Optimal Attitude Trajectory of Spacecraft with Pyramid-Type CMGs Using a Pseudo-Spectral Method

Abstract

A Control Moment Gyro (CMG) is an actuator suitable for agile spacecraft because it has large torque capability. However, CMG systems can fall into singular states where commanded torque can not be exactly generated and the spacecraft attitude control law becomes complicated. A control method which uses gimbal angle trajectories is effective for the singularity avoidance and the time optimization of the attitude change. In this study, focusing on the spacecraft equipped with four Single-Gimbal CMGs in a pyramid configuration, the procedure of time optimization using the Chebyshev-Pseudospectral method and a nonlinear optimization program is described. In addition, the tracking control method is investigated and the steering logic is demonstrated by conducting hardware experiments as well as numerical simulations.