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Nii Tete Mante, Gerard Medioni, Armand Tanguay, James D Weiland; A Vibrotactile Sensory Substitution Guided Feedback System For Object Localization. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4781.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to test our 'Object Localization and Tracking System' (OLTS), which assists visually impaired people with reaching and grasping for objects. The main goal was to explore how varying the visual angle of a computer generated feedback mechanism alters the accuracy of reaching and grasping in object localization tasks.
The OLTS utilized a wideangle (~100 degrees) monocular camera (Tanguay, Sahin), a central processing unit (CPU) and cranially positioned vibration motors. Computer Vision algorithms (Context Tracker, Dinh & Medioni) on the CPU parsed, and processed the camera input to determine object(s) position. Vibration motors produced haptic feedback "codes" for the blind test subject based on object position. Objects positioned on the periphery of the camera's visual field cause the vibration motors to fire. Objects within the “central-region” of the field of view cause the computer to stop vibration. Once the object was centralized within the cameras center of vision, test subjects were asked to reach out and touch the object. Eight blind test subjects evaluated the device. Five different “central-region” visual angles of the feedback algorithm were used (7.8, 15.6, 23.4, 31.2 and 39 degrees); 10 experiments per angle were conducted. Each experiment consisted of localizing and grasping for an object.
The results gathered included the average time to first grasp, average time to completion and average number of reaches for each of the five "central region" visual angles. The average times to first grasp for angles 7.8, 15.6, 23.4, 31.2 and 39 degrees were 15.87, 11.89, 12.70, 11.94 and 13.60 respectively. The average times to final grasp for angles 7.8, 15.6, 23.4, 31.2 and 39 degrees were 19.28, 13.74, 18.98, 18.12 and 20.29, respectively. The average number of reaches for the five angles were 1.38, 1.46, 1.61, 1.53 and 1.61, respectively.
The experiments conducted indicate subjects can accurately reach and grasp for object using the OLTS. Furthermore, experiments indicate that a visual angle of 15.6 degrees yields a fast localization and grasping time, as well as a low number reach attempts per localization task.
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