Bus Identification System for Visually Impaired Person

Lamya El alamy, Sara Lhaddad, Soukaina Maalal, Yasmine Taybi,Yassine Salih-Alj School of Science and Engineering Al Akhawayn University in Ifrane P.O. BOX 104, Ifrane, Morocco.

{L.Elalamy, S.Lhaddad, S.Maalal, Y.Taybi, Y.SalihAlj}@aui.ma

Abstract—Many technologies have recently made noticeable changes in several domains. This paper will shed the light on the field of transportation to improve the life quality of visually impaired persons (VIPs) using some of these technologies such as Radio Frequency identification (RFID) and wireless sensors network. Furthermore, a mechatronic system architecture and an appropriate design for its components will be proposed. This system will allow VIPs to safely catch buses with the help of an audio device and a tactile interface through a wireless communication system (Wi-Fi) between the transmitter and the receiver. VIPs will have the opportunity to get information about bus/transit stop locations and departure times or other transit schedule information. The motivation behind this project* is that buses are vital in enabling blind people to participate fully in society, access to facilities and services.

Keywords-RFID; VIPs; Distributed architecture; PDA; cost estimation.

I. INTRODUCTION Today, one of the most worldwide occupations is helping

and supporting visually impaired person. Those people live in a limited environment and have difficulty to sense what happen around them, which reduces their activities in several fields, such as education and transportation since they depend only on their own intuition. In addition, as the population ages, the number of VIPs has increased. At present, statistic showed that 285 million people are visually impaired worldwide: 39 million are blind and 246 have low vision [1]. Hence, we need to make their lives more comfortable by introducing a system that helps them enjoy transportation services independently and freely like ordinary people, without relying on others.

Most of existing systems have almost the same architecture. However, our system will have an added new feature in addition to the same components of the existing ones. The existing systems include a hardware part that involves a sensor, a radio frequency reader (RF) which is placed in the bus station. This reader will detect RFID tag (also called transponder) which consists of an Integrated circuit (IC) and * This work is carried out with Financial Support of Al Akhawayn University, Morocco.

small antenna, and will be placed in the bus after being informed of the existence of VIPs in the RF communication area [2]. Then, a vocal message will be announced to VIPs in the bus station. The reader is mainly based on the Radio Frequency Identification (RFID) which is a technology that uses wireless radio frequency transmission between a specific person and a device [3]. This technology is used in the enhancement of services related to transportation such as baggage tracking and bus identification, and it consists of a reader comprising of antenna, transceiver, RFID tag, Middleware, decoder, and a database for storing product information. On the other hand, the software part consists of a Wi-Fi installed in the bus station which detects the clients connected to the network of the bus and download information related to it [2].

Although the existing systems improve the life of blind people, they still miss some features that make them perfect since they lack interactivity between VIPs and bus station controllers. In order to overcome this problem and reach the previous mentioned goal, the new suggested system will include a Braille keyboard as an added feature to the existing ones. When the blind come to the bus station, he will use this Braille keyboard that is included in the PDA (Integrated RFID tag) to search for the bus number by writing his destination.

The second section will present the system modeling that summarizes the main components of the VIPs bus identification system, which include some functions of the mechatronic system. The system will also show the major relation between VIPs and the bus station controller that is exchanging information between them, followed by a flowchart description of the VIPs’ process to get the bus. The third section of the paper will present in details the suggested modified system, VIP bus identification system, consisting of three main parts: sensors and actuators, input/output signal conditioning and interfacing, and finally digital control. The third and last section of the paper will evaluate how feasible is the system by giving a detailed cost estimation of each device used to build the entire system.

2012 Sixth International Conference on Next Generation Mobile Applications, Services and Technologies

978-0-7695-4803-6/12 $26.00 © 2012 IEEE

DOI 10.1109/NGMAST.2012.22

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II. SYSTEM MODELING

1. System Architecture The architecture of the system is based on a distributed

model as shown in Fig. 1. In fact, the reading of the tags is not done at stationary points such as bus stations. Instead, RFID readers are placed in VIPs device to be able to detect the signal sent by the bus controller. The Bus station controller uses wireless communication by which he tracks the VIPs and gets information about their current location and the bus they want to take. This system’s base point is located at the base which is composed of the VIPs records and the current location, the information is then sent to the base that serves in this case as an interface with a database where the data is stored permanently.

Figure 1. Distributed System Architecture.

The distributed system architecture shown in Fig. 1 summarizes the different components of the VIPs bus identification system which consists of visually impaired person, bus station controller and the bus.

