Abstract
Over half of older adult falls are caused by tripping. Many of these trips are likely due to obstacles present on walkways that put older adults or other individuals with low foot clearance at risk. Yet, Minimum Foot Clearance (MFC) values have not been measured in real-world settings and existing methods make it difficult to do so. In this paper, we present the Minimum Foot Clearance Estimation (MFCE) system that includes a device for collecting calibrated video data from pedestrians on outdoor walkways and a computer vision algorithm for estimating MFC values for these individuals. This system is designed to be positioned at ground level next to a walkway to efficiently collect sagittal plane videos of many pedestrians’ feet, which is then processed offline to obtain MFC estimates. Five-hundred frames of video data collected from 50 different pedestrians was used to train (370 frames) and test (130 frames) a convolutional neural network. Finally, data from 10 pedestrians was analyzed manually by three raters and compared to the results of the network. The footwear detection network had an Intersection over Union of 85% and was able to find the bottom of a segmented shoe with a 3-pixel average error. Root Mean Squared (RMS) errors for the manual and automated methods for estimating MFC values were 2.32 mm, and 3.70 mm, respectively. Future work will compare the accuracy of the MFCE system to a gold standard motion capture system and the system will be used to estimate the distribution of MFC values for the population.
Highlights
Falls are a major health issue, especially among those who are 65 or older, for whom falling is the most common reason for non-fatal injuries [1]
Future work will compare the accuracy of the Minimum Foot Clearance Estimation (MFCE) system to a gold standard motion capture system and the system will be used to estimate the distribution of Minimum Foot Clearance (MFC) values for the population
A trip typically occurs during swing phase at or near the Minimum Foot Clearance (MFC) point if the trajectory of the foot is suddenly interrupted by an obstacle [6]
Summary
Falls are a major health issue, especially among those who are 65 or older, for whom falling is the most common reason for non-fatal injuries [1]. 3 million people in the United States suffer injuries caused by falls [2]. Existing research demonstrates that 13% of the older adults have MFC values below 6mm and that even healthy young adults would trip on an unseen 5 mm obstacle 1 in every 95 strides [12]. Conditions such as advanced age, Parkinson’s disease, performing dual tasks, or being fatigued, can cause individuals to have reduced mean MFC mean or increased.
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