Inventory of electronic mobility aids for persons with visual impairments: a literature review.
Independent travel in unfamiliar environments is one of the major challenges that persons who are visually impaired (both those who are blind and those who have low vision) have to face in their daily lives (Marston & Golledge, 2003). The main problems include the lack of preview, knowledge of the environment, and access to information for orientation (Golledge, Marston, & Costanzo, 1997; Harper, Pettitt, & Goble, 2003; Helal, Moore, & Ramachandran, 2001). These problems frequently lead to less engagement in travel and activities outside the home, which affects productivity, employment, leisure and self-maintenance activities (Marston & Golledge, 2003; Walker & Lindsay, 2006), resulting in less participation in society.
To support their ability to move safely and purposefully, people who are visually impaired make use of several kinds of assistance, including sighted guides, white or long canes, and dog guides (Baldwin, 2003; Farmer & Smith, 1997; Zelek, Bromley, Asmar, & Thompson, 2003). Of the estimated 1.1 million persons who are blind in the United States, 10,000 own dog guides and 109,000 use white canes. Almost two-thirds of these cane users are younger than age 65, a noteworthy figure, since only one-third of all persons with visual impairments are younger than 65 (Demographics Update, 1994). Reliable data on the use of mobility devices in the Netherlands do not yet exist (Finsveen, Redeker, & Van Rooij, 2004). The white cane, in itself, however, is not sufficient for mobility; the user needs to acquire strategies for using it, which require intensive training by orientation and mobility (O&M) instructors. Furthermore, the white cane has a number of shortcomings, including an incomplete capacity for discrimination and protection against drop-offs; limited object-, surface-, and foot-placement previews; and no protection against collision with obstacles on the upper part of the body (Farmer & Smith, 1997).
Electronic mobility aids were developed after World War II to augment the functionality of the conventional tools used for mobility by people with visual impairments or to replace them with new, comprehensive ones. In the 1960s, the first electronic mobility aids, such as Kay's Sonic Torch and Russell's Pathsounder, became commercially available. The introduction of the Global Positioning System (GPS) in the mid-1990s led to the emergence of a new type of electronic mobility aid to foster navigation. Innovative electronic mobility aids integrate technologies, which developed quickly in the mainstream consumer market, made electronic mobility aids affordable, small, lightweight, and portable. Standard devices, such as cell phones and personal digital assistants (PDAs), combined with infrared or sonar sensors and GPS navigation that make use of wireless connectivity and multiple input-output modalities, have promising potential for people who are visually impaired (Baldwin, 2003; Fruchterman, 2003; Gill, 2005).
The use of electronic mobility aids is not yet widespread. From the developers' point of view, this lack of use could be attributed to the fact that earlier devices did not fully meet the needs of persons with visual impairments, motivating the ongoing search for an ultimate solution. Little research on electronic mobility aids has dealt with questions related to the field of rehabilitation because most of the information is restricted to technical specifications (Farcy et al., 2006). Reports of users' experiences have thus far depicted the advantages of electronic mobility aids, described in general as increased safety, preview, mobility, and travel speed; a greater level of independence; the readiness to travel in unknown or unfamiliar environments; and the reduction of stress and discomfort. Many persons with visual impairments who have used electronic mobility aids have expressed that they are satisfied with their use (Blasch, Long, & Griffin-Shirley, 1989; Darling, Goodrich, & Wiley, 1977; Farcy et al., 2006).
As Strobel, Fossa, Panchura, Beaver, and Westbrook (2003) stated, "Assistive technology can mean a difference between gainful employment and unemployment; between success in the educational system and failure; and between integration into the community and segregation." For the effective application of electronic mobility aids in practice, users and involved professionals such as service providers need sound insights into the spectrum of existing devices and the functional capacities and abilities of these devices in daily life. This article addresses the first issue by reporting on a study of existing electronic mobility aids for persons who are visually impaired. After we conducted a broad survey of the variety of devices, systems, and recent developments in this field, we directed our attention to products that a person can use individually without environmental adaptations.
We conducted a review of the literature from October 2007 to March 2008. In so doing, we consulted PubMed/MedLine, Embase, PsycINFO, and INSPEC/IEEE using combinations of the following terms and medical subject headings: electronic travel aids, electronic mobility aids, electronic orientation aids, orientation, mobility, assistive technology, blindness, low vision, visually impaired persons, and self-help devices. In addition, we inspected the records in two databases of assistive technology, Abledata and Eastin; extensively searched the Internet; searched reference lists of papers, articles in relevant scientific journals and conference proceedings; and reviewed product information in catalogs of distributors or at trade fairs and in user guides, handbooks, and training manuals. To obtain a complete impression of this kind of assistive technology, we included different sources that covered a wide range of content in relation to quantity and quality. No references were excluded on the basis of restrictions related to methodological quality.
At the same time, we searched the literature for major criteria that would permit all information to be summarized in a standardized way. Every system or device was entered into a database by specifying the following:
1. the name of the device
2. the type of device: for obstacle detection and orientation or navigation
3. the distinction between a primary or secondary device
4. the intended aim and main functionalities, such as avoiding obstacles; protecting the (upper) body; detecting objects, landmarks, and dropoffs; perceiving the environment; planning routes; guidance on routes; and finding points of interest.
5. the components
6. a description of the device, provided in functional and technical terms
7. the range of detection and the system's purpose for indoor or outdoor use
8. the user interface divided into different input and output modalities: tactile, haptic, or proprioceptive; audio; and optic or visual
9. the handling of a device
10. whether training in the device deals with whether good O&M skills are a prerequisite for safe use and if special training is needed
11. technical specifications, including size, weight, power supply, and warranty
12. any operational problems
This database offers an overview that allowed us to categorize the devices in many different ways, according to their intended purposes. For practical considerations regarding the application of electronic mobility aids, this study focused on electronic mobility aids that people who are visually impaired can use without environmental adaptations. The available electronic mobility aids were classified in two main categories: (1) devices that are aimed at obstacle detection and orientation and (2) those that are navigation systems. This categorization is comparable to the classification introduced by Petrie et al. (1997), who distinguished between micronavigation (avoiding obstacles and locating a clear path) and macronavigation (the ability to find one's way in a large, not immediate, environment).
