IEEE Trans Biomed Eng. 2019 Dec;66(12):3534-3542. doi: 10.1109/TBME.2019.2907322. Epub 2019 Mar 26.
Measuring three-dimensional (3-D) foot trajectories with foot-worn inertial measurement units (IMUs) is essential for a variety of applications, such as gait analysis and fall risk assessment. IMU-based foot trajectory is usually reconstructed by double integrating the global coordinate acceleration, in which drifts of signals are accumulated and lead to unbounded error increase. To reduce drift errors, a smoother-based method is proposed in this paper.
The smoother-based method not only corrects initial values of integrations, but also smooths integrating processes through a backward update. Both the orientation estimation and the velocity estimation are improved in this concept, which contribute to the improvement of the trajectory estimation.
The final results are compared with an optical motion capture system as reference. Accuracy is evaluated with ground level walking of nine adult participants, 2302 strides in total. Errors are reduced by 62% on stride length and 44% on stride width of the estimation without our method, with final errors [Formula: see text] and [Formula: see text].
CONCLUSION/SIGNIFICANCE: Results prove that our method can improve the accuracy of 3-D foot trajectory estimation. Furthermore, this smoother-based method can reduce drift-related errors when estimating trajectories, which will allow it to expand its applications into other IMU-based measurements.
使用足部穿戴式惯性测量单元（IMU）测量三维（3-D）足迹轨迹对于各种应用至关重要，例如步态分析和跌倒风险评估。基于 IMU 的足迹轨迹通常通过对全球坐标加速度进行双重积分来重建，其中信号的漂移会累积并导致无限增加的误差。为了减少漂移误差，本文提出了一种基于平滑的方法。
基于平滑的方法不仅校正了积分的初始值，而且通过后向更新平滑了积分过程。该概念改进了方向估计和速度估计，有助于提高轨迹估计的准确性。
最终结果与光学运动捕捉系统作为参考进行比较。通过 9 名成年参与者的地面行走进行了精度评估，总共有 2302 步。与没有我们的方法相比，估计的步长和步宽误差分别减少了 62%和 44%，最终误差分别为[公式：见文本]和[公式：见文本]。
结论/意义：结果证明，我们的方法可以提高 3-D 足迹轨迹估计的准确性。此外，该基于平滑的方法可以在估计轨迹时减少与漂移相关的误差，从而使其能够将其应用扩展到其他基于 IMU 的测量中。
