Mo Shiwei, Chow Daniel H K
Department of Health and Physical Education, The Education University of Hong Kong, 10 Lo Ping Road, Tai Po, New Terries, Hong Kong Special Administrative Region.
Department of Health and Physical Education, The Education University of Hong Kong, 10 Lo Ping Road, Tai Po, New Terries, Hong Kong Special Administrative Region.
Gait Posture. 2018 Jan;59:93-98. doi: 10.1016/j.gaitpost.2017.10.009. Epub 2017 Oct 6.
Inertial measurement units (IMUs) have been extensively used to detect gait events. Various methods have been proposed for detecting initial contact (IC) and toe-off (TO) using IMUs affixed at various anatomical locations. However, the accuracy of such methods has yet to be compared. This study evaluated the accuracy of three common methods used for detecting gait events during jogging and running: (1) S-method, in which IC is identified as the instant of peak foot-resultant acceleration and TO is identified when the acceleration exceeds a threshold of 2g in the region of interest; (2) M-method, in which IC and TO are defined as the minimum before the positive peak shank vertical acceleration and the minimum in the region of interest, respectively; and (3) L-method, in which IC is indicated by the instant of peak pelvis anteroposterior acceleration and TO is identified by the maximum in the region of interest. The performance of the IMU-based methods in detecting IC and TO and estimating stance time (ST) were tested on 11 participants at jogging and running speeds against a reference provided by a force-platform method. The S-method was the most accurate for IC detection (overall mean absolute difference (MAD): 4.7±4.1ms). The M-method was the most accurate for TO detection (overall MAD: 7.0±3.5ms). A combination of M- and S-methods, called the MS-method, was the most accurate for ST estimation (overall MAD: 9.0±3.9ms). Thus, the MS-method is recommended for ST estimation; however, this method requires four IMUs for bilateral estimation.
惯性测量单元（IMU）已被广泛用于检测步态事件。人们提出了各种方法，通过固定在不同解剖位置的IMU来检测初始接触（IC）和离地（TO）。然而，这些方法的准确性尚未得到比较。本研究评估了三种用于检测慢跑和跑步过程中步态事件的常用方法的准确性：（1）S方法，其中IC被识别为足部合成加速度峰值的瞬间，TO被识别为感兴趣区域内加速度超过2g阈值时；（2）M方法，其中IC和TO分别被定义为小腿垂直加速度正峰值之前的最小值和感兴趣区域内的最小值；（3）L方法，其中IC由骨盆前后加速度峰值的瞬间指示，TO由感兴趣区域内的最大值识别。在11名参与者以慢跑和跑步速度运动时，针对力平台法提供的参考，测试了基于IMU的方法在检测IC和TO以及估计站立时间（ST）方面的性能。S方法在检测IC方面最准确（总体平均绝对差（MAD）：4.7±4.1毫秒）。M方法在检测TO方面最准确（总体MAD：7.0±3.5毫秒）。一种称为MS方法的M方法和S方法的组合在估计ST方面最准确（总体MAD：9.0±3.9毫秒）。因此，推荐使用MS方法进行ST估计；然而，该方法需要四个IMU进行双侧估计。
