Modeling and flat control law for a fine pointing system based on semi active magnetic bearings

In this paper aspects of nonlinear systems and flat control are studied for a specific application of a satellite fine pointing breadboard based on semi active magnetic bearings actuators. The authors propose a complete 6 degrees of freedom mechanical model which describes the system dynamics. A completely nonlinear and unstable system is obtained leading to implementation of nonlinear control laws. A combination of flat control, which ensures trajectory tracking and path planning, with a linear controller which rejects uncertainties and additive noise is implemented and simulated. Simulations proves the efficiency of control law, leading to a system which is stable and reaches the high precision performances desired for the application.