Scott S H, Winter D A
Department of Systems Design Engineering, University of Waterloo, Ontario, Canada.
J Biomech. 1993 Sep;26(9):1091-1104. doi: 10.1016/s0021-9290(05)80008-9.
A model of the human foot is proposed in which the foot is represented as eight rigid segments and eight monocentric, single-degree-of-freedom joints. The soft tissue under the foot is divided into seven independent sites of contact, or loading, and each of these is modelled as a nonlinear spring and a nonlinear damper in-parallel. The model was used to estimate the kinematics and kinetics of the foot during the stance phase of walking. The force sustained at each loading site was calculated from walking trials in which only portions of the foot landed on a small force platform. The position of the calcaneus was defined by surface markers, whereas the position of the distal segments were based upon chalk footprints and an estimate of the compression of the plantar soft tissue. The results suggest that the joints that constitute the longitudinal arch extend slightly when the forefoot is loaded. During push-off, these joints flex as the metatarsophalangeal joints extend. Similar kinematic results were estimated when the distal segments of the foot were defined by surface markers. The magnitude of the joint moments of force depended largely on the distribution of the load under the foot which varied considerably between subjects. The stable, yet resilient properties of the foot, as highlighted by this model, should be considered in three-dimensional dynamic models used to study human locomotion. The model provides an objective tool to quantify foot motion and loading, which may prove useful for describing foot function in normal and pathological conditions.
本文提出了一种人体足部模型，其中足部被表示为八个刚性节段和八个单中心、单自由度关节。足部下方的软组织被划分为七个独立的接触或加载部位，每个部位都被建模为一个非线性弹簧和一个非线性阻尼器并联。该模型用于估计步行支撑期足部的运动学和动力学。每个加载部位承受的力是通过步行试验计算得出的，在这些试验中，只有足部的部分区域落在一个小的测力平台上。跟骨的位置由体表标记定义，而远端节段的位置则基于粉笔脚印以及对足底软组织压缩的估计。结果表明，在前足加载时，构成纵弓的关节会稍有伸展。在蹬离阶段，随着跖趾关节伸展，这些关节会弯曲。当通过体表标记定义足部远端节段时，也得到了类似的运动学结果。关节力矩的大小很大程度上取决于足部下方载荷的分布，而这种分布在不同个体之间差异很大。该模型所突出显示的足部稳定而有弹性的特性，在用于研究人体运动的三维动力学模型中应予以考虑。该模型提供了一种量化足部运动和载荷的客观工具，这对于描述正常和病理状态下的足部功能可能是有用的。
