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ABSTRACT
This paper presents the architecture as well as the implementation of the system that helps the visually impaired person to
navigate autonomously in the indoor environment. This method utilizes the Global Positioning System (GPS) and it also
incorporates object avoidance technologies. The system applies a zigbee protocol to provide the continuous tracking of the
visually impaired person. It also consists of additional components like ATMEGA microcontroller, ultrasonic sensor and
microphone to provide more refined location and orientation information. The visually impaired person issues the command
and receives the direction response using audio signals. The latitude and longitude values are received continuously from the
GPS receiver and then transferred to the PC using the zigbee transceivers, using these values the localization of the visually
impaired person is attained using Google map.
KEYWORDS localization; visually impaired; zigbee; navigation.
I. INTRODUCTION
The goal of this work is to allow the visually
impaired persons navigate independently in the
indoor environment. Conventional navigational
systems in the indoor environment are expensive and
its manufacturing is time consuming. The visually
impaired are at considerable disadvantage as they
often lack the information needed while passing
obstacles and hazards. They have relatively little
information about land marks, heading and self
velocity information that is essential to navigate them
successfully through unfamiliar environments. In this
modern world providing security to each and every
human being in life gains a major consideration.
Everyone has realized the need to secure themselves
against hazards and unauthorized dealings. This work
aims at providing the navigation for the visually
impaired persons, by designing a cost – effective and
more flexible navigation system. It is our belief that
the recent advances in technologies could help and
facilitate in day – day operations of visually impaired
persons.
II. RELATED WORK
In 1991, Golledge et al; were the earliest to propose
the use of GIS, GPS, speech, and sonic sensor
components for navigation in a progress notes on the
status of GIS [4]. MOBIC is a GPS based travel aid
which uses a speech synthesizer to recite the
predetermined travel journey plans [5]. This test
prototype is implemented on a handheld computer
with preloaded digital maps and limited wireless
capabilities to get latest information from a remote
database. A similar system was implemented by
Golledge et al; using a wearable computer [4]. This
test prototype is implemented on a handheld
computer with preloaded digital maps and limited
wireless capabilities to get latest information from a
remote database. A similar system was implemented
by Golledge et al; using a wearable computer [6].
Similar kind of systems are developed by researchers
in which current position of the user is used to
overlay textual annotation and relevant information
from their web servers to coincide with the image
captured through their head mounted display [6,7].
Smart Sight, the tourist assistant developed by Yang
et al; is a slight variation to this approach. It gives
user multi-modal interface, which includes voice,
handwriting and gesture recognition. This approach is
more applicable to natural terrain environments.
Similar approach is used for registration in urban
environment with the exception that the line of sight
is registered by comparing the video frame or digital
image with a 3D virtual GIS model [8,9].
This system completely depends on Virtual Mapping
with object identification. The elements required to
perform the guidance process includes defining the
destination or target, identifying the current position
of the blind person and finally determining the best
path to be taken to reach the desired destination. In
order to identify user position, the guidance system
utilizes Zigbee based localization engine technique
that continuously updates the server with the user
location. A digital compass located in the push
mobile cart enables the system to identify the user
orientation. The proximity sensors incorporated in the
mobile push cart enable the detection of obstacles.
The user of the guidance system pushes the cart that
houses hardware components in front of him/her
while walking. The cart rolls on passive wheels that
support its weight during regular operation. Also the
wheels are equipped with encoders to determine the
relative motion of the user. This information is used
to refine the system localization process. Thus if
there exists any objects in front of the user, the object
will be identified and it will informed to the user for
the object identification. Thus the navigation is
carried out in this method [1].
III. LIMITATIONS IN THE EXISTING METHOD
Blind Navigation system using virtual mapping
method is very costly. The manufacturing time is
very high since the virtual mapping has to be carried
out throughout the indoor environment. This method
is applicable only for short distance. Once this
method is designed to use in a particular area, it can
be used only in that area, this system cannot be
relocated to use in any other place. This method
focuses on digital compass for direction
identification, but this compass will be useful only
for long distance navigation which is not possible in
this method. This system cannot be used in public
places like airports, hospitals, malls and public parks
since the construction and design for the entire
system cannot be carried out in such a big places and
this method is used only for a single user. If the
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
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indoor environment has to be modified or if it has
been changed according to the users convenience,
then again the reconstruction for the whole system
and design is required, which is time consuming and
costly for the whole system to be redesigned. Once
the virtual mapping is used throughout the indoor
environment and if there exist any change in the
value, then the whole system and design has to be
reconstructed. If the proximity sensor sends the
signal towards any object, that object will be
informed to the user unnecessarily since it creates the
confusion and it increases the panic level of the user
to move forward. The destination setting is quite
difficult, since the comparison takes a long time.
