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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=691227
• 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）是一种扩展航天器执行科学和其他任务能力的新型装置。其中，利用地球轨道内的电动力系绳或地球轨道外的静电系绳进行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，TSS由于其极长的长度和多变的结构而难以操作。因此，对TSS动力学和控制的透彻理解是任何成功的TSS任务的当务之急。******高保真的TSS建模不可避免地导致一组非线性、分布和耦合的偏微分方程。这种受随机扰动影响的系统的控制需要状态反馈。然而，沿系绳长度的内部状态是不可测量的，因为传感器只能在连接在系绳末端的航天器上使用。这导致了一个具有挑战性的反馈控制分布式系统只有边界观察。此外，发射前TSS控制律的实施和验证同样具有挑战性。为了将实际的TSS缩小到有限尺寸的试验台，需要新的地面试验设施和理论。******这个发现计划的目的是系统地研究地球轨道内外TSS的动力学和控制基础。在先前发现基金成功的基础上，柔性TSS的新计算控制将通过考虑多物理场、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来开发。首先，将开发一种新的节点位置有限元卡尔曼滤波器，根据系绳末端的反馈，沿系绳长度给出内部状态（运动和电压）的时空估计。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的部署/回收、电动力系绳有效和高效的空间碎片脱轨以及电太阳风帆的行星际旅行。第四，将进行地面试验以验证所提出的计算控制。最后，TSS的关键部件将在微重力条件下进行抛物线飞行测试，并在太空中展示电动力系绳脱轨装置的原型。******发现计划将训练HQP进行多物理建模、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。HQP还将通过与合作者和团队成员的讨论、参与真正的TSS太空任务以及与航天工业的合作，对专业发展进行培训