Attitude stabilization and power compensation control for spacecraft with VSCMGs

Based on dynamics model of variable speed control moment gyroscopes (VSCMGs), the mixed control equation plus subsystems- decoupling constraint equation were established. The attitude and energy mixed control steering law was developed synchronously via matrix projection method. Influence of flywheel rotor's moment of inertia error on attitude control subsystem was analyzed by using Lyapunov method. A power control compensator was proposed according to the error relationship between rotor's axial moment of inertia and power output. Torque and power solutions in the mixed steering law possess same forms, while the constraint equation makes the attitude and energy control subsystems decoupled. Performance analysis of closed-loop system considering actuator's characteristic becomes more convenient. Attitude control subsystem with the rotor's inertia error can maintain its stability due to the system's output dissipative property, while output error of energy control subsystem is proportional to the rotor's inertia error. The power output after being compensated can satisfy the control requirement.