Fig. 2 illustrates the steps that the VIPs will do to find the bus required. First, the VIPs will use a Braille keyboard that is included in the PDA (Integrated RFID tag) in order to search for the bus number and the destination. Secondly, and after receiving the request of the VIP, the bus station identifies the existence of the blind through RFID reader. Then, the bus station sends the bus number that the VIP wants to takes to all buses through signals. The buses receive information from the bus station in the RF communication area, if the number matches; blue light will appear in the desired bus and will announce the availability of the blind. However, the red light appears in the bus to shows the non-existing of the blind at the bus station. This system will announce the information about his number to the blind person when there is a 2 m distance between the bus and the bus station which mean that the VIP knows the coming bus and the waiting time from the bus station by headphones. The desired bus with blue light will stop in front of the blind person to allow him get in the bus. After this, the bus stops in the station, a voice message will be announced.

V IP searches h is destination and bus num ber using PD A

T he B S recognizes the ex istence of the V IP

The B S sends signals to all buses

E ach bus receives the num ber in R F area

T he B S inform s the V IP through a vocal m essage

O nly the bus w ith b lue light w ill stop

The B S inform s the V IP to take the bus

Figure 2. Search Process flowchart.

This flowchart illustrates the path that a blind person will follow to get the required bus. This blind person will start searching the required bus using PDA. The request will be received by the bus station that will send a message to the buses and receive information. If the number matches, a blue light will appear in the desired bus and stop in the bus station.

2. Mechatronic System The design of the mechatronic system involves all the

components illustrated in Fig. 3. These components are actuators, sensors, signal conditioning and interfacing unit, and digital control unit.

The actuators cause a sound heard by the audio ship; the sensors such as RFID tag detect the number and location of the bus, and deliver them to the signal conditioning and interfacing unit, which provide connections between the control circuits and the input/output devices by converting the input signals to digital ones. These latter are then processed by the ask decoder. The results of the processed signal are then given to sensors represented by the RFID tags and heard by the actuators (headphones).

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Figure 3. Mechatronic System Design.

A. Sensors and Actuators

i. RFID tag and reader

RFID systems are generally made of a reader and an appropriate tag. Tags come in three general varieties namely passive, active, or semi-passive. The passive ones do not require an internal power supply, while semi-passive and active tags require a power source, usually a battery.

In Fig. 4, Passive tags are powered from electromagnetic field generated by reader antenna which has to transmit enough power to provide energy to tag that transmits back data. Passive tags simply consist of a single transponder IC, antenna coil, and capacitors [1]. They operate below 100 MHz frequencies and its transferred energy is carried by magnetic field. This later generates voltage in the coil which is used as power supply also as data signal. Concerning the RFID reader, energizing, demodulating and decoding are its three major functions.

Figure 4. RFID tag and reader internal design.

The RFID reader has three main functions: energizing, demodulating and decoding. The reader, using a coiled antenna, emits a low-frequency radio wave field to power-up the tag. The information sent by the tag must be demodulated (like an AM radio), and then the amplifier transfers the signal to audio in order to be heard by VIPs.

The antenna in both reader and tag can be shaped and sized in different ways and can be designed to adequate any situation because of the small size of the tag [1].

ii. Audio ship (Headphones) Audio chip is a recorder that may store up to 130 second

of sound depending on the type of the message sent. For example, the shortest message can be received in 20 ms, and the message can be play backed to another user who will hear it [4].

B. Signal Conditionning and Interfacing

i. RF amplifier The radio frequency amplifier is a type of electronic

amplifier used to convert power from low RF signal into high RF signal to increase the gain of the signal transmitted. The output of this RF amplifier is transported to the antenna and sent out to the receiver through wireless [4].

ii. Filter A filter is a device that selectively sorts signals and passes

through a desired range to suppress unwanted signals by extracting them from the received transmission [3]. The Fig. 5 shows a simple configuration of series resonance circuits that achieve its minimum impedance at resonance and used also to stop the voltage of unwanted signs.

Figure 5. Series resonant circuit.

This filter will be used in the bus to avoid any noise or any other signals coming from the passenger’s devices. This filter is characterized by a quality factor Q that controls the range and the sharpness of this filter. The value of the resonant frequency f, and the quality factor Q of the filter are obtained using equations (1) and (2) after getting the exact values of the inductor L, capacitor C, and the resistance R [3].

� � ���

�� (1)

� �

����� (2)

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iii. Ask Decoder Amplitude shift keying (ASK) is a variation process that

communicates to a sinusoid two or more discrete amplitude levels. This system use an ASK which is an analogue symbol of digital data.

Achieving an ASK decoding needs the use of a diode detector. It works when taking an analogue signal to generate a DC signal and smoothing the transitions with the help of an RC filter. To achieve a fixed voltage for the suitable logic level a comparator is then used. Fig. 6 represents the diode detector that is used in the system.

Figure 6. Diode detector circuit.

