Voice and touchscreen operated wheelchair report.

Table of Contents
CHAPTER 1 1
INTRODUCTION 1
1.1 Objective of the Project 4
1.2 Need for the Project 4
CHAPTER 2 5
LITERATURE SURVEY 5
CHAPTER 3 10
HARDWARE COMPONENTS 10
3.1 Arduino UNO 10
3.2 Technical Specifications 11
3.3 Physical Characteristics of Arduino UNO 15
3.4 GSM Module 16
3.4.1 Features of SIM900 18
3.4.2 Indicator LED and Buttons 20
3.5 DC Motor 21
3.5.1 Characteristics of DC motor 24
3.6 Distance Sensors 26
3.6.1 Specification and limitations 28
3.7 LED (Light Emitting Diode) 29
3.8 Buzzers 32
3.8.1 Mechanical Buzzer 33
3.8.2 Electromechanical Buzzer 33
3.8.3 Piezoelectric Buzzer 33
3.9 Heart Beat Sensor 34
3.10 L293D Motor Driver 35
3.10.1 Features of Motor Driver 36
3.10.2 Technical Specifications 36
3.10.3 L293D IC 36
3.11 Temperature Sensor 38
3.11.1 Temperature Range 39
3.11.2 Accuracy of Temperature Sensor 39

3.11.3 Thermistor 39
CHAPTER 4 41
SOFTWARE DESCRIPTION 41
4.1 Embedded C 41
4.1.1 Advantages of Embedded C 42
Fig 4.1 Names of the window 43
CHAPTER 5 44
SYSTEM DESIGN 44
5.1 Block Diagram 44
5.2 Description of the Block Diagram 45
5.2.1 Voice recognition unit 45
5.2.2 Microcontroller 45
5.2.3 Android Mobile 46
5.2.4 Motor Driver circuit 46
5.2.5 Bluetooth Module 46
5.2.6 IR Module 47
5.2.7 L293D (Driver IC) 47
5.2.8 DC Motors 48
5.2.9 Power Supply Section 48
5.3 Flow Chart of the Voice and Gesture Based Wheelchair 49
5.4 Testing 51
5.4.1 Testing of the Motor and Obstacle Detection using Sensors 51
5.5 PROTOTYPE 53
CHAPTER 6 55
APPLICATION, ADVANTAGES AND LIMITATIONS 55
6.1 Applications 55
6.2 Advantages 55
6.3 Limitations 56
CHAPTER 7 57
CONCLUSION AND FUTURE SCOPE 57
BIBLIOGRAPHY 59

List of Figures
CHAPTER 2
Figure 2.1 Voice Operated Wheelchair 9
CHAPTER 3
Figure 3.1 Arduino UNO 10
Figure 3.2 Arduino Specifications 11
Figure 3.3 Arduino UNO Physical Characteristics 15
Figure 3.4 GSM Module 16
Figure 3.5 Sim900 17
Figure 3.6 Top View of Sim900 18
Figure 3.7 Sim900 Module 19
Figure 3.8 Top Map of GSM Module 20
Figure 3.9 DC Motor 22
Figure 3.10 Rotor and Stator 23
Figure 3.11 Ultrasonic Sensor Working 27
Figure 3.12 Ultrasonic Sensor 27
Figure 3.13 Working Principle of IR Sensor 28
Figure 3.14 LEDs 30
Figure 3.15 Working of LEDs 31
Figure 3.16 Buzzer 33
Figure 3.17 Heartbeat Sensor 34
Figure 3.18 L293D Motor Driver 35
Figure 3.19 Temperature Sensor 38
Figure 3.20 Types of Thermistor Bead 40
CHAPTER 4
Figure 4.1 Names of the Window 43
CHAPTER 5
Figure 5.1 Block Diagram 44
Figure 5.2 Flowchart of Voice and Touchscreen based Wheelchair 49
Figure 5.3 Initial Conditions when Obstacle is detected 50

Figure 5.4 Indicating Condition of Speed Reduction 51
Figure 5.5 Indicating the Condition where the motor stops 51
Figure 5.6 Prototype System 53

List of Tables
Table 3.1 Specifications of Sim900 19
Table 3.2 Net Status of LED 21

Voice and Touchscreen Operated Intelligent Wheelchair 2015-16
Dept. of Telecommunication Engineering, Dr.AIT Page | 1
CHAPTER 1
INTRODUCTION
The goal of this smart wheelchair project is to enhance an ordinary powered wheelchair using
sensors to perceive the wheelchair's surroundings, a speech interface to interpret commands.
Intelligent wheelchair will play an important role in the future welfare society. The use of
intelligent wheelchair encourages the view of the machine as a partner rather than as a tool. The
population of people with disabilities has risen markedly during the past century. In particular,
robotic wheelchairs may help in maneuvering a wheelchair and planning motion. Independent
mobility is critical to individuals of any age. Children without safe and independent self-
ambulation are denied a critical learning opportunity, which places them at a developmental
disadvantage relative to their self-ambulating peers. Adults who lack an independent means of
locomotion are less self-sufficient, which can manifest itself in a negative self-image. A lack of
independent mobility at any age places additional obstacles in the pursuit of vocational and
educational goals. While the needs of many individuals with disabilities can be satisfied with
power wheelchairs, some members of the disabled community (up to 40%) find operating a
standard power wheelchair difficult or impossible. This population includes, but is not limited to,
individuals with low vision, visual field neglect, spasticity, tremors, or cognitive deficits. To
accommodate this population, several researchers have used technologies originally developed
for mobile robots to create “smart wheelchairs.”
A wheelchair is a chair fitted with wheels. The device comes in variations allowing either
manual propulsion by the seated occupant turning the rear wheels by hand, or electric propulsion
by motors. There are often handles behind the seat to allow it to be pushed by another person.
Wheelchairs are used by people for whom walking is difficult or impossible due to illness,
injury, or disability. A “smart wheelchair” typically consists of either a standard power
wheelchair base to which a computer and a collection of sensors have been added or a mobile
robot base to which a seat has been attached. Two major concerns have to be taken into
account while designing a smart wheelchair for the disabled: the adaptability to the
individual and the fulfillment of safety requirements. In order to have a chance of being

