Event-triggered orbital and attitude station-keeping control for near-asteroid spacecraft

This paper introduces an event-triggered control strategy for spacecraft conducting near-asteroid missions, specifically orbiting an asteroid within a defined orbital radius area to enable precise observations and exploration using instruments like ground-penetrating radar. The strategy maintains stable attitude and orbital radius with much lower energy costs. An impulsive orbital control is proposed, in which an intermittent event-triggered mechanism with barrier functions could reduce the energy cost and extend the spacecraft's lifetime by avoiding unnecessary impulsive thrusts with lower times of impulsive controlled thrusts in an orbital period. For attitude stabilization, a sigmoid-based event-triggered mechanism is employed with a control dead zone to extend control intervals without sacrificing accuracy, thus to reduce most of computation costs. Gravitational orbit-attitude coupling and solar radiation pressure coupling are incorporated into the attitude-orbit dynamics modeling and compensated for in the control design. Stability analysis and numerical simulations validate the strategy's robustness and effectiveness.