The combined energy and attitude control system for small satellites-Earth observation missions

Small satellites are becoming the preferred option for low-cost Earth observation missions. However, the projected requirements have increased for the missions, which require more sophisticated and additional payloads nowadays. As a result, this would most probably be cumbersome and critical for the overall satellite mass/volume budgets. In this article, the idea of combining the energy storage and attitude control systems is presented in order to reduce the number of subsystems onboard. Such a system consists of a double counterrotating flywheel unit serving simultaneously for the satellite energy and attitude management. First, numerical treatments were conducted for the rotors to determine a failure-free condition corresponding to their stresses and natural frequencies. Further, the mathematical models describing the energy and attitude control are established, and the system onboard architecture is implemented. Numerical simulations for the developed architecture were conducted taking into account the ideal and non-ideal cases. The simulation results are discussed especially from the energy and attitude standpoints. The system performance complies with the mission requirements. Thus, this end-to-end system demonstration indicates that the combined system is judiciously feasible, and is a potential combined subsystem for small satellites.