Designing a personal guidance system to aid navigation without sight: progress on the GIS component

Experiments with RouteNav, A Wayfinding App for Blind Travelers in a Transit Hub

RouteNav is an iOS app designed to support wayfinding for blind travelers in an indoor/outdoor transit hub. It doesn't rely on external infrastructure (such as BLE beacons); instead, localization is obtained by fusing spatial information from inertial dead reckoning and GPS (when available) via particle filtering. Routes are expressed as sequences of "tiles", where each tile may contain relevant points of interest. Redundant modalities are used to guide users to switching goalposts within tiles. In this paper, we describe the different components of RouteNav, and report on a user study with seven blind participants, who traversed three challenging routes in a transit hub while receiving input from the app.

Techniques to Collect and Analyze the Cognitive Map Knowledge of Persons with Visual Impairment Or Blindness: Issues of Validity

This article is an assessment of a variety of techniques used by researchers in the fields of geography, psychology, urban planning, and cognitive science to collect and analyze data on how people with visual impairment or blindness learn, understand, and think about geographic space. The authors concluded that these techniques and their results need to be used cautiously. They also made recommendations for increasing the validity of future studies, including the use of multiple, mutually supportive tests; larger sample sizes, and movement from the laboratory to real-world environments.

Stated Preferences for Components of a Personal Guidance System for Nonvisual Navigation

This article reports on a survey of the preferences of visually impaired persons for a possible personal navigation device. The results showed that the majority of participants preferred speech input and output interfaces, were willing to use such a product, thought that they would make more trips with such a device, and had some concerns about the cosmetic acceptability of a device and the use of a single or stereo headphone interface.

Accessible GPS: Reorientation and Target Location among users with Visual Impairments

This article presents the results of two single-subject experiments that were designed to determine consumers’ ability to use a BrailleNote GPS. The participants decreased their mean orientation time from 6 minutes to 45 seconds and increased their target- location efficiency fourfold with BGPS than without BGPS. Additional results and implications for the field are presented.

Nonvisual Route following with Guidance from a Simple Haptic or Auditory Display

A path-following experiment, using a global positioning system, was conducted with participants who were legally blind. On- and off-course confirmations were delivered by either a vibrotactile or an audio stimulus. These simple binary cues were sufficient for guidance and point to the need to offer output options for guidance systems for people who are visually impaired.

Use of the global positioning system to measure the out-of-home mobility of older adults with differing cognitive functioning

Cognitive impairment manifests in changed out-of-home mobility. Until recently, the assessment of outdoor mobility relied on the reports of family care-givers and institutional staff and used observational approaches, activity monitoring or behavioural checklists. This article presents data for 41 mildly demented, mildly cognitively impaired and healthy men and women aged 64–90 years in Tel-Aviv (Israel) who took part in an interdisciplinary project, SenTra, that is studying the outdoor activities of elderly people using advanced tracking technologies and that involves researchers from geography, social work, gerontology, psychology and medicine. The participants were tracked for 28 consecutive days using a location kit that combined a global positioning system (GPS) with radio frequency identification. The high-resolution spatial and temporal data enabled detailed analysis of the differences in the timing and distance of the participants' daily outdoor mobility patterns. It was found that the spatial range of the mobility of elderly people with cognitive impairment is severely restricted, with most out-of-home time spent in close proximity to their residences. We conclude that GPS is an advanced research tool able to understand out-of-home behaviour better than was possible with previous methods.

Navigating without vision: basic and applied research

We describe some of the results of our program of basic and applied research on navigating without vision. One basic research topic that we have studied extensively is path integration, a form of navigation in which perceived self-motion is integrated over time to obtain an estimate of current position and orientation. In experiments on pathway completion, one test of path integration ability, we have found that subjects who are passively guided over the outbound path without vision exhibit significant errors when attempting to return to the origin but are nevertheless sensitive to turns and segment lengths in the stimulus path. We have also found no major differences in path integration ability among blind and sighted populations. A model we have developed that attributes errors in path integration to errors in encoding the stimulus path is a good beginning toward understanding path integration performance. In other research on path integration, in which optic flow information was manipulated in addition to the proprioceptive and vestibular information of nonvisual locomotion, we have found that optic flow is a weak input to the path integration process. In other basic research, our studies of auditory distance perception in outdoor environments show systematic underestimation of sound source distance. Our applied research has been concerned with developing and evaluating a navigation system for the visually impaired that uses three recent technologies: the Global Positioning System, Geographic Information Systems, and virtual acoustics. Our work shows that there is considerable promise of these three technologies in allowing visually impaired individuals to navigate and learn about unfamiliar environments without the assistance of human guides.

The NavBelt--a computerized travel aid for the blind based on mobile robotics technology

This paper presents a new concept for a travel aid for the blind. A prototype device, called the NavBelt, was developed to test this concept. The device can be used as a primary or secondary aid, and consists of a portable computer, ultrasonic sensors, and stereophonic headphones. The computer applies navigation and obstacle avoidance technologies that were developed originally for mobile robots. The computer then uses a stereophonic imaging technique to process the signals from the ultrasonic sensors and relays their information to the user via stereophonic headphones. The user can interpret the information as an acoustic "picture" of the surroundings, or, depending on the operational mode, as the recommended travel direction. The acoustic signals are transmitted as discrete beeps or continuous sounds. Experimental results with the NavBelt simulator and a portable prototype show that users can travel safely in an unfamiliar and cluttered environment at speeds of up to 0.8 m/s.

Assessing auditory distance perception using perceptually directed action

Three experiments investigated auditory distance perception under natural listening conditions in a large open field. Targets varied in egocentric distance from 3 to 16 m. By presenting visual targets at these same locations on other trials, we were able to compare visual and auditory distance perception under similar circumstances. In some experimental conditions, observers made verbal reports of target distance. In others, observers viewed or listened to the target and then, without further perceptual information about the target, attempted to face the target, walk directly to it, or walk along a two-segment indirect path to it. The primary results were these. First, the verbal and walking responses were largely concordant, with the walking responses exhibiting less between-observer variability. Second, different motoric responses provided consistent estimates of the perceived target locations and, therefore, of the initially perceived distances. Third, under circumstances for which visual targets were perceived more or less correctly in distance using the more precise walking response, auditory targets were generally perceived with considerable systematic error. In particular, the perceived locations of the auditory targets varied only about half as much in distance as did the physical targets; in addition, there was a tendency to underestimate target distance, except for the closest targets.