在过去几十年研究与探索中，空间系绳运输系统(tether transportation system, TTS)被认为在大规模远程低成本运输方面具有较大优势。空间系绳运输系统是由一个或两个灵活性较强的柔性系绳组成，系绳末端连接卫星并通过几个运输装置沿它们运输有效载荷。

南京理工大学王庆涛副教授和张智勇副教授团队、上海宇航系统工程研究所刘振东工程师、南京航空航天大学徐世东讲师和加拿大约克大学李刚强研究员共同在《国际机械系统动力学学报（英文）》(International Journal of Mechanical System Dynamics, IJMSD)发表了“基于绝对节点坐标法的环形空间系绳运输系统动力学建模与分析”研究论文。该文提出了一种环形空间系绳运输系统（looped TTS, L-TTS）的高保真模型，并研究该系统的大变形和较大的整体运动。文章采用基于绝对节点坐标法(absolute nodal coordinate formulation, ANCF)的细梁单元离散了两个系绳并建立了系统的精确模型，简要介绍了与系绳纵向和弯曲变形相关的非线性弹性力及其雅可比矩阵，采用基于ANCF的滑动铰模型描述了系绳和运输装置之间的相互作用。在系统运作时，由于科氏力的作用，运输装置与系绳之间存在碰撞风险。为了降低这些风险，该文研究了两种振动抑制策略，即运输装置相对于系绳做减速运动和每个系绳上放置多个运输装置。最后，该文通过仿真验证了两种策略在降低运输装置与系绳碰撞风险、L-TTS的整体振动以及系绳纵向弹性力大小方面的有效性，并且验证了该文提出的高保真模型在微重力条件下的良好性能。该研究结果为未来空间运输系统的建设提供了借鉴。

A high-fidelity multibody-system dynamic model of the looped tether transportation system (L-TTS) is proposed in this study to study its large deformation as well as large overall motion. The absolute nodal coordinate formulation (ANCF)-based gradient-deficient beam element is employed to establish the accurate model of the two flexible tethers subject to large deformations. The relative movement of climbers along tethers is described by using the sliding joint model based on ANCF. To reduce the collision risks between tethers and climbers, two libration suppression strategies, namely, the decelerated motion of climbers relative to tethers and multiple climbers per tether are investigated in this study. Several numerical simulations not only validate the effectiveness of the two strategies in reducing the collision risks between climbers and tethers, the overall librations of L-TTS, and the magnitudes of the longitudinal elastic force of tethers, but also verify the good performance of the high-fidelity model proposed in this study for dynamic simulation of the L-TTS in microgravity conditions.

该文亮点：

1. A high-fidelity multibody system dynamic model of the looped tether transportation system (L-TTS) is proposed, using gradient deficient beam element based on the absolute nodal coordinate formulation.
   
2. Two libration suppression strategies are proposed to reduce the collision risks between climbers and tethers in the climber movements on tethers.
3. Good performance of the proposed high-fidelity model of the L-TTS in microgravity conditions is verified by numerical simulations.

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