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8.5 Development Issues

Development of a GPS system for a blind or visually impaired individual requires certain transformations to the mass-market technology designed for sighted people. We cannot just take a GPS system out of a car, even those that talk, and hope to use it for navigation by blind people.

The main issues to be explored are:

•Choosing an appropriate platform for the device.

•Choosing the best GPS receiver.

•Creating a package that makes the system easy to carry.

•Deciding the issue of integration vs stand-alone.

8.5.1 Choosing an Appropriate Platform

In an ideal world, the GPS systems created for the sighted market would have a verbose setting for a blind user so that all the screen information could be accessible. Some of the commercial car GPS systems have speech output but the menus and settings displayed on the screen are not announced or described in speech.

In general, when a blind person uses a computer device, there are various ways to input the information, voice input, computer keyboard input (typing), or Braille keyboard input. Although voice recognition technology works reasonably well in indoor situations, it is less reliable in a noisy outdoor environment and the addition of a microphone adds complexity to the system. So that leaves either typing using a computer or a Braille keyboard. The choice between the two different types of keyboards is a personal one, for every person has preferences. It is advantageous to have the flexibility to provide both solutions.

There are two options for delivering the information to blind users, speech and Braille output. There is a conundrum with regard to speech output. Earphones are fine while listening in a vehicle or while stationary; however, a person’s ears should not be covered when walking or important mobility information could be obscured. Hence, a loud speaker is the practical trade-off. This speaker is best built into the PDA so as to avoid extra weight and wires, amplification and battery power.

Future interface solutions may include vibrating tactile or, more likely, Bluetooth earphones or sound tubes near, but not obscuring, the ears. Perhaps the user would wish to use wireless headphones while sitting on a bus bench. Since 3D location information has been shown to be useful, especially for displaying complex surroundings, there is reason to explore further the different ways to deliver this dimension to users.

For those who read Braille, it is helpful to have the information in refreshable Braille. Braille displays are designed to output one line of text at a time. When the user is finished with the line that they are reading, they can advance to the

next line. This is analogous to scrolling text on news broadcasts. Unfamiliar and complex street names are easier to feel in Braille than listening to speech.

Many people use speech and Braille together. There are advantages to using speech, Braille, or both. In general, speech is the faster way to receive bulk information and Braille is better for reading details. Those accessible PDAs, which provide both, are best. Refreshable Braille does add weight and two to three times the cost of speech to a system.

8.5.2 Choosing the GPS Receiver

Since the introduction of the first consumer GPS receivers in 1995, the metamorphosis of the GPS receiver has been dramatic. The variety of GPS receivers available includes receivers with different connectors (Serial, USB, Compact Flash, etc.), receivers of different sizes (from TV remote size to matchbook size), many different user applications (screens, maps, points of interest files), and so on. So which features are important when constructing a GPS system for use by visually impaired and blind individuals?

A small sized, lightweight device is important for the accessible GPS package. Durability, price and functionality must be considered when evaluating the tradeoffs with size.

Another important issue with GPS receivers is the accuracy reliability. A receiver must work well when there is marginal satellite visibility, for example, in the window of a bus or on the sidewalk close to a tall building. As stated before, the GPS information from the satellites has its limitations, but there are receivers that more efficiently capitalize on the information provided by the satellites. It is important to test various receivers and judge which ones are more reliable in marginal situations.

Many receivers offer a plethora of functions for sighted users. Unless they are made accessible, screens and programming buttons are of no advantage to a blind person. The optimal GPS receiver for this GPS system needs to be easy to use. It should have a distinct ON/OFF button, programming that requires little to no input from the user and an audible alert for low battery.

Durability is very important as blind users use the GPS more than the average recreational sighted user. Blind people are constantly putting the unit on and taking it off, using it in a vehicle and while walking. Cables and connectors should be rugged and eliminated when a wireless option is available.

8.5.3 Creating a Packaged System

Once a GPS receiver is selected, it is important to remember that this will be a system that is carried by its users and not left stationary in a vehicle like most systems for sighted users. Consider a blind person travelling down the street. The first thing that you might associate with that pedestrian is a long cane or guide dog. Both of these mobility aids require the use of a hand, leaving the other hand free

280 8 Accessible Global Positioning System and Related Orientation Technologies

Figure 8.15. Packaging the GPS system. Note: one hand is free to operate the GPS program

for operating the GPS system. One configuration is where the GPS system is carried like a shoulder bag and the GPS receiver clips into a shoulder strap (Figure 8.15).

Another benefit of having the system configured as seen in Figure 8.15 is that it can be efficiently removed and stowed when not in use. Once a visually impaired or blind person has reached their destinations, they probably do not want to continue to carry a GPS system.

8.5.4 Integration vs Stand-alone

As with most product acquisitions, there are cost benefit trade-offs when choosing an accessible GPS solution. When GPS is combined in one unit with other applications, the individual application costs go down but the integrated unit it is part of is probably more expensive than a stand-alone GPS unit. The same is true of the smaller incremental size of the GPS when part of an integrated unit. There are so many accessible devices that a blind person is forced to choose how many and which units to carry. These devices might include a cassette recorder for books on tape, a memo recorder for quick voice messages, a mobile phone, a PDA or laptop, a compass, a magnifier for a low vision person, maybe an obstacle detection device like the Miniguide and of course, GPS. It is very useful when any of the functions of these devices can be combined in a single unit because it reduces the incremental cost and size of each application. A similar situation exists in the mainstream GPS market there are dedicated GPS units and PDAs with add-on GPS applications to choose from.