Feedback control with nominal inputs for agile satellites using control moment gyros

Satellites orbiting the Earth require large-angle and rapid rotational maneuverability. Control moment gyros are expected to be applied to attitude control actuators of small agile satellites, because control moment gyros can generate high torque effectively. However, the control moment gyro has a singularity problem that affects its energy consumption and rapid actuation. To solve the problem, a feedforward control logic using an energy-optimal path planned by a Fourier basis algorithm is proposed here. However, this logic alone cannot maintain precise control under actual errors and disturbances. Therefore, a feedback control system was also designed in order to acquire robustness against errors and disturbances. The designed system included in this paper is characterized by using a system's limit state, which is a newly defined variable, and is predicted by numerical integrals using nominal control inputs. Several numerical simulations and experiments were carried out to verify the feasibility of the proposed logic in terms of the robustness, energy consumption, and the safe use of the control moment gyro.