The results of this systematic review indicated 146 products, systems, and devices. The aforementioned classification identified 12 electronic mobility aids in the first category (obstacle detection and orientation) that are currently available: Bat "K" Sonar Cane (Bay Advanced Technologies, n.d.a, n.d.b, n.d.c; Kay, n.d.), Hand Guide Obstacle Detector (Independent Living Aids, n.d.), LaserCane (Hearmore, n.d.), Miniguide (GDP Research, n.d.a, n.d.b; Guide Dogs NSW/ ACT, 2002), Mini-Radar (Bestpluton, n.d.b), Palmsonar PS231 (Takes Corporation, 2007a, 2007b, 2007c; Royal National Institute for the Blind, RNIB, 2007), Sonic Pathfinder (Heyes, n.d.a, n.d.b), Teletact (Damaschini, Legras, Leroux, & Farcy, 2005; Farcy et al., 2003, 2006), Tom-Pouce (Damaschini et al., 2005; Farcy et al., 2003, 2006), Ultra Body Guard (RTB, 2002, 2003), UltraCane (Hoyle & Dodds, 2006; Penrod, Corbett, & Blasch, 2005; Sound Foresight, n.d.), and Vistac Laser Long Cane (Vistac, 2004). The most important features of these devices are represented in Table 1 (Category 1); similarities and differences are discussed in the following paragraph, starting with their functionality as derived from their intended use.
All products are based on a comparable operating system. In a nutshell, a sensor unit emits an acoustic (ultrasound) or optic (laser or infrared) energy beam that is reflected by objects in its range. This range of detection depends on the number of sensors; their position; pointing and mounting; and the height, width, length, and shape of the energy beam covering diverse levels or planes. Received reflections are processed and transformed so that this information is made perceptible to the user who is visually impaired (Farmer & Smith, 1997). The use of all devices requires good O&M skills, which one can achieve only through extensive training. The amount of special or additional training that is needed to use an electronic mobility aid in this category efficiently varies considerably. It is closely linked with the intended functionality of the device, its range of detection, and its user interface, which are, of course, interrelated, and the ensuing quantity and kind of information that is presented. None of the available devices can substitute for a white cane or dog guide. Although six products are characterized as primary aids, they are categorized this way because they are integrated into, or mounted on, a white cane.
The aim of all these devices is to avoid obstacles, and hence to protect the (upper) body, through increased preview of the path ahead or detection of objects at different levels. If the avoidance of obstacles is the main functionality of the device, users are alerted solely to objects that they would otherwise collide with. This functionality is achieved in various ways, such as by the use of artificial intelligence to select relevant information about objects that would be encountered only during the next two seconds of travel, as with the Sonic Pathfinder, or by the range of detection being confined to a narrow, short beam, literally adding a second dimension to a white cane, as with the Vistac Laser Long Cane. For the detection of landmarks, a wider range of detection is useful. Actively searching for objects, landmarks, gaps, or doorways by scanning the surroundings is facilitated by handheld devices, among them those that are mounted on a cane. Making use of their proprioceptive perception, persons who are visually impaired can determine the direction of an object by the pointing position of their upper extremity at the moment the device's output is perceived.
Other options to indicate the direction of objects are the transmission of audible signals to the left, right, or both ears or tactile signals to discernible points on the user's body. The distance of objects is made perceptible through knowledge of the range of detection, the varying frequency of audible or tactile signals (the faster the signals, the nearer the object), the corresponding pitch of sound, a scale of musical tones, or spoken messages (distance in feet or decimeters). Information on distant objects and cardinal directions help users align themselves to the path of travel and to minimize veering. To assist in shorelining (that is, traveling along a wall, fence, or hedge), a device needs to be able to detect objects along the sides. The LaserCane is the only device whose range covers the ground level and thus is capable of detecting drop-offs. The most comprehensive and complex information on the surrounding environment is offered by the Teletact, with its 15-meter-range audio output mode in the form of multiple tones, referred to as "melody," and by the Bat "K" Sonar, which is supposed to act as a substitute for vision. These devices can recognize not only distance and direction, but the characteristics of objects, such as their shape or surface.
The input modality of all devices is tactile: One or more switches can be used to turn the devices on or off, to change from one mode to another, or to control the volume of audio output. In some cases, the range of detection, as well as features of the cane, such as its length or tip, are adjustable and customizable to the individual user's needs.
According to its manufacturer, the CityCane (Kemper Hilfstechnik, 2008; Verein zur Forderung der Blindenbildung, 2006), whose only intended functionality is to make a green traffic light audible to its user, was launched at the Sight City trade fair in Frankfurt in 2008.
Several more aids in the same category are no longer available: LaserCane, Model N 2000 (Abledata, 2008); Mowat Sensor-MS01(Abledata, 2008); N-8 laser cane (Abledata, 2008); Nottingham Obstacle Detector (Borenstein & Ulrich, 1997); Oscar: Obstacle Scan and Report (Abledata, 2008); Pathsounder (Abledata, 2008); Polaron (Abledata, 2008); Sensory 6 (Abledata, 2008); Sherpa-I (Slechtziend.nl, 2007; iRv Hulpmiddelen Wijzer, n.d.); Sonicguide (Abledata, 2008; Bay Advanced Technologies, n.d.c; Zabonne, 2006); Walkmate (KOC Vlibank, 2005); and Wheelchair Pathfinder (Abledata, 2008).
