{sabeeh84, fahad_lotus, yahyakm}@yahoo.com. Abstractâ In this paper, we have presented a system utilizing. Radio Frequency Identification (RFID) for the ...
RFAIDE – An RFID Based Navigation and Object Recognition Assistant for Visually Impaired People Mohsin Murad, Abdullah Rehman, Arif Ali Shah
Salim Ullah, Muhammad Fahad, Khawaja M. Yahya
University of Engineering and Technology Peshawar, Pakistan {mohsin_murad, abdullah.rehman7, arfimania}@yahoo.com
University of Engineering and Technology Peshawar, Pakistan {sabeeh84, fahad_lotus, yahyakm}@yahoo.com
Abstract— In this paper, we have presented a system utilizing Radio Frequency Identification (RFID) for the assistance of blind people. The proposed system incorporates a mobile RFID reader module with an integrated ZigBee transceiver [1] for transmitting the tag’s information. Utensils and other objects in the house or building are embedded with passive RFID tags (transponders) along with an audio file, recorded for and unique to each object, residing on the server. This system further takes in the way finding technique by employing an RFID tag grid [4] using an ample separation area. The reader reads the tags and transmits the data wirelessly to the server PC which in turn scans for the particular ID in the database and plays the corresponding audio file. A self designed coordinates system with a server side routing application is used for routing the person to a particular room requested, based on his current tag coordinates. The audio playback is relayed wirelessly using an FM transmitter to either a headset with FM receiver or a Smart Phone’s FM radio. The feasibility and reliability of the developed system was tested by deploying the proposed system at Government Institute for Blind, Peshawar, Pakistan [6]. Keywords-rfid; assistant; blind; zigbee; rfaide; navigation; recognition; class room; house; tag-grid
I.
INTRODUCTION
One of the basic senses of a normal human is sense of Sight which enables one to see the vibrant life. As it is regarded as one of the basic senses so any defect or malfunction in it is quite difficult to cope with and can cause much misinterpretation in daily life chores. It is the mix observation of senses that enables one to progress in right dimensions so impairment in one can cause heavy shift of reliance on other senses and supporting devices. Sight, being one of the leading senses in the routine jobs, renders life quite difficult for a visually impaired person as compared to a person in good physical shape. From the handicapped point of view the facilities available are pretty bleak. They are not able to see the world and enjoy life like the rest and a dearth of aides also adversely affects their life. RFID has proved to be an effective technology for providing path and objects information to the visually impaired people. RFID is the technology of choice when it comes to tagging objects for identification purposes. It makes use of radio waves to store and retrieve data from an identification chip or an RFID tag. RFID tagging systems consist of two major components: an RFID tag or transponder and a reader/writer (Figure 1). The tag includes a microchip and an
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antenna. Each tag has a unique E-coding which can be used to identify target objects. The reader/writer requests or alters information contained in the tag by sending an RF signal to it. The tags have a passive communication circuit and therefore can be embedded almost universally owing to its, virtually, no energy requirement.
Figure 1. RFID Reader reading Tag’s information
In this work we have presented an RFID based solution for blind people to recognize objects in a home/class room along with path finding. It consists of a portable and low power hand mounted RFID reader for fetching tag’s information and sending it wirelessly to the server running the database. Two zigbee transceiver modules are interfaced with the reader circuit and the PC for data transmission. The hand mounted reader reads the information stored on the tag and transmits it using the zigbee module to a nearby server; PC with a zigbee receiver and running a database. On the server side, the received tag ID or unique number is searched in the database and an audio file against that particular tag is retrieved and transmitted on an FM band. The blind person is provided with a headset having a low power FM receiver tuned at the transmitter’s frequency. We also tested the possibility of sending the audio files using GPRS network but due to voice delay and increased complexity of the system we decided to go ahead with the FM transmitters. Using a cell phone’s built in FM radio makes the system further inexpensive. II.
RELATED WORK
Willis et al. [2] have described a navigation and location determination system for people with visual impairments using an RFID tag grid. RFID tags are programmed upon installation with spatial coordinates and information describing the surroundings. This allows for a self-describing, localized information system with no dependency on a centralized database or wireless infrastructure for communications.
