Fixed-Time Sliding Mode Coordinated Deployment Control for Space Triangle Tethered Formation System

Triangle tethered formation system (TTFS) has been widely studied for its potential in space applications. Successful deployment of TTFS is a prerequisite for all operations. Maintaining the consistency among member satellites and the consisency between satellites and tethers is the key for successful deployment of TTFS. In this article, a decentralized control framework is proposed to describe the acutal matching relationship between satellites and tethers, which cannot be reflected under the centralized framework. Control strategies for both thrusts and motors are designed. In the proposed scheme, a nonsingular sliding variable is given. The settling time independent of initial conditions is obtained through therotical proof to ensure arbitrary convergence time of system deployment. Moreover, coordination terms are designed to improve the accuraccy of formation tracking. The simulation results show that the system deployment along the desired trajectory smoothly. The system maintains a perfect formation configuration throughout the entire process while tethers match satellites perfectly.