Pointing Stability Improvement of Astronomy Satellites by Integration of Actuators.

Abstract

As pointing requirements of astronomy satellites become more demanding, a conventional momentum-exchange scheme for attitude-pointing control is sometimes not enough to satisfy stringent stability requirements. This paper presents a new attitude control system for improving the attitude-pointing stability of astronomy satellites/and earth-observation satellites. In our proposed control system, an actuator system is composed of wheel-rotor drive motors and magnetic torquers driven by a newly devised “cooperative drive law.” The pointing stability is improved by torque control of the actuator system so that the total torque acting on the satellite body is minimized with the use of disturbance observers and in a way that shortcomings of the actuators are compensated for by each other. In the torque control, attitude control and momentum management are both treated consistently. In this paper, the mathematical formulation of our proposed scheme is presented, and the results of numerical simulations are also presented to demonstrate the stability improvement.