Shoe-Floor Interactions During Human Slip and Fall: Modeling and Experiments

Abstract

Shoe-floor interactions such as friction force and deformation/local slip distributions are among the critical factors to determine the risk for potential slip and fall. In this paper, we present modeling, analysis, and experiments to understand the slip and force distributions between the shoe sole and floor surface during the normal gait and the slip and fall gait. The computational results for the slip and friction force distribution are based on the spring-beam networks model. The experiments are conducted with several new sensing techniques. The in-situ contour footprint is accurately measured by a set of laser line generators and image processing algorithms. The force distributions are obtained by combining two types of force sensor measurements: implanted conductive rubber-based force sensor arrays in the shoe sole and six degree-of-freedom (6-DOF) insole force/torque sensors. We demonstrate the sensing system development through extensive experiments. Finally, the new sensing system and modeling framework confirm that the use of required coefficient of friction and the deformation measurements can real-time predict the slip occurrence.

A robotic bipedal model for human walking with slips

“…7(c) shows the coefficient of friction (COF) of the stance-foot contact during the slip recovery process. Before slips start (around 0.32 s), the required (actual) COF lies in a range of |μ| < 0.2, which is far less than the available footfloor friction coefficient (measured as close to 1 of the dry rubber-wood contact [9]). At t = 0.32 s, the available COF is less than 0.05 due to the fluidic soap film on surface.…”

“…We use an integrated sensor suite inside shoes to measure the 3D GRF. The details of these sensors are discussed in [9]. Combining with the wearable motion sensors (e.g., [16]), we obtain the limb poses and forces in indoor or outdoor environment.…”

“…The GRF sensors and the motion capture system are synchronized for data collection. The details of discussion about the experimental setup are reported in [9].…”

“…Unlike the bipedal model in [7] that only deals with single-stance human locomotion, the proposed model includes the human trunk and also the double-stance phase in walking gaits, which is crucial for slips and fall motion. Compared with the work in [6] that include the double-stance, the proposed model includes the active ankle joints and also generates the experiments-matched ground reaction forces (GRF) [9].…”

A Perturbation Mechanism for Investigations of Phase-Dependent Behavior in Human Locomotion

“…Examples of mechanisms capable of producing multi-joint perturbations can be found in [3], [4], [19], [27]–[30], where different hypotheses and properties were studied. In [30] the response of people to slipping conditions was studied, whereas in [27] a multi-axial machine was specifically built and validated to alter the gait cycle in different directions.…”