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

基于卫星的技术如今无处不在，对我们的日常生活至关重要。然而，它们不断受到运行卫星与环绕地球轨道上所有无功能物体构成的空间碎片碰撞的可能性的威胁。目前有人提议用机器人来处理大型碎片，以减少此类碰撞的风险。本研究的目的是发展知识，将非合作空间物体的自主缆索反滚付诸实践。将考虑系绳网系统，将其扔向碎片，缠绕或关闭它，并提供一个链接，将其拖到处置轨道。本文的研究重点是在两星相对运动特别危险的情况下，对捕获后的追-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，而且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参与的活动将包括为本科生提供研究经验，将研究成果纳入课程，以及在贫困小学开展推广活动。本研究的目标将通过(1)高保真建模和分析基于缆索的机器人与目标之间的相互作用，以及(2)基于缆索的机器人的控制来实现。在提出的工作的一个推力中，将开发高保真模型来表示基于电缆的机器人的动力学以及与目标的摩擦相互作用。将创建减少顺序但动态等效的模型，以提供有效但准确的替代方案。提出了一种估计未知非合作目标惯性参数的方法。另一个研究部分旨在利用基于缆索的机器人有限的控制权限来合成可靠和鲁棒的控制方法。将考虑与主缆绳的绞车以及追逐者的推进器有关的选择。采用反馈控制同时稳定跟踪器和目标航天器的相对平动和姿态动力学。还将验证控制对不确定性的鲁棒性。这些贡献预计将使空间应用的自主电缆系统取得重要的技术进步，同时推进非线性系统动力学、基于模型的估计和有限权限的复杂非线性系统控制的知识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.