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The main reason why most of these first devices worked with ultrasonic signals instead of optic or radio frequency seems to lie in propagation speed : the large reflection delay of sound waves allowed them to be used for distance measurements (sonar).
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Both of these will be described in Section 2.2. Some of the most representative prototypes are Leslie Kay’s sonar-based Sonic Torch and Binaural Sonic Guide. This was mainly caused by the fast development of radar and sonar systems, which was encouraged by the Second World War. Over the last 70 years, researchers have worked on various prototypes of electrical obstacle detection devices for BVI people known as electronic travel aids (ETA). Finally, Section 4 and Section 5 include a brief introduction to user-centered design approaches, and a discussion of the currently available technical resources, respectively.Ģ.1. Next, Section 3, on related innovation fields, reviews several representative devices to introduce a set of technical resources that are yet to be fully exploited, e.g., remote processing techniques, simultaneous localization and mapping (SLAM), wearable haptic displays, etc. This is particularly important in the field of non-visual human‒machine interface, as the perceptual and cognitive processes remain the same. Section 2 presents a historical overview that gathers together previous systems in order to present a novel survey of the principles, key points, strategies, rules, and approaches of assistive device design that are currently applicable. Given the purpose of this work, its content and structure differ from recent reviews on the same topic (e.g., ).
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Thus, this study was undertaken to re-evaluate the perspective of navigation systems for the blind and visually impaired (BVI) in this new context, attempting to integrate key elements of what is frequently a disaggregated multidisciplinary background. Nevertheless, in recent years, we have seen unprecedented scientific and technical improvements, and new tools are now at our disposal to face this challenge. As we will see, researchers working in this field have yet to find effective, efficient, safe, and cost-effective technical solutions for both the outdoor and indoor guidance needs of blind and visually impaired people. In this regard, a navigation system’s purpose is to provide users with required and/or helpful data to get to a destination point, monitoring their position in previous modeled maps. Past work described this as a “cognitive collage”. Those tasks are usually grouped under the categories of “orientation” or “wayfinding,” while the capability to detect and avoid nearby obstacles relates to “mobility.” A lack of vision heavily hampers the performance of such tasks, requiring a conscious effort to integrate perceptions from the remaining sensory modalities, memories, or even verbal descriptions. Generally, individuals rely primarily on vision to know their own position and direction in the environment, recognizing numerous elements in their surroundings, as well as their distribution and relative location. The affected have their autonomy jeopardized in terms of many everyday tasks, with the emphasis being placed on those that involve moving through an unknown environment. Recent studies on global health estimate that 217 million people suffer from visual impairment, and 36 million from blindness. These functionalities could then be further boosted by means of remote resources, leading to cloud computing schemas or even remote sensing via urban infrastructure. In line with this, smartphones and wearables with built-in cameras will then be indicated as potentially feasible options with which to support state-of-art computer vision solutions, thus allowing for both the positioning and monitoring of the user’s surrounding area. Finally, several technological achievements are highlighted as they could underpin future feasible designs.
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Thereafter, user-centered design fundamentals are addressed, including the main points of criticism of previous approaches. To that end, previous solutions will be briefly described and analyzed from a historical perspective, from the first “Electronic Travel Aids” and early research on sensory substitution or indoor/outdoor positioning, to recent systems based on artificial vision. In this context, this paper’s objective is to provide an updated, holistic view of this research, in order to enable developers to exploit the different aspects of its multidisciplinary nature. Over the last decades, the development of navigation devices capable of guiding the blind through indoor and/or outdoor scenarios has remained a challenge.