Chumkamon et al. [3] have developed a tracking system for indoor environment of a building for blind people based on RFID. They have deployed an ultra high frequency (UHF) RFID system which can provide the reader with required location information within a proximity range up to 10 meters. The system depends upon the location information from a tag and key component includes a routing server where the shortest route from the user’s current location to the destination is calculated. Their navigation device communicates with the routing server using GPRS.
The XBee transceivers can communicate within 150 meters indoor range using the chip antenna with very low transmission and reception power utilization. B. FM Transmitter Inspired by the schematics from a hobbyist website, a USB powered FM transmitter (Figure 3) was designed. In our test system we have used 90MHz band. The voice quality was excellent within a 100 meters range.
Jinying et al. [4] focused on embedding RFID tags in the tiles of a blind path for better navigation. Their portable RFID reader has a microcontroller for processing the incoming data and a wireless headphone is used for playing the incoming voice data. Authors have used GSM network for sending street and shops information to the subject from the database server. Saaid et al. [5] proposed Radio Frequency Identification Walking Stick (RFIWS); a stick mounted device intended to assist the blind while walking on sideways. They have presented, in detail, all the key components required with detailed configurations like antenna polarization, tag performance, tag orientation sensitivity and tag communication distance for UHF RFID systems. III.
TEST BENCH COMPONENTS
A. RFID Reader Module The hand/cane mounted tag reading system includes a Robotic Connection’s low power RedBee RFID reader [7]. ZigBee transceivers (XBee) were introduced later in order to remove the wired RS232 link between the PC running the database server and the RFID tag reader.
Figure 2. RedBee RFID Reader with XBee modules having Chip Antennas
The tag reader module has an excellent range of 5” which was increased to almost 10” with a few tweaks. Furthermore, the XBee communication modules allow a host computer to communicate with more than one reader module using Broadcast Personal Area Network (BPAN).
Figure 3. RedBee modules forming a BPAN with the basestation XBee transceiver
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Figure 4. USB power FM tranmitter with Audio Jack feeding the input
C. Database Server The PC used was an HP DV5, 2GHz laptop running Windows 7. Visual Basic was used as the database frontend design language. The database was developed and maintained using MS SQL Server. One reason for choosing MS SQL Server as a database management tool was to allow online monitoring of people, using the tag IDs received from their cane mounted RFID reader. A small applet was written to remotely return tag coordinates of a user, to the monitor, if he is using the reader for navigational purposes. For handling incoming data, a small code segment was added to the database front end code based on VB.NET SerialPort Class. It was used to receive the data (Tag ID) from the serial port (USB in our case), compare it with the list of Tag IDs in the database and finally to play corresponding audio file whose location was stored in the database using VB.NET’s built in library functions. Two different databases were maintained for cane and hand mounted readers with different sets of Tags IDs associated with each. For routing in tag grid, a custom route calculation applet is used which calculates the route from user’s current location in tag grid to his final destination. Conforming to the calculated conditions, an audio message of either left, right front or backward is relayed to the user. D. RFID Tags Tagging process can employ different objects for example wallet, a book, utensils etc. These objects were mounted with small circuit serving as tags and the mounting techniques varied from sticker mounting to key chain embedded tags. After the hardware integration, comes the process of making tags useful for objects identification. For this purpose the return ID of tags are stored in the database and against each id is an entry of an audio file that contains the relevant and easily recognizable information about the tagged object e.g. voice playback of object name. Now when the reader comes into close proximity with tag and energizes it, the tag returns an ID that is searched in database and the audio file corresponding to that entry is played. If a tag is unregistered, i.e. it has no entry in database, there would be no response. Other application of tags was in making a grid for navigational purposes. The grid was made in such a way that each tag was surrounded by four more tags each 2 feet away from central tag. The movement along straight lines is allowed but along a diagonal is redundant. Following this pattern the
whole building occupied by Deparment of Computer Systems Engineering was tagged and for initial test the destination had to be entered manually. On the server side the application relates tags with 4 audio files and also identifies these tags as the hard coordinate of the customized grid. The audio files are for left, right, forward and backward direction identifiers. Now when a destination is entered, the application calculates the route to the destination from the current location and helps one to move along tags via reader-tag interaction.
