Research On Workflow And Mission Scheduling Algorithms For On-orbit Servicing Of Spacecraft

As a new research direction in space field,spacecraft on-orbit service technology can effectively solve the problems of spacecraft availability,flexibility of task,scalability and lack of working life.Therefore,the spacecraft on-orbit service technologies have significant hidden value in military and civilian.It is necessary to carry out relevant research of spacecraft in-orbit service.Spacecraft on-orbit service involves the rendezvous and docking of spacecraft and scheduling of service tasks in orbit.Rendezvous and docking of spacecraft is the prerequisite of carrying out on-orbit service,and the mission scheduling of on-orbit service can maximize the efficiency.In the paper,model and mission scheduling problem of on-orbit refueling is studied as an example of on-orbit service.The space rendezvous and docking is the basis of implementing on-orbit refueling task.Therefore,three kinds of strategies suitable for space rendezvous will be introduced.Phasing maneuvers and Lambert’s problem will be used to solve GEO orbit spacecraft rendezvous problem.Linear dynamic equations with J₂ perturbation is used to solve the near-circular low-Earth-orbit spacecraft rendezvous problem.Two kind patterns of on-orbit refueling for multiple geostationary based on propellant depot is studied in this article.GEO spacecraft will as target spacecraft in the“k-1-n”pattern of on-orbit refueling and near-circular low-Earth-orbit spacecraft will as target spacecraft in the“1-1-n”pattern.According to the characteristics of each mode,the relationship and the constraint conditions are determined of each spacecraft,and scenario will be described.Then the model for the on-orbit refueling mission is established.The refueling sequence and orbital transfer time are used as design variables,whereas the mission completion time and propellant consumed by orbital maneuvers are used as design objectives.The criteria assessment based on the amount of spacecraft propellant remaining is identified.The genetic algorithm and NSGA-II,which solve the scheduling of spacecraft on-orbit refueling mission,are presented.Finally,the scheduling of spacecraft on-orbit refueling mission is simulated.GEO spacecraft and SSO spacecraft are used as target spacecraft.The simulation results show that the proposed scheduling model and scheduling algorithm are feasible.