Frequency weighted LQG control of spacecraft attitude

A frequency-weighted linear-quadratic-Gaussian (LQG) approach to control of pitch attitude and pitch wheel momentum of an Earth-orbiting spacecraft is presented. Attitude is measured by an Earth horizon sensor, and control torque is produced by magnetic torquer bars and a pitch momentum or reaction wheel. Environmental disturbances are estimated for disturbance rejection. The design features control weighting so that low-frequency control is effected by the torquer bars and high-frequency control is effected by the pitch wheel. Control weighting is also used to provide a steep roll-off of the open-loop gain to achieve a wide bandwidth while avoiding control-structural interaction. A frequency response analysis and simulation results are provided