite body spins at a constant rate about an axis which is fixed in satellite coordinates. The relative orientation of this axis in both satellite and inertial coordinates can be determined from expressions in this paper. Expressions are also derived for the satellite angular velocities and angular position of the gimbal at each equilibrium state. The gimbal is actively controlled so that nutation damping occurs for all conditions of satellite unsteady rotation. In addition to extensive analog computer simulation studies, a prototype gimbal and momentum wheel system was designed and then tested on a spherical air bearing platform. (Author)