Autonomous assembly of multiple spacecraft by tether-aided rendezvous and docking: From theory to experiment

Utilizing the tether-aided rendezvous and docking to realize an on-orbit autonomous assembly of multiple spacecraft is a novel and prospective space mission. The paper presents the dynamics and control of this assembly mission mode in a spinning scenario numerically and experimentally. The system equations in general form are first established. Based on several feasible assumptions, the coupling effects among the chaser spacecraft are eliminated, a set of simplified governing equations described by the tether length and the libration angle are then obtained. By employing the trapezoidal tether retrieval law, an assembly strategy composed of the tangential and normal thrust controllers is proposed. The operation constraints of the tether tension and the libration angle are explicitly considered. Numerical simulation results verify the feasibility and effectiveness of the designed control strategy. In addition, the corresponding tether-aided assembly process is further validated by the air-bearing experiment based on the upgraded system SOOHLS.