We found nine available electronic mobility aids, aimed at navigation, that people who are visually impaired can use individually, which means that no environmental adaptations are needed: Blind Navigator (Bestpluton, n.d.a), BrailleNote GPS and VoiceNote GPS (Abledata, 2008; Greenberg & Kuns, 2008; HumanWare, n.d.a; Sendero Group, n.d.a), Geotact (Farcy et al., 2006), GPS Petit-Poucet GRAND RAID (Bestpluton, n.d.a), Loadstone GPS (Loadstone GPS Team, n.d.a, n.d.b), PAC Mate + Street Talk (Freedom Scientific, 2005, n.d.), Trekker (HumanWare, n.d.b), Wayfinder Access (Wayfinder, n.d.a, n.d.b), and Way To Go (Sendero Group, n.d.b, n.d.c). BrailleNote and VoiceNote GPS are also called Sendero GPS. For an overview of these devices, see Table 2 (Category 2).
All these products, except Way To Go, operate with a GPS, which was developed by the U.S. Department of Defense as a precision-navigation and location-information tool for military purposes. Receiving precisely timed specific electronic data signals from at least 3 of 24 orbiting satellites, GPS calculates the exact position expressed in geographic coordinates by triangulation. Transformed and combined with additional information, this technology can help users who are visually impaired travel independently (Dusling & Uslan, 2002; Farmer & Smith, 1997; Van den Breede & Engelen, 2004).
Table 2 reveals three different ways in which users can travel independently with the devices. The first relies on digital maps and databases, providing detailed navigation information on street names and addresses and information on intersections, waypoints, points of interest, distance, direction, time, and speed of travel. The main functionalities are route planning and route guidance, based on automatically created routes, information about the user's current location or position, and exploration of the environment. The second uses databases only to generate routes by loading certain points from a list of checkpoints that the person who is visually impaired is guided along to his or her destination, as is done with Loadstone GPS.
The third functions without digital maps or databases, and users have to create routes themselves. Personal announcements of street names, waypoints, individual points of interest, or any other remarks, referred to as "vocal landmarks," are recorded, together with GPS-based electronic waypoints while traveling a route for the first time with a sighted guide. Stored routes offer route guidance through spoken advice en route, but can also be explored virtually (as with the GPS Petit-Poucet GRAND RAID). With most comprehensive devices, users can choose among all these possibilities as different modes or functionalities. To improve the travel skills of persons who are visually impaired, Geotact provides minimal information only. Users are guided through a few points--four on a 2-kilometer (about 1.2-mile) route are considered to be sufficient-and have to determine a suitable path on their own. Way To Go, whose main functionality is to present extensive map material in an accessible way, differs from the other systems in that it does not provide any route guidance. With regard to the hardware components of the products that are currently available, one can distinguish among
* those that are designed especially for users who are visually impaired: BrailleNote or VoiceNote and PAC Mate accessible pocket PC
* systems that make use of mainstream hardware, such as pocket PCs, PDAs, or mobile (cell) phones running Symbian (Series 60), combined with access software, and
* stand-alone products like GPS Petit-Poucet GRAND RAID, which is also obtainable as an additional function of one Category 1 device, the Mini-Radar.
All these devices are secondary aids, which implies that they have to be used in conjunction with a white cane or a dog guide. Evidently, the efficient use of these devices requires not only good O&M skills, but, with the exception of GPS Petit-Poucet GRAND RAID, the ability to use mobile phones and computers. Because of the limited available information about Geotact, it is not possible to provide more details on its components and mode of operation.
One product--Trekker Breeze (HumanWare, 2008)--is advertised as being commercially available in summer 2008. As may be concluded from the brief description of the product that was provided, its functionality seems comparable to that of GPS Petit-Poucet GRAND RAID, which uses recorded user-created routes. Atlas Speaks (Abledata, 2008); On Track (Abledata, 2008); and Strider (Abledata, 2008), which used the Atlas Speaks talking map program, are no longer available.
The remaining 107 systems and devices are not described in detail here, since they cannot actually be used for one or both of the following reasons: They are prototypes or are not meant for personal or individual use in the sense of being constructed for residential settings or relying on environmental adaptations. To give at least a brief impression, recent developments are outlined next.
One group of prototypes could be characterized as variations on devices of Category 1, aimed at obstacle detection and orientation. Research has dealt primarily with different input and output modalities; besides the use of ultrasound, infrared, and laser, other operating systems for the perception of the surrounding environment have been tested. The second group addresses the shortcomings of the available GPS systems of Category 2, aimed at navigation, which could be summed up in general as being applicable only outdoors; however, they have limited accuracy and lose track because of urban canyons, trees, or weather conditions. Still other devices combine the functionalities of both categories, in some cases providing additional support for physical mobility. Further advancements have included products that focus on intuitive use, minimizing the amount of special or additional training; products that are tailored to individual needs, offering different and customizable input and output modalities; and modular devices with diverse combinations of functionalities.
At present, the use of available electronic mobility aids requires good O&M skills. Because of the increasing number of persons who become visually impaired in old age or who also have cognitive impairments, the development of electronic mobility aids has focused on devices that can be used by older persons who do not have good O&M skills and will probably have difficulty learning them through extensive, time-consuming, and demanding training.
The last group covers a wide range of systems that are based on environmental adaptations. Within these environmental adaptations, two functionalities can be distinguished: providing guidance on predetermined routes or making information about the surroundings accessible to users who are visually impaired. This information is not restricted to assistance with O&M, wayfinding, or route guidance; related activities of daily living, such as the use of public transportation or grocery shopping, are considered, too.