Fig. 6 shows how ASK data can be transformed into digital data. The signal can be passed through a comparator to yield the corresponding digital data [3].

iv. Braille Keyboard Since Braille became one of the most important ways for

VIPs to learn and get information, Bus identification system for VIPS will be improved using Braille keyboard. The Braille PDA does not have a screen, only eight buttons with Braille code written upon them to enter the data and a headphone to get the information from the bus station. The main functionalities of the standard Braille Keyboard are communicating the desired direction, and finding the bus number. This keyboard will be simple and practical to make using the PDA much easier for the blind people [3].

C. Digital control architecture

i. Microcontroller A microcontroller is a device in the form of a small chip

integrated in our system. Its main use is to intercept the data being sent to the bus identification tag. In fact, the system’s microcontroller stors explicitly the bus identification message in order to extract the bus number and the desired direction from the message and convert the data to a bit stream.

In order to convert the digital into a signal, the microcontroller is used to generate square waves with different frequencies. If the output resembles a triangle wave, the microcontroller receives the bit stream from the decoder. The data can then be decoded into the required ASCII code that represents the bus number and the direction desired [8].

III. COST ANALYSIS The Cheapest RFID labels are the passive tags. Their cost

depends on the frequency tag, the amount of copper in the antenna, the packaging of the RFID readers, and finally the design of the antenna. These passive tags have the lowest frequency compared to active and semi-passive tags (also known as battery-assisted) since they have less amount of copper in the antenna. Their cost ranges from 7 to 15 U.S cents and may increase to $ 40 if the tag is fixed in a thermal transfer label and its bar code can be printed. Furthermore, the passive tags are physically smaller than the active ones and require no internal power source, also they have unlimited operational lifetime.

The readers that will detect passive RFID tags have the lowest costs due to their design and their antenna. Their costs are usually less than $ 100 [7].

The cost of Braille keyboard is usually high. However, the Braille keyboard used in our system has the lowest cost in the market, since it has 12 Braille cell display, 8 Braille input keys, internal rechargeable battery with overcharge protection and finally it has a Bluetooth connection with the bus station. The cost of such Braille keyboards is $ 1000.

Concerning the headphones related to PDA used in this system, their cost is only $ 20 due to their huge availability in the market.

Microcontrollers are available from any manufacturer with a very low price. The common microcontrollers types used today are PICs because they are feasible and cheap. The cost of this type of microcontrollers range from $ 0.25 to $ 3.35 depending on their peripherals and pin configurations; for instance, the PIC10F200 costs $ 0.49, the PIC16F684 costs $ 0.7, and PIC16F628 costs $ 3.35. For our system, we may use the PIC10F200 that cost $ 0.49.

This table illustrates the cost that will be used to buy the equipment for the construction of the devise that will be used by the VIPs to find the required bus.

TABLE I. THE COST FOR THE BUS IDENTIFICATION SYSTEM FOR VIPS

Equipment Cost RFID tag 0.07 to $0.15 RFID readers less than $100 Braille keyboards $1000 PDA $20 Microcontrollers (PIC10F200) $0.49 Total $1120.64 The cost of installation for the whole system depends on the

number of bus stations, the training of employees, the time required, and finally the quality of the product. However, the total cost mentioned is a suitable and affordable price for this system.

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IV. CONCLUSION Helping blind people to get familiar with technology in

order to become more independent on their daily life is a necessity that everyone should be aware of. Thus, this paper presented a new approach to bus identification system for VIPs using a Braille Keyboard. This new keyboard has many advantages which make it a good alternative to the current approaches since it facilitates for the VIPs the searching of the destination and the finding of the appropriate bus number. With this added device, a whole life of those people will change and now they can contribute positively to their society and overcome their weaknesses related to the ability to move freely and without the help of anyone. Also, the financial analysis showed that the components of such a system are cheaper than other systems; however, the performance is higher.

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[3] R. Wong, “Bus Identification for the vision impaired,” Web, pp. 12, Oct. 2002.

[4] T. Yap, “Bus Identification for the vision impaired,” Department of Information Technology and Electrical Engineering, Oct. 2003.

[5] P. A. Blenkhorn, “RFID system components and costs - RFID journal,” in RFID Journal - RFID Technology News & Features, Web, Nov. 2011.

[6] A. Jonathen, “Braille Pen 12,” in living made easy, Electronics, Web, pp. 96-100, Feb. 2012.

[7] L. Zhou, G. Sousa, J. Chanet, K. Hou, J. Li, C. Vaulx, and M. Kara, “An Intelligent Wireless Bus-Station System Dedicated to Disabled, Wheelchair and Blind Passengers,” in Wireless, Mobile and Multimedia Networks, IET International Conference, Oct. 2006.

[8] O.Venard, G. Baudoin, and G. Uzan, “Field Experimentation of the RAMPE Interactive Auditive Information System for the Mobility of Blind People in Public Transport,” in the 9th International Conference Intelligent Transport Systems Telecommunications,(ITST), Apr. 2009.

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