Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, MS 39216, USA.
Gait Posture. 2010 Mar;31(3):403-6. doi: 10.1016/j.gaitpost.2010.01.009. Epub 2010 Feb 6.
Footswitches, instrumented insoles, and forceplates are commonly used for detecting footfall instants during treadmill walking. This study aimed to explore the feasibility of using an optoelectronic light curtain for detecting initial foot contact (FC) and toe-off (TO) instants during treadmill walking. A commercial light curtain comprised of an array of parallel infrared light beams was installed 5 mm above the treadmill belt. Ten subjects walked on the treadmill at 0.5, 1.0 and 1.4 m/s and their gait was captured using seven optoelectronic cameras. Footswitches were secured over the heel and big toe of the right foot and the corresponding areas of the shoe. Footfall instants from the light curtain, markers, and foot footswitches were compared with the shoe footswitches serving as a criterion. The respective time differences were computed for each step and used to evaluate the agreement with the criterion and variability across subjects. FC instants from foot footswitches were on average within 10ms of the criterion. Both video and light curtain FC instants were detected at least 30 ms before the criterion. For TO, both the foot footswitches and video instants preceded the criterion. In contrast, the TO from the light curtain occurred >110 ms after the criterion but the variability was the smallest. The results indicated that using a light curtain for detecting footfall instants is feasible. The advantages of light curtain are relatively low cost, no subject preparations, and real-time signals. Greater accuracy is expected with further optimization of the setup.
足底开关、足底传感器和测力板常用于检测跑步机步行时的足跟着地和足尖离地时刻。本研究旨在探讨使用光电光幕检测跑步机步行时初始接触（FC）和足尖离地（TO）时刻的可行性。一个商业的光电光幕由一系列平行的红外光束组成，安装在跑步机皮带上方 5 毫米处。10 名受试者以 0.5、1.0 和 1.4m/s 的速度在跑步机上行走，他们的步态由七个光电摄像机捕获。足底开关固定在右脚的脚跟和大脚趾以及鞋子的相应区域。光电光幕、标记和足底开关的足跟着地和足尖离地时刻与作为标准的鞋式足底开关进行比较。分别计算每个步的时间差异，并用于评估与标准的一致性和受试者间的变异性。足底开关的 FC 时刻平均比标准快 10ms。视频和光电光幕的 FC 时刻都至少在标准时刻前 30ms 检测到。对于 TO，足底开关和视频都在标准时刻之前。相比之下，光电光幕的 TO 发生在标准时刻之后>110ms，但变异性最小。结果表明，使用光电光幕检测足跟着地和足尖离地时刻是可行的。光电光幕的优点是成本相对较低、无需受试者准备且可实时获取信号。进一步优化设置后，预计会有更高的准确性。
