Soft robots leverage deformable bodies to achieve different types of locomotion, improve transportability, and safely navigate cluttered environments. In this context, variable-stiffness structures provide soft robots with additional properties, such as the ability to increase forces transmitted to the environment, to lock into different body configurations, and to reduce the number of actuators required for morphological change. Tensegrity structures have been recently proposed as a biologically inspired design principle for soft robots. However, the few examples of tensegrity structures with variable stiffness displayed relatively small stiffness change (i.e., by a factor of 3) or resorted to multiple and bulky actuators. In this article, we describe a novel design approach to variable-stiffness tensegrity structures (VSTSs) that relies on the use of variable-stiffness cables (VSCs). As an example, we describe the design and implementation of a three-strut tensegrity structure with VSCs made of low melting point alloys. The resulting VSTS displays unprecedented stiffness changes by a factor of 28 in compression and 13 in bending. We show the capabilities of the proposed VSTS in three validation scenarios with different tensegrity architectures: (1) a beam with tunable load-bearing capability, (2) a structure that can self-deploy and lock its shape in both deployed and undeployed states, and (3) a joint with underactuated shape deformations.

中文翻译：

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基于相变材料的变刚度张拉整体结构。


软机器人利用可变形的身体来实现不同类型的运动，提高可运输性，并安全地在杂乱的环境中导航。在这种情况下，可变刚度结构为软机器人提供了额外的特性，例如增加传递到环境的力的能力，锁定不同的身体配置，以及减少形态变化所需的执行器数量。最近提出张拉整体结构作为软机器人的受生物学启发的设计原理。然而，具有可变刚度的张拉整体结构的少数示例表现出相对较小的刚度变化（即，3倍）或诉诸于多个笨重的致动器。在本文中，我们描述了一种依赖于使用变刚度拉索（VSC）的变刚度张拉整体结构（VSTS）的新颖设计方法。作为一个例子，我们描述了由低熔点合金制成的 VSC 的三支柱张拉整体结构的设计和实现。由此产生的 VSTS 显示出前所未有的刚度变化，压缩时增加了 28 倍，弯曲时增加了 13 倍。我们在具有不同张拉整体架构的三种验证场景中展示了所提出的 VSTS 的功能：（1）具有可调承载能力的梁，（2）可以自行部署并在部署和未部署状态下锁定其形状的结构， (3) 具有欠驱动形状变形的关节。