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Inventory of electronic mobility aids for persons with visual impairments: a literature review.

Abstract: This literature review of existing electronic mobility aids for persons who are visually impaired and recent developments in this field identified and classified 146 products, systems, and devices. The 21 that are currently available that can be used without environmental adaptation are described in functional terms.


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

13. availability

14. price

15. reference

16. distributor

17. illustration

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 (, 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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Verein zur Forderung der Blindenbildung. (2006). CityCane. Retrieved from http:// d&grp=7&type=&id=1844&title=Citycane

Vistac. (2004). Laser-Langstock Bedienungsanleitung. Teltow, Germany: Author.

Vistac. (n.d.). The Laser Long Cane. Retrieved from LLc_gb/LLCane_detailed_description.pdf

Walker, B. N., & Lindsay, J. (2006). Navigation performance with a virtual auditory display: Effects of beacon sound, capture radius, and practice. Human Factors, 48, 265-278.

Wayfinder. (n.d.a). Wayfinder Access: GPS navigation for the visually impaired. Retrieved from

Wayfinder. (n.d.b). Wayfinder Access online manual. Retrieved from http://

Zabonne. (2006). History. Retrieved from = product& id=10582&category=10049

Zelek, J. S., Bromley, S., Asmar, D., & Thompson, D. (2003). A haptic glove as a tactile-vision sensory substitution for Wayfinding. Journal of Visual Impairment & Blindness, 97, 621-632.

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: <>. Gert Jan Gelderblom, Ph.D., senior researcher, Vilans; e-mail: <>. Mathijs Soede, Ph.D., senior researcher, Vilans, and associate professor, Zuyd University, Postbus 550, 6400 AN Heerlen, the Netherlands; e-mail: <>. 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: <>.
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), 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

 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
 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-

 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
 (protects the

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

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

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

 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

 3. LaserCane Foldable Laser
 (MEDmarket- white advanced, cane technology,
 Maxi-Aids; see 2 AA
 Hearmore, n.d.) rechargeable

 4. Miniguide (GDP Handheld 2 ultrasonic
 Research, echolocation
 n.d.a, n.d.b) sensors,
 1 switch,
 socket, 123
 type lithium
 battery (100-
 1,000 hours
 of use), wrist

 5. Mini-Radar Carried Ultrasound,
 [Bestpluton, around earphone,
 n.d.b] the 2 buttons
 to the

 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
 pointing left,
 right, and
 ahead; 2
 mounted on
 a headband,
 by a
 (to select

 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,
 with memory
 light sensor,
 switch and 3
 buttons, 2
 (English and

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
 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
 batteries (4
 hours of

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,
 chip, and

 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, 3 levels: skills required;
 Maxi-Aids; see head height, customized to the
 Hearmore, n.d.) straight user's height
 ahead, and
 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

 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
 45 degrees

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
 (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

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

 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
 mode: to
 alert the
 when to
 make turns
 along the

 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
 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
 (navigation), map

 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

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"

 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

 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

 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)
 distance, speed,
 direction, altitude,

 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
 compass heading
 in degrees

10. Trekker Street names, Output: audio
 Breeze intersections, (speech)
 (HumanWare, reference
 2008 landmarks, turn-

Device Routes Components

 1. Blind automatically PDA (pocket-
 Navigator created created PC) GPS
 (Bestpluton, by the user receiver
 n.d.a) (EGNOS
 PDA maps
 (all European

 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
 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
 multimedia card
 (MMC) reader,

 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

 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,

 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
 compatible text-
 Nuance Talks
 and Mobile
 Speak; mobile
 phone Internet
 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
COPYRIGHT 2008 American Foundation for the Blind
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2008 Gale, Cengage Learning. All rights reserved.

Article Details
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Author:Roentgen, Uta R.; Gelderblom, Gert Jan; Soede, Mathijs; de Witte, Luc P.
Publication:Journal of Visual Impairment & Blindness
Geographic Code:4EUNE
Date:Nov 1, 2008
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