Comparison of MARG Sensor Results for Different Mounting Positions and Physiques for Accurate Knee Joint Motion Measurement

This study aims to validate the accuracy of sensor-based pose estimation techniques by comparison with the orientation obtained with an optical motion capture system as a reference. We used two magnetic, angular rate and gravity (MARG) sensors and attached them to the thigh and shank. MARG sensors were attached with three different position patterns (all lateral, all anterior, and lateral on the thigh and anterior on the shank), and reflective markers were attached based on point cluster technique. Two participants with different physiques performed three separate motions (knee flexion/extension, walking, and knee flexion/valgus/external rotation). We compared knee angle data acquired from two methods and evaluated the RMSE of the knee angle between different mounting positions. As a result, we found that lateral mounting was able to achieve high-accuracy measurement of lower-extremity motion with MARG sensors.