Parametric formation control of multiple nanosatellites for cooperative observation of China Space Station

Abstract

This study proposes a parametric formation control method for the cooperative observation of the China Space Station (CSS) using multiple nanosatellites. First, a simplified geometrical model of the CSS is constructed using fundamental solids, such as the capsule body and cuboid. Second, the spacecraft formation configuration for the observation mission is characterized by a three-dimensional (3D) Lissajous curve using related design parameters under the full-coverage observation requirements of specific parts, such as the CSS connecting section and collision avoidance constraints. Third, a double-layer control law is designed for each nanosatellite, in which the upper layer is a distributed observer for recognizing the target formation configuration parameters, and the lower layer is a trajectory-tracking controller to make the nanosatellite converge to its temporary target position calculated from the upper layer’s outputs. The closed-loop control stability is proven under the condition that the communication network topology of the nanosatellite cluster contains a directed spanning tree. Finally, the control method is verified by numerical simulation, where the CSS connecting section is selected as the observation target, and ten small nanosatellites are assumed to perform the cooperative observation mission. The simulation results demonstrate that the double-layer control law is robust to single-point communication failures and suitable for the accompanying missions of large space objects with multiple nanosatellites.