ESA GNC Conference Papers Repository

Electric propulsion is nowadays a well-established technology for space missions. The high specific impulse of electric motors allows for a significant reduction of propellant mass. This major advantage comes with several constraints that have to be managed by an appropriate guidance and control system design. Upcoming rendezvous and servicing missions can benefit from electric propulsion. Nevertheless their requirements in terms of reactivity and safety can hardly be fulfilled by electric thrusters, so that an auxiliary cold-gas or chemical propulsion system must be designed. This paper addresses the design of a shrinking horizon Model Predictive Control algorithm for a hybrid propulsive configuration (electric plus auxiliary thrust), that can be used to re-plan rendezvous and close proximity operations maneuvers autonomously. Vision based relative navigation constraints are managed by the algorithm, as well as thrust inhibition during eclipses. The algorithm is tested on a representative closed loop simulator that comprises a complete vision-based navigation chain, as well as electric and auxiliary propulsion models. Its performance in executing homing and closing maneuvers is determined for a reference servicing scenario in low Earth orbit.