SPACECRAFT PITCH AND ROLLIYAW ACTUATIONS USING CONTROL MOMENT GYROSCOPES FOR ATTITUDE STABILIZATION

Abstract

This paper investigates the pitch and roll/yaw actuation using control moment
gyroscopes (CMGs) fo r spacecraft, i.e., International Space Station (ISS). CMGs
act as a control hardware for an active stabilization technique in order to keep the
spacecraft attitude within a desired orientation at all time with a good pointing
accuracy. In this regards, the critical aerodynamic disturbance torques acting on
a spacecraft can be suppressed and without employ ing attitude thrusters. The
analysis starts with a study ofthe spacecraft dynamics and behavior based on the
Euler linearized equations ofmotion. Then, the imp lementation of the pitch and
roll/yaw control architectures using those equations are carried out.
Subsequently, the control algorithms are tested using the MATLAB® and
Simulink®. It is shown that via tuning the control gain values, the pointing errors
can be minimized. The responses of the attitude control obtained .from the
fee dback system show that good pointing accuracies can be accomplished with
dedicated attitude controllers.