An apparatus and a method for determining the slip resistance of shoes and floors by simulation of human foot motions

Abstract

An apparatus to measure the coefficient of kinetic friction (μ_k) between the shoe sole and the underfoot surface was constructed, and a method including criteria to evaluate the risk of slipping during walking was developed. The apparatus is a prototype stationary step simulator capable of simulating the movements of a human foot and the forces applied to the underfoot surface during an actual slip, and the drainage capability of the contact surface between the shoe sole and the flooring when different lubricants or contaminants are used. The apparatus consists of a movable artificial foot controlled by a computer with the aid of three hydraulic cylinders. The frictional force (F_μ), the normal force (F_N) and their ratio (μ_k = F_μ/F_N) are measured with a two-way force platform when the foot slides along its surface. Two separate gait patterns, heel-slide (μ_k1) and sole-slide (μ_k2) gait pattern, are used for the evaluations. The method classifies studied shoe, lubricant and underfoot surface combinations into five slip resistance classes according to the measured μ_k1 The slip resistance assessments are specified with some complementary safety criteria, e.g., the ratio μ_k1/ μ_k2 The reliability of the developed measurement method was assessed in an international comparison test. According to available results discussed in this paper, our method seems to be valid and the slip resistance measurements seem to be repeatable.