Toward a passive low-cost in-home gait assessment system for older adults

Abstract

In this paper, we propose a webcam-based system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed, step time, and step length from a 3-D voxel reconstruction, which is built from two calibrated webcam views. The gait parameters are validated with a GAITRite mat and a Vicon motion capture system in the laboratory with 13 participants and 44 tests, and again with GAITRite for 8 older adults in senior housing. Excellent agreement with intraclass correlation coefficients of 0.99 and repeatability coefficients between 0.7% and 6.6% was found for walking speed, step time, and step length given the limitation of frame rate and voxel resolution. The system was further tested with ten seniors in a scripted scenario representing everyday activities in an unstructured environment. The system results demonstrate the capability of being used as a daily gait assessment tool for fall risk assessment and other medical applications. Furthermore, we found that residents displayed different gait patterns during their clinical GAITRite tests compared to the realistic scenario, namely a mean increase of 21% in walking speed, a mean decrease of 12% in step time, and a mean increase of 6% in step length. These findings provide support for continuous gait assessment in the home for capturing habitual gait.

Fig. 1

Webcam gait assessment system overview.

Fig. 2

(a) Two raw camera images monitoring the same scene of one subject is walking on the GAITRite in the lab (b) Human silhouettes (c) The reconstructed three-dimensional voxel person.

Fig. 3

An elderly participant during an in-home scenario test (see section V). Color features are used to track the human in a two-person scenario.

Fig. 4

(a) An illustration of a peak frame, i.e., feet are apart. Left: voxel person representation, Right: top view of the foot region projection (b) Step length variation at different frames (c) An illustration of a valley frame, i.e., feet are together. Left: voxel person representation, Right: top view of the foot region projection.

Fig. 5

In-lab validation results. (a) Velocity (b) Step Time (c) Step Length results for the webcam, GAITRite and Vicon systems. The test runs are sorted by velocity in ascending order.

Fig. 6

Comparison of the scenario results (mean and standard deviation) with a clinical test results using the GAITRite. The participant IDs are sorted based on gender and velocity. Female ID1–4; male ID5–10. (a) Velocity (b) Step time (c) Step length.