accepted by its potential users, a smart wheelchair must be adaptable to the needs of each
individual person. Especially in the Context of supporting handicapped people, the focus
should be how the remaining skills of the human operator could adequately be complemented.
A smart wheelchair is a highly interactive system which is jointly controlled by the
human operator and the software of the robot. That is why the design of the human-machine
interface is a key issue in the development of a smart wheelchair. An estimate of 2.3 million
people aged 15 and older used wheelchair in the year 1999. Out of these 2.3 million people 1.4
to 2.1 million people used smart wheelchair that is 61 to 91% of the total wheelchair users. They
do not need smart wheelchair all the time. It simply means that 61 to 91% of the individuals
would have benefited from smart wheelchairs at least some of the time. The number of
wheelchair users has increased at an average annual rate of 5.9% a year. By 2010 the users were
increased to 4.3 million people where about 3.9 million people were the users benefited from
smart wheelchair. The smart wheelchairs have typically been considered a niche market with
population that is limited to individuals with significant disabilities. Investment in smart
wheelchairs has much greater potential impact than the ordinary wheelchairs.
Adapting the built environment to make it more accessible to wheelchair users is one of the
key campaigns of disability rights and movements and the Americans with Disabilities Act of
1990 (ADA). The most important principle is Universal design - that all people regardless of
disability are entitled to equal access to all parts of society like public transportation and
buildings. A wheelchair user is less disabled in an environment without stairs. Sometimes it is
necessary to add structures like ramps or elevators in order to permit people in wheelchair (and
those using crutches, canes, walkers and so forth, or those with unsupported walking disabilities)
to use a particular building. Other important adaptations are powered doors, lowered fixtures
such as sinks and water fountains, and toilets with adequate space and grab bars to allow the
person to maneuver him or herself out of the wheelchair onto the fixture. In the United States,
most new construction for public use must be built to ADA standards of accessibility.
With the aging of the population, architects are seeking to design wheelchair ramps for private
homes that are less obtrusive and harmonize better with the overall design of the home’s

structure. Other important adaptations to private homes are larger bathroom doors that can
accommodate wheelchairs and showers and bathtubs that are designed for accessibility. These
designs can permit the use of mobile shower chairs or transfer benches to facilitate bathing for
people with disabilities. Wet rooms are bathrooms where the shower floor space and bathroom
floor are one continuous surface. Such floor designs allow a patient in a shower chair to be
pushed directly into the shower without needing to overcome a barrier or lip. The construction of
low floor trams and buses is being encouraged, whereas the use of paternosters in public
buildings without any alternative method of transportation has been criticized due to the lack of
access for wheelchair users.
Modern urban architecture now incorporates better accessibility for people with disabilities. In
many countries, such as the UK, the owners of inaccessible buildings are advised to keep a
lightweight portable wheelchair or scooter access ramp on hand to make premises disabled-
friendly. Public transit accessible vehicles are public transportation revenue vehicles which do
not restrict access, are usable and provide allocated space and/or priority seating for people who
use wheelchairs. In Los Angeles there is a program to remove a small amount of seating on some
trains to make more room for bicycles and wheelchairs. New York City’s entire bus system is
wheelchair-accessible, and a multi-million-dollar renovation program is underway to provide
elevator access to many of the city's 485 subway stations.
In Adelaide, Australia, all public transport has provision for at least two wheelchairs per bus,
tram or train. In addition all trains have space available for bicycles. The Washington, D.C.
Metro system features complete accessibility on all its subways and buses. In Paris, France, the
entire bus network, i.e. 60 lines, has been accessible to wheelchair users since 2010. In the
United States a wheelchair that has been designed and tested for use as a seat in motor vehicles is
often referred to as a "WC19 Wheelchair" or a "transit wheelchair". ANSI-RESNA WC19 is a
voluntary standard for wheelchairs designed for use when traveling facing forward in a motor
vehicle. ISO 7176/19 is an international transit wheelchair standard that specifies similar design
and performance requirements as ANSI- RESNA WC19.

1.1 Objective of the Project
The main objective of this project is to design and develop a system that allows the user to
interact with the smart wheelchair with touch screen and voice recognition system at different
levels of control for obstacle detection and collision avoidance providing efficient risk
management. This project introduces a new design model of wheelchair for physically disabled
which can be used for moving from one place to another. The project provides a helping tool to
the disabled and helps them move around, additionally the voice recognition system which is
installed makes it user friendly. The wheelchair provides safety by adopting features such as
obstacle detection for collision avoidance and hollow detection to avoid danger which they might
encounter in their day to day life such wheelchair designed reduces dependency on caretakers
and family members and promotes the feeling of self-reliance. The smart wheelchair avoids or
stops in front of obstacles. Speed is often decreased to avoid minimum obstacle clearance, speed
is reduced to allow wheelchair to approach closer obstacles/objects.
1.2 Need for the Project
As the data come from the National Health Interview Survey (NHIS), two distinct trends have
contributed to the increasing overall prevalence of disability: a gradual rise, due largely to
demographic shifts associated with an aging population, as well as a rapid increase that is due to
health impairments and accidents. Many individuals have problems to use a conventional
wheelchair. A recent clinical survey indicated that 9%-10% of patients who received power
wheelchair training found it extremely difficult or impossible to use it for their activities of daily
living, and 40% of patients found the steering and maneuvering tasks difficult or impossible.
These people, suffering from motor deficits, disorientation, amnesia, or cognitive deficits, are
dependent upon others to push them, so often feel powerless and out of control Intelligent
wheelchair has the potential to provide these people with effective ways to alleviate the impact
of their limitations, by compensating for their specific impairments.

CHAPTER 2
LITERATURE SURVEY
A wheelchair is a chair fitted with wheels. The device comes in variations allowing either
manual propulsion by the seated occupant turning the rear wheels by hand, or electric propulsion
by motors. There are often handles behind the seat to allow it to be pushed by another person.
Wheelchairs are used by people for whom walking is difficult or impossible due to illness,
injury, or disability. People who have difficulty sitting and walking often make use of a wheel
bench.
The earliest records of wheeled furniture was an inscription found on a stone slate in China and a
child’s bed depicted in a frieze on a Greek vase, both dating back to the 5th century BCE. The
first records of wheeled seats being used for transporting the disabled date to three centuries later
in China; the Chinese used their invented wheel barrow to move people as well as heavy objects.
A distinction between the two functions was not made for another several hundred years, around
525 CE, when images of wheeled chairs made specifically to carry people begin to occur in
Chinese art. Later dates relate to Europeans using this technology during the German
Renaissance. The invalid carriage or Bath Chair seems to date from around 1760. In 1887,
wheelchairs ("rolling chairs") were introduced to Atlantic City so invalid tourists could rent them
to enjoy the Boardwalk. Soon, many healthy tourists also rented the decorated "rolling chairs"
and servants to push them as a show of decadence and treatment they could never experience at
home.
Harry Jennings and his disabled friend Herbert Everest, both mechanical engineers, invented the
first lightweight, steel, collapsible wheel chair in 1933. Everest had broken his back in a mining
accident. The two saw the business potential of the invention and went on to become the first
mass-manufacturers of wheelchairs: Everest and Jennings. Their "x-brace" design is still in
common use, albeit with updated materials and other improvements.

