A novel concept of a looped tether transportation system with multiple rungs (L-TTS-R) is proposed for highly efficient payload transfer in space. In addition to two huge platforms connected by two parallel tethers with multiple moving climbers, some rigid rungs are evenly distributed between the two tethers in L-TTS-R to suppress the libration movement of the system and to reduce or avoid the risk of collision between climbers and tethers in the process of payload transportation. To establish an accurate model of L-TTS-R in the framework of multibody system dynamics, the gradient deficient beam elements of the absolute nodal coordinate formulation (ANCF) are used to mesh two tethers. The sliding joint based on ANCF is introduced to build up the contact interaction model between tethers and climbers. The generalized forces acting on the L-TTS-R, for example, the gravitational force and the elastic force, are derived in brief. The generalized-alpha method is used to solve the dynamics equations of the constrained flexible multibody systems. Some representative examples are given to validate the effectiveness of the proposed L-TTS-R model for space payload transfer missions and to assess the influence of rungs on the system libration suppression, the climber collision risk avoidance, the relative oscillation and pitching motion of platforms, and the tether tensions. The numerical results reveal that the L-TTS-R shows distinct effects on suppressing the overall libration of the system, reducing or even avoiding the risk of collision between climbers and tethers and decreasing significantly the oscillating magnitudes of the relative distances between two platforms, and these effects are more visible with increasing the number of rungs.

提出了一种具有多个梯级的环形系绳运输系统 (L-TTS-R) 的新概念，用于在空间中进行高效的有效载荷传输。除了由两条平行绳索连接的两个巨大平台外，还有一些刚性梯级均匀分布在 L-TTS-R 的两条绳索之间，以抑制系统的振动，减少或避免碰撞风险。有效载荷运输过程中的登山者和系绳。为了在多体系统动力学框架下建立 L-TTS-R 的精确模型，使用绝对节点坐标公式 (ANCF) 的梯度缺陷梁单元对两个系绳进行网格剖分。引入基于 ANCF 的滑动关节，建立绳索与攀爬者之间的接触交互模型。作用在 L-TTS-R 上的广义力，例如，引力和弹力，是简单的推导出来的。广义α法用于求解受约束柔性多体系统的动力学方程。给出了一些具有代表性的例子来验证所提出的 L-TTS-R 模型在空间有效载荷转移任务中的有效性，并评估梯级对系统振动抑制、爬升器碰撞风险避免、平台相对振荡和俯仰运动的影响，以及系绳张力。数值结果表明，L-TTS-R在抑制系统整体振动、降低甚至避免攀爬者与系绳碰撞的风险以及显着降低两个平台之间相对距离的振荡幅度方面表现出明显的效果，