Wayfinding encompasses all of the ways in which people orient themselves in physical space and navigate from place to place.
Over the last thirty years, engineers have devoted considerable resources to developing electronic location-based services to help a blind person, particularly travellers, orient themselves and wayfinding systems to navigate to a destination. These have used technologies such as ultrasonics, lasers and infra-red, and more recently Satellite navigation or Global Positioning System (GPS), Dead Reckoning, wireless, Bluetooth and WiFi.
Types of wayfinding technology
The most widely used and available system – the GPS system – is based on the use of radio signals transmitted from satellites orbiting the Earth and with whose assistance it is possible, with the use of special receivers, to get a position on the Earth's surface in the form of coordinates. This kind of reference can be transformed into, for example, an indication on an electronic map on a GPS receiver.
The American Global Positioning System (GPS), can be used to determine one's position to a few metres. However this requires line-of-sight to three or four satellites, which means being outdoors and not close to tall buildings. This position is just given as latitude and longitude, so it needs to be integrated with a detailed digital map of the area.
The Russian GLONASS system is a radio-based satellite navigation system developed by the former Soviet Union and now operated for the Russian government by the Russian Space Forces. As of March 2008, the system is not fully available, however it is maintained and remains partially operational with 16 operational satellites. The goal is to provide global coverage by 2009.
GALILEO will be based on a constellation of 30 satellites and ground stations providing information concerning the positioning of users in many sectors such as transport. This system is designed to be well-adapted for European environments in particular. However, it is still presently at the testing phase with the second navigation test sateliite launched just recently. It is anticipated that all 30 satellites will be in position by 2013.
Assisted GPS (AGPS) can be used in situations where the signals from the satellites are too weak. This may be appropriate indoors, but also outdoors under less favourable circumstances. Examples of such circumstances are when only a small number of satellites can be reached or when moving around on narrow streets surrounded by high buildings or other similar environments – the so called canyon-effect.
Enhanced GPS (EGPS) is a technology designed for mobile phones on the Global System for Mobile Communications (GSM) and Wideband Code Division Multiple Access (W-CDMA) - a type of 3G network, to augment GPS signals to deliver faster location fixes, lower cost implementations and reduced power and processing requirements. It is currently being developed by Cambridge Silicon Radio who have partnered with Motorola.
A digital map is a computer-readable representation of a geographic area, such as can be seen on the screen of a car drivers' GPS receiver or "SatNav".
The availability of sufficiently detailed digital maps has proved to be a significant problem. Digital maps designed for car drivers do not give the detail needed by a blind or physically impaired pedestrian. Ideally the map should not just show the destination and the route but also provide additional information to aid accessibility, for example, at a road crossing a wheelchair user will need to know where the drop level kerbs are, at a bus stop a blind or visually impaired person would find it useful to know which buses stop there. The inclusion of transitory information, such as current roadworks would also make digital maps more useful for those with impairments.
Currently developed GPS systems tend not to work in indoor environments or when obstacles, like tall buildings, block satellite signals. Dead Reckoning (DR) is a wayfinding technology that can be used to identify locations indoors. It is especially helpful as a tool for working in combination with GPS. When GPS signals are blocked, location based information processing can be passed on to Dead Reckoning systems for analysis and reporting. DR can access geographic databases similarly to GPS. Accuracy of DR is often better than for current GPS systems. Nano technology breakthroughs hold promise that these DR systems can be as small as one inch cubes, and therefore perfect for wearable computing applications.
DR uses a very sophisticated electronic compass, with mechanisms for calculating speed, position, heading, and distance to destinations (just like GPS). Movement detection systems are also built in (accelerometers, gyros, pedometers). Unlike GPS, Dead Reckoning can also provide vertical coordinates, for example, what floor of a building the blind person is on.
WLAN – Wireless Local Area Network – which are local, radio-based networks that send information to, for example, a mobile telephone or PDA about what is located in the vicinity.
Bluetooth is a wireless protocol that could use landmarks to aid navigation. A landmark is an identifiable point in the surroundings that one can relate to in order to determine ones position and navigate successfully. For people with visual impairments audio landmarks are used.