A 1993 report prepared by Rehabilitation Engineering center suggests that the selection of
wheelchairs depends on one’s physical status, functional capabilities and usage requirements.
Light-duty chairs do not provide much in terms of support, and rarely provide the means to
adjust the chair to the user. As a basic wheelchair to use if the user wants to take a break from
walking, this is the most cost effective choice .Heavy-duty chairs solve many of the comfort and
adjustment issues that light-duty chairs lack at the expense of some compactness. These types
can be with seat cushions and hard backs which greatly increase the comfort and support for the
user
When an unfortunate event affects the motor capacity of a person, it is necessary to use devices
like wheelchairs that offer a means of displacement for patients with motors problems of the
lower limbs. Tremendous leaps have been made in the field of wheelchair technology. However,
even these significant advances haven’t been able to help quadriplegics navigate wheelchair
unassisted. The thought of realizing Automation in a wheelchair at lower cost lead us to study
various papers related to automation of wheelchair. Some of the points which caught the sight
from referred materials are listed below:
Automated wheelchair for physically disabled people is a dependent user recognition voice
system and ultrasonic and infrared sensor systems have been integrated in this proposed
wheelchair. In this an automatic wheelchair which can be driven using voice commands and with
the possibility of avoiding obstacles by using infrared sensors and down stairs or hole detection
by using ultrasonic sensors was proposed. The wheelchair has also been developed to work on
movement of accelerometer which will help for the person whose limbs are not working. The
speech is recognized by the HM2007 IC and processed thus giving commands to the
microcontroller accordingly and hence to the robot. When accelerometer moves or tilts its
position, thus gives analog signal to microcontroller and convert it into appropriate digital level
so as to move the motors of wheelchair. Infrared sensors is used detect the obstacle .If any
obstacle is detect then it gives signal to microcontroller and it will stop the motors.
Microcontroller controls the movements of the robot.

Automated Wheelchair using Gesture Recognition is a dependent-user recognition using
Head movements and infrared sensor integrated with wheelchair. Wheelchair which can be
driven using acceleration sensor and Head Movements with the possibility of avoiding obstacles.
Obstacle in the way can be determined by wheelchair and wheelchair will stop automatically.
The wheelchair can also integrate with Head movements and computers. The pilot can use the
same controls to drive the wheelchair and operate another assistive device, so handicap person
who cannot make use of his hands can drive chair by Head movements.
Hand Gesture Based Wheelchair Movement Control for Disabled Person Using MEMS-
this project discusses to develop a wheel chair control which is useful to the physically disabled
person with his hand movement or his hand gesture recognition using Acceleration technology.
This paper also demonstrates that accelerometers can be used to effectively translate finger and
hand gestures into computer interpreted signals. For gesture recognition the accelerometer data is
calibrated and filtered. The accelerometers can measure the magnitude and direction of gravity in
addition to movement induced acceleration.
Voice and Accelerometer controlled wheelchair- Intended users control the chair by wearing a
glove fitted with accelerometer for controlling the movement and direction of the wheelchair.
The wheel chair is also assisted with a Voice recognition kit, with the help of which the user can
guide the wheelchair through voice commands. Ultrasonic sensors are used for real-time obstacle
detection. The possibility of avoiding obstacles with removed by ultrasonic sensor which detects
obstacles within 25cm range. The wheelchair has also been developed to allow manual driving.
The prototype of the wheelchair is built using a micro-controller, chosen for its low cost, in
addition to its versatility and performance in mathematical operations and communication with
other electronic devices.
Voice Activated Wheelchair with Collision Avoidance Using Sensor Information- this
project develops a functional voice activated wheelchair. The system applies the collision
avoidance function (CAF) by which wheelchair avoids the wall or obstacle without voice
command by using the information of two kinds of sensor. The wheelchair is equipped with ten
sensors; two ultrasonic and eight IR, user inputs voice command to laptop through headset

microphone. The platform is PIC system which uses Japanese fifteen instruction commands eight
basic movement commands, four little movement commands, two speed control commands and
one repetition command and two verification commands the user controls the wheelchair by the
interactive operation. Then, proposed system prevents the wheelchair to take incorrect movement
by false recognition. The top movement is set to prevent collision to both the stationary obstacle
such as the wall and moving obstacle such as person. The avoidance movement provides the
reduction of this problem. This movement rotates the posture of the wheelchair to parallel to the
wall or obstacle when the wheelchair diagonally closes the wall or obstacle deceleration
movement. This movement slows down the moving speed so that the user avoids the wall or
obstacle himself by voice command before applying the stop movement when it is close to the
wall or obstacle.
2.1 VOICE OPERATED WHEELCHAIRS
Few patients such as quadriplegics’ and multiple sclerosis type cannot drive joystick operated
powered wheelchair so they are dependent on other people or helpers to move from one place to
another and in such a way they don’t have the freedom of mobility. So it is needed to develop a
powered wheelchair which operates on real analogous voice signal of patient or user on that
wheelchair. This powered wheelchair motor control and drive system which consists of
microcontroller and DC motors. The voice recognition system is used to detect and recognizes
the patient’s voice and its output in the digital form will be sent to microcontroller which then
controls the wheelchair according to its program.
Voice operated wheelchair is the modified version of the manual wheelchair as shown in Figure
2.1. It is operated on the voice of patient (i.e. commands such as forward, left, right, stop,
etc.).The wheelchair does not require any person to move it as it is automated with motors .Such
kind of wheelchair are very less observed in India as compared to the other countries (USA,
Europe, China, etc.).Hence this wheelchair provides the need of the quadriplegic patients and
makes them independent for mobility at reasonable rate. The Future scope of this kind is that the
current system limits its application in noise free environment. Future studies should aim at
making it insensitive to noise by introducing proper noise filter into it. By making advanced and

partial modifications, this wheelchair be used in acoustic control of vehicles’ braking systems
thus reducing risk of accidents. Also, the wheelchair can be done by using soft computing on
MATLAB for efficient output. We can also add the GSM/GPS system to the present module so
that it can help anyone to track if any accidents occur as the patients would not be in a condition
to call someone.
Fig 2.1 Voice Operated Wheelchair
Several researchers have described voice control mechanisms for a power wheelchair, but voice
control has yet to become a commercially viable control alternative. One problem with voice
control is that the voice’s limited bandwidth renders it impossible to make frequent small
adjustments to the wheelchair’s velocity. And also the tone of the speaker should match the
threshold set by the manufacture. If the set threshold is not reached then the commands
instructed by the speaker will not be performed. One possible solution is to utilize voice control
in combination with the navigation assistance provided by “smart wheelchairs,” which use
sensors to identify and avoid obstacles in the wheelchair’s path.
.

