Analysis of Joint Kinematics using Waterproof IMU and Motion Capture: A Case Study

The current gold standard for clinical gait analyses is marker-based motion-capture (Mocap). However, treatment regimens for some clinical populations rely on aquatic environments where motion capture is not feasible. A less expensive, portable, and waterproof option is inertial measurement units (IMUs), which are sensors that are able to track body movements. However, they require validation before becoming an accepted alternative to Mocap. The purpose of this case study was to assess a waterproof IMU system’s accuracy during walking at various speeds using Mocap as the gold-standard. One healthy adult male completed three self-selected speed walking trials: normal, slow, and fast, over a 5m path. Mocap movement data were recorded using a lower extremity marker set and tri-axial waterproof Wavetrack IMU sensors were secured to both feet, shins, thighs, and one on the pelvis. Preliminary results demonstrate that IMU-based joint range of motion (ROM) of the hip have the greatest accuracy, followed by the knee, and ankle, compared to Mocap-based joint ROM. As a first step, this case report provides data to quantify measurement differences between joint angles calculated with IMUs compared to Mocap