Figure 6. System Architecture
Figure 5. Various RFID Tagged Items
IV.
EXPERIMENTAL TESTBED
The system was deployed and tested in Government Institute for Blind, Peshawar [6]. The environment, in which he system was tested, was initially controlled by minimizing the disturbances from external agents and also by reducing the interference in radio interface by available means. The contact between reader and tag was made to occur in line and similar patterns were ensured for tags grid. There were no physical obstacles and physical distances were kept to a low level in the initial deployment to test the system for any inherent issues. All the tags responded quite well in this fashion and even increase in physical distance didn’t significantly affect the working of system. The system performed well within a 100 meters indoor range. Now when system is in operation, if someone has to use a single reader for both purposes, he is provided with a button to switch between Way-Finding and Object-Recognition modes. A data byte is sent to the server telling it to select one of the two databases. In case of dual readers, if somehow the cane mounted reader is able to read tags embedded into objects, it won’t trigger an audio signal playback as the way-finding specific database is not having any object’s tag id and vice versa. Figure 5 shows the system’s architecture. We’re currently working on making the navigational system more intelligent e.g. by replacing the manual text based destination entry system with the speech input of destination and that can be made possible with introduction of a DSP Processor running a speech recognition algorithm.
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V.
CONCLUSION
In this paper an effort, made to assist visually handicapped people in some way by deploying a system that first tags the objects making these visible through predefined identities, is presented. The system deployed is a number of units communicating via Radio waves. When the reader is in close proximity to one of the tags, he is informed about the object’s details via an audio file on server. In a similar way a grid of tags (on pathways) with some suitable spacing helps the person with reader to identify the location and anticipate any further movement safely. The deployed system gave good results in a controlled indoor environment and was further giving healthy results in relatively rough environment but required some refinement and required the use of relatively accurate reader modules to handle interference problems otherwise the system proved to be scalable and ease in its use being one of its distinguishing mark. We’re working on making the system more robust, dynamic and portable so that it can withstand the interferences from a real environment encountered by a handicapped person and also giving service to multiple persons. We’re further developing an insight into effectiveness of the parameters of the system for example, replacing FM transmitter module by a ZigBee transceiver which reduces the broadcast/reception of the message to unintended destinations. Another point worth mentioning is the cost of the system on which we’re currently working as to make it more affordable and in the long run widely available by using a custom designed RFID readers instead of commercial off the shelf ones.
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XBee Modules, Digi International, [Online] Available: http://www.digi. com/products/wireless-wired-embedded-solutions/zigbee-rf-modules /zigbee-mesh-module/xbee-digimesh-2-4.jsp Willis, S. Helal, S. Comput., “RFID information grid for blind navigation and wayfinding,” in Proceedings of Ninth IEEE International Symposium on Wearable Computers, 2005. Chumkamon, S. Tuvaphanthaphiphat, P. Keeratiwintakorn, “A blind navigation system using RFID for indoor environments,” in Proceedings of 5th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2008. Jinying Chen Zhi Li Min Dong Xuben Wang, “Blind Path Identification System Design Base on RFID,” in Proceedings of (ICECE), 2010 International Conference on Electrical and Control Engineering, 2010. Saaid, M.F. Ismail, I. Noor, M.Z.H., “Radio Frequency Identification Walking Stick (RFIWS): A device for the blind,” in the Proceedings of 5th International Colloquium on Signal Processing & Its Applications, 2009. Government Institute for Blind, Peshawar, Pakistan. [Online] Available: http://www.khyberpakhtunkhwa.gov.pk/Departments/Social Welfare/schools-for-blind-children.php. Redbee RFID Reader, Robotic Connection, [Online] Available: http://www.roboticsconnection.com/p-99-redbee-rfid-reader-v11.aspx
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