Soft Actuators with Stiffness and Shape Modulation Using 3D-Printed Conductive Polylactic Acid Material
Soft Actuators with Stiffness and Shape Modulation Using 3D-Printed Conductive Polylactic Acid Material
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DOI：
10.1089/soro.2018.0056
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发表时间：
2019-06-01
期刊：
影响因子：
7.9
通讯作者：
Tan, Xiaobo
中科院分区：
文献类型：
--
作者：
Al-Rubaiai, Mohammed;Pinto, Thassyo;Tan, Xiaobo
近年来，软机器人领域引起了越来越多的关注和发展。刚度调节是软机器人的一个理想特性，因为它能够自适应地调节机器人的承载能力、形状和运动行为。在本文中，提出了一种基于三维印刷导电聚乳酸（CPLA）材料的紧凑且经济高效的刚度调节机制，并通过能够进行刚度和形状调制的软气动执行器（SPA）展示了其在软机器人领域的潜力。特别是，CPLA 材料的导电特性允许通过焦耳热方便地控制温度和刚度。首先表征 CPLA 的机械、热塑性和电性能。该材料的杨氏模量降低了98.6%，从室温（25℃）时的1 GPa降低到80℃时的13.6 MPa，材料冷却至初始温度后完全恢复，其玻璃化转变温度为55℃，此时杨氏模量为室温下的60%。然后将通过实验确定的材料参数用于有限元建模和仿真，以研究与 CPLA 层集成的 SPA 的行为。制作了由 CPLA 支持的具有三个虚拟关节的软执行器原型，并进行了弯曲实验，以证明刚度调整和形状控制的有效性，并支持有限元模型的有效性。最后，制造了一个由两个软执行器作为手指组成的夹具，以展示局部抓取姿势以及在 CPLA 冷却后即使在压力输入关闭时也能以所需的锁定姿势承载负载的能力。
The field of soft robotics has seen increasing interest and developments in recent years. Stiffness tuning is a desirable characteristic for soft robots since it enables adaptively modulating the load-bearing capability, shape, and locomotion behavior of the robots. In this article a compact and cost-effective mechanism for stiffness tuning is proposed based on a three-dimensional printed conductive polylactic acid (CPLA) material, and its potential in soft robotics is demonstrated through a soft pneumatic actuator (SPA) capable of stiffness and shape modulation. In particular, the conductive nature of the CPLA material allows convenient control of temperature and stiffness through Joule heating. Mechanical, thermoplastic, and electrical properties of the CPLA are first characterized. The material shows 98.6% reduction of Young's modulus, from 1 GPa at room temperature (25 degrees C) to 13.6 MPa at 80 degrees C, which is fully recovered after the material is cooled down to its initial temperature, and its glass transition temperature is 55 degrees C, at which its Young's modulus is at 60% of that under room temperature. The experimentally identified material parameters are then used in finite-element modeling and simulation to investigate the behavior of a SPA integrated with a CPLA layer. A soft actuator with three virtual joints enabled by CPLA is prototyped, and bending experiments are conducted to both demonstrate the effectiveness of stiffness tuning and shape control and support the efficacy of the finite element model. Finally, a gripper composed of two soft actuators as fingers is fabricated to demonstrate localized gripping posture and the ability to carry load in a desired locked posture even when the pressure input is turned off, after the CPLA is cooled down.