In the first phase of the review, we emphasized a general overview of the variety of electronic mobility aids for persons who are visually impaired. Our intent was to compile a full list of products, systems, and devices, so we sought data widely and collected and summarized all kinds of information, as was described in the Method section. With regard to the available devices, not all information was published in the scientific literature. Some information on products was confined to secondary sources, and a number of Internet sites that we referred to are no longer retrievable. Several products that were no longer available were retained in the Abledata database for reference. A few references could not be taken into account because they were presented in languages that we did not know.
In the second phase of the review, we focused on electronic mobility aids that could be used by a person who is visually impaired without environmental adaptation. Detailed and valuable information on these devices is provided in their user guides, handbooks, training manuals, and the like, leading to a better understanding of the functionality of the devices than would be obtained from studying the product information alone. Since these sources were sometimes not (electronically) published, we contacted distributors, manufacturers, and developers by telephone or e-mail. This additional step was also necessary for the proper selection of products, since information on the availability of products, as provided by various sources, turned out not to be always reliable or up to date. Nevertheless, the amount and detail of information were different for different products. When one looks at the results and presentation of important features in Tables 1 and 2, one should keep in mind that these findings stem solely from a review of the literature; we neither tested nor evaluated these products.
The inventory of electronic mobility aids encompassed 146 systems, products, and devices. With regard to the application of electronic mobility aids in practice, we focused on products that people who are visually impaired can actually use without environmental adaptations. A process of selection and classification resulted in the systematic functional description of 21 currently available electronic mobility aids, 12 in Category 1, aimed at obstacle detection and orientation, and 9 in Category 2, aimed at navigation. Two more devices were identified that will be available soon. Presented as practical guidelines and information on products, these results can offer relevant knowledge for users and service providers. Thus, they can contribute to the matching of individual users with the most appropriate assistive devices. In addition to awareness of the range of available devices, more insights are needed into the way the devices provide functional assistance in daily life. Future research should therefore assess the functionality of electronic mobility aids and their effects on the mobility of their users.
Reviewing all the products, systems, and devices that we entered into the database allowed us to summarize recent developments in the field of assistive technology in the Results section. The different groups that we mentioned show not only various trends in research, but a great number of different products or solutions within each category. It is remarkable that many products, particularly those in Category 1, are no longer available and that many systems and devices are prototypes that are either in development or failed to enter the market. Further research should investigate the reasons for this situation. Moreover, the historical development and trends of the applied technologies should be analyzed. Functions and capabilities, as well as the inherent advantages and disadvantages, of different technologies should be described with regard to the consequences for the functionality of the assistive devices. The continuous development of systems can be regarded as a strong indicator of the potential of the field of assistive technology, and future research could well support further advancements.
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The authors thank the In Sight Society for funding this study within the In Sight program of ZonMw, the Netherlands organization for health research and development.
Uta R. Roentgen, M.Sc., Ph.D. candidate, Vilans, Centre of Excellence in Long-term and Social Care, Postbus 8228, 3503 RE Utrecht, the Netherlands; e-mail: <email@example.com>. Gert Jan Gelderblom, Ph.D., senior researcher, Vilans; e-mail: <firstname.lastname@example.org>. Mathijs Soede, Ph.D., senior researcher, Vilans, and associate professor, Zuyd University, Postbus 550, 6400 AN Heerlen, the Netherlands; e-mail: <email@example.com>. Luc P. de Witte, M.D., Ph.D., program manager, Vilans, professor, Zuyd University, and professor for technology in care, Faculty of Health, Medicine and Life Science, Maastricht University, Postbus 616, 6200 MD Maastricht, the Netherlands; e-mail: <firstname.lastname@example.org>.
Table 1 Electronic Mobility Aids: Category 1. Device Functionality Interface 1. Bat "K" Sonar Acts as a vision Input: tactile (Bay Advanced substitute: spatial (switches), output: Technologies, perception, audio (multiple n.d.a, n.d.b) recognition of tone complexes, objects, detection referred to as of landmarks and "sound the distance and language"); the direction of closer the object, objects, avoidance the lower the of obstacles pitch; the more (protection of the distant the object, body), assists with the higher the alignment with the pitch travel path (minimizes veering) and shorelining 2. Hand Guide Avoidance of Input: tactile (1 Obstacle obstacle to the control switch), Detector front and above output: audio (Independent the wrist or waist (chirp), or tactile Living Aids, (protection of the (vibration); n.d.; Penrod, body); detection of increased Bauder, & the distance and frequency as Simmons, 2004 direction of object comes objects, closer landmarks, open doors, and hallways; assists with shorelining 3. LaserCane Detection of the Output: audio (MEDmarket- distance and (audible tones) place.com, direction of and tactile Maxi-Aids; see objects, (vibrating Hearmore, n.d.) landmarks, and stimulators under drop-offs the index finger); avoidance of audible tone turn- obstacles