Three-axis Satellite Attitude Control Based on Magnetic Torquing

Magnetic torquing is attractive for generation of control torques on small satellites. The concept is that interaction between the Earth's magnetic eld and a magnetic eld generated by a set of coils in the satellite is used for actuation. This principle is inherently nonlinear, and diicult to use because control torques can only be generated perpendicular to the geomagnetic eld vector. So far, this has prevented control in all three axes using magnetorquers only. This paper shows that three axis control can be achieved with mag-netorquers as sole actuators in a low Earth orbit. It considers the problem from a time-varying, nonlinear system point of view and suggests controllers for three-axis stabilization. A rigorous stability analysis is presented, and detailed simulation results show convincing performance over the entire envelope of operation of the Danish rsted satellite.