Validation of Fuze IMU system for ergonomics assessments

This study aims to validate the Fuze system (SwiftMotion, CA, USA), against the gold standard for motion capture, a 3D infra-red motion capture system (Vicon Nexus, Oxford, UK). Fuze system uses inertial measurement units and proprietary algorithms to calculate position and orientation of each body segment Six subjects (3M and 3F) performed two activities that simulate common occupational physical activities. For both systems, we calculated the following joint angles: trunk relative to horizontal, left and right shoulder and hip joint angles. We also calculated the horizontal distance of each wrist relative to the the fifth lumbar vertebra. For each measurement, we calculated Bias (average difference between Fuze and Vicon system) and root mean squared error (RMSE). We also compared each measurement using a Statistical Parametric Mapping (SPM) method with a statistical significance level set at 0.05. Compared to Vicon, Fuze system had a maximum Bias of 5.63 {+/-} 1.60 degrees for the left shoulder angle and a maximum RMSE of 10.03 {+/-} 2.73 degrees for the left hip angle. SPM analysis evidenced that for all the measurements, comparisons were within the critical thresholds for significance for the whole duration of the trials, indicating that we could not find a significant difference between Vicon and Fuze measurements. In conclusion: the Fuze system compares well with the Vicon system and provides reliable data for the measurement of joint angles and body positions, that can be used in particular in non labbased settings, for example in ergonomics risk assessments.