Large angle maneuver and high accuracy attitude pointing steering law for variable speed control momentum gyroscopes

Abstract

In the variable speed control momentum gyroscopes (VSCMG), the output torque of the VSCMG can be supported by the gyroscopic torque by a large margin with low resolution. The output torque of the VSCMG can be only supported by the reaction torque of the flywheels with high resolution when the gimbals are locking. Consequently, the torque error that is determined by the low spin rate fluctuation or servo tracking error of the gimbals can be vanished, and the VSCMG can be suitable for large maneuver and high accuracy attitude pointing as the actuator. Unfortunately, the singularity of the flywheel torque co-plane may be encountered. In this paper, the singularity of the flywheel torque co-plane is visualized based on geometry method. The singularity can be effectively avoided by locking gimbals. The locking gimbals positions are optimized with the maximum angular momentum. The steering laws with two phases are proposed to operate the task of the large angle maneuver and high accuracy control for a spacecraft. In the phase 1, a large margin torque can be achieved by the new designed steering law, and the gimbals can be steered to the optimization gimbals positions at the final stage of the phase 1. In the phase 2, the high precision torque can be achieved by only steering the flywheels and the locking the gimbals. Consequently, the torque error that is caused by the spin rate fluctuation or servo tracking error of the gimbals can be effectively eliminated.