CHAPTER 3
HARDWARE COMPONENTS
3.1 Arduino UNO
Fig 3.1 Arduino UNO
The Arduino Uno is a microcontroller board based on the ATmega328. It has 14 digital
input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal
oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains
everything needed to support the microcontroller; simply connect it to a computer with a USB
cable or power it with a AC-to-DC adapter or battery to get started. The Uno differs from all
preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features
the Atmega8U2 programmed as a USB-to serial converter. "Uno" means one in Italian and is
named to mark the upcoming release of Arduino 1.0. The Uno and version1.0 will be the

reference versions of Arduino, moving forward. The Uno is the latest in a series of USB Arduino
boards, and the reference model for the Arduino platform.
3.2 Technical Specifications
 Microcontroller ATmega328
 Operating Voltage 5V
 Input Voltage (recommended) 7-12V
 Input Voltage (limits) 6-20V
 Digital I/O Pins 14 (of which 6 provide PWM output)
 Analog Input Pins 6
 DC Current per I/O Pin 40 mA
 DC Current for 3.3V Pin 50 mA
 Flash Memory 32 KB of which 0.5 KB used by boot loader
 SRAM 2 KB
 EEPROM 1 KB
Fig 3.2 Arduino Specifications

POWER
The Arduino Uno can be powered via the USB connection or with an external power supply. The
power source is selected automatically. External (non-USB) power can come either from an AC-
to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-
positive plug into the board's power jack. Leads from a battery can be inserted in the Gnd and
Vin pin headers of the POWER connector. The board can operate on an external supply of 6 to
20 volts. If supplied with less than 7V, however, the 5Vpin may supply less than five volts and
the board may be unstable. If using more than 12V, the voltage regulator may overheat and
damage the board. The recommended range is 7 to 12 volts. The power pins are as follows:
 VIN. The input voltage to the Arduino board when it's using an external power source (as
opposed to5 volts from the USB connection or other regulated power source). You can
supply voltage through this pin, or, if supplying voltage via the power jack, access it
through this pin.
 5V. The regulated power supply used to power the microcontroller and other components
on the board. This can come either from VIN via an on-board regulator, or be supplied by
USB or another regulated 5V supply.
 3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50
mA.
 GND. Ground pins.
The Atmega328 has 32 KB of flash memory for storing code (of which 0,5 KB is used for the
boot loader); It has also 2 KB of SRAM and 1 KB of EEPROM (which can be read and written
with the EEPROM library). Each of the 14 digital pins on the Uno can be used as an input or
output, using pin Mode(), digital Write(), and digital Read() functions. They operate at 5 volts.
Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor
(disconnected by default) of 20-50kOhms. In addition, some pins have specialized functions:
Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins
are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip.

External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt on a low
value, a rising or falling edge, or a change in value. See the attach Interrupt() function for details.
PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analog Write() function.
SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication,
which, although provided by the underlying hardware, is not currently included in the Arduino
language.
LED: 13. There is a built-in LED connected to digital pin 13. When the pin is HIGH value, the
LED icon, when the pin is LOW, it's off. The maximum length and width of the Uno PCB are
2.7 and 2.1 inches respectively, with the USB connector and power jack extending beyond the
former dimension. Three screw holes allow the board to be attached to a surface or case. Note
that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even multiple of the 100
mil spacing of the other pins. The Uno has 6 analog inputs, each of which provides 10 bits of
resolution (i.e. 1024 different values). By default they measure from ground to 5 volts, though is
it possible to change the upper end of their range using the AREF pin and the analog Reference()
function. Additionally, some pins have specialized functionality:
• I 2C: 4 (SDA) and 5 (SCL). Support I2C (TWI) communication using the Wire library.
There are a couple of other pins on the board:
• AREF: Reference voltage for the analog inputs. Used with analog Reference().
• Reset: Bring this line LOW to reset the microcontroller. Typically used to add a reset button to
shields which block the one on the board. See also the mapping between Arduino pins and
Atmega328 ports.
Arduino can sense the environment by receiving input from a variety of sensors and can affect its
surroundings by controlling lights, motors, and other actuators. The microcontroller on the board
is programmed using the Arduino programming language (based on Wiring) and the Arduino
development environment (based on Processing). Arduino projects can be stand-alone or they
can communicate with software on running on a computer (e.g. Flash, Processing, Max MSP).

The Arduino Uno has a number of facilities for communicating with a computer, another
Arduino, or other microcontrollers. The ATmega328 provides UART TTL (5V) serial
communication, which is available on digital pins 0 (RX) and 1 (TX). An ATmega8U2 on the
board channels this serial communication over USB and appears as a virtual com port to
software on the computer. The '8U2 firmware uses the standard USB COM drivers, and no
external driver is needed. However, on Windows, an *.ino file is required.. The Arduino software
includes a serial monitor which allows simple textual data to be sent to and from the Arduino
board. The RX and TX LEDs on the board will flash when data is being transmitted via the
USB-to serial chip and USB connection to the computer (but not for serial communication on
pins 0 and 1). A Software Serial library allows for serial communication on any of the Uno's
digital pins. The ATmega328 also support I2C (TWI) and SPI communication. The Arduino
software includes a Wire library to simplify use of the I2C bus.
Rather than requiring a physical press of the reset button before an upload, the Arduino Uno is
designed in a way that allows it to be reset by software running on a connected computer. One of
the hardware flow control lines (DTR) of the ATmega8U2 is connected to the reset line of the
ATmega328 via a 100 nano farad capacitor. When this line is asserted (taken low), the reset line
drops long enough to reset the chip. The Arduino software uses this capability to allow you to
upload code by simply pressing the upload button in the Arduino environment. This means that
the boot loader can have a shorter timeout, as the lowering of DTR can be well-coordinated with
the start of the upload. This setup has other implications. When the Uno is connected to either a
computer running Mac OS X or Linux, it resets each time a connection is made to it from
software (via USB). For the following half-second or so, the boot loader is running on the Uno.
While it is programmed to ignore malformed data (i.e. anything besides an upload of new code),
it will intercept the first few bytes of data sent to the board after a connection is opened. If a
sketch running on the board receives one-time configuration or other data when it first starts,
make sure that the software with which it communicates waits a second after opening the
connection and before sending this data. The Uno contains a trace that can be cut to disable the
auto-reset. The pads on either side of the trace can be soldered together to re-enable it. It's
labeled "RESET-EN". You may also be able to disable the auto-reset by connecting a 110 ohm
resistor from 5V to the reset line; see this forum thread for details. The Arduino Uno has a

resettable poly fuse that protects your computer's USB ports from shorts and over current.
Although most computers provide their own internal protection, the fuse provides an extra layer
of protection. If more than 500 mA is applied to the USB port, the fuse will automatically break
the connection until the short or overload is removed.
3.3 Physical Characteristics of Arduino UNO
The maximum length and width of the Uno PCB are 2.7 and 2.1 inches respectively, with the
USB connector and power jack extending beyond the former dimension. Three screw holes allow
the board to be attached to a surface or case. Note that the distance between digital pins 7 and 8
is 160 mil (0.16"), not an even multiple of the 100 mil spacing of the other pins.
Fig 3.3 Arduino Uno Physical Characteristics

