Realization of Spin Motion of Spacecraft by Two Wheels

Abstract

We investigate a method of attitude control with two wheels when a spacecraft has initial angular momentum. If we assume the wheels as attitude control actuators, the spacecraft body generally rotates since the whole angular momentum of the spacecraft is conserved in the inertial system. Assuming the motion of the spacecraft body as pure spin motion around a certain axis, we consider the problem of directing the axis of rotation to the desired direction in the inertial system. The attitude control law proposed here has a very simple form and can achieve the desired motion with the wheels by devising the attitude variables and the direction of the inertial system. Finally, we confirm the effectiveness of this attitude control law by numerical simulations.