Serina E R, Mockensturm E, Mote C D, Rempel D
Department of Mechanical Engineering, University of California, Berkeley, USA.
J Biomech. 1998 Jul;31(7):639-46. doi: 10.1016/s0021-9290(98)00067-0.
The fingertip pulp modulates the force transmitted to the underlying musculoskeletal system during finger contact on external bodies. A model of the fingertip pulp is needed to represent the transmission of forces to the tendons, muscles, and bone during these contacts. In this study, a structural model of the in vivo human fingertip was developed that incorporates both the material inhomogeneity and geometry. Study objectives were to determine (1) if this fingertip model can predict the force-displacement and force contact area responses of the in vivo human fingertip during contact with a flat, rigid surface, and (2) if the stresses and strains predicted by this model are consistent with the tactile sensing functionality of the in vivo human fingertip. The in vivo fingertip pulp was modeled as an inflated, ellipsoidal membrane, containing an incompressible fluid, that is quasi-statically compressed against a flat, frictionless surface. The membrane was assigned properties of skin (Veronda and Westmann, 1970) and when inflated, possessed dimensions approximating those of a human fingertip. Finite deformation was allowed. The model was validated by the pulp force-displacement relationship obtained by Serina et al. (1997) and by measurements of the contact area when the fingertip was pressed against a rigid surface with contact forces between 0.25 and 7.0 N. Model predictions represent the experimental data sufficiently well, suggesting that geometry, inhomogeneous material structure, and initial skin tension appear to represent the nonlinear response of the in vivo human fingertip pulp under compression. The predicted response of the fingertip pulp is consistent with its functionality as a tactile sensor.
指尖肉垫在手指接触外部物体时，会调节传递至其下方肌肉骨骼系统的力。需要一个指尖肉垫模型来描述这些接触过程中力向肌腱、肌肉和骨骼的传递。在本研究中，构建了一个包含材料不均匀性和几何形状的体内人体指尖结构模型。研究目的是确定：（1）该指尖模型能否预测体内人体指尖在与平坦刚性表面接触时的力-位移和力-接触面积响应；（2）该模型预测的应力和应变是否与体内人体指尖的触觉传感功能一致。体内指尖肉垫被建模为一个充有不可压缩流体的膨胀椭圆形膜，该膜在准静态下被压向一个平坦、无摩擦的表面。该膜被赋予皮肤的属性（Veronda和Westmann，1970年），充气后其尺寸近似于人体指尖。允许有限变形。通过Serina等人（1997年）获得的肉垫力-位移关系以及当指尖以0.25至7.0 N的接触力压在刚性表面上时接触面积的测量结果对模型进行了验证。模型预测结果与实验数据拟合良好，这表明几何形状、不均匀材料结构和初始皮肤张力似乎能够体现体内人体指尖肉垫在压缩状态下的非线性响应。指尖肉垫的预测响应与其作为触觉传感器的功能一致。