3.4 GSM Module
Fig 3.4 GSM Module
This is a GSM/GPRS-compatible Quad-band cell phone, which works on a frequency of
850/900/1800/1900MHz and which can be used not only to access the Internet, but also for oral
communication (provided that it is connected to a microphone and a small loud speaker) and for
SMSs. Externally, it looks like a big package (0.94 inches x 0.94 inches x 0.12 inches) with L-
shaped contacts on four sides so that they can be soldered both on the side and at the bottom.
Internally, the module is managed by an AMR926EJ-S processor, which controls phone
communication, data communication (through an integrated TCP/IP stack), and (through an
UART and a TTL serial interface) the communication with the circuit interfaced with the cell
phone itself. The processor is also in charge of a SIM card (3 or 1,8 V) which needs to be
attached to the outer wall of the module. In addition, the GSM900 device integrates an analog
interface, an A/D converter, an RTC, an SPI bus, an I²C, and a PWM module. The radio section
is GSM phase 2/2+ compatible and is either class 4 (2 W) at 850/ 900 MHz or class 1 (1 W) at
1800/1900 MHz. The TTL serial interface is in charge not only of communicating all the data
relative to the SMS already received and those that come in during TCP/IP sessions in GPRS

(the data-rate is determined by GPRS class 10: max. 85.6 kbps), but also of receiving the circuit
commands (in our case, coming from the PIC governing the remote control) that can be either
AT standard or AT-enhanced SIM Com type. The module is supplied with continuous energy
(between 3.4 and 4.5 V) and absorbs a maximum of 0.8 A during transmission.
The SIM900 is a complete Quad-band GSM/GPRS solution in an SMT module which can be
embedded in the customer applications. Featuring an industry-standard interface, the SIM900
delivers GSM/GPRS 850/900/1800/1900MHz performance for voice, SMS, Data, and Fax in a
small form factor and with low power consumption. With a tiny configuration of 24mm x 24mm
x 3 mm, SIM900 can fit almost all the space requirements in your M2Mapplication, especially
for slim and compact demand of design.
 SIM900 is designed with a very powerful single-chip processor integrating
 AMR926EJ-S core
 Quad - band GSM/GPRS module with a size of 24mmx24mmx3mm
 SMT type suit for customer application
 An embedded Powerful TCP/IP protocol stack
 Based upon mature and field-proven platform, backed up by our support service, from
definition to design and production.
Fig 3.5 SIM900

Fig 3.6 Top View of SIM900
3.4.1 Features of SIM900
 Quad-Band 850/ 900/ 1800/ 1900 MHz
 Dual-Band 900/ 1900 MHz
 GPRS multi-slot class 10/8GPRS mobile station class B
 Compliant to GSM phase 2/2+Class 4 (2 W @850/ 900 MHz)
 Class 1 (1 W @ 1800/1900MHz)
 Control via AT commands (GSM 07.07 ,07.05 and SIMCOM enhanced AT Commands)
 Low power consumption: 1.5mA(sleep mode)
 Operation temperature: -40°C to +85 °C

Fig 3.7 SIM900 Module
Table 3.1 Specifications of SIM900
PCB size 71.4mm X 66.0mm X1.6mm
Indicators PWR, status LED, net LED
Power supply 5V
Communication Protocol UART
RoHS Yes

Fig 3.8 Top Map of GSM module
3.4.2 Indicator LED and Buttons
STATUS: Power status of SIM900.
PWR: Power status of GSM module.
PWR: After the GSM module power on, you need to press the POWER button for a moment to
power on the SIM900 module.
RESET: Reset the SIM900 module.

Table 3.2 NET STATUS: The status of the NET STATUS LED is listed in following table:
3.5 DC Motor
A DC motor is any of a class of electrical machines that converts direct current electrical power
into mechanical power. The most common types rely on the forces produced by magnetic fields.
Nearly all types of DC motors have some internal mechanism, either electromechanical or
electronic; to periodically change the direction of current flow in part of the motor. Most types
produce rotary motion; a linear motor directly produces force and motion in a straight line. DC
motors were the first type widely used, since they could be powered from existing direct-current
lighting power distribution systems. A commonly used dc motors is shown in figure 3.9.
Electromagnetic motor: A coil of wire with a current running through it generates
an electromagnetic field aligned with the center of the coil. The direction and magnitude of the
Status Description
Off SIM900 is not running 64ms On/800ms
Off SIM900 not registered the network
64ms On/3000ms Off SIM900 registered to the network
64ms On/300ms Off GPRS communication is established

magnetic field produced by the coil can be changed with the direction and magnitude of the
current flowing through it.
Fig 3.9 DC Motor
A simple DC motor as in fig 3.9 has a stationary set of magnets in the stator and
an armature with one more windings of insulated wire wrapped around a soft iron core that
concentrates the magnetic field. The windings usually have multiple turns around the core, and in
large motors there can be several parallel current paths. The ends of the wire winding are
connected to a commutated. The commutator allows each armature coil to be energized in turn
and connects the rotating coils with the external power supply through brushes. (Brushless DC
motors have electronics that switch the DC current to each coil on and off and have no
brushes.)The total amount of current sent to the coil, the coil's size and what it's wrapped around
dictate the strength of the electromagnetic field created.
Since the series-wound DC motor develops its highest torque at low speed, it is often used in
traction applications such as electric locomotives, and trams. The DC motor was the mainstay of
electric traction drives on both electric and diesel-electric locomotives, street-cars/trams and
diesel electric drilling rigs for many years. The introduction of DC motors and an electrical
grid system to run machinery starting in the 1870s started a new second Industrial Revolution.
DC motors can operate directly from rechargeable batteries, providing the motive power for the
first electric vehicles and today's hybrid cars and electric cars as well as driving a host
of cordless tools. Today DC motors are still found in applications as small as toys and disk
drives, or in large sizes to operate steel rolling mills and paper machines. Large DC motors with
separately excited fields were generally used with winder drives for mine hoists, for high torque
as well as smooth speed control using thruster drives. These are now replaced with large AC
motors with variable frequency drives. If external power is applied to a DC motor it acts as a DC

generator, a dynamo. This feature is used to slow down and recharge batteries on hybrid car and
electric cars or to return electricity back to the electric grid used on a street car or electric
powered train line when they slow down. This process is called regenerative braking on hybrid
and electric cars. In diesel electric locomotives they also use their DC motors as generators to
slow down but dissipate the energy in resistor stacks. Newer designs are adding large battery
packs to recapture some of this energy.
Construction: DC motors consist of one set of coils, called armature winding, inside another set
of coils or a set of permanent magnets, called the stator as shown in figure 3.10. Applying a
voltage to the coils produces a torque in the armature, resulting in motion.
Fig 3.10 Rotor and stator
 The magnetic field can alternatively be created by an electromagnet. In this case, a DC coil
(field winding) is wound around a magnetic material that forms part of the stator.
 The stator is the stationary outside part of a motor.
Rotor
 The rotor is the inner part which rotates
 The rotor is composed of windings (called armature windings) which are connected to the
external circuit through a mechanical commutator.
 Both stator and rotor are made of ferromagnetic materials. The two are separated by air-gap.
Winding
A winding is made up of series or parallel connection of coils.

