Dynamics and Control of Electrodynamic Tether Systems

电动系绳(EDT)是一种创新的方法，可以在不消耗推进剂的情况下为航天器的助推和离轨机动和航天器上的电力提供动力。在过去的50年里，26次轨道和亚轨道系绳飞行任务中，有12次使用了EDT。然而，由于洛伦兹力的时变激励，系统容易发生长期不稳定。因此，透彻地了解EDT系统的长期动态稳定性对于其在太空中的有用应用是至关重要的。尽管在EDT理论和电动系留系统方面取得了很大的成就，但在耦合EDT动力学和长期动态稳定性的基础上仍然存在一些有趣的挑战。因此，这一发现计划的目标是系统地研究EDT系统的机电耦合动力学和长期稳定性的最优控制。在这一新方法中，我们将利用轨道运动限制理论建立一个裸露和柔性的EDT与发电耦合的多物理动力学模型。基于新的多物理模型，EDT系统的参数将通过应用多目标优化程序来优化：(A)最快的助推或脱轨机动时间；(B)在给定航天器有效载荷的情况下，最大限度地产生能量，同时最小化EDT长度和末端质量。EDT系统的长期动态稳定性是通过利用非线性规划优化方法和鲁棒有限滚动控制理论在时变EDT系统的稳定振荡和给定的任务目标之间找到最佳平衡点来实现的。最后，进行了地面试验，以验证动力学和控制策略。拟议的研究计划的结果将是(I)对EDT系统至关重要的高保真多物理EDT模型，(Ii)稳健的最优控制算法，以及(Iii)在跨学科和协作环境中对14名HQP进行培训。它将为未来的太空探索推进我们在新的推进器或发电方面的知识，并提高加拿大航天工业的竞争力。

Electrodynamic tethers (EDTs) are an innovative approach to generate propulsion for boost and deorbit maneuver and electricity onboard spacecraft without consuming propellant. Over the past five decades, 12 out of 26 orbital and suborbital tether missions flew with EDTs. However, the system is prone to the long-term instability caused by the time-varying excitation of Lorentz force. Thus, a thorough understanding of the long-term dynamic stability of an EDT system is essential for its useful application in space. In spite of great achievements in the EDT theory and electrodynamic tethered systems, a number of interesting challenges still exists in the fundamentals of coupled EDT dynamics and long-term dynamic stability. Therefore, the objectives of this discovery program are to systematically study the coupled electro-mechanical dynamics and optimal control of the long-term stability of EDT systems. In this new approach, we will formulate a multiphysics model of dynamics of a bare and flexible EDT coupled with electricity generation by orbit motion limited theory. Based on the new multiphysics model, the parameters of EDT systems will be optimized by applying multiobjective optimization procedure for (a) fastest time in boost or deorbit maneuver or (b) maximum energy generation for given payloads onboard spacecraft, while minimizing the EDT length and end masses. The long-term dynamic stability of an EDT system will be achieved by finding an optimal balance between a stable oscillation of a time-varying EDT system and given mission objectives using the nonlinear-programming optimization procedure and the robust finite receding horizon control theory. Finally, ground testing will be conducted to validate the dynamics and control strategy. The outcome of the proposed research program will be (i) a high-fidelity multiphysics EDT model essential for EDT systems, (ii) a robust optimal control algorithm, and (iii) training of 14 HQP in an interdisciplinary and collaborative environment. It will advance our knowledge in new propulsion or power generation for future space exploration and enhance the competitiveness of Canadian space industry.