|
 |
 |
| ||||
|
Summary | Market Needs | State-of-the-Practice | Issues to Consider | References SummaryImproved wayfinding has been identified as a high priority need by persons with low vision and blindness, researchers and assistive technology manufacturers. The functions and capabilities of these wayfinding technologies include providing critical orientation, mobility, navigation, and spatial perception capabilities for maximizing travel independence for people who are blind. Wayfinding needs include accurate navigation, signage and landmark information, interior and exterior architectural details (i.e., stairs, restrooms), business addresses, street maps, emergency warnings, transportation schedules, etc. Improved wayfinding technology would enable a person to plan complicated travel routes, navigate new surroundings, and independently access previously unknown facilities. Advancements to these technologies would meet significant enduser needs and represent significant business opportunities for assistive technology manufacturers. [ Top of Page ] Market NeedsIn order to effectively function within society, all people must have the ability to plan comprehensible routes, follow routes, and maintain orientation along the way. People must also be able to traverse any given location without being struck by moving traffic, confounded by new construction sites, or stumbling upon a decaying sidewalk or roadway. People who have visual impairments face unique challenges in achieving independent mobility, as there is no easy way for them to identify potential hazards, or to immediately access information about their surroundings without an assistive technology device or assistance from a sighted person. There are an estimated 13.5 million people in the United States who cannot recognize a friend from across a room, even when wearing glasses. It is likely that this group of individuals has difficulty recognizing landmarks, signs, and obstacles while traveling. Further, an estimated 7.2 million individuals cannot recognize a friend at arm's length, even with correction (Lighthouse Inc., 1995). These individuals may find it difficult or impossible to travel independently without some form of assistive technology device to aid them in avoiding obstacles in the immediate environment and maintaining the path of travel to a point in the distance. According to data from the National Health Interview Survey on Disability that was completed in 1994, approximately 288,000 persons in the U.S. use some type of vision device to enhance their traveling capability (Russell, Hendershot, LeClere, Howie and Adler, 1997). Of that number, 130,000 people use white canes and guide dogs are employed by more than 7,000 people in the U.S. (Leonard, 2002). Even with currently available assistive technology to aid in wayfinding, people with visual impairments lose their lives to pedestrian accidents more than their non-disabled peers (Martinez, 2000). According to a study conducted by the American Council of the Blind, cars at intersections hit almost 8% of visually impaired respondents. Twenty-eight percent of respondents reportedly had their white canes, used to locate obstacles in their path, run over by careless motorists (Carroll and Bentzen, 1999). Further advancement in wayfinding technologies is needed in order to enable people with visual impairments to take full advantage of all that society has to offer in terms of education, employment, and recreation. The realization of such a device represents significant business opportunities, as this device could potentially benefit both the visually impaired population as well as non-disabled persons who are traveling in unfamiliar environments. [ Top of Page ] State-of-the-PracticeToday there are a variety of aids that assist blind and visually impaired travelers in their efforts to independently access the community. The most common forms of aid are white canes, telescopic lenses, travel magnifiers and guide dogs. More technologically-related aids include devices such as canes for accessing the immediate environment, the utilization of infrared and radiofrequency technology for accessing the local environment, and satellite-based positioning and information systems to access the global environment. For the purposes of this document, wayfinding has been roughly categorized into Immediate, Local and Global needs. Wayfinding in the Immediate EnvironmentImmediate wayfinding needs include obstacle avoidance in the immediate path of travel and locating specific architectural and environmental fixtures in/outdoors (e.g., tree branches, doors, curbs). Immediate wayfinding translates roughly into items within physical reach of the individual. Though the state-of-the-practice in wayfinding has dramatically improved over the last decade, there still exist a number of problems to current systems. For example, in learning the proper use of a white cane and guide dogs, extensive training is required. Specific techniques, environmental landmarks, and clues must be learned to provide the independent traveler enough information to manage multiple stimulations. Technologies that help with orientation, mobility, and spatial perception in the immediate environment include clear path indicators, ultrasonic binaural sensing, guide dogs, white canes, and laser canes. Clear Path Indicators put out an ultrasonic beam that creates the clear-path cone for detection of signals. If an object is in the ultrasound beam path, then some sound is reflected back to the device. Signals (auditory and vibratory) are provided to the user only if an object is detected in a field of about 2 feet in diameter and about 6 feet from the user. Clear path indicators are ideal for persons in manual wheelchairs (since both hands are free) and for persons who are both deaf and blind (combination of auditory and tactile feedback). Guide dogs provide a dependable transportation aid as they are able to steer their masters around obstacles. The white cane is designed to maximize tactile and auditory input from the immediate environment of the user. The shaft and tip work together to sense and then relay the tactile information to the grip. Laser canes bounce laser beams off any obstacles at head height and in the path of travel, sending an audible signal back to the user through an earpiece. The cane itself is used to identify holes in the ground or steps down. It extends the range of the standard cane and adds the capability of detecting overhangs. Ultrasonic binaural sensing devices detect obstacles by emitting a beam of ultrasound energy and monitoring the echoes received when the beam is reflected from objects in its path. The components of the ultrasonic binaural sensing aid are "eyeglasses with built-in range detectors, earphones, and a base unit containing the power and electronics" (Cook and Hussey, 1995). Sonar Vision Glasses allow a user to obtain information via auditory feedback about the existence of obstacles within approximately 3.5 yards. Information is obtained through an auditory warning signal; the proximity of the obstacle is indicated by the pitch of the warning signal. A higher pitch warns of a closer obstacle and a lower pitch means an obstacle is farther away. An absence of sound means that there is no nearby obstacle. The device is able to detect obstacles in a 40-degree cone in front. As