Dynamics and Control of Tethered Spacecraft Systems

系留航天器系统的动力学与控制

• 批准号: RGPIN-2018-05991
• 负责人: Zhu, ZhengHong
• 金额: $ 4.66万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=669907
• 关键词: Dynamics; Control; Tethered; Spacecraft; Systems

Tethered Spacecraft Systems (TSS) are novel devices to extend the capability of spacecraft to conduct scientific and other tasks. Among them, the propellantless propulsion by electrodynamic tethers in Earth orbits or electrostatic tethers beyond Earth orbits is an appealing alternative to existing rocket propulsion. However, TSS are difficult to operate due to their extreme long length and variable configurations. As such, a thorough understanding of dynamics and control of TSS is a preoccupation for any successful TSS mission.******High-fidelity modeling of TSS inevitably leads to a set of nonlinear, distributed and coupled partial differential equations. The control of such systems subject to stochastic perturbative effects requires feedback of states. However, interior states along tether length are not measurable as sensors are only available at spacecraft connected at tether ends. This leads to a challenging feedback control for distributed systems with only boundary observation. Furthermore, the implementation and validation of control laws for TSS before launch are equally challenging. Novel ground test facility and theory are required to scale down the real TSS into testbeds with limited dimensions.******The aim of this discovery program is to systematically study fundamentals of dynamics and control of TSS in and beyond Earth orbits. Builds on the success of previous Discovery Grant, new computational control for flexible TSS will be developed by considering multiphysics, coupled rigid-flexible dynamics, orbital perturbations, and boundary feedback control with limited observation at boundary. First, a new nodal position finite element Kalman filter will be developed to give spatial and temporal estimates of interior states (motion and electric voltage) along tether length based on feedback at tether's ends. Second, a novel computational control without explicit structures for TSS will be developed by combining a dual adaptive model predictive control with the nodal position finite element Kalman filter. Third, the derived computational control will be used for tether deployment/retrieval, effective and efficient space debris deorbit by electrodynamic tether, and interplanetary travel by electrical solar wind sail. Fourth, ground tests will be conducted to validate the proposed computational control. Finally, key components of TSS will be tested in microgravity by parabolic flights and prototype of electrodynamic tether deorbit device will be demonstrated in space.******The discovery program will train HQP in multi-physical modeling, coupled rigid-flexible dynamics, astrodynamics, advanced control theory, space environment, software, hardware, and experimental validation. HQP will also be trained in professional development through discussion with collaborators and team members, participation in real TSS space mission, and collaboration with space industry.**

系留航天器系统(TSS)是一种用于扩展航天器执行科学和其他任务能力的新型设备。其中，地球轨道上的电动绳索或地球轨道外的静电绳索的无推进剂推进是现有火箭推进的一种有吸引力的替代方案。然而，TS由于其极长的长度和可变的配置而难以操作。因此，透彻地了解TSS的动力学和控制是任何TSS任务的首要任务。TSS的高保真建模不可避免地会导致一组非线性、分布和耦合的偏微分方程组。受随机扰动影响的这类系统的控制需要状态反馈。然而，沿着系绳长度的内部状态是不可测量的，因为传感器只在连接在系绳末端的航天器上可用。这给只有边界观测的分布式系统的反馈控制带来了挑战。此外，在发射前实施和验证TSS的控制律也同样具有挑战性。需要新的地面测试设备和理论来将真实的TSS缩小到有限尺寸的试验台。*该发现计划的目的是系统地研究TSS在地球轨道内外的动力学和控制基础。在以往探索基金成功的基础上，将通过考虑多物理、刚柔耦合动力学、轨道摄动和边界有限观测的边界反馈控制，开发新的柔性TSS的计算控制。首先，开发了一种新的节点位置有限元卡尔曼滤波器，基于系绳末端的反馈，给出了沿系绳长度的内部状态(运动和电压)的空间和时间估计。其次，将双自适应模型预测控制与节点位置有限元卡尔曼滤波相结合，提出了一种新型的无显式结构的TSS计算控制方法。第三，推导出的计算控制将用于系绳部署/回收、通过电动系索有效和高效地使空间碎片脱轨以及通过电动太阳风帆进行星际旅行。第四，将进行地面测试，以验证拟议的计算控制。最后，TSS的关键部件将通过抛物线飞行进行微重力测试，并将在太空中演示电动系绳离轨装置的原型。*发现计划将在多物理建模、刚柔耦合动力学、天体动力学、先进控制理论、空间环境、软件、硬件和实验验证方面对HQP进行培训。HQP还将通过与合作者和团队成员的讨论、参与真实的TSS空间任务以及与航天行业的合作，接受专业发展方面的培训。