Effect of foot-floor friction on the external moment about the body center of mass during shuffling gait: a pilot study

Effects of foot-ground friction and age-related gait changes on falls during walking: a computational study using a neuromusculoskeletal model

We used a neuromusculoskeletal model of bipedal walking to examine the effects of foot-ground friction conditions and gait patterns on slip- and trip-induced falls. We developed three two-dimensional neuro-musculoskeletal models in a self-organized manner representing young adults, elderly non-fallers, and elderly fallers. We simulated walking under different foot-ground friction conditions. The static friction coefficient between the foot and the ground was varied from 0.05 to 2.0. Under low friction conditions, the three gait models demonstrated slip-induced falls. The elderly faller model experienced the most slip. This is because the RCOF was higher in the elderly faller model due to its short stride length but much smaller foot clearance. Under high friction conditions, only the elderly faller model demonstrated trip-induced falls. Based on the analysis using the margin of stability, the forward postural stability of the model gradually decreased under high-friction conditions, with the toe of the swing foot contacting the ground and subsequently falling forward. These results imply that there is an optimal coefficient of friction for the ground to prevent slip- and trip-induced falls by people with less stable gaits, which may provide new insights into the design of shoes and floor surfaces for the elderly.

Machine learning prediction of footwear slip resistance on glycerol-contaminated surfaces: A pilot study

Slippery surfaces due to oil spills pose a significant risk in various environments, including industrial workplaces, kitchens, garages, and outdoor areas. These situations can lead to accidents and falls, resulting in injuries that range from minor bruises to severe fractures or head trauma. To mitigate such risks, the use of slip resistant footwear plays a crucial role. In this study, we aimed to develop an Artificial Intelligence model capable of classifying footwear as having either high or low slip resistance based on the geometric characteristics and material parameters of their outsoles. Our model was trained on a unique dataset comprising images of 37 indoor work footwear outsoles made of rubber. To evaluate the slip resistant property of the footwear, all samples were tested using a cart-type friction measurement device, and the static and dynamic Coefficient of Frictions (COFs) of each outsole was determined on a glycerol-contaminated surface. Machine learning techniques were implemented, and a classification model was developed to determine high and low slip resistant footwear. Among the various models evaluated, the Support Vector Classifier (SVC) obtained the best results. This model achieved an accuracy of 0.68 ± 0.15 and an F1-score of 0.68 ± 0.20. Our results indicate that the proposed model effectively yet modestly identified outsoles with high and low slip resistance. This model is the first step in developing a model that footwear manufacturers can utilize to enhance product quality and reduce slip and fall incidents.

Different flooring surfaces affect infants' crawling performance

This study assessed the influence of different types of flooring on infants' crawling motion patterns and performance. Each participating infant (range: 8.7-12.4 months) was encouraged to crawl on a tatami mat made of woven straw as well as other flooring types such as hardwood, carpet, and joint mat. Material tests were conducted to quantify the friction and shock absorption of the flooring. A three-dimensional motion capture system was used to measure spatiotemporal and kinematic variables during hands-and-knees crawling. An increased crawling rate was associated with a faster cadence of cyclic arm movements, but not with crawling stride length. Hardwood flooring had a significantly lower crawling rate and longer duration of hand-floor contact than tatami, while the crawling stride length and range of motion of joint movements were hardly affected by flooring type. The results of this study suggest a drawback of hardwood flooring in terms of infants' effective quadrupedal locomotion.