New approach to attitude/momentum control for the Space Station

Abstract

A new approach to control moment gyro (CMG) momentum management and attitude control of the space station is presented. The control algorithm utilizes both the gravity-gradient and gyroscopic torques to seek torque equilibrium attitude in the presence of secular and cyclic disturbances. It is shown that, depending on mission requirements, either pitch attitude or pitch-axis CMG momentum can be held constant. It is also shown that a combination of yaw attitude and roll-axis CMG momentum can be held constant, whereas a combination of roll attitude and yaw-axis CMG momentum cannot. As a result, the overall attitude and CMG momentum oscillations caused by cyclic aerodynamic disturbances are minimized. A state feedback controller with minimal computer storage requirements for gain scheduling is also presented. An inherent physical property of the coupled roll/yaw dynamics is discussed in terms of a transmission zero of a multivariable system.