Nonlinear Attitude Control of a Tether-Connected Multi-Satellite in Three-Dimensional Space

The objective of the current research is to analyze the attitude dynamics and control of a tethered satellite formation flying where the tethered units are modeled as extended rigid bodies. The three-inline array system is used in this study, and the general formulation of the equations of motion of the system is obtained through a Lagrangian approach. In this research, attitude motions of the tethered satellite system are analyzed in a three-dimensional free-space system to complement previous works. The state-dependent Riccati equation (SDRE) controller is used to regulate the attitude errors. The stability region for the SDRE-controlled tethered satellite system is also estimated using a numerical method to show globally asymptotic stability for the control method. Centralized and decentralized approaches are applied to the dynamic system to compare the performance of controlling the attitude motion. The SDRE controller performs well in both the centralized and decentralized approaches for the attitude control of tethered satellites in formation flying.