Satellite attitude control using environmental forces based on variable structure control

The present thesis examines the use of environmental forces for satellite attitude control using variable structure control. The system comprises of a satellite with control flaps to utilize environmental forces such as solar radiation pressure and aerodynamic forces. A variable structure control approach has been adopted to develop control law for suitably rotating the control flaps to achieve desired satellite attitude performance. The detailed numerical simulation of the governing nonlinear system equation of motion including the effects of various system parameters on the controller performance establishes the effectiveness of the proposed control strategy. The numerical simulation matches with the analytical results. Furthermore from analysis, the proposed controller is found to be robust against parameter uncertainties and external disturbances and its performance is superior in comparison to other strategies proposed in the literature. Thus, the robustness of the proposed control strategy and utilizing natural environmental forces for attitude control makes the proposed concept attractive for future space applications.