International Journal of Scientific & Engineering Research, Volume 3, Issue 11, November-2012 1
ISSN 2229-5518
Intelligent Belt for the Blind
Sneha Venkateswar, Ninad Mehendale
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HIS project aims at helping the blind to travel inde- pendently using sensors attached to a belt. The sensors
give a signal to the microcontroller which in turn plays a
pre-recorded alert with the help of an APR and relays which
warn the blind person about the obstacle ahead. The blind
person has the option of using both headphones and speak-
ers making the belt user friendly and useful.
The user is expected to wear the belt on the waist. The belt contains IR sensors which are interfaced with the microcon-
troller circuit.Whenever the Infrared receiver receives the infrared light there is a drop of voltage across it, which is given to the comparator to generate logic 0 which is given to the microcontroller.The programming of Atmega 8 is done such that whenever logic 0 comes on any of the input ports it sends logic 1 to the corresponding output port.The output port is connected to the ULN 2003 which drives the relays of the corresponding playback circuit. Thus whenever there’s an obstacle in any one of the direction i.e. front, back, left and right the playback circuit would indicate the same.
Fig. 1. Block Diagram
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Ninad Mehendale is currently Assistant Proffesor in the electronics and telecommunication department in Mumbai University, India, PH-
919820805405. E-mail: ninad243@yahoo.com
Fig. 2. Circuit Diagram
IJSER © 2012
International Journal of Scientific & Engineering Research, Volume 3, Issue 11, November-2012 2
ISSN 2229-5518
The system is using four obstacle sensors that are made up of transmitters and receivers. The transmitter always transmits the signal and as soon as we detect an obstacle with reflec- tion, the transmitter sends a signal to the receiver which is detected by the latter. An infrared transmitter LED and an infrared receiver or a photo diode for reception will be used. The signal is then given to the amplifier. The amplified signal is converted into digital logic via a comparator. The compara- tor will check whether the signal has been reflected back from the obstacle or not. Accordingly the comparator forms the digital logic and gives it to Atmega 8.The system will have four sensors, in the front, behind, left and right. Each of the four sensors is connected to the comparator and the com- parator output is given to the microcontroller. The compara- tor output i.e. the digital logic will give a signal to the micro- controller indicating where obstacle has been detected (i.e. left, right, behind or forward). The microcontroller ATMEGA
8 is connected to APR 9301 (Audio Program Recorder) in which it will be pre-recorded messages e.g. ‘obstacle on left’- if the obstacle has been detected by the sensor on the left. Similarly there exists an APR 9301 for each of the other three sensors (right, front, behind). Each APR will have a ‘Play’ button. Each of these ‘Play’ buttons is connected to relay. The relay is driven by ULN 2003 IC. The system is using pins 16,
15, 14 and 13 of ULN 2003 to drive the relays. And the other ends of the relays are connected to pin number 9 which is given to a common 12 volts supply. The relay has a common contact, NC (normally connected) and NO (normally open). The common and NO terminals are shorted when the relay is excited. The ‘Play’ button of the APR is given to the relays common terminal and the other one will go to the NO termi- nal of the relay. The ULN is triggered by the microcontroller ATMEGA 8. The ULN 2003 receives triggers from the micro- controller at the pins 1, 2, 3 and 4. As soon as the relay is trig- gered the APR gets the signal and produces the pre-recorded message which will be given to the speaker. In order to ena- ble the blind person the use of headphones there is an extra SPDT (Single Pole Double Throw) in the same relay circuitry. The speaker will throw on this switch. Hence one terminal of the speaker is connected to the common terminal which is connected to all the speakers. When the ‘Play’ button of the APR is pressed then the output of specific APR is given to this speaker by completing the connection and the blind per- son will hear the pre-recorded message from that specific APR. The duration of the message e.g. 20 seconds can be con- trolled by a simple resistor connected at APR 9301 pin 6.
There is a direct supply voltage of +5volts for the APR to work. Now to design the +5 volts supply for the entire cir- cuit, a 9 volts rechargeable battery is used whose output is given to the IC 7805 at pin 1 and pin 2. Pin 2 of the 7805 acts as circuit ground and pin 3 of 7805 generates the required +5 volts supply. In order to filter the supply there is a capacitor of 10 micro farad and 16 volts. For microcontroller basic cir- cuitry there is one resistor of 10 k between pins 1 and 7 for reset circuitry pulled up by Vcc with pin 8 grounded. Pin numbers 9 and 10 of ATMEGA 8 are connected piezoelectric crystal between them of 16 MHz frequency. Pins 11,12,13,14 are used to trigger ULN 2003 and pins 3,4,5,6 of Atmega 8 are used to get data from the digital output i.e. output of the comparator. Hence as the sensor detects any obstacle the blind person will get the message from the APR on both the speaker and the headphones.
Fig. 3. Flow Chart
IJSER © 2012
International Journal of Scientific & Engineering Research, Volume 3, Issue 11, November-2012 3
ISSN 2229-5518
This project aims at making the visually impaired travel safe- ly and autonomously. All obstacles will be detected by the blind belt and the blind person shall receive a pre-recorded message as a warning. Hence the blind person can travel in- dependently.
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We would like to thank the respected Principal Dr. Hari Vasudevan of D.J.Sanghvi College of Engineering and Head of Department of Electronics and Telecommunication, Dr. Amit Deshmukh for supporting us and giving us facilities and immense guidance. We would also like to thank Shri Vile Parle Kelavani Mandal for encouraging us in such co curricu- lar activities
[1] \bibitem{IEEEhowto:kopka}
[2] http://www.atmel.com/images/doc2486.pdf
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