Earth-observation satellite attitude control using passive and active hybrid magnetically suspended flywheels

The control strategy is presented using passive and active hybrid magnetically suspended flywheels (P&A MSFWs), which can help meet the requirements of high precision and high stability for earth-observation satellites. Compared with the conventional flywheel, P&A MSFW has more rotation degrees of freedom (DOFs) since the rotor is suspended by magnetic bearings, and thus requires more efficient controllers. A modified sliding mode control law (SMC) to our novel nonlinear and coupled system is presented, which is interrupted by inertia matrix uncertainties and external disturbances. SMC law via Lyapunov method is improved, and a fuzzy control scheme is used to attenuate the chatting and control attitude accuracy and maintain the robustness of SMC. Simulation results are provided to illustrate the efficiency of our model by using our control law.