Pundlik Shrinivas, Tomasi Matteo, Moharrer Mojtaba, Bowers Alex R, Luo Gang
Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, Massachusetts *
Optom Vis Sci. 2018 Sep;95(9):747-756. doi: 10.1097/OPX.0000000000001264.
This work describes a preliminary evaluation of a wearable collision warning device for blind individuals. The device was found to provide mobility benefit in subjects without (or deprived of) vision. This preliminary evaluation will facilitate further testing of this developmental stage device in more naturalistic conditions.
We developed a wearable video camera-based device that provided tridirectional collision warnings (right, center, and left) via differential feedback of two vibrotactile wristbands. We evaluated its mobility benefit in blind and normally sighted (NS) blindfolded individuals in indoor mobility courses.
Three evaluation experiments were conducted. First, the ability of the device to provide warnings for hanging objects not detected by a long cane was evaluated in eight NS and four blind subjects in an obstacle course with and without the device. Second, the accuracy of collision warning direction assignment was evaluated in 10 NS subjects as they walked toward a hanging object at random offsets and verbally reported the obstacle offset position with respect to their walking path based on the wristbands' vibrotactile feedback. Third, the mobility benefit of collision warning direction information was evaluated by 10 NS and 4 blind subjects when walking with and without differential wristband feedback.
In experiment 1, collisions reduced significantly from a median of 11.5 without to 4 with the device (P < .001). Percent preferred walking speed reduced only slightly from 41% without to 36% with the device (P = .04). In experiment 2, the most likely reported relative obstacle positions were consistent with the actual positions. In experiment 3, subjects made more correct navigational decisions with than without the collision warning direction information (91% vs. 69%, P < .001).
Substantial mobility benefit of the device was seen in detection of aboveground collision threats missed by a long cane and in enabling better navigational decision making based on the tridirectional collision warning information.
本研究描述了一种针对盲人的可穿戴碰撞预警设备的初步评估。该设备被发现能为无视力（或视力丧失）的受试者提供行动便利。这一初步评估将有助于在更自然的条件下对该处于研发阶段的设备进行进一步测试。
我们开发了一种基于可穿戴摄像机的设备，该设备通过两个振动触觉腕带的差异反馈提供三向碰撞预警（右、中、左）。我们在室内行动路线中评估了其对盲人和正常视力（NS）但被蒙住眼睛的个体的行动便利。
进行了三项评估实验。首先，在有和没有该设备的情况下，在障碍路线中对8名正常视力受试者和4名盲人受试者评估该设备为长手杖未检测到的悬挂物体提供预警的能力。其次，在10名正常视力受试者随机走向悬挂物体时，评估碰撞预警方向分配的准确性，他们根据腕带的振动触觉反馈口头报告障碍物相对于其行走路径的偏移位置。第三，10名正常视力受试者和4名盲人受试者在有和没有差异腕带反馈的情况下行走时，评估碰撞预警方向信息的行动便利。
在实验1中，碰撞次数从无设备时的中位数11.5显著减少到有设备时的4次（P <.001）。偏好步行速度百分比仅略有下降，从无设备时的41%降至有设备时的36%（P =.04）。在实验2中，最常报告的相对障碍物位置与实际位置一致。在实验3中，与没有碰撞预警方向信息相比，受试者在有该信息时做出了更多正确的导航决策（91%对69%，P <.001）。
在检测长手杖错过的地面碰撞威胁以及基于三向碰撞预警信息做出更好的导航决策方面，该设备具有显著的行动便利。
