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INTRODUCTION
Out the 6.7 billion people that populate the world, 161 million are visually
impaired. Each visually impaired individual faces different challenges based on their
specific level of vision. With the rise of various support-based organizations, more visually
impaired people have been given the opportunity to education and many other means. But
still the issues of navigation for the blind are very complex and troublesome especially
when they walked down in street and also navigate to distant places by public transport
system. For a visually impaired person, doing things such as reading traffic signals and
street signs can be extremely challenging, if not it is impossible to do.
In order to overcome these challenges, a visually impaired person might use walking cane,
guide dog, and sighted guide. These alternatives also called as assistive devices can be
helpful to the blind but not so effective. The sighted guide can be immensely effective, as
well provide social comfort, but it restricts the independence of the blind individual. Guide
dogs and walking canes allow for a more independent means of travelling, but they are
limited in unfamiliar environments. RFID is feasible and cost effective but it is more
suitable for indoor communication only. Also it provides only one way communication and
a very short range of identification. A system with an augmented walking cane, a pair of
augmented glasses and identifiable items tagged with semacode/data matrix tags is used
for outdoor navigation of blind people. If a man has to take the bus, he walks along the
pavement and his walking cane recognizes a tag. But the image quality of the web camera
is fairly poor. Tag recognition in darkness or in bad lightning conditions might be a
problem. Another issue is that camera needs a visual, so if a tag is hidden behind a person
or another object, then the camera cannot detect it. Tags on all environments will properly
contaminate the environment and meet resistance from many citizens.
To overcome the drawbacks of currently available assistive devices, we propose a Wireles
sensor network system with ZigBee for blind identification by the bus and embedded
system for providing the bus number and finally GPS for destination indication. Wireless
sensor network (WSNs) consists of sensors that continuously monitors the environmental
conditions and send their data to the main network. ZigBee is an embedded device for use
in a WSN which is tiny in size. These nodes have processing and computational capability
and generally consist of an RF transceiver, memory, on board sensors/actuators and a
power source.
ZigBee have CC2420 which is a true single-chip 2.4 GHz IEEE 802.15.4 compliant RF
(Radio Frequency) transceiver designed for low-power and low-voltage wireless
applications so we can send or receive useful information through using this chip. The
number of the bus parked in front of the blind is send to the ZigBee in the blind system.
Another function of ZigBee is identification of blind in the bus station. If both the numbers
match the buzzer in the bus unit alarms and indicates the driver that there is blind in the
bus station.
The software part is Embedded C with MPLAB IDE (Operating System) for programming
the controller. MPLAB IDE runs as a 32-bit application on MS Windows, is easy to use
and includes a host of free software components for fast application development and
super-charged debugging. MPLAB IDE also serves as a single, unified graphical user
interface for additional Microchip and third party software and hardware development
tools.
LITERATURE SURVEY
The basic idea behind doing literature survey is to gain knowledge regarding the
related work. There are various methodologies were used in order to develop navigation
system for the blind people. But still the issues of navigation for the blind are very complex
and troublesome especially when they walked down in street and also navigate to distant
places by public transport system. So many research papers were taken these things into
consideration and studied. Stress has been laid to summarize the concept of different
authors who has worked in this field.
Ravi Mishra and Sornnath Koley presented a paper titled “Voice Operated Outdoor
Navigation System for Visually Impaired Persons” which aimed to create a portable, simple
less costly system that will allow Blind peoples to travel through familiar and unfamiliar
environments without the aid of guides. Several guidance system has been developed for
vision impaired people, but these systems tends to be expensive, also make use of a client
server approach. This Navigation system consists of two distinct components: sensing of
the immediate environment for blind people to travel (e.g., obstacles and hazards) and
navigating to remote destinations beyond the immediately perceptible environment. It
focused on the development and evaluation of a Navigation system that makes use of GPS
(the Global Positioning System), voice and ultrasonic sensor for obstacle detection.