off option (protection of the body) 4. Miniguide (GDP Avoidance of Input: tactile Research, obstacles to the (1 switch) output: n.d.a, n.d.b) front and above tactile (vibration) the wrist or waist or audio (sound (protection of the feedback); the body); detection of faster the signal, landmarks, the the nearer the distance and object direction of objects, and persons approaching one's personal space; assists with shorelining; allows user to actively search for objects, landmarks, gaps, and doors 5. Mini-Radar Mode 1: avoidance Input: tactile [Bestpluton, of obstacles (buttons to switch n.d.b] (protection of the between the 2 body); Mode 2: modes and light detection of detection) output: landmarks, light, audio (spoken alignment with the messages: "stop," travel path, and "free the distance of way"/distance in objects; optional: feet or directional decimeters/daylight, stability dark, light in sight; (device announces optional: position deviation from the compared with path); minimizes North, for veering (allowing example, "Cape one to cross in a 100," headed straight line); direction, such as optional: talking "Northeast") compass (device announces headed direction in 8 sectors); optional: GPS "Petit- Poucet" 6. Palmsonar PS 231 Avoidance of Input: tactile (1 (RNIB, 2007; obstacles switch button); Takes (protection of output: tactile Corporation, the body); (vibration): the 2007a, 2007b, detection of faster the signal, 2007c) landmarks and the nearer the the distance object and direction of the closest object in the beam; assists in shorelining and active scanning 7. Sonic Pathfinder Avoidance of Input: output: audio (Heyes, nd.a, obstacles to the (8 tones nd.b) front and above correspond to the waist notes on the (protection of musical scale, the body); analogous to detection of the distance: the distance and nearer the object, direction of the the lower the nearest object tone; each tone only; in the represents a absence of any distance of 0.3 such object, the meters [about 12 device switches inches); direction to its lower is indicated by priority function tones to the left or and assists in right ear or both shorelining ears) 8. Teletact Recognition of Input: Output: tactile (Damaschini et objects (2 vibrating devices al., 2005; (shapes), located under 2 Farcy et al., detection of different fingers: 2003, 2006 landmarks the 1st codes and the distances between 3 distance and meters [about 10 direction of feet] and 6 meters obstacles, [about 20 feet] avoidance of by discrete vibration obstacles between 1.5 meters (protection of [about 5 feet] and 3 the body), meters by strong finds the vibration; the 2nd best travel codes distances less path than 1.5 meters) or by audio (to 15 meters [about 49 feet]; 28 different musical notes correspond to 28 unequal distance intervals (shorter for short distances): the higher the tone, the shorter the distance; transcrip- tion of the profile of an obstacle into a "melody" 9. Tom-Pouce Avoidance of Output: tactile (Farcy et al., obstacles to (vibration located 20,032,006 the front and on the pinky above the finger) wrist or waist (protects the body) 10. Ultra Body Avoidance of Input: tactile (1 Guard (RTB, obstacles to switch, 3 buttons); 20,022,003 the front and output: tactile n.d.) above the (vibration; vibrating wrist or pin on the device or waist vibrating band worn (protects the on the neck or body); placed on the detection of shoulder; the faster, landmarks, the nearer the light, and the object) and audio distance and (spoken information direction of pedometer, musical objects; tones light sensor, assists with spoken compass alignment to directions; "left" or the travel "right" directional path; stability) provides for the storage of travel routes 11. UltraCane Avoidance of Input: tactile (on or (Sound obstacles to off or range switch); Foresight, the front and output: tactile (2 n.d.a, n.d.b, above the vibrating buttons: n.d.c, n.d.d) wrist or farthest away: waist feedback forward (protection of beam-the faster, the the body); closer the object; detection of closest to the body: landmarks feedback upper beam- and the obstacles at shoulder distance and or head height, direction of strong vibrations) objects; aids in the alignment of the travel path and shorelining 12. Vistac Laser Avoids Input: tactile (1 Long Cane obstacles switch), output: (Vistac, 2004, above the tactile (vibration n.d.) wrist or felt through the waist entire grip of the (protects the handle; continuous: body); warning of obstacles; detects the intermittent: low direction of battery or internal objects fault) 13. CityCane Makes a green Output: audio (audible (Kemper traffic light signal) Hilfstechnik, audible to its 2008 user Device Mounting Components 1. Bat "K" Sonar Handheld KASPA (Bay Advanced or ultrasound Technologies, attached headphones, n.d.a, n.d.b) to the rechargeable handle battery (lasts of a 1 day), cane 3 switches (volume up/ down, range control) 2. Hand Guide Handheld Infrared Obstacle or sensor, 2 AA Detector clipped batteries, (Independent onto a pocket or Living Aids, pocket belt clip, n.d.; Penrod, or belt wrist strap, Bauder, & 1 switch Simmons, 2004 (turn on or off, change output mode) 3. LaserCane Foldable Laser (MEDmarket- white advanced place.com, cane technology, Maxi-Aids; see 2 AA Hearmore, n.d.) rechargeable batteries, battery charger 4. Miniguide (GDP Handheld 2 ultrasonic Research, echolocation n.d.a, n.d.b) sensors, 1 switch, earphone socket, 123 type lithium battery (100- 1,000 hours of use), wrist strap 5. Mini-Radar Carried Ultrasound, [Bestpluton, around earphone, n.d.b] the 2 buttons neck or fixed to the belt 6. Palmsonar PS 231 Handheld, Ultrasonic (RNIB, 2007; worn echolocation, Takes on the CR 2032 Corporation, palm battery, 2007a, 2007b, 1-switch 2007c) button; wrist strap and palm band 7. Sonic Pathfinder Head Pulse-echo (Heyes, nd.a, mounted sonar nd.b) system (3 receivers pointing left, right, and straight ahead; 2 transmitters), mounted on a headband, controlled by a microcomputer, "artificial intelligence" (to select relevant information only), earpieces 8. Teletact Usually Handheld laser (Damaschini et clipped telemeter al., 2005; onto a Farcy et al., white 2003, 2006 cane 9. Tom-Pouce Clipped Infrared beams (Farcy et al., onto a generated by 20,032,006 white collimated cane LEDs 10. Ultra