Abstract
Millions of blind and visually impaired are able to perceive information better through the sense of touch. This knowledge of these people helps us in developing a guidance mechanism. Existing display techniques use piezoelectric crystals, non-refreshable displays and also electronic Braille displays. However, these are either not cost effective or not refreshable. Hence, we propose an innovative technique based on the Global System for Mobile Communication (GSM technology) that incorporates the Global Positioning System (GPS), the Geographic Information Systems (GIS) and GSM modem, which is completely automated without any human intervention and is dynamic in nature. This serves as a tactile based route guidance system for the Visually Challenged People.

We propose to execute this project, first by designing a micro-controller circuit to enable the GSM module to receive the positional information from the GPS and transfer it to the service center as SMS (Short Message Service). At the service center, this SMS is received through a mobile interfaced with a personal computer. Based on the geographical position of the user (known from the GPS), the user is tracked on a digitized map. The optimal route found between the source and destination is converted to bit format and is transmitted to the user by means of SMS. At the user another micro-controller circuit aids in the projection of this information onto the display.

The consequence of this product-oriented project would result in producing an automated route guidance mechanism for the Visually Handicapped People. The device would enable the Visually Handicapped People to navigate without any human assistance.



INTRODUCTION
The days when man used to navigate his way with the help of simple compasses is long gone. Today several advanced technologies are available to precisely inform man about his current location and guide him to his intended destination. However, such guidance systems fail to provide suitable help to the visually handicapped people who are unable to perceive their surroundings as well as interpret the visual guidance that is provided by these systems. Hence, in their case it is necessary to capture their current position automatically and also provide them guidance in a form that is easily perceivable by them.

Some of the already existing Location Based Service (LBS) providing systems are given below:

Drishti, an Integrated Navigation System for Visually Impaired and Disabled is a wireless pedestrian navigation system. It integrates several technologies including wearable computers, voice recognition and synthesis, wireless networks, Geographic Information System (GIS) and Global positioning system (GPS).

BrailleNote GPS is a commercially available talking digital map. BrailleNote GPS uses a cell-phone size GPS receiver to relay information from GPS satellites. It calculates where you are and plots the route to a destination you choose.

GPS-GSM Mobile Navigator combines the GPS’s ability to pinpoint location along with the ability of the Global System for Mobile Communications (GSM) to communicate with a control center in a wireless fashion. The navigator is based on a microcontroller-based system equipped with a GPS receiver and a GSM module. This system is now being used in Shanghai Port, China for navigation and monitoring of ships.

The principles behind the working of the above LBS systems are utilized in the devising of a route guidance system for the Visually Impaired.

METHODOLOGY
To achieve this Route Guidance System for the blind and visually impaired we device a novel system that is based on the interplay of the GIS, GPS and GSM technologies.

The Global Positioning System (GPS) is a satellite-based navigation system made up of a constellation of 24 satellites placed into orbit by the U.S. Department of Defense. The location of the GPS receiver is determined using the satellite positions as reference points. Tracking is one of the fastest growing GPS applications. This kind of a tracking system can be utilized in identifying the position of visually impaired person on the roads who is searching his way to a destination of his choice. With the advancement in wireless communication the information provided by a GPS could be transferred to a server that can be customized to answer the queries of the visually impaired and guide him to his intended destination.

The second requirement of such a device would be to provide a tactile based display of the plotted route to be perceived by the blind. Since the current visual displays are not perceivable by them we require a display that can be perceived by the sense of touch. Further, such a display can remove any ambiguity that can arise due to distortion in noise signals, which can occur in the case of voice based route guidance alone. The Dot Matrix Display is an Electromagnetic Display Module consisting of an array of display elements. Every element consists of a disk, which has two different types of surfaces, one side is smooth and the other side is having a round projection, which can be felt by the sense of touch. It is this property of the elements that serves the need for a tactile based display.

This application can be discussed across two ends: the client end and the server end. The GPS at the client end captures the positional information which is then processed to extract the latitudinal and longitudinal values. This information is sent as sms via a GSM modem to the server end. The intended destination information is transferred as voice signal. The Geographic Information System (GIS) at the server end plots the optimal route for the request, on a digitized map. The route information is processed and sent back to the client device that is responsible for converting the information and representing it suitably on the tactile display.

The basic methodology involved is as follows:

• Transference of the positional information of the visually impaired via SMS to the central server.
• Obtaining the intended destination from the visually impaired and transfer as voice to the central server.
• Convert the destination information from voice to text at the central server.
• Querying the GIS to obtain an optimal route, from the current location to the intended destination.
• Performance of image processing on the obtained map to convert into a form, suitable for the display.
• Transference of the image back to the blind.
• Providing a tactile display that is perceivable by the blind.

