A Two-Dimensional Nonlinear Volumetric Foot Contact Model

Abstract

This paper presents the development of a two-dimensional (2D) multibody foot contact model consisting of a volumetric model of foot pad. The volumetric model employs nonlinear springs and linear dampers to represent the complex material behavior of the foot pad, typical of a visco-hyperelastic material. The nonlinear springs of the foot contact model are motivated by an Ogden-type material that can describe the nonlinear constitutive behavior of a wide variety of biological tissues and rubbers. The geometry of the foot pad is modeled as three simplified ellipse which represent the heel, balls of the feet, and toe. The efficacy of the developed foot contact model is established by driving the simulation model with kinematics observed from walking experiments and comparing the generated ground reaction force with the experimental data.

Foot–ground contact modeling within human gait simulations: from Kelvin–Voigt to hyper-volumetric models

“…Although the spherical volumetric elements produced reasonable results, which were much better than the point contact models as they provide a wider contact patch, more complicated shapes like an ellipsoid as in [25] and Ch. 6 of [18] can be employed in the future.…”

“…Additionally, the proposed hyper-volumetric model had a different concept than that presented by Sandhu and McPhee [25]. Their model was nonlinear, but they did not compute any closed-form volumes; they computed the deformed volumes numerically, which leads to slower simulations.…”

“…This concept has been used to model the foot-ground interaction by spherical ( [6] and Sec. 4.4 of [20]), cylindrical ( [17,35]), and elliptical ( [18,25]) elements. These volumetric contact elements are claimed to be more efficient than point contact nodes during simulations (nearly 18% faster and approximately 37% numerically less stiff); see Ch.…”

Constrained Dynamic Optimization of Sit-to-Stand Motion Driven by Bézier Curves

“…The chair is assumed to be of steel construction, rigid, backless, armless, and of standard adjustable height [32]. A hyperbolic tangent regularized friction model, previously used for feet [33], is included between the buttocks and chair with coefficient of friction of canvas on steel [34].…”