Jain P.C, Vijaygopalan .K .P. published a paper “RFID and Wireless Sensor Networks” in
which RFID is used to detect presence and location of objects while WSN is used to sense
and monitor the environment. Integrating RFID with WSN not only provides identity and
location of an object but also provides information regarding the condition of the object
carrying the sensors enabled RFID tag. It can be widely used in military, environmental
monitoring and forecasting, healthcare, intelligent home, intelligent transport vehicles,
warehouse management, and precision agriculture. This paper presents a brief introduction
of RFID, WSN, and integration of WSN and RFID, and then applications related to both
RFID and WSN.
Rishabh Gulati presented the paper “GPS Based Voice Alert System for the Blind” in which
GPS is employed to find the position of the user on the earth. This information is provided
by the GPS with the help of the data it receives from the satellites.
GPS based voice alert system for the blind uses the current location and gives the alert to
the blind man if it was his destination area. The system has a dynamic user interface and is
easily operable. The system is realised using a GPS module (SR-92) and a Voice Module
(APR9600) interfaced with a PIC16F877 microcontroller. The working of the system
incorporates two stages; first the location based audio recording stage and second, the
navigation of the blind person using the signal from the GPS receiver. The system employs
a user friendly design and provides for an automatic location name announcement system.
MATERIALS AND METHODS
3.1 Voice Recognition Unit
Speech recognition system is used to help the blind to know the particular buses for
a given location. When the blind speaks through the microphone, the speech recognition
system analyse the input which is then processed by the microcontroller, and then produces
the required output in the audio format which is heard by the user through the headphones.
The speech recognition system here we use is HM2007.It is a single chip voice recognition
LSI circuit with on the chip voice analysis, recognition process and system control
functions. It may consist of microphone, keyboard, RAM and some other components.
The word length select pin is used to control the length of word we are providing
as input. When the pin WLEN is set high, 1.92 sec is selected. In this way only 20 words
can be recognized. DEN pin is used to enable the data. When the recognition process is
complete the chip will place its response on the data bus DO -D7 and which can be latched
on to the microcontroller by this pin. When the device is ready for the voice input in training
or recognition mode, a low signal is sent by the RDY pin. If the chip is busy then a high
signal is sent. When the waiting control input pin is set Low, the chip will enter the waiting
state and do not accept the voice input until the pin is set to High.
There are two modes of operation. During the power on the chip will start its
initialization process. If the wait pin is Low the chip will do the memory check and if the
pin is H then the chip skips the memory check. After the initialization recognition is done.
Ready pin is set low to allow the voice to be recognized. Once the voice input is detected
the ready pin is set high and recognition begins. We should train the word pattern before
the beginning of the recognition process. After the process is completed the result will
appear on the D-bus with the activation of DEN pin.
To train or clear a voice pattern, we must select the word number to process first. The
number of word is composed of two digits. The digits are entered one digit at a time through
keypad. When number key is pressed, the number of key will be echoed to the D-bus. When
the word number is entered press the function key to choose the operation function. If the
function key CLR is pressed the word pattern is cleared. If the function key TRN is pressed
training process begins. To clear the entire patterns key 99 is entered and clear is pressed.
3.2 Voice Synthesizer System
APR9600 is a low-cost high performance sound record/replay IC incorporating flash
analogue storage technique with a sampling rate for a 60 second recording period is 4.2
kHz that gives a sound record/replay bandwidth of 20Hz to 2.1 kHz. APR9600 device
offers true single-chip voice recording, non-volatile storage and playback capability for 40
to 60 seconds. The voice synthesizer is used to generate speech signal output of the bus
number and the current destination of the blind people. The voice synthesizer is connected
to the microcontroller. Microcontroller accepts input from voice recognition system and
GPS.
The device supports both random and sequential access of multiple messages. Each
memory cell can store 256 voltage levels. This technology enables the APR9600 device to
reproduce voice signals in their natural form. It eliminates the need for encoding and
compression, which often introduce distortion. Storage is accomplished through a
combination of the Sample and Hold circuit and the Analog WritelRead circuit.
