Coordinated formation control strategy of the rotating hub-spoke tethered formation system

The hub-spoke tethered formation system (HS-TFS) is attractive in many space applications, such as multi-point measurements, providing flexible frame for solar sail and other membrane or net structures. To utilize the specific advantages of the system, such as reduction of fuel consumption, promotion of the formation stability, the HS-TFS is usually designed as a rotating system. However, the rotating motion will increase the complexity of the formation control of the HS-TFS. In this paper, the formation control of the rotating HS-TFS is investigated. First, an analytical model based on several reasonable assumptions is introduced to describe the dynamics of the rotating HS-TFS. Based on this model, two coordinated formation control strategies are proposed and described in detail, in which the tension forces of the tethers, propulsions of the sub-spacecraft, and the torque of the master-spacecraft are used as control inputs. Then a closed-loop control system is constructed to validate the proposed coordinated formation control strategies. Finally detailed numerical simulations are implemented based on the closed-loop control system. The simulation results show that the proposed coordinated control strategies are capable of assigning the operating time of the torque of the master-spacecraft and improving the efficiency of the formation control of the rotating HS-TFS.