IV. PROPOSED METHOD
In order to overcome the difficulties in the existing
method and to provide the cost effective and user
friendly system for blind navigation, the following
designed is carried out.
A. PROJECT DESCRIPTION
Fig 1 shows that this project mainly consists of eight
parts namely Micro controller, GPS receiver, Zigbee
transceiver, Ultrasonic sensor, HM 2007, APR 9600,
Keypad and LCD display. The software in this
project comprises of ‘embedded c’ coding which is
used in the micro controller and visual basic 6 is used
for receiving the GPS value in the system.
(i) MicroController
The MicroController used in this system is
ATMEGA 164PV since it is necessary to provide the
dual serial communication which is possible using
this controller. This controller provides the High
performance and it consumes very less power.
(ii) GPS Receiver
The GPS receiver used in this project is iTRAX02
which produces and interprets message in accordance
with the National Marine Electronics Association
Standards (NMEA). It provides the latitude,
longitude values of every position in this world.
(iii) Zigbee Transceiver
The wireless protocol is provided to the system using
the Zigbee transceivers. This wireless transceiver is
used to provide the continuous transmission of GPS
values to the system.
(iv) Ultrasonic Sensor
In order to provide the Obstacle Avoidance,
Ultrasonic sensor is used. The Ultrasonic sensor has
the maximum range of 10.7 metres, which is far more
than normally required. The current consumption is
about 2.5 Amps during the sonic burst is exposed. It
has the short 10uS pulse as the trigger input to start
the ranging. The sensor will send out an 8 cycle burst
of ultrasound at 40 kHz and raise its echo line high. It
then listens for an echo, and as soon as it detects one
it lowers the echo line again. The echo line is
therefore a pulse whose width is proportional to the
distance to the object. By timing the pulse it is
possible to calculate the range in inches/centimeters
or anything else. If nothing is detected then the
sensor will lower its echo line anyway after about
36mS.
(v) HM2007
HM2007 is a single chip CMOS voice recognition
LSI circuit with the on chip analog front end, Voice
analysis, recognition process and the system control
functions.The speech recognition system is a
completely assembled and easy to use programmable
speech recognition circuit. It has 8 bit data out which
can be interfaced with any microcontroller for further
development.
(vi) APR 9600
APR 9600 is a low cost high performance sound
record/reply IC incorporating flash analogue storage
technique. This circuit is designed to record the voice
signal. The microphone is used to pick up the voice
signal. Then the signal is given to APR 600 multi
section sound record and replay IC. Record sound is
retained even after power supply is removed from the
module. The replayed sound exhibits high quality
with low noise level. Total sound recording time can
be varied from 32 seconds to 60 seconds by changing
the value of a single resistor. The IC can operate in
two mode such as serial mode and parallel mode.
(vii) Keypad
The keypad used in this project consists of 5 keys
namely increment, decrement and enter key. This
keypad is used to type the GPS values for setting the
destination.
(viii) Liquid Crystal Display
The key material of the liquid crystal display is the
liquid crystal or neumatic fluid. This neumatic fluid
is sandwiched between two glass plates. An AC
voltage is applied across the neumatic fluid, from the
top metalized segments to the metalized back plane.
When affected by magnetic field of the AC voltage,
the neumatic fluids transmit light differently and
energized segment appear as the black on a silvery
background. One such LCD is used in this project. It
is used to view the position of the system using the
GPS values updated; otherwise the distance between
the system and the obstacle will be displayed.
(ix) Speaker
The speaker is used in this project for guiding the
visually impaired persons to navigate independently
by amplifying the pre-defined voice signals.
(x) Max 232
In telecommunications, RS-232 is a standard for
serial binary data interconnection between a DTE
(Data terminal equipment) and a DCE (Data Circuitterminating
Equipment). It is commonly used in
computer serial ports. In order to provide the
communication between the Zigbee transceiver and
the PC, MAX 232 IC is used. Since the Zigbee
accepts the positive and negative values as 5V and
0V where as the PC accepts the positive and negative
values as +12V and -12V.
(xi) Power Supply Circuit
Since all electronic circuit work only with low D.C.
voltage we need a power supply unit to provide the
appropriate voltage supply. This unit consists of
battery, rectifier, filter and regulator. AC voltage
(typically 230 V rms) is connected to a transformer,
which steps that AC voltage down to the level to the
desired AC voltage. A diode rectifier then provides a
full – wave rectified voltage that is initially filtered
by a simple capacitor filter to produce a DC voltage.
