Simultaneous attitude stabilization and power tracking for a spacecraft with two VSCMGs

An integrated power and attitude control system with two variable speed control moment gyroscopes positioned with their spin axes nominally co-aligned on the longitudinal roll axis of spacecraft is discussed. The system facilitates the management of electrical power and the generation of attitude control torque by accelerating or decelerating the flywheels to change the amounts of their angular momentum. Furthermore, the attitude control torque is also generated by providing the gimbal angular velocity with respect to the spacecraft body. The present research provides detailed description of the flywheel configuration and develops the complete equations of motion. A discontinuous time-invariant feedback control law is developed for attitude stabilization of the underactuated system under the restriction of zero total angular momentum. Simultaneous power tracking is completed by using a null space solution. This proposed conception is supposed to provide useful operation over very long-duration flights in light weight and low cost because of eliminating the traditional propulsive system and utilizing less flywheels than previous researches.