Body Handheld Ultrasound, Guard (RTB, or Microprocessor, 20,022,003 worn talking n.d.) around compass, the directional neck stability, pedometer with memory function, light sensor, speaker, switch and 3 buttons, 2 languages (English and German) 11. UltraCane Mounted 2 ultrasound (Sound on a sensors; 2 Foresight, foldable vibrating n.d.a, n.d.b, white buttons; 2 n.d.c, n.d.d) cane AA batteries, dry cell or rechargeable; wrist strap, on or off or range switch 12. Vistac Laser Mounted Laser, Long Cane on a asymmetrical (Vistac, 2004, white handle, on/ n.d.) cane off switch, 2 mignon rechargeable batteries (4 hours of continuous use) 13. CityCane Mounted A foldable (Kemper on the ergonomically Hilfstechnik, handle designed 2008 of a cane with a foldable shock ergonomically absorber, designed color cane sensors, computer chip, and speaker Device Range of detection Handling 1. Bat "K" Sonar Outdoors and Used with a white (Bay Advanced indoors up cane or dog Technologies, to 6 meters guide. Best n.d.a, n.d.b) (about method: Hold the 20 feet), "K" Sonar at long range: arm's length, with 5 meters sonar and hand (about near the hip joint; 16 feet) with correct the angle slower of the beam pulses, short relative to the range: ground. Good 2 meters O&M skills and (about special training 6.5 feet) with required (basic faster pulses training concepts) 2. Hand Guide Outdoors and Used with a white Obstacle indoors; cane or dog Detector range of guide; good O&M (Independent detection, skills required Living Aids, 1.2 meters n.d.; Penrod, (about Bauder, & 4 feet) Simmons, 2004 3. LaserCane Outdoors and Used as a white (MEDmarket- indoors at cane; good O&M place.com, 3 levels: skills required; Maxi-Aids; see head height, customized to the Hearmore, n.d.) straight user's height ahead, and drop-offs; ahead and to the sides 4. Miniguide (GDP Outdoors and indoors; Used with a white Research, 23 modes of use; cane or dog n.d.a, n.d.b) basic settings: 4 guide, good O&M meters (about 13 skills and special feet), 2 meters training required, (about 6.5 feet), 1 detailed training meter (about 3 feet), package available, 0.5 meter (about 1.6 correct hand feet), 8 meters position (about 26 feet); range advanced settings 4 meters, 2 meters, 1 meter; gap- finding ranges; watchdog mode 5. Mini-Radar Outdoors and indoors Used with a white [Bestpluton, range of detection, 3 cane or dog n.d.b] meters (about 10 guide; good O&M feet); width of beam, skills required 60 centimeters (about 24 inches); height, 1.2 meters (about 4 feet) 6. Palmsonar PS 231 Narrow horizontal Used with a white (RNIB, 2007; beam 15 degrees cane or dog guide; Takes to both sides; wide good O&M skills Corporation, vertical beam 30 and special 2007a, 2007b, degrees up and training required; 2007c) down; different daily practice is modes: 4 meters considered to be (about 13 feet), 1 important (it may meter (about 3 take 3 months to feet), 0.5 meter gain confidence (about 1.6 feet), and 1-2 years to 0.3 meter (about continue to 12 inches), 1.2 progress); 2 holes meters (about must be aligned 4 feet), 1.4 meters vertically, so the (about 5 feet); narrow beam can 2-meter (about be used 6.5-foot) beam horizontally 7. Sonic Pathfinder Outdoors, range of 2 Used with a white (Heyes, nd.a, seconds cane or dog guide; nd.b) (information solely good O&M skills about objects that and special would be training required (5 encountered or 6 training during the next 2 sessions, spread seconds of travel); over 2 or 3 days), maximum range: training course 2.76-3.06 meters (theoretical and (about 9-10 feet); practical sessions) minimum range 0.0-0.75 meters (0-30 inches) 8. Teletact Outdoors and indoors Users have to scan (Damaschini et up to a 6-meter (20- the environment; al., 2005; foot) range (tactile used with a white Farcy et al., output) and up to a cane or dog 2003, 2006 15-meter (49-foot) guide; good O&M range (audio output); skills and special beam is pointing training required; users have to start with the Tom-Pouce and then continue with the tactile output version limited to the 6-meter range; 15-meter range only with audio output; requires users to develop a new cognitive process; users need to filter and interpret a great amount of information 9. Tom-Pouce Outdoors and indoors; Used with a white (Farcy et al., 3 distances of cane or dog 20,032,006 detection: 0.5 meter guide; good O&M (about 1.6 feet), 1.5 skills and special meters (about 5 training required feet), and 3 meters (10 to 20 sessions (about 10 feet); 20 spread over 3-4 degrees horizontal months) 50 degrees vertical; beam width: 0.6 meters-3 meters (about 24 inches to 10 feet) 10. Ultra Body Outdoors and Used with a white Guard (RTB, indoors, cane or dog 20,022,003 range of guide; good O&M n.d.) detection: skills and special 0.3 meters training required (about 12 inches) to 3.2 meters (about 10.5 feet); 15 degrees horizontal, 45 degrees vertical 11. UltraCane 2 ranges Used as a white (Sound forward cane; good O&M Foresight, sensor: skills and special n.d.a, n.d.b, short, 2 training required; n.d.c, n.d.d) meters training material (about 6.5 or courses can be feet); long: 4 customized to a meters user's personal (about 13 style and height; feet); upper scanning to locate sensor: 1.5 landmarks meters (about 5 feet) 12. Vistac Laser Laser beam is Used as a white Long Cane narrow: cane, good O&M (Vistac, 2004, width 30 skills and special n.d.) degrees training (at least 1 vertically, 5 hour to obtain the millimeters correct positioning (0.2 inches) and grip), simple horizontally, yes or no 1.4 meters information (1.6 feet) provided ahead; adjustable distance setting 13. CityCane Outdoors; the Used as a white (Kemper color cane; at traffic Hilfstechnik, sensors have lights, the color 2008 to be sensors have to positioned be positioned directly in directly in front of front of the the green traffic traffic light light; good O&M skills and special training (4-20 hours) required Table 2 Electronic Mobility Aids: Category 2. Device Functionality Modes 1. Blind Provides route planning Pedestrian Navigator and. route guidance mode (Bestpluton, through spoken advice; vehicular n.d.a) searches points of mode free interest; user can walk mode around, and street names are announced (free mode); stores recorded user-created routes; allows for virtual exploration of a route; provides