LQG/LTR pitch attitude control of an earth-orbiting spacecraft

The control of pitch attitude and pitch momentum of an Earth-orbiting spacecraft is considered in this paper. The control approach uses loop shaping techniques based on the linear quadratic-Gaussian and the loop transfer recovery (LQG/LTR) methodology. Attitude is measured by an Earth horizon sensor and control torque is produced by magnetic torquer bars and a pitch momentum. The controller must achieve good tracking, environmental disturbance rejection, and robustness to modeling errors. Loop shaping filters are used so that the roll and yaw magnetic torquer bars control pitch attitude at low frequency, while the pitch wheel controls pitch attitude at high frequency. The controller design and the simulation results are presented and discussed