An Orientation and Navigation System for Blind Pedestrians
Dr John Gill,
Chief Scientist, RNIB
The MoBIC Project
The aim of the MoBIC project has been to increase the independent mobility of visually disabled people travelling in unknown environments. The project has developed a family of orientation and navigation aids.
Visually disabled and elderly persons have problems in travelling independently. Firstly, they have difficulties in accessing the information they need to plan their journeys. Once on a journey they have problems in knowing where they are and keeping to the planned route.
This brochure explains the work to date of MoBIC (Mobility of Blind and Elderly People Interacting with Computers) which is a project supported by the Commission of the European Union. MoBIC is developing a route planning system which is designed to allow a blind person access to information from many sources such as bus and train timetables as well as electronic maps of the locality. The planning system will help blind persons to study and plan their routes in advance, indoors.
With the addition of devices to give the precise current position and orientation of the blind pedestrian, the system can then be used outdoors. The system is intended to be complementary to primary mobility aids such as the long cane and guide dog.
The outdoor positioning system is based on signals from satellites which give the longitude and latitude to within a metre; the computer converts this data to a position on an electronic map of the locality. The output from the system is in the form of spoken messages.
To ensure the usability of this system, an extensive part of the design project focuses on user requirements. This includes the participation of visually disabled people in both the specification and implementation phase of the project. One outcome of the project will be a detailed specification of user requirements which will be independent of the specific technology. Two field trials are being undertaken to evaluate the prototype systems against this specification.
The aims of this part of the project were:
- to obtain an understanding of how visually disabled and elderly people find their way in a complex environment,
- to inquire what problems they experience in orientation and mobility,
- to find out what information a travel aid should present in order to alleviate these problems.
Two main methods were used: the first was to make an analysis of earlier investigations on related problems, and the second to interview visually impaired and elderly people, as well as mobility trainers. In addition, mock-ups or working prototypes of different parts of the systems were tested by potential users in realistic situations.
The unfulfilled needs of visually disabled and elderly people are in the areas of planning before travel and orientation during travel. Earlier studies suggest that blind people, in comparison to sighted people, need more detailed information before travel and have to rely on less perceptual information from the environment during travel. A review of literature on earlier investigations provided data that was relatively abstract. However, interviews with both visually impaired and elderly potential users provided information on a more concrete level, as well as feedback on attitudes to different aspects of the current MoBIC travel aid.
Visually impaired individuals would like information included on the location of bus and tube stops and useful landmarks. Information is also wanted on obstacles on the pavement as well as road works. Obstacles at headheight were often mentioned. Suitable places to cross streets is another example of urgently needed environmental information.
The visually impaired travellers indicated a reluctance to consider a system involving the use of headphones because it might block environmental sounds. The appearance of the aid is considered very important by potential users wanting to avoid looking conspicuous.
Information was also collected from mobility trainers who felt that the MoBIC system could easily be integrated into current training programs, but they stressed the necessity of the trainers being given sufficient training in using the devices before they were expected to teach students.
The MoBIC route planning system involves a personal computer with synthetic speech output. The software permits a blind person to explore the electronic map as well as planning the optimum route to the desired destination. The route can be described in speech; for example "Go straight ahead for 100 metres, then turn right at the street crossing and continue for another 50 metres". A future development will be the ability for the blind user to specify the criteria for an optimum route (eg minimum number of road crossings or avoiding complex road junctions).
The operational outdoor system uses the computer used in the route planning system and incorporates a differential global positioning system which receives signals from satellites, to give precise information on the users position to within a metre, and an electronic compass. The user interacts with the outdoor system by using a small hand-held keypad with the output being in synthetic speech with clock-type directional instructions (eg "change direction to 3 oclock and continue for 100 metres to High Street"). The user hears the spoken messages using a special earphone which does not prevent the user hearing other sounds from the environment.
Since the available electronic maps do not include all relevant information (eg the entrances to public buildings or which buses go from a particular bus stop), the MoBIC system includes the facilities to add or change information in the electronic maps. Tactile information could be provided by embossed maps and a touch tablet as an optional part of the system.
The incorporation of a mobile telephone link would permit obtaining information from a central service centre while outdoors. Future developments may include the integration of a dead reckoning system to overcome the problems caused by loss of the signals from the satellites (eg when walking under a bridge or close to a tall building).
The prototype systems use standard components to provide a large range of facilities needed during the experimental phase of the project.
Essential features of the final products will be that they are reliable and affordable, and that the portable system is lightweight and compact.
The first field trial of the route planning and outdoor systems was undertaken in Berlin from September to November 1995. In this trial six people (four blind and two partially sighted) attended a total of 25 tutorial sessions. The two test routes were of about 1200 metres along unfamiliar roads. Both the planning and outdoor systems performed well, and participants were impressed by the accuracy and quantity of the information provided by the systems. These trials identified some technical aspects which needed improvement.
The second series of field trials will take place in Birmingham starting in mid-1996. The systems have been modified to take into account the results of the Berlin trials. The Birmingham trials will be evaluating the use of a number of MoBIC devices over a six month period. It is intended that a number of blind participants will use the devices for the duration of the trial; they will keep the devices in their homes and will be trained to plan and make journeys.
A range of quantitative research methodologies will be employed during the trial. It is predicted that when using the MoBIC device individuals will be able to plan and make journeys more effectively, and gain a richer understanding of their spatial environment; this will be assessed through completion of test routes.
It is also predicted that MoBIC will give participants opportunities to make journeys and decisions which were not possible before. Detailed diaries of how MoBIC was used over the trial period will be generated through regular interviews with each participant. This will reveal the qualitative changes to peoples lives that this technology can make possible.
Although the technology in this area is likely to change dramatically in the next decade, the needs of blind pedestrians will evolve gradually. The user needs specification will be largely independent of the technology so it will be applicable to other systems for helping blind people with orientation and navigation. It is difficult to predict the rate of technological progress, but the trends are for this type of technology to decrease in cost, size and weight, and thus become more practical and beneficial for a large number of visually disabled and elderly people.
The MoBIC Consortium
Prof Thomas Strothotte (Project Leader), Kathrin Weese, Petra Specht,
Andreas Raab, Rainer Michel, Jörg Hamel
Universität Magdeburg, Germany.
Jürgen Bornschein, Matthias Roxer
F H Papenmeier Gmbh & Co KG, Germany.
Dr John Gill
Royal National Institute of the Blind, England.
Dr Helen Petrie, Valerie Johnson
University of Hertfordshire, England.
Prof Gunnar Jansson, Emily Holmes
Uppsala University, Sweden.
Lars Reichert, Axel Schalt
Freie Universität Berlin, Germany.
Stephen Furner, Don Golding
BT Labs, England.
Dr Michael Tobin, Nick Bozic, Graeme Douglas, Eileen Hill
University of Birmingham, England.
The MoBIC project is being supported by the Commission of the European Union through the TIDE program (Technology Initiative for Disabled and Elderly people). The Swedish participation is funded by Uppsala University and the Swedish Work Environment Fund.
Information about MoBIC is at: www.tiresias.org/reports/mobicf.htm
Last updated: 20.11.2009 © Copyright reserved Website design: Digital Accessibility Team