additional functions of a PDA 2. BrailleNote Plans route to a destination Navigation GPS and (address, point of interest, mode; VoiceNote virtual explore position, or different GPS latitude & longitude); route- (Sendero provides route guidance, following GPS) current location or modes: in (HumanWare, position ("Where am I"?), Turns-Only n.d.a; user points of interest; or Detailed Sendero allows user to explore Waypoint Group, n.d.a) surroundings and to mode, explore locations without different being there (virtual LookAround explore mode); records modes: GPS information while automatic, traveling, so user can multiple play it back (GPS replay repeat, and files); records messages; manual; has odometer and virtual additional functions of the explore BrailleNote notetaker mode 3. Geotact Provides minimum (Farcy et route guidance; al., 2006) users have to decide on their own how to travel between 2 points (intended to foster users' O&M skills); has several features for entering points from an address, the facility to use Google Earth (for example, to reach a point without an address), and the facility to register personal points 4. GPS Petit- Stores recorded user- Pedestrian Poucet GRAND created routes; record RAID provides route mode, (Bestpluton guidance through vehicular n.d.a) spoken advice; record allows for virtual mode, exploration of a guiding route: user can listen mode, go-on to the details of a mode, go- route without back mode, traveling it; has step-to-step additional functions mode (virtual of the Mini-Radar exploration) 5. Loadstone Provides route guidance by Navigation GPS guiding the user from point mode and (Loadstone to point on a manually exploration GPS team, created route (heading, mode n.d.a, direction of travel, n. d. b) checkpoint, and distance to that point), provides information about the current environment; gives user the ability to explore and interact with points in a maplike fashion; user can virtually navigate from point to point, find a certain point by entering search criteria; shows a list of points surrounding the current position and the starting point 6. PAC Mate Provides current location or Planner mode: and position ("Where am I"?), to create a StreetTalk route planning, route route or find (Freedom guidance; allows user to points of Scientific, explore the environment interest 2005, n.d.) ("What is around me?") when the GPS is not available; navigation mode: to alert the traveler when to make turns along the created route 7. Trekker Provides route Pedestrian (HumanWare, guidance, route mode, 2008, n.d.a, planning, current motorized n.d.b, n.d.c) location or mode (less position ("Where detailed am I?"); allows information), user to explore and free the outdoor mode (used environment in unmapped ("What is around areas) me?"), detect intersections and points of interest, and search points of interest (by distance or by address); has additional functions of the Maestro (optional) 8. Wayfinder Allows for Access continuous (Wayfinder, exploration of the n.d.a, current n. d. b) environment; provides current location and position ("Where am I?"), route guidance (navigation), map exploration 9. Way To Go Provides the equivalent Virtual Explore, (Sendero of print maps in Routes, Group, accessible formats; points of n.d.b, n.d.c) allows for the virtual interest exploration and understanding of the user's surroundings; provides a mental picture of the environment, route planning, points of interest; additional functions: records messages, has an odometer 10. Trekker Provides route Breeze guidance, (HumanWare, navigational 2008 assistance for visual impaired users who are not comfortable with computers and screen readers Device Information Interface 1. Blind Street names distance, Input: tactile Navigator distance covered, (buttons) and (Bestpluton, remaining distance audio (speech) n.d.a) direction speed of output: audio travel, time, date (speech) points of interest customizable: user created points verbosity (amount of interest spoken of information advice like "towards provided) the left", "towards the right", "go straight", "U-turn" etc. 2. BrailleNote More than 13 million Input: tactile (9-key GPS and points of interest are braille keyboard VoiceNote stored in the or QWERTY GPS database: user- computer-style (Sendero created points of keyboard); output: GPS) interest; street tactile (18- or 32- (HumanWare, names; approximate cell refreshable n.d.a; addresses; distance braille display) Sendero (and heading and audio Group, n.d.a) direction) to the next (speech, sounds intersection; current to signal different waypoint; next turn warnings), audio or destination; speed output alone of travel; latitude, (VoiceNote GPS); longitude, altitude; customizable: GPS time, date; volume; speed stopwatch; and pitch control; orientation heading sound cues (can (clock face or left or also be turned right distance off); interval in heading); compass seconds for heading (4 repeating directions, given automatic after clock face or announcements left or right position of heading and announcement) and distance to compass heading in current waypoint, degrees next turn, or destination 3. Geotact Has a restricted Output: audio (Farcy et amount of (speech) only on al., 2006) information: does request not indicate whether there is a direct path between 2 points; 4 points on a 2- kilometer (1.2-mile) route are considered to be sufficient; distance (in meters) and direction (system of the clock) to the next point are given 4. GPS Petit- Spoken advice like Input: audio (speech Poucet GRAND "toward the left," "vocal RAID "toward the right," landmarks") and (Bestpluton "go straight," and tactile (2 buttons: n.d.a) "U-turn"; "menu" and additional: time, "validation"); time spent, output: audio distance covered, (speech) remaining distance, speed, direction, altitude, date 5. Loadstone Provides the closest Input: tactile GPS point to the current (mobile phone (Loadstone position in any keypad); GPS team, direction, speed, output: blind n.d.a, direction and user: audio n. d. b) altitude, longitude (speech, screen and latitude reader); user coordinates; has an with low vision: alphanumeric label optical (display to the coordinates in and magnifier) the form of a "point"; provides heading in degrees, 12/8 cardinal compass directions, or clock face 6. PAC Mate Has