 Armature winding - The winding through which the voltage is applied or induced.
 Field winding - The winding through which a current is passed to produce flux (for the
electromagnet).
3.5.1 Characteristics of DC motor
Nominal voltage: The voltage that corresponds to the highest motor efficiency. Try to choose a
main battery pack which most closely matches the nominal voltage of your drive motors. For
example, if the motor’s nominal voltage is 6V, use a 5x 1.2V NiMh pack to get 6V. If your
motor operates at 3.5V nominal, you can use either a 3xAA or 3xAAA NiMh pack or a 3.7V
LiPo or LiIon pack.
If you operate a motor outside of its nominal voltage, the efficiency of the motor goes down,
often requiring additional current, generating more heat and decreasing the lifespan of the motor.
Aside from a “nominal voltage” DC motors also have an operating voltage range outside of
which the manufacturer does not suggest operating the motor. For example a 6V DC Gear motor
may have an operating range of 3-9V; it will not operate as efficiently as compared to 6V, but it
will still run well.
No Load RPM: This is how fast (angular velocity) the final output shaft will rotate assuming
nothing is connected to it. If the motor has a gear down and the motor’s speed is not indicated
separately, the no load rpm value is the shaft speed after the gear down. The motor’s RPM is
proportional to the voltage input. “No Load” means the motor encounters no resistance
whatsoever (no hub or wheel mounted to the end). Usually the No Load RPM provided is
associated with the nominal voltage.
Power rating: If a motor’s power is not listed, it can be approximated. Power is related to
current (I) and voltage (V) by the equation P = I*V. Use the no load current and nominal voltage
to approximate the motor’s power output. The motor’s maximum power (which should only be
used for a short time) can be approximated using the stall current and nominal voltage (rather
than maximum voltage).

Stall Torque: This is the maximum torque a motor can provide with the shaft no longer rotating.
It is important to note that most motors will sustain irreparable damage if subjected to stall
conditions for more than a few seconds. When choosing a motor, you should consider subjecting
it to no more than ~1/4 to 1/3 the stall torque.
Stall Current: This is the current the motor will draw under maximum torque conditions. This
value can be very high and should you not have a motor controller capable of providing this
current, there is a good chance your electronics will fry as well. If neither the stall nor the
nominal current are provided, try to use the motor’s power rating (in Watts) and the nominal
voltage to estimate the current: Power [Watts] = Voltage [Volts] x Current [Amps].
Ideal Specifications: Many motor manufacturers are now listing additional information that can
be very useful when selecting the right motor. Below is some additional information you might
come across when searching for DC motors
Voltage vs. RPM: Ideally, the manufacturer would list the graph of a motor’s voltage vs. rpm.
For a quick approximate, consider using the no-load rpm and nominal voltage: (nominal voltage,
rpm) and the point (0, 0). See “gear down” below for motors with a gear down.
Current is a value that cannot be easily controlled. DC motors use only as much current as they
need. Ideal specifications include this curve, and approximations are not easily reproduced. The
stall torque is related to the stall current. A motor that is prevented from turning will consume
maximum (“stall”) current and produce the maximum torque possible. The current required to
provide a given torque is based on many factors including the thickness, type and configuration
of the wires used to make the motor, the magnets and other mechanical factors. Speed is
controlled by varying the rotor voltage and hence the rotor current, or by varying the magnetic
flux in the air gap by changing the current in the field windings. With access to both the field and
rotor windings, all DC motors offer the facility of simple speed and torque control. In our
prototype we are using 4 DC motors.

S4 are closed (and S2 and S3 are open) a positive voltage will be applied across the motor. By
opening S1 and S4 switches and closing S2 and S3 switches, this voltage is reversed, allowing
reverse operation of the motor. Using the nomenclature above, the switches S1 and S2 should
never be closed at the same time, as this would cause a short circuit on the input voltage source.
The same applies to the switches S3 and S4. This condition is known as shoot-through.
3.6 Distance Sensors
The emitter is simply an IR LED (Light Emitting Diode) and the detector is simply an IR
photodiode which is sensitive to IR light of the same wavelength as that emitted by the IR LED.
A typical IR sensor is shown in figure 3.11. When IR light falls on the photodiode, its resistance
and correspondingly, its output voltage, change in proportion to the magnitude of the IR light
received. This is the underlying principle of working of the IR sensor.
IR sensors are also used to distinguish between black and white surfaces. White surfaces reflect
all types of light while black surfaces absorb them. Therefore, depending on the amount of light
reflected back to the IR receiver, the IR sensor can also be used to distinguish between black and
white surfaces. The black box model is as shown in Figure. An infrared emitter, or IR emitter, is
a source of light energy in the infrared spectrum. It is light emitting diode (LED) that is used in
order to transmit infrared signals from a remote control. In general, the more they are in quantity
and the better the emitters are, the stronger and wider the resulting signal is. A remote with
strong emitters can often be used without directly pointing at the desired device. Infrared
emitters are also partly responsible for limits on the range of frequencies that can be controlled.
An IR emitter generates infrared light that transmits information and commands from one device
to another. Typically one device receives the signal then passes the infrared (IR) signal through
the emitter to another device.

Fig 3.11 Ultrasonic Sensor Working
The Infrared Receiver is used to receive infrared signals and also used for remote control
detection. There is an IR detector on the Infrared Receiver which is used to get the infrared light
emitted by the Infrared Emitter. The IR detector has a demodulator inside that looks for
modulated IR at 38 KHz. The Infrared Receiver can receive signals well within 10 meters. If
more than 10 meters, the receiver may not get the signals. We often use the two Groves-the
Infrared Receiver and the Grove - Infrared Emitter to work together. This Medium Range
Infrared sensor offers simple, user friendly and fast obstacle detection using infrared; it is non-
contact detection. The implementations of modulated IR signal immune the sensor to the
interferences caused by the normal light of a light bulb or the sun light. The sensing distance can
be adjusted manually.
Fig 3.12 Ultrasonic Sensor

The product features include:
 5V powered, low current consumption, less than 10mA.
 3 pin interface which are signal, GND and 5V.
 Small LED as indicator for detection status.
 Obstacle detection up to 8 cm
 Adjustable sensing range (2cm – 8cm).
 Small size makes it easy to assembly.
 Single bit output
 Compatible with all types of microcontrollers
3.6.1 Specification and limitations
Infrared sensor uses special sensor to modulate IR signal emitted from 2 IR transmitters and
detects the modulated IR signal reflected back from a nearby object. This sensor has a built-in IR
LED driver to modulate the IR signal at 38 KHz to match the built-in detector. The modulated IR
signal immunes the sensor from the interferences caused by the normal light of a light bulb or the
sunlight. The module will output a HIGH if no object is detected and a LOW if an object is
detected. The sensitivity of the IR Sensor is tuned using the potentiometer.
Fig 3.13 Working principle of IR sensor

