1Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.
2Advanced Robotics Center, National University of Singapore, Singapore, Singapore.
Soft Robot. 2019 Aug;6(4):468-482. doi: 10.1089/soro.2018.0084. Epub 2019 Jun 3.
The use of soft robotic actuators is on the rise because these soft systems offer the advantage of being highly flexible, which affords safer robot-environment interactions and the gentleness necessary to handle delicate objects. However, this advantage becomes a shortcoming in high-force applications where flexible components fold and fail under large loads. Various methods were sought to meet this challenge by providing a level of rigidity to soft components, but previously proposed solutions bring their own drawbacks including bulky systems, addition of superfluous weight, and restriction of actuator motion. Alternatively, this article presents Tubular Jamming, a new and effective means of stiffening that is adaptable to motion, lightweight, and can be implemented with minimal equipment. In this study, the mechanism of tubular jamming is expounded and is demonstrated through two exemplary soft structures: a tubular jammed beam (TJB) and a tubular jammed hinge (TJH). Both TJB and TJH are exhibited in areas of fabrication, characterization, and a few possible examples of implementation in soft robotic systems. In the TJB structure, tubular jamming is found to increase bending stiffness by nearly threefold at the maximum pressure and packing ratio tested, compared with a traditional soft pneumatic actuator (SPA) beam. The TJB is shown to require less supply pressure to achieve the same performance as a traditional SPA and is shown to perform better in maintaining the vertical position of a borne object. A triangular support configuration made from TJBs is demonstrated to be proficient in weight bearing, supporting a load of nearly 33 times its own weight. In the TJH structure, tubular jamming is shown to have a compound effect on torque output, as three jammed tubule hinges produce approximately four times the torque of a single tubule hinge. The TJH is exhibited in a wearable elbow flexion device. Tubular jamming opens new possibilities for soft components to achieve the stiffness needed to perform high-force tasks such as weight bearing and large-scale actuation while retaining the suppleness to enable a safe robot-to-environment interface.
软机器人致动器的使用正在增加，因为这些软系统具有高度灵活性的优势，这为机器人与环境的安全交互提供了保障，并能够轻柔地处理精细物体。然而，在需要高力应用的情况下，这种优势就变成了一个缺点，因为柔性组件在大负载下会折叠和失效。人们寻求了各种方法来应对这一挑战，为软组件提供一定程度的刚性，但以前提出的解决方案都有其自身的缺点，包括系统庞大、增加不必要的重量以及限制致动器运动。或者，本文提出了管状卡紧，这是一种新的有效的加固方法，它适应运动，重量轻，并且可以用最少的设备来实现。在这项研究中，阐述了管状卡紧的机理，并通过两个示例软结构：管状卡紧梁（TJB）和管状卡紧铰链（TJH）进行了演示。TJB 和 TJH 都在制造、特性化方面进行了展示，并在一些软机器人系统中的实现示例中进行了展示。在 TJB 结构中，与传统的软气动致动器（SPA）梁相比，管状卡紧在最大压力和填充比下可将弯曲刚度提高近三倍。TJB 只需较小的供应压力即可实现与传统 SPA 相同的性能，并且在保持承载物体的垂直位置方面表现更好。展示了由 TJB 制成的三角形支撑结构在承重方面非常出色，能够支撑近自身重量 33 倍的负载。在 TJH 结构中，管状卡紧对扭矩输出有复合效应，三个卡紧的管状铰链产生的扭矩约为单个管状铰链的四倍。TJH 在可穿戴的肘部弯曲装置中进行了展示。管状卡紧为软组件提供了新的可能性，使其能够获得执行高力任务（如承重和大规模致动）所需的刚度，同时保持柔软性，以实现安全的机器人与环境接口。
