Serchi V, Peruzzi A, Cereatti A, Della Croce U
Annu Int Conf IEEE Eng Med Biol Soc. 2014;2014:3727-30. doi: 10.1109/EMBC.2014.6944433.
Inaccurate visual sampling and foot placement may lead to unsafe walking. Virtual environments, challenging obstacle negotiation, may be used to investigate the relationship between the point of gaze and stepping accuracy. A measurement of the point of gaze during walking can be obtained using a remote eye-tracker. The assessment of its performance and limits of applicability is essential to define the areas of interest in a virtual environment and to collect information for the analysis of the visual strategy. The current study aims at characterizing a gaze eye-tracker in static and dynamic conditions. Three different conditions were analyzed: a) looking at a single stimulus during selected head movements b) looking at multiple stimuli distributed on the screen from different distances, c) looking at multiple stimuli distributed on the screen while walking. The eye-tracker was able to measure the point of gaze during the head motion along medio-lateral and vertical directions consistently with the device specifications, while the tracking during the head motion along the anterior-posterior direction resulted to be lower than the device specifications. During head rotation around the vertical direction, the error of the point of gaze was lower than 23 mm. The best accuracy (10 mm) was achieved, consistently to the device specifications, in the static condition performed at 650 mm from the eye-tracker, while point of gaze data were lost while getting closer to the eye-tracker. In general, the accuracy and precision of the point of gaze did not show to be related to the stimulus position. During fast walking (1.1 m/s), the eye-tracker did not lose any data, since the head range of motion was always within the ranges of trackability. The values of accuracy and precision during walking were similar to those resulting from static conditions. These values will be considered in the definition of the size and shape of the areas of interest in the virtual environment.
不准确的视觉采样和脚步放置可能导致行走不安全。虚拟环境，具有挑战性的障碍物谈判，可用于研究注视点与步幅准确性之间的关系。可以使用远程眼动仪获得行走过程中注视点的测量值。评估其性能和适用范围的限制对于定义虚拟环境中的感兴趣区域以及收集用于分析视觉策略的信息至关重要。当前的研究旨在表征在静态和动态条件下的注视眼动仪。分析了三种不同的条件：a）在选定的头部运动期间注视单个刺激物；b）注视分布在屏幕上不同距离的多个刺激物；c）在行走时注视分布在屏幕上的多个刺激物。眼动仪能够在头部沿中外侧和垂直方向运动期间按照设备规格一致地测量注视点，而在头部沿前后方向运动期间的跟踪结果低于设备规格。在头部绕垂直方向旋转期间，注视点的误差低于23毫米。在距离眼动仪650毫米处进行的静态条件下，按照设备规格实现了最佳精度（10毫米），而在靠近眼动仪时注视点数据丢失。一般来说，注视点的准确性和精确性与刺激物位置无关。在快速行走（1.1米/秒）期间，眼动仪没有丢失任何数据，因为头部的运动范围始终在可跟踪范围内。行走期间的准确性和精确性值与静态条件下的结果相似。这些值将在定义虚拟环境中感兴趣区域的大小和形状时予以考虑。
