Robert-Lachaine Xavier, Mecheri Hakim, Larue Christian, Plamondon André
Institut de Recherche Robert Sauvé en Santé et en Sécurité du Travail, 505 Maisonneuve Ouest, Montréal, QC, Canada.
Institut de Recherche Robert Sauvé en Santé et en Sécurité du Travail, 505 Maisonneuve Ouest, Montréal, QC, Canada.
Appl Ergon. 2017 Sep;63:123-132. doi: 10.1016/j.apergo.2017.04.011. Epub 2017 Apr 26.
Inertial measurement units (IMUs), a practical motion analysis technology for field acquisition, have magnetometers to improve segment orientation estimation. However, sensitivity to magnetic disturbances can affect their accuracy. The objective of this study was to determine the joint angles accuracy of IMUs under different timing of magnetic disturbances of various durations and to evaluate a few correction methods. Kinematics from 12 individuals were obtained simultaneously with an Xsens system where an Optotrak cluster acting as the reference system was affixed to each IMU. A handling task was executed under normal laboratory conditions and imposed magnetic disturbances. Joint angle RMSE was used to conduct a three-way repeated measures analysis of variance in order to contrast the following disturbance factors: duration (0, 30, 60, 120 and 240 s), timing (during the disturbance, directly after it and a 30-second delay after it) and axis (X, Y and Z). The highest joint angle RMSE was observed on rotations about the Y longitudinal axis and during the longer disturbances. It stayed high directly after a disturbance, but returned close to baseline after a 30-second delay. When magnetic disturbances are experienced, waiting 30 s in a normal condition is recommended as a way to restore the IMUs' initial accuracy. The correction methods performed modestly or poorly in the reduction of joint angle RMSE.
惯性测量单元（IMU）是一种用于现场采集的实用运动分析技术，它配备磁力计以改善节段方向估计。然而，对磁干扰的敏感性会影响其准确性。本研究的目的是确定在不同持续时间的磁干扰的不同时刻下IMU的关节角度准确性，并评估几种校正方法。通过Xsens系统同时获取12名个体的运动学数据，其中一个作为参考系统的Optotrak集群被固定在每个IMU上。在正常实验室条件下并施加磁干扰的情况下执行一项操作任务。使用关节角度均方根误差（RMSE）进行三因素重复测量方差分析，以对比以下干扰因素：持续时间（0、30、60、120和240秒）、时刻（干扰期间、干扰刚结束时以及干扰结束后30秒延迟）和轴（X、Y和Z）。在绕Y纵轴旋转以及较长干扰期间观察到最高的关节角度RMSE。干扰刚结束时它保持在较高水平，但在30秒延迟后恢复到接近基线水平。当遇到磁干扰时，建议在正常条件下等待30秒，作为恢复IMU初始准确性的一种方法。这些校正方法在降低关节角度RMSE方面表现一般或较差。
