A Remote Assistant Platform for the Blind Based on GIS

Jing Tian, Nan Xing, Hong Zhu, Wenjing Wang, Huawen MaThe Faculty of Automation and Information Engineering

Xi’an University of Technology Xi'an China

Abstract—At present, urban transportation systems are increasingly developed. But there are still many unresolved problems for the blind who have visual obstacle in the travel, particularly in a long journey by car. In this paper we present a remote assistant platform for the blind based on GIS, which can exchange the information with the portable navigation devices in the blind, to help them travel.

Keywords—GPS; GIS; assistant platform; blind navigation; one-to-many tasks

I. INTRODUCTION

Due to their visual impairment, the blind will experience many difficulties in their travel such as how to choose the path. Thus, referring to car navigation equipment, computer servers, and urban public transport systems and such concepts and ideas, this article designs a remote assistant platform, using a remote PC, and wireless communication equipment to help blind people travel safely.

II. SYSTEM DESIGN

Taking the need of navigation in the blind’s travel into account, this article designs the following system architecture. As shown in Figure 1, it includes the travel path planning, public transport fare navigation, special places (hospitals, hotels, etc.) information, emergency alerts and other modules. Through the GPS (Global Positioning System) location, as well as long-range wireless communication and GIS (Geographic Information System), it can complete the information exchange between the blind and the system.

As the core of the whole system, the remote assistant platform receives the data from the portable navigation device GPS in the blind, and display it in the GIS graphically as the reference for the staff. At the same time, it replies a variety of the requests from the device terminals, providing assistance for the blind’s travel.

Figure1. Schematic diagram of the Remote Assistant Platform.

The platform achieves its functions based on a medium of electronic maps. The various layers of electronic map are achieved by MapInfo Professional, including the main street layers, resident layers, layer names, etc. Figure 2 shows a layer of XX city's main streets, as well as XX city’s electronic map with a number of information layers.

(a) (b) Figure2. (a) XX City's main street layer.

(b)X City's Map.

The databank includes geospatial data and non-spatial data. Spatial data includes location of bus stations, bus trips, special places (hospital, hotel) location and so on. Non-spatial data includes basic properties and GPS data.

GPS analysis management module: To achieve the functions such as positioning the blind currently and emergency alerts. This part processes the received data, and gives feedback.

Public transportation information query module: To complete the work including bus route inquiry, boarding

978-1-4244-4994-1/09/$25.00 ©2009 IEEE

program design, boarding navigation, as well as the query of all the map information and analysis.

GIS analysis management module: To achieve the functions such as the map enlargement, reduce, roaming, search, label.

III. FUNCTION REALIZATION

A. GPS real-time location As shown in Figure 3, the GPS module in navigator sends

the coordinates of the current point to the background through the wireless communication device from time to time, assisting the platform to receive the data through the RS232 serial interface. And it transmits the received data into the operating GIS, then displays the converted data in the visual software interface, facilitating the platform operators to control the real-time travel of the blind.

Figure3. GPS Positioning

In the GPS signal reception and transmission process, it uses GPS NMEA 0183 standard protocol.As the process is shown in Figure 4, when the data is sent into the PC-buffer, the platform according to NMEA 0831 protocol to decode it efficiently, giving the variables with the corresponding meaning in structure. On top of it a new target’s display layer is established, in which it uses the MAPX function to paint point at the specified coordinates, refreshing the layer. When new data comes in, it removes the old pixel, draws a new pixel, keeping the latest data show in time.

Figure4. GPS positioning data flow diagram..

B. One-To-Many Tasks Because many GIS platforms provide the services to only a single terminals, this will not lead to only massive waste of resources, but also difficulties to meet different users’ requirements. This platform aims at this problem to achieve one-to-many tasks, making them capable to support multiple remote blind navigators. For processing the one-to-many tasks, its difficulties are mainly reflected in:

• Variety of data package’s formats. GPS protocol defines five different formats of data packets, and this packet will be updated per second.

• Large volumes of pending data. The number of data to be requested instruction is about 90-95 characters, and GPS data packets can be up to 120 characters. While tracking multiple targets at the same time, the amount of data to be dealt with is very large.

• Timely processing data. It includes: to get the GPS data from different targets, display it on the map, and deal with different requests sent by multiple targets simultaneously and other instructions.

According to these problems, in the realization of one-to-many tasks, we use different methods to achieve them. First of all, in order to track more than one goals, we sign different targets, then through the different ID numbers to identify their data packets. At the same time, the calculated results by platform will be fed back to different navigators through the ID numbers. Secondly, in the face of the data packets of various formats, we will classify them in the first level in accordance with their length, including the GPS data packets and requests for instruction packets. Then, we classify the GPS packets in a second level. Therefore the GGA, RMC, GLL data packets contain latitude and longitude information. Then according to NMEA1083 agreement the gained data will be translated. Taking the large amount of data into account, it specially opens up 1024 bytes of storage space for temporary storage of data, preventing their loss. Finally, in order to promote processing speed, we have adopted the multi-threading technique to parallelly process the tasks. In the realization we take the full advantage of MFC's full support for multi-threaded, use the main thread (i.e. the user interface thread) for user’s interaction to enable it to respond quickly to the commands, and through the assistant thread (i.e. worker thread) detect serial port processing.

Figure5. The Picture of one-to-many tasks.

C. Optimal Route Planning When the blind send the destination to the platform through

the Navigator, the platform calculates the optimal path, feed the results back to the terminals, then through the voice told the blind. Figure 5 is the flow chart to find the optimal path algorithm. In our algorithm, the optimal path with the way on foot is defined as the shortest path, while the index of the optimal path with the way by car is that the smallest comprehensive transfer times, lowest cost and shortest path. Among them, the nonstop train has the highest weight. If there is a direct train, regardless of the other cost, even if it appears detour situation, it is the best choice.

Figure6. Optimal path algorithm flow chart..

As shown in Figure 7, it is an example to the optimal path.

Figure7. Optimal path calculation .

D. Other functions • Special places inquiry. When a blind man needs to

inquiry the nearest hospital, hotels and other special venues from the current point, he presses the key to send a request to the background. The assistant platform receives the request, finds the nearest goal places based on his current position, and sends the path

back to him. Details of its realization as shown in Figure 8.

Figure8. The Picture of Special Places inquiry.

• Emergency alarms. When confronted with an emergency situation, the blind can press one click to send the weft to the assistant platform through the data radio. The assistant platform quickly issues a warning signal, reminding the staff to the scene to aid in time. At the same time, the platform will automatically reply a message that the weft has been received. Details of its realization as shown in Figure 9.

Figure9. Emergency alarms.

• Auto-Bus Navigation. While in the commuter car, the portable device will send the real-time GPS data to the assistant platform. When the blind man arrives in a transit point or destination, the platform will automatically send information to the terminals, suggesting that he gets off in time. At the same time, if he needs to switch a car, the platform will promptly send interchange program to the blind.

IV. CONCLUSION

This system combines the practical demands of blind people in the travel with its uniqueness to design a practical remote assistant platform. For the request issued by the blind, the systems are able to achieve fully automatic calculation and reply. With this platform, the blind can travel safely and smoothly.

REFERENCES

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