DYNAMIC MOMENTUM BIAS FOR YAW STEERING

摘要

A combination pointing requirement for a low earth orbit communication satellite antenna system and sun orientation for power accumulation can be met with a momentum biased attitude control that maintain nadir pointing and sustains yaw steering simultaneously. During time intervals when direct yaw sensing is not available, momentum bias systems have successfully been used to provide stabilization for nadir pointing satellites. Such systems, however, restrain vehicle yaw rotations to small perturbations about zero without direct yaw sensing. Those systems use a momentum wheel with fixed alignment along the spacecraft pitch axis, horizon sensors to detect pitch and roll attitude errors and mass expulsion devices for actuation. Such systems preclude yaw steering. This paper develops a control algorithm that maintains the advantage of gyroscopic momentum bias stabilization in addition to a controlled open loop yaw steering.