Working principle of IR sensor is shown in Figure 3.13. The potentiometer is tunable in both the
directions. Initially tune the potentiometer in clockwise direction such that the Indicator LED
starts glowing. Once that is achieved, turn the potentiometer just enough in anti-clockwise
direction to turn off the Indicator LED. At this point the sensitivity of the receiver is maximum.
Thus, its sensing distance is maximum at this point. If the sensing distance (i.e., Sensitivity) of
the receiver is needed to be reduced, then one can tune the potentiometer in the anti-clockwise
direction from this point. Further, if the orientation of both Tx and Rx LED’s is parallel to each
other, such that both are facing outwards, then their sensitivity is maximum. If they are moved
away from each other, such that they are inclined to each other at their soldered end, then their
sensitivity reduces.
Tuned sensitivity of the sensors is limited to the surroundings. Once tuned for a particular
surrounding, they will work perfectly until the IR illumination conditions of that region nearly
constant. For example, if the potentiometer is tuned inside room/building for maximum
sensitivity and then taken out in open sunlight, it will require retuning, since sun’s rays also
contain Infrared (IR) frequencies, thus acting as a IR source (transmitter). This will disturb the
receiver’s sensing capacity. Hence it needs to be returned to work perfectly in the new
surroundings. The output of IR receiver goes low when it receives IR signal. Hence the output
pin is normally low because, though the IR LED is continuously transmitting, due to no obstacle,
nothing is reflected back to the IR receiver. The indication LED is off. When an obstacle is
encountered, the output of IR receiver goes low; IR signal is reflected from the obstacle surface.
This drives the output of the comparator low. This output is connected to the cathode of LED.
The key application of infrared technology is night vision devices, infrared astronomy, tracking,
art and restoration, gas detectors, rail safety, petroleum exploration etc.
3.7 LED (Light Emitting Diode)
A light-emitting diode (LED) is a two-lead semiconductor light source. It is a pn-junction diode,
which emits light when activated. When a suitable voltage is applied to the leads, electrons are
able to recombine with electron holes within the device, releasing energy in the form of photons.

This effect is called electroluminescence, and the color of the light (corresponding to the energy
of the photon) is determined by the energy band gap of the semiconductor.
Early LEDs were often used as indicator lamps for electronic devices, replacing small
incandescent bulbs. They were soon packaged into numeric readouts in the form of seven-
segment displays, and were commonly seen in digital clocks. Recent developments in LEDs
permit them to be used in environmental and task lighting. LEDs have many advantages over
incandescent light sources including lower energy consumption, longer lifetime, improved
physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in
applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting,
traffic signals, and camera flashes. A typical LED is shown in Figure.
Fig 3.14 LEDs
LEDs emit more lumens per watt than incandescent light bulbs. The efficiency of LED lighting
fixtures is not affected by shape and size, unlike fluorescent light bulbs or tubes. They can emit
light of an intended color without using any color filters as traditional lighting methods need.
This is more efficient and can lower initial costs. LEDs can have a relatively long useful life.
One report estimates 35,000 to 50,000 hours of useful life. Being solid-state components are
difficult to damage with external shock, unlike fluorescent and incandescent bulbs, which are
fragile.

Fig 3.15 Working of LED
Early LEDs were often used as indicator lamps for electronic devices, replacing small
incandescent bulbs. They were soon packaged into numeric readouts in the form of seven-
segment displays, and were commonly seen in digital clocks. Recent developments in LEDs
permit them to be used in environmental and task lighting. LEDs have many advantages over
incandescent light sources including lower energy consumption, longer lifetime, improved
physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in
applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting,
traffic signals, and camera flashes. However, LEDs powerful enough for room lighting are still
relatively expensive, and require more precise current and heat management than compact
fluorescent lamp sources of comparable output.
The working of LED is depicted in Figure 3.15. The LED consists of a chip of semiconducting
material doped with impurities to create a p-n junction. As in other diodes, current flows easily
from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-
carriers electrons and holes flow into the junction from electrodes with different voltages. When
an electron meets a hole, it falls into a lower energy level and releases energy in the form of a
photon. This is shown in Figure below.
The wavelength of the light emitted, and thus its color, depends on the band gap energy of the
materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes
usually recombine by a non-radiative transition, which produces no optical emission, because

these are indirect band gap materials. The materials used for the LED have a direct band gap
with energies corresponding to near-infrared, visible, or near-ultraviolet light. LEDs are usually
built on an n-type substrate, with an electrode attached to the p-type layer deposited on its
surface. P-type substrates, while less common, occur as well. Many commercial LEDs,
especially GaN/InGaN, also use sapphire substrate.
3.8 Buzzers
A buzzer or beeper as in Figure 3.16 is an audio signaling device, which may be mechanical,
electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm devices,
timers and confirmation of user input such as a mouse click or keystroke. A buzzer or beeper as
shown in Figure is a signaling device, usually electronic, typically used in automobiles,
household appliances such as a microwave oven, or game shows. It most commonly consists of a
number of switches or sensors connected to a control unit that determines if and which button
was pushed or a preset time has lapsed, and usually illuminates a light on the appropriate button
or control panel, and sounds a warning in the form of a continuous or intermittent buzzing or
beeping sound. Initially this device was based on an electromechanical system which was
identical to an electric bell without the metal gong (which makes the ringing noise).
Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding
board. Another implementation with some AC-connected devices was to implement a circuit to
make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a
cheap 8-ohm speaker. Nowadays, it is more popular to use a ceramic-based piezoelectric sounder
like a Son alert which makes a high-pitched tone. Usually these were hooked up to "driver"
circuits which varied the pitch of the sound or pulsed the sound on and off.
The word "buzzer" comes from the rasping noise that buzzers made when they were connected to
the electromechanical devices, operated from stepped-down AC line voltage at 50 or 60 cycles.
Other sounds commonly used to indicate that a button has been pressed are a ring or a beep.

