Lee Kyoung-Soub, Kim Yusung, Park Hyung-Soon
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.
ACS Appl Mater Interfaces. 2024 Feb 21;16(7):8974-8983. doi: 10.1021/acsami.3c15179. Epub 2024 Feb 8.
Soft wearable robots have been gaining increasing popularity for enhancing human physical abilities and assisting people who have physical limitations. These robots typically use tendon-driven mechanisms (TDMs) to enable remote actuation to provide better usability with compact design. TDMs comprise an actuator, an end-effector, and a transmission system by using cables or tendons to transfer forces from the actuator to the end-effector. Tendons are typically routed by frictionless guiding tubes to minimize force losses, variations in the force direction, and the volume. To make soft wearable robots even smaller, brakes need to be compacted because brakes are irreplaceable to ensure safety and energy efficiency. This study presents a shape memory alloy-based reactive tubular (SMART) brake for designing a compact and portable TDM-based device. The SMART brake actively adjusts the friction force between the brake and tendon, making it easy to achieve the desired friction state, ranging from low-friction states for free movement to high-friction states for effective braking. The brake is designed in a tubular shape, serving multifunctions as both a brake and a guiding tube. The brake's performance and theoretical model were validated through experiments and demonstrated by two wearable devices. The brake could hold a significant brake force of 19.37 N/11 mm while weighing only 0.3 g. These findings have major implications for the future development of TDM-based devices and soft wearable robots, paving the way for enhanced system portability, safety, and energy efficiency.
软可穿戴机器人在增强人类身体能力和辅助身体有局限的人方面越来越受欢迎。这些机器人通常使用腱驱动机制（TDM）来实现远程驱动，以便在紧凑设计下提供更好的可用性。TDM由一个致动器、一个末端执行器和一个传动系统组成，通过使用电缆或腱将力从致动器传递到末端执行器。腱通常通过无摩擦的导管布线，以尽量减少力的损失、力方向的变化和体积。为了使软可穿戴机器人更小，制动器需要紧凑化，因为制动器对于确保安全性和能源效率是不可替代的。本研究提出了一种基于形状记忆合金的反应式管状（SMART）制动器，用于设计一种紧凑且便携的基于TDM的设备。SMART制动器能主动调节制动器与腱之间的摩擦力，使其易于实现所需的摩擦状态，范围从自由移动的低摩擦状态到有效制动的高摩擦状态。该制动器设计为管状，兼具制动器和导管的多种功能。通过实验验证了制动器的性能和理论模型，并由两个可穿戴设备进行了演示。该制动器在仅重0.3克的情况下，能保持19.37牛/11毫米的显著制动力。这些发现对基于TDM的设备和软可穿戴机器人的未来发展具有重大意义，为提高系统的便携性、安全性和能源效率铺平了道路。
