Simulation Development and Analysis of Attitude-Control

Control-moment gyroscopes (CMGs) are spacecraft attitude-control actuators which control the spacecraft's orientation and pointing. CMGs operate on electrical power and therefore obey the the conservation of angular momentum. Single-gimbal CMGs are equipped with a high-speed flywheel which can be gimbaled to impart gyroscopic torques. The net reaction torques are observed by the spacecraft resulting in pure rotation. A CMG based attitude control system (ACS) is favorable compared to a cold gas thruster ACS because of fundamental differences in how the reaction torques are produced. CMGs provide a continuous range of motion while RCS thrusters are limited by the minimum on-off time for the thruster valves. This minimum open-close time leads to a bang-bang response as opposed to the smoother CMG response. Fur-thermore, CMGs are powered using batteries and can therefore be recharged, while RCS thrusters use propellant which depletes over time. CMG sizing, the act of de