millions of points Input: tactile and of interest: personal (braille Perkins- StreetTalk points of interest; style keyboard (Freedom street addresses; or QWERTY Scientific, directions: "turn left" laptop-style 2005, n.d.) or "turn right"; keyboard); provides cardinal shortcut directions only at keystrokes; the start, bearing, output: tactile speed, distance to (20 or 40 cells the destination, of refreshable distance traveled; braille) and GPS information: audio (speech) latitude, longitude, or audio and time (speech) only 7. Trekker More than 1,5 million Input: tactile (mobile (HumanWare, points of interest: phone keyboard 2008, n.d.a, personal points of can be configured n.d.b, n.d.c) interest, street as a braille names, street keypad); output: mapping, audio (speech) intersections, automatically crossings; announced on announces whether request; the user is On Route; customizable: provides heading verbosity (detailed direction (such as information or North or Northeast), summary), voice direction to take (go rate of speech, right, left, go uncontracted or straight, or go back), contracted braille distance, route information (name, distance remaining and traveled, length), speed, latitude, longitude, altitude, GPS status 8. Wayfinder Intersections, points of Input: tactile (mobile Access interest, more than phone numeric (Wayfinder, 20 million locations, keypad); output: n.d.a, provides door-to- audio (speech); n. d. b) door voice optional: braille directions, navigation input and output; instructions (clock- customizable: based format or volume of the compass-based voice instructions, format with 8 number of voice directions) instructions given during navigation, backlight settings, language, amount of information (detailed or brief) 9. Way To Go More than 15 million Input: tactile (9-key (Sendero points of interest; braille keyboard or Group, provides distance QWERTY n.d.b, n.d.c) and direction to a computer-style business, street keyboard); output: address, or tactile (18- or 32- intersection; cell refreshable orientation heading braille display) (clock face or left and audio or right); distance (speech); heading; compass customizable: heading (4 sound cues (can directions, given also be turned off) after the clock face or left or right position is announced); compass heading in degrees 10. Trekker Street names, Output: audio Breeze intersections, (speech) (HumanWare, reference 2008 landmarks, turn- by-turn instructions Device Routes Components 1. Blind automatically PDA (pocket- Navigator created created PC) GPS (Bestpluton, by the user receiver n.d.a) (EGNOS compatible) speaker microphone access software PDA maps (all European countries) database 2. BrailleNote Automatically BrailleNote GPS and created; manually notetaker; VoiceNote created (if user built-in GPS prefers different speaker; (Sendero route or maps are GPS GPS) unavailable) receiver; (HumanWare, pedestrian routes, Sendero n.d.a; vehicular routes; GPS Sendero GPS replay files; software, Group, n.d.a) routes can be version 4.22; used in maps; conjunction with database; the LookAround carrying information; case routes can be customized, saved, edited, and exchanged with other users 3. Geotact Pedestrian routes GPS system, (Farcy et inertial sensor to al., 2006) reduce the effects of degradation of GPS information at urban canyons 4. GPS Petit- Created by the user GPS receiver, 2 Poucet GRAND with assistance of buttons, power RAID a sighted guide, supply: 4 (Bestpluton pedestrian routes, batteries AAA R3 n.d.a) vehicular routes; (100-200 hours many routes can of use) or AA R6 be stored: up to (200-400 hours 3,500 kilometers of use); also (about 2,175 available as an miles) with 1 point optional function every 2 meters of the Mini-Radar (about 6.5 feet) (pedestrian routes) or up to 25,000 kilometers (about 15,534 miles) (vehicular routes) 5. Loadstone Manually created Mobile (cell) phone GPS routes only; user running Symbian (Loadstone has to add (Series 60), GPS team, significant points access software n.d.a, on a route every 15 (screen reader or n. d. b) meters (about 49 magnifier), feet); user can also Bluetooth GPS load a point from a receiver, list of checkpoints; Loadstone GPS points can be software, imported to and Loadstone exported from the database; user's database optional: USB Bluetooth dongle, Bluetooth headset, multimedia card (MMC) reader, high-capacity MMC 6. PAC Mate Pedestrian routes, PAC Mate QX or and vehicular routes, BX; accessible StreetTalk "breadcrumb" Pocket PC; (Freedom routes (recording of Bluetooth GPS Scientific, user's position receiver; 2005, n.d.) every 3 seconds or StreetTalk, every 3 meters version 2.0 (about 10 feet); not (accessibility in unmapped interface to the areas, based on Destinator Destinator's map application- data); saved turn- Destinator is a by-turn directions; satellite-based custom routes navigation designed on the system); maps; go; routes can be database printed, embossed, beamed, or e- mailed to other users 7. Trekker Pedestrian routes PDA (Pocket PC), (HumanWare, and vehicular Bluetooth GPS 2008, n.d.a, routes receiver, Royal n.d.b, n.d.c) Tek RBT 2100, clip-on case, external speaker with audio cable, Power Splitter, strap, travel bag GPS maps on CD and storage card, database, microphone 8. Wayfinder Pedestrian routes Mobile (cell) phone Access and vehicular running Symbian (Wayfinder, routes (by (Series 60); n.d.a, passenger car or Bluetooth GPS n. d. b) taxi); routes can receiver; be loaded, saved, Wayfinder played, or erased Access software, version 1..24 or higher; compatible text- to-speech application Nuance Talks and Mobile Speak; mobile phone Internet connection; maps; database 9. Way To Go Automatically BrailleNote or (Sendero created or VoiceNote, Group, manually created mPower, Way To n.d.b, n.d.c) pedestrian routes Go software, and vehicular maps on DVD, routes database 10. Trekker Created by the user Breeze with the (HumanWare, assistance of a 2008 sighted guide; pedestrian routes and vehicular routes; routes can be recorded, previewed, or activated for future use
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|Author:||Roentgen, Uta R.; Gelderblom, Gert Jan; Soede, Mathijs; de Witte, Luc P.|
|Publication:||Journal of Visual Impairment & Blindness|
|Date:||Nov 1, 2008|
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