Ultra-Wideband Radar-based Gait Analysis System for Non-Contact Knee Angle Monitoring

Variations in knee angles are important parameters used for clinical gait analysis. They are measured using gold-standard marker-based motion capture systems in clinical research. However, these systems are difficult to operate for longer durations and are limited to laboratory environments. Although camera-based approaches are available, they require a direct line of sight, adequate ambient lighting, and a clear background. Ultra-wideband radar technology (UWB) has the potential to address these limitations and support moving away from strict laboratory settings. This paper presents a UWB radar-based gait analysis system to capture walking gait, a novel algorithm, a unique detection intensity level algorithm (DILA), registering detections in a 3D space, and a PointNet-inspired neural network (DIL-PointNet) for knee angle estimation. The proposed system is validated against knee angles calculated with the Qualisys marker-based motion capture system. It achieved a mean absolute error (MAE) of 7.9° and a root mean squared error (RMSE) of 11.1°. Thus, the proposed system has the potential for long-term remote gait monitoring in real world environments.