Bluetooth technology can then be used to provide guidance by means of small radio transmitters positioned at strategic points in the environment. When one approaches such a transmitter carrying an appropriate receiver, pre-recorded information will be read out, which could include anything from advertising to the identification of, for example, a bus stop. Bluetooth transmitters need an energy supply in the form of, for example, an integral battery.
However it is worth noting that Bluetooth technology does not support information concerning direction or relative distance between the user and the Bluetooth transmitter, but merely if a user is within range of its signal.
WiFi is the trade name for the popular wireless technology used for home networks, mobile phones and video games. The purpose of Wi-Fi is to enable wireless access to applications and data, media and streams. The main aims of Wi-Fi are:
- to make access to information easier
- to ensure compatibility and co-existence of devices
- to eliminate cabling and wiring
- to eliminate switches, adapters, plugs, pins and connectors.
A WiFi enabled device can connect to the Internet when it is within range of a wireless network connected to the Internet. Due to the very limited practical range of WiFi, mobile use is essentially confined to such applications as inventory taking machines in warehouses, barcode reading devices at check-out stands or receiving / shipping stations. Mobile use of WiFi over wider ranges, such as in outdoor navigation, is limited to move, use, move, for example, as in an automobile moving from one hotspot to another.
Problems encountered by disabled people and the ageing population using wayfinding technologies
Some wayfinding technologies do not give sufficient information for blind and partially sighted people to complete a journey. For example, digital maps designed for car drivers using GPS positioning do not give the detail needed by a blind pedestrian. Ideally a map should not just show a bus stop, but also provide information about which buses stop there.
Most wayfinding systems rely on the user being able to hear audio commands. In busy, noisy streets, people with hearing impairments may have trouble hearing these spoken instructions.
A person with physical impairments may not be able to walk up more than ten steps, or use an escalator that they have been led to by their wayfinding system. Ideally, there should be a unified service which can provide this information, taking into account the user's special needs. As well as the total journey time and the total cost of the various options, it would be helpful if the navigation system was able to indicate where the stairways, lifts and alternative options were situated.
Some navigation systems can give a list of audio instructions or provide a huge amount of detail which those with cognitive impairments may find difficult to remember. Instructions that are overly long and complicated may also cause confusion.
Elderly people often experience changes in vision, hearing and understanding as they age, therefore they may encounter issues with the lack of detail about an environment, too many instruction provided by the receiver and external noise interference when listening to audio instructions.
- The display should have good contrast and use a clear typeface.
- Text should not be scrolling or flashing while it has to be read.
- There should be minimal visual flicker or image flashing.
- Minimise glare on the display and control surfaces.
- Provide adequate back lighting.
- There is the ability to alter the length of activation time for the back lighting.
- The user should be able to increase the font size.
- Text should be in upper and lower case and not all in capitals.
- Use Arabic and not Roman numerals.
- On colour displays, red/green and blue/yellow combinations should not be used.
- Provide colours with different hues and intensity so that coloured objects can be distinguished on a black and white screen.
- Good visual contrast between the keys and the body of the receiver.
- Key tops should be convex or flat with a raised edge.
- Keys should be as large as possible without reducing the distance between the keys to less than half the key width.
- Ideally the keys should be internally illuminated, but the internal illumination should not reduce the legibility of the numbers in daylight.
- The visual markings on the keys should be high contrast, clear, and as large as is possible on the key top.
- Keys should be raised above the body of the receiver (preferably by 5 mm).
- The pressure to activate a key should be between 0.5 and 1 Newton.
- There should be auditory and tactual feedback of key activation.
- Function keys should be tactually discernable from the letter or numeric keys.
- There should be a tactual indication on the '5' key or on a QWERTY keyboard on the 'F' and 'J' keys.
- A voice mode selection that announces all key presses.
- One-touch buttons are provided for ease of performing repeated tasks.
- Provide rotational or linear-stop controls.