Figure 1. System Flowchart

IMPLEMENTATION
The project essentially consists of the following major modules: namely, the GPSGSM interface, Communication system, Route Attainment Module and Display Module.



Figure 2. Component Architecture

GSM-GPS Interface
The Global Positioning System (GPS) is a satellite-based navigation system. GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. By measuring the travel time of signals transmitted from each satellite, a GPS receiver can calculate its distance from the satellite. The location of the GPS receiver is determined using the satellite positions as reference points. The positional information received from the GPS receiver is transferred to the microcontroller which is programmed to retrieve the necessary information namely latitude and longitude. This information is directed to the GSM module to be sent as SMS.

Global System for Mobile Communication (GSM) is a novel communication technology. It is a digital cellular radio network that operates using radio frequency. AT commands have been used to program the GSM module. For every SMS that is to be sent, the microcontroller sends the AT commands providing the server’s mobile number (a mobile unit was used in the server side). The positional information is delivered as the message to be sent. On receiving the send command from the microcontroller, the GSM module sends the message as SMS. Further, the microphone of the GSM modem is used by the visually handicapped to specify his destination name. At the other end, the server, the SMS and the audio information are used for generating the optimal route between the two points.

Communication System
At the server, a mobile device is interfaced with the Personal Computer. The SMS that is sent by the GSM modem (held by the user) is received by this device and is passed to the server. On receiving the sms from the user, the sms contents are copied into the input file, with which GIS query will be generated automatically. The GIS system finds the optimal path and generates the output image. This output image is transferred back to the mobile client again as sms.

Route Attainment Module
GIS software is a powerful, easy-to-use tool that brings geographic information to your desktop. GIS software gives the power to visualize, explore, query and analyze data spatially. The Network Analyst is an extension product of GIS software designed to help use networks more efficiently. The GIS Database is first loaded with spatial attributes of that area represented in a digitized map. The Network Analyst was then used in finding the optimal path between the source and the required destination. The route that is obtained is then compressed and processed to get the route information as a binary file to be sent as sms to the client device.

Display Module
A 16*16 Electromagnetic Dot matrix Display was used to provide the route information as tactile image to the Visually Impaired Persons. The module is used to convert the binary image file as voltages to drive the display. The micro controller was programmed suitably to facilitate this process.

With the help of the above four modules, a system for the automated route guidance of the Visually Challenged People was developed. This complete setup is selfsufficient and does not require any manual intervention.

CONCLUSION
Though the GPS has been widely used these days for fleet management and other tracking purposes, devices like this open another new application field for the GPS. Further, the combining of the GSM services with GPS and GIS technologies provides the necessary Location Based Services (LBS) for route guidance to the visually impaired. The Display device that has been used for the purpose helps in providing tactile based information for the visually impaired making it easier for them to understand the route and navigate to their preferred spots without human assistance.

REFERENCES

• John Roberts & Oliver Slattery, A New Refreshable Tactile Graphic Display Technology for the Blind and Visually Impaired, National Institute of Standards and Technology - Reference from the net.
• R Dan Jacobson, Postgraduate researcher, Institute of Earth Studies, University of Wales, Navigation for the visually handicapped: Going beyond tactile Cartography - Reference from the net.
• Deane Blazie, President of Blazie Engineering, Refreshable Braille, Now and in the Years Ahead Book - Reference from the net.
• Eric Abbott and David Powell, Land Vehicle Navigation using GPS, Proceedings of the IEEE, 1999,Vol.87
• John Roberts, NIST Refreshable Tactile Graphic Display: A New Low- Cost Technology, Technology and Person with Disabilities Conference 2004, University of California.
• Joshua A. Miele, Ph.D.,Tactile Map Automated Production (TMAP): Using GIS data to generate Braille maps, Technology and Person with Disabilities Conference 2004, University of California.
• Dr.S.P.Sekar, Assistant Professor, SAP, Anna University, ICCHP 2000- International Conference on Computers Helping People with Special Needs, July 2000, A design approach for Electronic Route Guiding System using GIS and GPS for Visually Handicapped Persons
• C.Jeganathan, Engineer SD, Geo Informatics, Indian Institute of Remote Sensing, Dehra Dun, Uttaranchal, Utilization of Location Based Services for the benefit of Visually Handicapped Persons