Ma Xiaolong, Chen Lingfeng, Gao Yanfeng, Liu Daliang, Wang Binrui
College of Mechanical and Electrical Engineering, China Jiliang University, Hangzhou 310018, China.
The Key Laboratory of Special Purpose Equipment and Advanced Processing Technology, College of Mechanical Engineering, Ministry of Education and Zhejiang Province, Zhejiang University of Technology, Hangzhou 310023, China.
Biomimetics (Basel). 2023 Sep 1;8(5):398. doi: 10.3390/biomimetics8050398.
Soft fingertips have distinct intrinsic features that allow robotic hands to offer adjustable and manageable stiffness for grasping. The stability of the grasp is determined by the contact stiffness between the soft fingertip and the object. Within this work, we proposed a line vector representation method based on the Winkler Model and investigated the contact stiffness between soft fingertips and objects to achieve control over the gripping force and fingertip displacement of the gripper without the need for sensors integrated in the fingertip. First, we derived the stiffness matrix of the soft fingertip, analyzed the contact stiffness, and constructed the global stiffness matrix; then, we established the grasp stiffness matrix based on the contact stiffness model, allowing for the analysis and evaluation of the soft fingertip's manipulating process. Finally, our experiment demonstrated that the variation in object orientation caused by external forces can indicate the contact force status between the fingertip and the object. This contact force status is determined by the contact stiffness. The position error between the theoretical work and tested data was less than 9%, and the angle error was less than 5.58%. The comparison between the theoretical contact stiffness and the experimental results at the interface indicate that the present model for the contact stiffness is appropriate and the theoretical contact stiffness is consistent with the experiment data.
柔软的指尖具有独特的内在特征，可使机器人手在抓握时提供可调节和可控制的刚度。抓握的稳定性取决于柔软指尖与物体之间的接触刚度。在这项工作中，我们提出了一种基于温克勒模型的线向量表示方法，并研究了柔软指尖与物体之间的接触刚度，以实现对夹爪抓握力和指尖位移的控制，而无需在指尖集成传感器。首先，我们推导了柔软指尖的刚度矩阵，分析了接触刚度，并构建了全局刚度矩阵；然后，我们基于接触刚度模型建立了抓握刚度矩阵，以便对柔软指尖的操作过程进行分析和评估。最后，我们的实验表明，外力引起的物体方向变化可以指示指尖与物体之间的接触力状态。这种接触力状态由接触刚度决定。理论工作与测试数据之间的位置误差小于9%，角度误差小于5.58%。界面处理论接触刚度与实验结果的比较表明，当前的接触刚度模型是合适的，理论接触刚度与实验数据一致。
