CRII: RI: Robotic cable-based de-tumbling of demised spacecraft

如今，基于卫星的技术无处不在，对我们的日常生活至关重要。然而，它们不断受到业务卫星与空间碎片之间碰撞的可能性的威胁，空间碎片是由地球轨道上所有非功能物体形成的。目前正在提议采用机器人任务来处理大型碎片，以降低此类碰撞的风险。这项研究的目的是开发知识，以实现基于缆索的不合作空间物体的自主去翻滚。绳网系统将被考虑，这些系统被抛向碎片，缠绕或包围它，并提供一个链接，将它拖到处置轨道上。本文的研究重点将放在两颗卫星相对运动特别危险的情况下，对捕获后的追踪器-网-目标航天器系统进行建模、分析和控制。基于电缆的机器人不仅为碎片捕获和在轨服务等应用提供了创新的解决方案，还为小行星偏转和无人机拦截提供了创新的解决方案。这项研究带来的进步有可能对国防产生积极影响，增加航天器解决方案的经济竞争力，促进国家繁荣。扩大STEM参与的活动将包括本科生的研究经验，研究成果在课程中的整合，以及在贫困小学的推广。本研究的目的将通过(1)缆基机器人与目标之间的高保真建模和分析，以及(2)缆基机器人的控制来实现。在拟议工作的一个主要方面，将开发高保真模型来表示缆索机器人的动力学以及与目标的摩擦相互作用。将创建减少订单但动态等效的模型，以提供高效但准确的替代方案。还将提出一种估计未知、不合作目标惯性参数的方法。另一个研究部分旨在利用缆索机器人有限的控制权限来综合可靠和健壮的控制方法。将考虑与主系绳的绞合以及追逐者的推进器有关的选项。采用反馈控制同时稳定追踪器和目标航天器的相对平移动力学和姿态动力学。还将验证该控制对不确定性的稳健性。这些贡献预计将推动空间应用中基于电缆的自主系统的重要技术进步，同时促进非线性系统动力学、基于模型的估计和有限权威的复杂非线性系统控制的知识。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Technologies based on satellites are nowadays ubiquitous and essential to our everyday life. However, they are continuously threatened by the possibility of collisions between operational satellites and space debris, formed of all non-functional objects in orbit around the Earth. Robotic missions to dispose of large debris are currently being proposed to reduce the risk of such collisions. The objective of this research is to develop knowledge to put in practice autonomous cable-based de-tumbling of uncooperative space objects. Tether-net systems will be considered, which are thrown toward debris, entangle it or close around it, and provide a link to tug it to a disposal orbit. Focus of this research will be the modeling, analysis, and control of the chaser-net-target spacecraft system after capture, when the relative motion of the two satellites is particularly dangerous. Cable-based robots provide innovative solutions not only to applications such as debris capture and on-orbit servicing, but also asteroid deflection and drone interception. The advancements brought about by this research have the potential to positively impact national defense, increase the economic competitiveness of spacecraft solutions, and advance national prosperity. Activities to broaden participation in STEM will include research experiences for undergraduates, integration of research results in the curriculum, and outreach in underprivileged elementary schools.The objective of this research will be attained by (1) high-fidelity modeling and analysis of the interactions between the cable-based robot and the target, and (2) control of the cable-based robot. In one thrust of the proposed work, high fidelity models will be developed to represent the dynamics of the cable-based robot as well as frictional interactions with the target. Reduced order but dynamically equivalent models will be created to provide an efficient but accurate alternative. A methodology to estimate the inertial parameters of the unknown, uncooperative target will also be proposed. The other research component aims to leverage the limited control authority of the cable-based robot to synthesize reliable and robust control methods. Options related to the winching of the main tether as well as to the thrusters of the chaser will be considered. Feedback control will be employed to stabilize at the same time the relative translational and attitude dynamics of the chaser and the target spacecraft. The robustness of the control to uncertainties will also be verified. These contributions are expected to enable important technological advancements of autonomous cable-based systems for space applications, while advancing the knowledge of nonlinear systems dynamics, model-based estimation, and control of complex nonlinear systems with limited authority.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.