- For keys that do not have any physical travel, audio or tactile feedback should be provided so the user knows when the key has been activated (e.g. a toggle swtich or a push-in/pop-out switch).
- Where timed responses are required allow the user to adjust them or set the amount of time allocated to the task.
- The user should be able to set the volume of the audio output.
- Provide text versions of audio prompts that are synchronised with the audio so that the timing is the same.
- There should be audio cutoff when an external listening device is connected.
- An industry standard connector for headphones or personal listening devices should be provided (e.g. a standard 9mm miniature plug-in jack).
- There should be consistent design of the user interface whenever possible.
- There should be an audio and visual indication when the receiver is switched on or off.
- The user should be able to return to the previous state or return to the default status at any stage in the process.
- Error messages should be comprehensible to the non-technical user.
- All labels and instructions should be in short and simple phrases or sentences. Avoid the use of abbreviations where possible.
- Basic functions should be usable without having to use the visual display.
- It should be possible to use the receiver one-handed.
- A function to raise an alarm or communicate with an information or alarm centre for personal support and assistance is available.
- The receiving device has 3G technology so users can send pictures or video clips from their surroundings to a support person.
- There is a "localisation" function so that it is possible to locate a user when they have lost the capacity to orientate themselves.
Instruction manuals / documentation
- Use simple clear concise language.
- Have a table of contents and a good index.
- Be task orientated.
- Provide instructions in alternate formats (e.g. audio tape, large print).
- Use a typeface with good legibility.
- Information contained in pictures should also be explained in the text.
- Provide information on what to do if the wayfinding system does not work correctly, or the user is unable to understand the instructions (e.g. a telephone help number).
- ANSI C.63.19 American National Standard for methods of measurement of compatibility between wireless communications devices and hearing aids
- IEEE Standard 802.15.1 (2002) Wireless MAC and PHY specifications for wireless personal area networks (WPANs)
- ISO 19133 (2005) Geographic information - Location-based services - Tracking and navigation
- T1.TR.32 (1994) Service capabilities for low-power wireless access to personal communication services
- TIA-835.1-C-2 (2008) CDMA 2000 Wireless IP Network standard: Introduction
- U.S. space-based positioning, navigation, and timing policy 2004
- Baldwin (2006) Wayfinding textbook project: GPS [accessed 25/09/08].
- EGPS Forum (2008) [accessed 26/09/08].
- Global Positioning System. [accessed 25/09/08].
- Information for Travellers - Wayfinding
- Institute for Innovative Blind Navigation (n.d.) Wayfinding. [accessed 18/07/08].
- Intellect (2007) Satellite navigation - myths and answers. [accessed 26/09/08].
- Russian Space Agency (n.d.) Information Analytical Centre. [accessed 25/09/08].
- Wikipedia (2008) Assisted GPS. [accessed 26/09/08].
- Wikipedia (2008) Bluetooth. [accessed 26/09/08].
- Wikipedia (2008) Dead reckoning. [accessed 26/09/08].
- Wikipedia (2008) GPS for the visually impaired. [accessed 30/09/08].
The information contained in this section was taken from the following sources:
- Anon. (2008) American GPS gets more competition as Europe launches 2nd navigation test satellite. Web in France Magazine [online]. [accessed 25/09/08].
- Baldwin, D. (2006) Wayfinding textbook project: dead reckoning/sentient computing [accessed 25/09/08].
- Directorate-General Energy and Transport (2007) GALILEO European Satellite Navigation System. [accessed 25/09/08].
- Gill, J. M. (2007) Accessibility for Visitors. [accessed 17/07/08].
- Lindström, J-L. (2007) Safe navigation with wireless technology. In: Roe, P. R. Towards an inclusive future. Brussels: COST. pp 9-23. [accessed 17/07/08].
- Wikipedia (2008) Enhanced GPS. [accessed 26/09/08].
- Wikipedia (2008) GLONASS. [accessed 26/09/08].
- Wikipedia (2008) WiFi. [accessed 30/09/08].
Last updated: 20.11.2009 © Copyright reserved Website design: Digital Accessibility Team