a result the device can detect obstacles on either side, above, and below the user as he turns his head (University of New Mexico, Center for Development and Disability, 2002). It is important to note that sonar glasses only warn users of the obstacles within its scanning range, and the stem-implanted mechanism only points in the direction of the user's head, which is primarily in front of the user. In addition, this device may be unable to indicate small holes or other obstacles just in front of the user's feet. As a result, it is only considered a complimentary device to the white cane or guide dog. Wayfinding in the Local EnvironmentLocal wayfinding needs include the identification of the ambient environment as the traveler is en route. This can include the recognition of buildings, signs, and the ability to identify environmental and architectural landmarks. Local wayfinding translates roughly into objects within the sight of a person without visual impairment. Products that assist persons to navigate the local environment include binoculars, monoculars, video telescopes and remote infrared signage. Mobility and orientation training are required to be able to successfully use these devices. Video telescopes use digital image processing, microelectronics, and advanced optics for distance viewing and have been optimized for a wide range of hand sizes and dexterities. They contain the highest magnification, a wide field of view and contrast enhancement capabilities similar to digital video magnifiers or close captioned televisions (CCTV) but in a portable device. Telescopic lenses and travel magnifiers are affected by the availability of light and the ability to get the correct angle. There are many different systems and the user must work with a clinician to ensure that the device will meet his needs. Contraindications for these devices include "history of severely decreased vision, poor contrast, rapidly progressive vision loss, hemorrhaging, or multiple pathologies (Rosenthal, 2001)." These devices limit the amount of information that can be perceived at one time. Unlike Braille, raised letters, or voice signs which passively label a location or give instructions to a predefined location, Talking Signs® provide a repeating, directionally selective voice message which originates at the sign and is transmitted by infrared light to a hand-held receiver some distance away (Crandall, 2000). Within the past five years, approximately 1,000 Talking Signs® units have been installed in San Francisco. Talking Signs can also be found in nine other cities in the USA and in four other countries. Japan hosts the most extensive program of permanently installed units with over 2,000 transmitters installed at street intersections in 17 cities (Crandall, Bentzen, Myers, and Brabyn, 2001). In order to use Talking Signs, the user must carry a receiver in his/her hand. In addition, infrared signals are directional, so if the signal is blocked or hindered, reception may be impeded. Talking Signs® are installed in relatively few locations and do not provide a "blanket" solution at this time. Wayfinding in the Global EnvironmentGlobal wayfinding needs are those needs that span beyond the person's immediate environment. These needs include the ability for planning out a route, identifying travel impediments (i.e., construction sites/detours) and travel status (i.e., where you are in your route), and identifying the compass direction of travel. Global wayfinding translates roughly into "out-of-sight" wayfinding issues. Products that assist people with visual impairments to navigate the global environment commonly rely upon the Global Positioning System (GPS) and the Global Information System (GIS). GPS is a satellite-based navigation system that provides accurate location, velocity, and time information by broadcasting coded satellite signals to devices equipped with proper GPS receivers (Dana, 1994). GPS is funded and controlled by the United States Department of Defense (DOD) and has military and governmental applications and provides a lower quality signal for civilian applications. GPS systems access the Global Information System (GIS) to gather information. A GIS is a computer system capable of assembling, storing, manipulating, and displaying geographically referenced information (i.e., data identified according to their locations). GIS is limited to its data set and unfortunately these databases are currently either under developed or non-existent in many locations (US Geological Survey, n.d.). GIS data is collected from within a certain locality, as identified by the GPS system. This may include streets, buildings, and landmarks. It may also include a listing of services offered by various localities in a particular area. Although GIS is becoming more comprehensive as it is updated around the world, problems include getting the most up-to-date information due to changing names of building locations and streets. In addition, the data for each location must be stored in a portable device, usually the GPS receiver. This may require the user to purchase access to a database and its updates. Currently, there is no way to add local information to the GIS database, which makes it difficult to use for local wayfinding. Some databases are incomplete and may include only a certain city, block area, or topography. Therefore the information contained in the GIS database is often overlapping or disjointed, and access is not guaranteed. The GPS system should be able to automatically download local GIS databases. Examples of technologies currently using GPS and GIS are the Braille Note GPS, the Victor Trekker, Atlas Speaks (talking map) and Strider (GPS access system). Some AT products use software that ties into the GIS provided by another company. For example, Victor Trekker works in conjunction with at GIS system called Navtech (http://www.navtech.com). The Braillenote GPS incorporates a Braille note taker with a GPS system receiver that lets users learn about the physical layout of a neighborhood, city, or state and navigate from location to location. In the GPS industry, there is a lack of standardization which results in a lack of product integration. Some manufacturers are reluctant to integrate navigation components as it may make their current product obsolete. GPS systems that cannot be transported easily are a burden and of no use to the consumer who is seeking a solution for wayfinding. GPS can currently be affected by overcast weather conditions. Lost connections exist when low-flying planes or helicopters appear overhead. Voice output on systems is sometimes unable to be heard due to a high level of environmental noise, such as traffic or windy weather conditions. In addition, accuracy is not optimal especially due to urban canyon effects and the signal may be lost inside buildings and subways (May, 2000). When using the Atlas Speaks system, the user must obtain map information from their computer before they leave home. The device is not precise, and as a result, is not very reliable. Human operators must be trained in how to provide travel information to visually impaired travelers. In order to be effective, the device will have to provide the following information, preferably in multiple languages:
[ Top of Page ] Issues to Consider
[ Top of Page ] References
[ Top of Page ] |
|
||
|
| |