These circuits are clocked by either the Internal Oscillator or an external clock source.
When playback is desired the previously stored recording is retrieved from memory, low
pass filtered and amplified. The signal can be heard by connecting a speaker to the SP+ and
SP- pins.
Random access mode supports 2, 4, or 8 messages segments of fixed duration.
Record or playback can be made randomly in any of the selected messages. The length of
each message segment is the total recording length available (as defined by the selected
sampling rate) divided by the total number of segments enabled. The bus number and the
destination which is recorded are played back in this mode.
On power up, the device is ready to record or play back, in any of the enabled
message segments. To record, ICE must be set low to enable the device and IRE must be
set low to enable recording.
We recording by applying a low level on the message trigger pin that represents
the message segment we intend to use. To playback, I CE must be set low to enable the
device and IRE must be set high to disable recording & enable playback. You initiate playback
by applying a high to low edge on the message trigger pin that representing the
message segment you intend to playback.
Playback will continue until the end of the message is reached. If a high to low
edge occurs on the message trigger pin during playback, playback of the current message
stops immediately. The IBusy pin when low indicates to the host processor that the device
is busy and that no commands can be currently accepted. When this pin is high the device
is ready to accept and execute commands from the host. The IStrobe pin pulses low each
time a memory segment is used.
Counting pulses on this pin enables the host processor to accurately determine how much
recording time has been used, and how much recording time remains. The APR9600 has a
total of eighty memory segments. The IM7 _END pin is used as an indicator that the device
has stopped its current record or playback operation. During recording a low going pulse
indicates that all memory has been used. During playback a low pulse indicates that the last
message has played
3.4 PIC Microcontroller
PIC is a family of Harvard architecture microcontrollers made by Microchip Technology,
derived from the PIC16F887 originally developed by General Instrument's
Microelectronics Division.
The name PIC initially referred to "Peripheral Interface Controller".It uses RISC
architecture and has only few instructions. It operates at a frequency 0-20MHz and has
8krom memory in flash technology, 368bytes ram memory and 256bytes EEPROM
memory helps in writing data more than 1,000,000 times. In our system two controllers are
used. One in the bus unit and other in the blind unit. Microcontroller is connected to the
level converter, speech recognition system, GPS and voice synthesizer. LCD display is
connected to the output of controller in bus unit. The coding is done using embedded C
language and Hi-tech C compiler. The output of the microcontroller is connected to the
voice synthesizer in blind unit. The output of speech recognition system, GPS and level
converter is connected to the input ports of microcontroller
The HM2007 is a 48 pin IC which provides speech recognition function. It works in two
modes: Manual mode or CPU mode. In both modes, the IC is first trained to recognize
words by the user saying each word for corresponding number pressed on the key. The IC
stores each word signal in the memory location corresponding to the word. The data output
from the IC is interfaced to the Microcontroller from where it is displayed on the
LCD.tences.HM2007 consists of a RDY pin which is an active low indicating that the IC
is ready for training purpose.HM2007 speech recognition system consist of MICIN pin to
which voice input can be provided through microphone. The IC is interfaced with a keypad
which is used to provide number input corresponding to each word. This IC has a two
function clear & train. When a train is key pressed on keyboard the IC begins its training
process. If the user should press a number key before pressing the ‘TRAIN’ function key
and should say the required word to the microphone.
3.6 Finding the destination
The Global Positioning System (GPS) is a space based radio navigation system that
provides reliable positioning, navigation, and timing services to civilian users on a
continuous worldwide basis. GPS receiver will provide location and time. It receives the
latitude and longitude values from the satellite.
