A 3-axis simulator for spacecraft attitude control research

This article presents the details of a new 3-axis simulator for spacecraft attitude control research and simulation. The air bearing allows the test bed to rotate about three axes with tiny friction. The attitude determination system consists of three fibre optical gyros, an inclinometer and a magnetometer. The actuator of the system consists of three reaction flywheels and four control moment gyros (CMG). Mathematical models of the sensors and actuators are given to help algorithm design. An extended Kalman filter was designed to provide attitude information for controller. Mathematical simulation results prove the attitude determination system can achieve high precision. A coulomb friction model of reaction wheels is given with experimental results. A friction compensation algorithm was developed to raise the pointing accuracy of the control system. The article also describes the details of the hardware structure. A PD stabilizing controller is implemented to test the validation of the whole control system at last.