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，它们不断受到运行中的卫星与空间碎片碰撞的可能性的威胁，空间碎片是由环绕地球轨道的所有无功能物体构成的。目前正在提议由机器人执行处理大型碎片的任务，以减少这类碰撞的风险。这项研究的目的是积累知识，以便对不合作的空间物体实施自主的基于电缆的防翻滚。将考虑使用绳网系统，这种系统被抛向碎片，将碎片缠绕或靠近碎片，并提供一个连接，将碎片拖到弃星轨道。本文的研究重点是在双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解决方案，而且还为小行星偏转和无人驾驶飞机拦截提供了创新解决方案。这项研究所带来的进步有可能对国防产生积极影响，提高航天器解决方案的经济竞争力，促进国家繁荣。为了扩大STEM的参与度，将开展面向本科生的研究体验、将研究成果融入课程、面向贫困小学的拓展等活动。本研究的目的是通过（1）对缆索机器人与目标物之间的相互作用进行高精度建模和分析，（2）实现缆索机器人的控制。在所提出的工作的一个推力，高保真度模型将被开发来表示电缆为基础的机器人的动力学以及与目标的摩擦相互作用。将创建降阶但动态等效的模型，以提供高效但准确的替代方案。还将提出一种估计未知非合作目标惯性参数的方法。另一个研究部分的目的是利用有限的控制权的电缆为基础的机器人合成可靠和鲁棒的控制方法。将考虑与主系缆的绞盘以及猎空艇的推进器有关的备选方案。将采用反馈控制来同时稳定追踪器和目标航天器的相对平移和姿态动力学。还将验证控制对不确定性的鲁棒性。这些贡献有望推动空间应用自主电缆系统的重要技术进步，同时推进非线性系统动力学知识、基于模型的估计和有限权限的复杂非线性系统控制。该奖项反映了NSF的法定使命，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.