GPS based blind man device with user input interfacing (voice based) intellectually finds
the current location and gives the alert to the blind man if it was his destination area. The
system designed consists of a GPS receiver and a voice circuit which is interfaced to the
microcontroller. The microcontroller is programmed in such a way that depending on the
satellite information of location the predefined location name will be announced. Three
satellites are enough to solve for position, since space has three dimensions. However a
very small clock error mUltiplied by the very large speed of light the speed at which
satellite signals propagate results in a large positional error. The receiver uses a fourth
satellite to solve for x, y, z, and t which is used to correct the receiver's clock.
Microcontroller is the heart of the device. It stores the data of the current location which it
receives from the GPS system, so that it can make use of the data stored to compare with
the destination location of the user. By this it can trace out the distance from the destination
and produce an alarm to alert the user in advance. This device is designed to provide a
voice based announcement for the user, i.e., the user gets the voice which pronounces his
destination location. GPS-634R is a highly integrated smart GPS module with a ceramic
GPS patch antenna.
The antenna is connected to the module via an LNA. It is capable of receiving signals
from up to 65 GPS satellites and transferring them into the precise position and timing
information that can be read over either UART port or RS232 serial port.
3.7 Transmission Unit
ZigBee is wireless technology developed by IEEE 802.15.4 - 2003 standard for low cost,
low power, wireless sensor networks that is used for Low-Rate Wireless Personal Area
Network (LR- WPANs). Zigbee Alliance is a group of more than 300 companies including
industry majors like Philips, Mitsubishi Electric, Epson, Atmel, Texas Instruments etc.
which are committed towards developing and promoting this standard. The alliance is
responsible for publishing and maintaining the ZIgbee specification and has updated it time
and again after making it public for the first time in 2005. The manufacturers which are
members of the Alliance provide software, hardware and reference designs to anyone who
wants to build applications using Zigbee.
The standard takes full advantage of IEEE 802.15.4 physical radio specification that
requires a low data rate, long battery life and secure networking. ZigBee is present with the
blind people and in the bus which is the used instead of RFID [21. The ZigBee with the
blind recognizes the bus which is few meter distance away from blind and gives intimation
to the blind who is carrying it. The intimation is given through the headphones.
The ZigBee in bus receives the signal from blind people and stops in bus station. If
the blind gets the required bus, he gets into bus or else he waits for the bus which he desires
to get into to reach his destination. The advantage over of ZigBee over RFID is that it is
less cost than RFID tag and RFID reader [31. Secondly, it has two-way communication
that is to send and receive signal at higher speed without interfering other signals like radio
waves.
RESULTS AND DISCUSSION
When the person reaches the bus station, he can find the buses that pass through a
particular location with the help of voice recognition system and voice synthesizer. When
the bus approaches the bus station, there is an indication in the bus by the beep sound of a
buzzer that there is a blind person available in the bus station. This is achieved with the
help of ZigBee unit both in the bus unit and blind unit. Finally when the bus reaches the
station the bus number is announced to the blind through headphones.
There are currently available systems for the outdoor navigation but they will not assist in
travelling to unfamiliar areas. Some systems use PDA which is not so economic and cannot
be afforded by all. In most of the systems RFID tags are used which are required in 1000s
of numbers for tracking of route. Also it provides only one way communication. The system
we use is a mobile unit, weightless and economically feasible.
ADVANTAGES
The entire system is very cost effective.
All the module are very easy to handle.
Convenient to the user.
Low power platform.
The device is designed to provide with a greater advantage producing voice based
announcement for the user.
APPLICATIONS
Easy navigation of blind.
CONCLUSION
Primarily, the blind person in the bus station is identified with RF communication. The
blind informs the location he needs through the microphone which is given to the voice
recognition system which produces the output of bus numbers in the voice synthesizer unit
which is heard in headset. Then this location is transmitted to the transceiver in the bus. If
the names in the transceiver in the bus matches with that of the name send by the blind,
then there is an alarm in the bus unit alerting the presence of blind and a voice to the user's
headset that the particular bus has arrived. With the help of GPS tracker connected with
audio output the destination chosen by the blind is intimated when the bus reaches the
correct location. PDA's can be used for GPS tracking but it is not cost effective.