Autonomous and Optimized Agile Attitude Control with CMGs for Small Satellites Platforms

Kurzfassung

Agile Earth-observation small satellites can benefit from Control Moment Gyroscopes (CMGs), which provide high torque capability at favorable mass and power efficiency. This paper summarizes an ESA study investigating onboard attitude guidance and CMG steering for a possible agile variant of the EIS/InnoSat platform. One central question is whether attitude maneuver planning and CMG steering should be treated separately or in a combined prediction-based formulation. The study shows that a separated architecture based on a configuration-independent commanded-torque interface cannot in general guarantee maneuver feasibility, because the instantaneous torque authority of a CMG array depends on its internal gimbal configuration and the finite momentum envelope constrains sustained torque generation. The combined method formulates the attitude and CMG trajectory control as a free-final-time nonconvex optimal-control problem and solves it using successive convexification (SCvx). This approach provides the most general benchmark solution but is demanding for onboard computation. Closed-loop simulation results are presented for the resulting guidance trajectories together with embedded execution results.