Dynamics analysis and deorbit efficiency study of electrodynamic tether system based on current control

The electrodynamic tether generates Lorentz force through the interaction of a conductive tether with the Earth's magnetic field and facilitates the system deorbiting. During this process, the stability of the libration motion of tether is crucial for successful deorbit. Stabilizing the tether's attitude by regulating the tether current is a simple, low-cost, and easily implementable control strategy, as it does not require additional actuators, such as jet propulsion system. The innovation of this paper lies in studying the tether attitude dynamics under the current-based control strategy and providing a method to calculate the desired attitude angle that nearly maximizes the deorbit efficiency under controllable conditions. In this paper, the nonlinear analysis theory of the Duffing equation is utilized to further investigate the attitude dynamics of the tether under the current-based control strategy. The perturbation acceleration caused by the Lorentz force is derived as a function of the desired in-plane angle. Based on this function, the desired attitude angle that maximizes deorbit efficiency can be determined. The results of this paper provide methods for designing the upper limitation of the tether current and selecting the desired attitude angle to improve deorbit efficiency, while ensuring the stability of the tether's attitude.