We have been developing a vibro-visual system for the visually impaired (Vibro-eyesight by Walking; VieW), which makes the user perceive space by providing vibration stimuli based on the difference in distance from obstacles caused by walking or head rotation. The purpose of this research is to clarify the points to be considered in developing the VieW that assists the visually impaired users to perceive the surrounding space and walk without colliding with walls, assuming an indoor corridor environment, and to verify the modifications that should be made to the VieW. Through walking experiments in a corridor with walls on both sides, we confirmed the importance of the perception of veering, i.e., the shift in the movement direction, and the perception of the veering direction. The results suggest that a vibration presentation method that clearly differentiates between approaching and moving away from a wall is effective.
We have been developing a helmet-type spatial perception support system that provides the user with vibration stimuli in response to the distance variation to an obstacle. The purpose of this research is set to propose a method for generating vibration stimuli that appropriately represent two environmental elements, walls and apertures, and verify its effectiveness for the aperture passage perception. The five vibro-motors are positioned at directional angles of 0 degree in front, 30 and 60 degrees to left and right, and generate vibration stimuli of an intensity calculated by assigning appropriate damping weights. We set the distance-dependent damping weights separately for each directional angle in the calculation of the vibration intensity to be generated for each motor. Experimental results demonstrate that the subjects were able to pass through the aperture in approximately 91 % of trials. This suggests that the developed system and the proposed vibration stimuli generation method are effective in perceiving space from the vibration stimuli provided to the head.
The purpose of this research is to verify that the proposed method, which generates vibro-stimuli according to the distance variation, has a capability of supporting depth edge detection for aperture localization. We have proposed a method to support the visually impaired understanding their surrounding environment via modality conversion from distance variation to haptic vibration information, and have developed the wearable device to provide the user with vibro-stimuli generated from visual variation inspired by optical flow characteristics. The characteristic of this vibration stimulus is that the user feels a strong vibration when the distance difference per unit time is large. It is inferred that this feature is effective in perceiving the boundary of obstacles, i.e., depth edge, which may contribute to the user's aperture localization. To verify the effectiveness of the proposed method, an aperture localization experiment was conducted to compare it with the ETAslike conventional method by changing the number of vibration motors and the method of vibration stimuli. We asked six blindfolded subjects to guess the location of the aperture. The experimental results showed that the proposed method achieved using a single motor a 98.3% correct rate. The contributions of this research are to propose the way of vibrostimuli based on distance variation for aperture localization, which is one of the important environmental elements, and to validate its effectiveness.
The purpose of this research is to propose the method providing visually impaired users with environment understanding via haptic vibration information. According to studies on ecological perception, optical flow, which represents dynamical visual variation, plays a significant role in environment understanding for humans. We have developed a head-mounted wearable device equipped with a 2-dimensional distance sensor and five vibro-motors arranged around the head. The vibration magnitude of vibro-motors is defined as not only a static distance to an obstacle but also dynamic distance variation caused by the user movement. The vibro-stimuli are generated based on the optical flow characteristics. The feature of the vibro-stimuli is the user feels no vibration when the distance to obstacles keeps constant. Therefore, we considered less discomfort caused by vibro-stimuli generated on the proposed method than the vibro-stimuli based on only static distance. To investigate uncomfortable feelings against the vibro-stimuli of the proposed method, we moved an obstacle closer to eight subjects for five minutes. Then, we evaluated impression for the vibro-stimuli using Semantic Differential scale composed of 15 impression word pairs. As a result, the proposed method gave fewer impressions related to uncomfortable feelings than the vibration based on only static distance. The experiment demonstrated the basic usability of the proposed method.
The purpose of this research is to propose the method providing the visually impaired users with environment understanding via modality conversion from visual distance to haptic vibration information. According to studies on ecological perception, optical flow, which represents dynamical visual variation, plays significant roles in environment understanding for human. We have developed a head-mounted wearable device equipped with a 2-dimensional distance sensor and five vibro-motors arranged around the head. The vibration magnitude of vibro-motors is defined as not static distance to the obstacle but dynamic distance variation caused from the user movement. The vibro-stimuli are generated based on the optical flow characteristics. Thus, if the user moves to the obstacle dynamically, the user feels stronger vibration; in contrast, if the user pauses, the user feels no vibration since the distance to obstacles keeps constant. To evaluate basic performance of the proposed method, we asked five blindfolded subjects to walk toward the wall 50 times each. First 10 trials performed by each subject are considered as practice phase; hence, the remaining 40 trials are evaluated. In total 200 trials, the 97.5% of trials are considered as success ones; the almost subjects were able to perceive the wall existence and stopped without the collision with the wall. The experiment demonstrated the basic validity of our proposed method. The main contribution of this paper is utilizing dynamic distance variation to determine vibration magnitude and providing the user with vibro-stimuli simulated by optical flow to support the user’s localization in the environment.
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