基于流固耦合的手指触觉生物力学研究

【作者】 邱跃统；

【导师】 孙中圣；

【作者基本信息】 南京理工大学 ， 机械制造及其自动化， 2012， 硕士

【摘要】 自上世纪九十年代,虚拟现实技术得到蓬勃发展,当前已经成为一个热门的研究领域。在虚拟现实系统中,触觉的模拟和再现是增强系统真实感,营造沉浸效果的重要手段。但是目前虚拟现实系统中触觉信息的引入尚存在不足,这使得系统的沉浸程度和交互程度大打折扣。触觉的研究主要集中在两方面：触觉生物力学的研究和触觉接口设备的研究。前者主要是触觉机理的研究,后者主要是触觉再现的研究。触觉生物力学的研究可以增强对触觉感知机理的理解,分析触觉感知的影响因素,有助于触觉再现接口设备的设计。本文主要是从数值模拟和实验来对触觉生物力学进行研究,主要包括研究单喷嘴下以静态载荷及动态载荷方式作用时手指的力学响应,从而为触觉接口的设计提供依据以及为纹理再现打下基础。首先,在当前触觉生物力学研究的基础上,从手指的几何结构以及材料属性出发建立手指三维线性和非线性有限元模型,以及建立喷嘴的流体有限元模型。并根据实际的气动触觉接口工作情况,采用流固耦合研究算法,对所建的模型进行流固耦合计算,并建立触觉表征参数。其次,从数值模拟角度进行触觉生物力学研究,分析在不同形式载荷下手指的力学响应。静态载荷下,采用触觉表征参数分析喷嘴入口压力、喷嘴直径以及接触高度对手指内部力学响应的影响,从而指导触觉接口的设计；动态载荷则分析了在阶跃载荷下手指蠕变特性和应力松弛特性,以及正弦变化载荷下频率和振幅对手指力学响应的影响,为纹理再现打下基础。最后,从实验角度进行触觉生物力学研究,包括建立试验系统并与数值模拟结果进行对比。主要从手指受到的力以及手指的变形两个方面进行对比,手指的变形又包括变形轮廓、最大变形以及手指变形的时程响应。实验结果证明在触觉生物力学研究中非线性模型更为合理,以及流固耦合数值模拟的正确性。更多还原

【Abstract】 Virtual reality technology has flourished since 1990s, and it is a research hotspot at present. In virtual reality system, tactile sense simulation and display is an important tool to strengthen the realistic sensation and construct the immersion. But the introduction of tactile information in virtual system is not enough now, which greatly decreasing the immersion and interaction.The tactile research focuses on two aspects:tactile biomechanics research and tactile interface research. The former mainly researches tactile mechanism, and the latter mainly researches tactile display. The research of tactile biomechanics is helpful for enhancing the understanding of tactile mechanism and analyzing the factors how to influence tactile sense, which is greatly useful to the design of tactile interface.This paper researches tactile biomechanics by numerical simulations and experiments, mainly including the response of fingertip under static stimulus and dynamic stimulus by single nozzle, which aimed to supply basis for the design of tactile interface and lay foundations for displaying surface texture.Firstly, based on current research status of tactile biomechanics, three-dimensional linear and nonlinear finite element models of fingertip are built from geometry and material properties, and fluid finite element model of nozzle is built. Meanwhile, based on the actual working conditions of pneumatic tactile interface, fluid-structure coupling algorithm is applied. Numerical simulation of fluid-structure interaction is performed based on former models, and the characteristic parameters of tactile are established.Secondly, tactile biomechanics is researched by numerical simulations, and the mechanical responses are analyzed under different loads. The influence of inlet pressure, diameter of nozzle, contact height on the response of fingertip under static stimulus are analyzed relying on characteristic parameters of tactile, which is helpful for the design of tactile interface; the response of fingertip under dynamic stimulus is analyzed, including the features of creep and stress relaxation under step load as well as the response under the load changing as sine wave with time, which is helpful for displaying surface texture.At the last, tactile biomechanics are researched by experiments, which are including building experiment system and the comparison between numerical simulations and the experiments results. The comparison is conducted from two aspects:the force applied to fingertip by nozzle and the deformation of fingertip under pressure. The aspect of deformation includes the deformation profile of fingertip, the maximum deformations under different conditions and the time history response of deformation. The results of experiments prove the nonlinear model is more reasonable in tactile biomechanics research, and the correctness of fluid-structure coupling numerical simulation.更多还原