Department of Mechanical and Automation Engineering, T Stone Robotics Institute, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
Hong Kong Center for Logistics Robotics, Hong Kong, China.
Soft Robot. 2021 Dec;8(6):720-734. doi: 10.1089/soro.2019.0188. Epub 2021 Mar 25.
Jamming technologies are one of the promising approaches of variable stiffness mechanisms. However, there are problems limiting the broad application of jamming-based approaches such as a limited stiffening capacity and restricted stiffening position. This article presents a variable stiffness mechanism to achieve a rapid flexible to rigid state transition with biocompatibility, fail-safe design, and enhanced stiffening capacity. A novel strategy of reconfiguration of stiffening regions, which is entitled variable stiffness reconfiguration, is exploited to control not only the stiffnesses but also the positions and areas of the stiffening regions. At first, this article provides a new approach to the variable stiffness soft robotics community to enable both stiffness control and stiffening region adjustment. In this way, additional functions of the variable stiffness mechanisms including reproducing complex manipulator postures or customizing the soft gripper, through delivering functional units into or out of the devices, are demonstrated. Through reconfiguration, our design provides a generally applicable solution for a wide range of complex manipulator postures reproduced and objects grasped by reconfiguration of the stiffening regions. The variable stiffness mechanism is empirically evaluated with a comparison with other variable stiffness strategies in which the proposed solution shows greater stiffening capability, and an experimental search of optimal parameters of the honeycomb structure is presented. Finite element models, which have shown reasonable agreement with the empirical results, are constructed to model the stiffnesses, and an analytic model of the manipulator is derived to predict the posture.
变刚度机构的一种有前途的方法是使用阻塞技术。然而，存在一些限制基于阻塞的方法广泛应用的问题，例如刚度增强能力有限和增强位置受限。本文提出了一种变刚度机构，以实现具有生物相容性、故障安全设计和增强的刚度增强能力的快速灵活到刚性状态的转变。利用一种新的增强区域的重新配置策略，即变刚度重新配置，不仅可以控制刚度，还可以控制增强区域的位置和区域。首先，本文为变刚度软机器人社区提供了一种新的方法，使刚度控制和增强区域调整成为可能。通过将功能单元送入或送出设备，可以实现变刚度机构的附加功能，包括再现复杂的机械臂姿态或定制软抓手。通过重新配置，我们的设计为通过重新配置增强区域再现的复杂机械臂姿态和抓取的物体提供了一种通用的解决方案。通过与其他变刚度策略进行比较，对变刚度机构进行了实证评估，结果表明，所提出的解决方案具有更大的刚度增强能力，并提出了蜂窝结构的最优参数的实验搜索。构建了有限元模型来模拟刚度，并推导出机械臂的解析模型来预测姿态，这些模型与实验结果具有很好的一致性。
