Attitude Control of Large Angle Maneuver for Microsatellite Using Variable Speed Control Moment Gyros

The multi-projects rapid attitude maneuver problem for agile microsatellites with VSCMG （Variable Speed Control Moment Gyros） as actuators was investigated. VSCMG is a recently introduced actuator for spacecraft attitude control, and it is a hybrid one between two types of internal torque generators; namely, a conventional control moment gyro and a reaction wheel. These actuators can provide unique torque, angular momentum and slew rate capabilities to microsatellites without any increase in power, mass or volume. This will help microsatellites become more agile. The attitude dynamic equation of a spacecraft with VSCMG attached was presented, the attitude was described by MRP （Modified Rodrigues Parameters）. A nonlinear feedback controller based on Lyapunov stability condition was developed under various physical constraints, including the actuator saturation, slew rate limit, control bandwidth limit, etc. A numerical simulation was presented on the sample of the attitude maneuver of a microsatellite with VSCMG. Simulation results demonstrate the effectiveness and robust performance of the proposed nonlinear feedback control system.