Portable Support Polygon Measurement System in Walking Aid Supported Gait

Accurate measurement of the support polygon is crucial for assessing balance and stability during gait. This is of particular concern for individuals requiring a walking aid such as a cane or crutch. However, existing methods require fixed infrastructure or time-consuming setup, hindering community-based assessments and applications. This work introduces a novel system that uses sensors mounted to a cane or other gait aid and a manifold extended Kalman filter (MEKF) technique to estimate the relative contact surface locations between the user and the ground, even in the presence of intermittent measurements. The proposed technique serves as a versatile framework for various applications requiring relative pose information. The performance of a computer-tethered prototype was evaluated in three configurations against a laboratory-based motion capture system yielding mean absolute errors (MAEs) of 20–62 mm in the horizontal plane for the feet and crutch positions. To isolate the effects of measurement intermittency from measurement accuracy, the algorithm was also run with simulated measurements with zero error, but with the same intermittency, resulting in MAEs of 8–20 mm. These findings demonstrate the feasibility of the approach and underscore the significance of sensor accuracy. Due to only requiring sensors on the walking aid, the proposed system may offer a practical solution for balance evaluation in community-based applications.