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Preliminary Evaluation of a Wearable Camera-based Collision Warning Device for Blind Individuals

Pundlik, Shrinivas, PhD1*; Tomasi, Matteo, PhD1; Moharrer, Mojtaba, PhD1; Bowers, Alex R., PhD, MCOptom, FAAO1; Luo, Gang, PhD1

doi: 10.1097/OPX.0000000000001264

SIGNIFICANCE 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.

PURPOSE 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.

METHODS 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.

RESULTS 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).

CONCLUSIONS 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.

1Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, Massachusetts *

Submitted: December 22, 2017

Accepted: May 22, 2018

Funding/Support: U.S. Department of Defense (W81XWH-15-C-0072; to GL and ARB).

Conflict of Interest Disclosure: Authors GL and SP are listed as inventors on a patent related to the collision warning technology (patent assigned to Schepens Eye Research Institute). There are no conflicts of interest for the other co-authors. The sponsor provided financial and material support, but had no role in the study design, conduct, analysis and interpretation, or writing of the report.

Author Contributions and Acknowledgments: Conceptualization: SP, MT, ARB, GL; Data Curation: SP, MT, MM; Formal Analysis: SP; Funding Acquisition: ARB, GL; Investigation: SP, MT, ARB, GL; Methodology: SP, MT, MM, ARB, GL; Project Administration: ARB, GL; Resources: ARB, GL; Software: SP; Supervision: ARB, GL; Writing – Original Draft: SP; Writing – Review & Editing: SP, MT, MM, ARB, GL.

The authors thank Amy Doherty and Vilte Baliutaviciute for their help with data collection and Xuedong Yuan for his help in hardware design.

The research was funded in part by the U.S. Army Medical Research and Material Command under contract no. W81XWH-15-C-0072.

The views, opinions, and/or findings contained in this report are those of the authors and should not be construed as an official Department of Army position, policy, or decision unless so designated by other documentation.

© 2018 American Academy of Optometry