Fundamental Research on Postural Stability in Response to Disturbance Stimuli Aimed at Preventing Falls on Winter Road Surfaces

Takeshi Tsuruga, Tomohiro Nomura

Winter road surface, Fall prevention, External stimulus, Postural stability

Falls on winter road surfaces in cold regions are a serious problem, especially for the elderly, as the possibility of injury is high. This study provides an important step in the developmentof a system to prevent falls by alerting people when they are walking on slippery surfaces. In this paper, as a basic study, to quantitatively investigate the effect of foot slippage on postural stability, we first created a system that presents a disturbance stimulus by moving the ground surface forward at heel strike and verified its performance. We parameterized the external disturbance stimulus by varying the acceleration and displacement of the foot.We first verified the accuracy of the system using 72 combinations of acceleration (4 to 20 m/s², in 2 m/s² increments) and acceleration distance (10 to 80 mm, in 10 mm increments) and confirmed that stimuli could be produced with high accuracy(maximum moving distance error: 80 μm, maximum acceleration percent error: 10%). Next, using the external disturbance stimulus presentation system, we investigated the combinations of foot acceleration and displacement that lead to falls in 12 healthy males. We confirmed that the conditions for external disturbance stimuli that lead to falls could be grouped within a certain range. Based on these results, we constructed a fall prediction model using a support vector machine (SVM). The overall accuracy of the model was 93%, and the fall reproduction rate was 1.00, indicating that it is possible to predict the risk of falling with high accuracy. We believe that the results of this study will provide an important foundation for the practical application of a fall prevention system on winter road surfaces.

https://doi.org/10.31871/IJNTR.10.11.4