On the attitude recovery of an underactuated spacecraft using two control moment gyroscopes

In recent years there has been a growing interest in development and utilization of small satellites (smallsats) for scientific missions using single or multiple spacecraft (SC). Due to their small size and low mass, it is not generally possible to equip smallsats with redundant actuators. In case of a failure in the SC´s attitude control actuators, one has to reconfigure the control laws in order to maintain the SC´s attitude by using only the remaining healthy actuators. In this work, an algorithm that is based on nonholonomic control theory and hybrid control systems is presented for recovery of an underactuated axis-symmetric SC (having only two control torque channels). Our goal is that the recovered SC, in addition to being stabilized, can slew to a desired attitude. Using Lyapunov analysis, the asymptotic stability of the system is guaranteed by employing the proposed control law. Simulations are performed to demonstrate the performance capabilities of the recovered system.