A 3-D Nonhomogeneous FE Model of Human Fingertip Based on MRI Measurements
A 3-D Nonhomogeneous FE Model of Human Fingertip Based on MRI Measurements
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DOI：
10.1109/tim.2012.2205102
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发表时间：
2012-07
影响因子：
5.6
通讯作者：
Zhongkui Wang;Lijuan Wang;V. A. Ho;S. Morikawa;S. Hirai
中科院分区：
文献类型：
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作者：
Zhongkui Wang;Lijuan Wang;V. A. Ho;S. Morikawa;S. Hirai
为了更好地理解人类手指感觉机制，基于磁共振成像测量，建立了灵长类动物指尖的三维非均匀有限元动力学模型。利用磁共振成像系统测量了人体指尖的几何形状，并获得了一系列二维图像。利用边界跟踪方法，从每个图像切片中跟踪指尖和远端指骨的边界，并生成一组边界节点以构建指尖的3-D四面体网格。三维网格，然后利用制定一个非齐次有限元动力学模型来模拟指尖的行为。本构模型，其中包括弹性和粘性元素，用于控制单个四面体有限元的动态行为。有限元模型进一步扩展到处理指尖和外部仪器之间的接触相互作用。与传统的指尖模型不同，本文提出的模型不仅能够更好地表示人体指尖的内部和外部几何形状，而且还考虑了组织粘性。仿真和实验进行了不同的压痕操作下的人的手指和指尖幻影。我们发现，Voigt模型可以模拟指尖体模的力行为，但很难再现人类指尖的力松弛行为。因此，我们引入了一个并行的五参数物理模型来解决这个问题。
A 3-D nonhomogeneous finite-element (FE) dynamic model of a primate fingertip is developed in this paper based on magnetic resonance (MR) imaging measurements for better understanding the mechanism of human finger sensation. The geometries of a human fingertip are measured using an MR system, and a series of 2-D images is obtained. Utilizing a boundary tracking method, boundaries of the fingertip and distal phalanx are tracked from each image slice and a set of boundary nodes is generated to construct a 3-D tetrahedral mesh of the fingertip. The 3-D mesh is then utilized to formulate a nonhomogeneous FE dynamic model for simulating the fingertip behaviors. The constitutive model, which consists of elastic and viscous elements, is employed to govern the dynamic behaviors of individual tetrahedral FE. The FE model is further extended to deal with contact interaction between the fingertip and an external instrument. Differing with conventional fingertip models, the model presented in this paper is able to not only better represent internal and external geometries of a human fingertip but also take the tissue viscosity into consideration. Simulation and experiments are performed with both a human finger and a fingertip phantom under different indentation operations. We found that the Voigt model can simulate the force behaviors of a fingertip phantom but has difficulty to reproduce the force relaxation behavior of a human fingertip. We have therefore introduced a parallel five-parameter physical model to solve this problem.