Using Wearable Sensors to Capture Posture of the Human Lumbar Spine in Competitive Swimming

Motion capture based on wearable inertial sensors is a promising technique for swimmers' training. To apply motion capture techniques properly, a swimming motion evaluation method based on inertial motion capture technology is proposed. Our proposed method uses a multisensor data fusion algorithm for swimmers’ attitude estimation, and the swimming posture is reconstructed in combination with a human biomechanical model. Furthermore, a comparative experiment between our proposed motion capture system and the NDI motion tracking system shows that our system performs reliably and accurately, and the estimation errors are well controlled. In addition, the accuracy of the orientation estimation algorithm ranges from $\text{1.65}^{\circ }$ to $\text{3.66}^{\circ }$ . The system can capture swimmers’ lumbar spine in four competitive swimming styles. A kinematic analysis of lumbar spine movement indicates that the patterns of swimmers’ lumbar spine movement can be used to evaluate training performance and provide quantitative data for swimmers.