This resulting DC voltage usually has some ripple or
AC voltage components. A regulator circuit use this
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.III/ Issue II/April-June, 2012/40-43
DC input to provide DC voltage with muss less ripple
voltage and remains constant in spite of the variations
in the input DC voltage or changes in the load.
Fig 1. General block diagram (Tx and Rx section)
V. WORKING OPERATION
This project uses all the above mentioned parts. The
GPS (Global Positioning system) receiver
continuously receives the latitude and longitude
values for every position of the system and it is
interfaced with the Microcontroller to display the
values in the liquid crystal display. The
Microcontroller is programmed to interface the
ultrasonic sensor to distinguish the distance between
the ultrasonic transceiver and the obstacle to maintain
at 10inch and above. The ultrasonic transmitter
continuously transmits the sound waves with a
frequency of 40KHZ using the oscillator inbuilt in
the ultrasonic sensor. The received analog signal in
the ultrasonic receiver is converted into the digital
signal using the signal conditioner unit and it is given
to the microcontroller. The sensor provides an echo
pulse proportional to distance. If the width of the
pulse is measured in uS, then dividing by 58 will give
you the distance in cm, or dividing by 148 will give
the distance in inches. uS/58=cm or uS/148=inches.
The HM 2007 is programmed in the sense that the
user can train the words that the circuit can
recognize. This voice is stored in the microcontroller
as the address values, each address values is used for
recognizing the destinations. The keypad with 5 keys
are used for setting the destination values by
analyzing the latitude and longitude values received
in the Liquid crystal display.
The APR 9600 is an amazing playback and record IC
used for the voice navigation. Using the two switches
of playback and record, the predefined voices can be
stored in it and it can be verified for the future use,
since the recorded voices can be retained even after
the power supply is removed. . The replayed sound
exhibits high quality with low noise level. The
keypad used in this project consists of 5 keys namely
increment, decrement and enter key. This keypad is
used to type the GPS values for setting the
destination.
The Zigbee transceiver is connected to the system
and it continuously transmits the values of latitude
and longitude that has been updated using the GPS
receiver. The Microcontroller is responsible for
transmitting the digital data through this transceiver
and it is received in another transceiver connected to
the PC. The digital value received in the zigbee
transceiver connected to the PC has the positive and
negative values which have been received as +5v and
0V.
The Max 232 IC is used to interface the zigbee
transceiver and the PC, since the PC accepts the
values as +12V and -12V. Thus the values are
continuously transmitted between the transceiver and
the PC. The values received in the PC are observed
using the visual Basic 6 and it is linked to the Google
map. Hardware implementation of navigational
system is shown in Fig 2.
Fig 2: Hardware implementation
Fig 3. Spatial layout of home
Fig 4. Comparison graph between existing and
proposed method in operation time
The GPS value will be attained for every position in
the earth. Fig 3 shows that the four latitude and
longitude values are experimentally obtained using
the GPS receiver in a particular place (home) and it
clearly shows that the values of latitude and
longitude gets varied for every position. This change
in the value provides the comfortable navigation in
the indoor environment. Fig 4 shows the latitude and
longitude values are received continuously in the PC
using the zigbee transceiver and the inference of
these values are observed in the Google map.
VI. RESULTS AND DISCUSSIONS
The GPS receiver provides the latitude and longitude
values of every positioning of the system. These
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.III/ Issue II/April-June, 2012/40-43
values received in the GPS module are transferred to
the PC (Personal Computer) using the zigbee
transceiver connected to the system. Another Zigbee
transceiver connected to the PC is responsible for
receiving the values from the system and it is
interfaced to the Google map using the Visual Basic
6. The zigbee transceiver is operated at the baud rate
of 9600 and thus the continues tracking of the
visually impaired person is possible using this
protocol which is shown in Fig 5.
Fig 5. Localization using Google map
A. Advantages
• Low design time
• Low production cost
• This system is applicable for both the indoor
and outdoor environment
• Setting the destination is very easy
• This system be capable of using in public
places
• It is a dynamic system
• Less space
• Low power consumption
B. Applications
• This system can be used in the home,
hospitals and colleges
• This system can be used in both the known
and unknown environments like airports,
malls and public parks etc.,
The comparison of the existing method and proposed
method of navigation system for visually impaired
person is shown in Fig 6. Based on these parameters,
this method overcomes the limitations in the existing
method.
Fig 6. Comparison between the existing method
and proposed method
VII. CONCLUSION
This paper provides full autonomy system for global
navigation (path planning and localization) but relies
on the skills of the user for local navigation (Obstacle
avoidance) and offers innovative solutions in order to
replace the conventional methods of guiding visually
impaired person. In addition, it can be easily applied
anywhere where it can handle places like malls
,airports etc., This system also satisfying the present
day needs of allowing the visually impaired to move
independently.