3.8.1 Mechanical Buzzer
Mechanical Buzzers is a Solid State circuit which is self-oscillating that converts the electrical
energy to a magnetic field. As the magnetic field is turning on and off it changes the magnetic
field polarity in the coil. The membrane includes a miniature permanent magnet which reacts
with the coil magnetic field pulling or pushing the membrane and producing the sound. A joy
buzzer is an example of a purely mechanical buzzer. They require a driver.
3.8.2 Electromechanical Buzzer
Early devices were based on an electromechanical system identical to an electric bell without the
metal gong. Similarly, a relay may be connected to interrupt its own actuating current, causing
the contacts to buzz. Often these units were anchored to a wall or ceiling to use it as a sounding
board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made.
3.8.3 Piezoelectric Buzzer
A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal
source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate that a
button has been pressed are a click, a ring or a beep. The piezo can be connected to digital
outputs, and will emit a tone when the output is HIGH. Alternatively, it can be connected to an
analog pulse-width modulation output to generate various tones and effects. In our project we
use buzzer during emergencies, in order to alert other people.
Fig 3.16 Buzzer

3.9 Heart Beat Sensor
Fig 3.17 Heartbeat Sensor
Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute
(bpm). Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide
changes during exercise or sleep. The measurement of heart rate is used by medical professionals
to assist in the diagnosis and tracking of medical conditions. It is also used by individuals, such
as athletes, who are interested in monitoring their heart rate to acquire maximum efficiency. The
wave interval is the inverse of the heart rate 0. Changes in lifestyle and unhealthy eating habits
have resulted in a dramatic increase in incidents of heart and vascular diseases. Furthermore,
heart problems are being increasingly diagnosed on younger patients. Worldwide, Coronary
heart disease is now the leading cause of death 0. Thus, any improvements in the diagnosis and
treatment tools are welcomed by the medical community. In a clinical environment, heart rate is
measured under controlled conditions like blood measurement, heart beat measurement, and
Electrocardiogram (ECG) 0. However, there is a great need that patients are able to measure the
heart rate in the home environment as well 0. A heart rate monitor (HRM) is a simple device that
takes a sample of the heartbeat signal and computes the bpm so that the information can easily be
used to track heart conditions. The HRM devices employ electrical and optical methods as means
of detecting and acquiring heart signals. Heartbeat rate is one of the very important parameters of
the cardiovascular system. The heart rate of a healthy adult at rest is around 72 bpm. Athletes

normally have lower heart rates than less active people. Babies have a much higher heart rate at
around 120 bpm, while older children have heart rates at around 90 bpm. The heart rate rises
gradually during exercises and returns slowly to the rest value after exercise. The rate at which
the pulse returns to normal is an indication of the fitness of the person. Lower than normal heart
rates are usually an indication of a condition known as Brady cardia, while higher than normal
heart rates are known as tachycardia 0.
The basic heartbeat sensor consists of a light emitting diode and a detector like a light detecting
resistor or a photodiode. The heart beat pulses causes a variation in the flow of blood to different
regions of the body. When a tissue is illuminated with the light source, i.e. light emitted by the
led, it either reflects (a finger tissue) or transmits the light (earlobe). Some of the light is
absorbed by the blood and the transmitted or the reflected light is received by the light detector.
The amount of light absorbed depends on the blood volume in that tissue. The detector output is
in form of electrical signal and is proportional to the heart beat rate. This signal is actually a DC
signal relating to the tissues and the blood volume and the AC component synchronous with the
heart beat and caused by pulsatile changes in arterial blood volume is superimposed on the DC
signal. Thus the major requirement is to isolate that AC component as it is of prime importance.
3.10 L293D Motor Driver
Fig 3.18 L293D Motor Driver
The L293D motor driver is available for providing User with ease and user friendly interfacing
for embedded application. L293D motor driver is mounted on a good quality, single sided non-
PTH PCB. The pins of L293D motor driver IC are connected to connectors for easy access to the

driver IC’s pin functions. The L293D is a Dual Full Bridge driver that can drive up to1Amp per
bridge with supply voltage up to 24V. It can drive two DC motors, relays, solenoids, etc. The
device is TTL compatible. Two H bridges of L293D can be connected in parallel to increase its
current capacity to 2 Amp.
3.10.1 Features of Motor Driver
 Easily compatible with any of the system
 Easy interfacing through FRC (Flat Ribbon Cable)
 External Power supply pin for Motors supported
 Onboard PWM (Pulse Width Modulation) selection switch
 2pin Terminal Block (Phoenix Connectors) for easy Motors Connection
 Onboard H-Bridge base Motor Driver IC (L293D)
3.10.2 Technical Specifications
 Power Supply : Over FRC connector 5V DC
 External Power 9V to 24V DC
 Dimensional Size : 44mm x 37mm x 14mm (l x b x h)
 Temperature Range : 0°C to +70 °C
3.10.3 L293D IC
L293D IC is a dual H-bridge motor driver IC. One H-bridge is capable to drive a dc motor in
bidirectional. L293D IC is a current enhancing IC as the output from the sensor is not able to
drive motors itself so L293D is used for this purpose. L293D is a 16 pin IC having two enables
pins which should always be remain high to enable both the H-bridges. L293D IC is a dual H-
bridge motor driver IC. One H-bridge is capable to drive a dc motor in bidirectional. L293D IC
is a current enhancing IC as the output from the sensor is not able to drive motors itself so
L293D is used for this purpose. L293D is a 16 pin IC having two enables pins which should

always be remain high to enable both the H-bridges. The driver IC L293D is quad push-pull
drivers capable of delivering output currents to1A per channel respectively. Each channel is
controlled by a TTL compatible logic input and each pair of drivers (a full bridge) is equipped
with an inhibit input available at pin 1 and pin 9.The motor will run only when chip inhibit is at
high logic i.e. chip inhibit is enabled.
 Motor Driver Input (10pin Box Header / J1)
The input to the motor driver IC is controlled by the controller through its motor driver input
connector. Pin Headers with plastic guide box around them are known as “Box Headers” or
“Shrouded Headers” and are normally only used in combination with a Flat Ribbon Cable (FRC)
connector. A notch (key) in the guide box normally prevents placing the connector the wrong
way around. Box Header (denoted as J1 on board)can be connected using FRCs and also Single
Berg Wires for individual pin connections.
 Motor Output / 2pin Terminal Block / Phoenix Connector (J2 and J3)
Two pin Terminal Block (also known as Phoenix connectors) are used for motor connection.
With one IC L293D, two motor can be interfaced and hence two 2pin Terminal Blocks (Phoenix
connectors denoted as J2 and J3) are provided onboard for easy motor connection. Each terminal
Block has two pockets to insert wire into it. User just needs to insert uninsulated wire into one of
the pocket and then tighten the screw to fit wire into it.
 PWM selection Switch (SW1) and Enable pins (J4)
This is push-on push-off DPDT Switch (denoted as SW1 on board). When switch is in OFF state
then 100% PWM (Pulse Width Modulation) is provided irrespective of the voltage levels at
Enable pins (denoted as Chip Inhibit pins in diagram of IC, denoted as J4 onboard), whereas
when switch is ON then the PWM will be set according to the voltage level at enable pins.

 VCC, GND and VIN pins (J5)
These pins are used to provide power supply to L293D IC as well as motors connected through
Phoenix Connectors (J2 and J3). VCC (denoted as +5V on board) is +5V DC supply pin where
User needs to provide external +5V input voltage for IC. GND (denoted as GND on board) is 0V
supply pin to make common ground for other system through which motor will be controlled.
VIN (denoted as +12V onboard) is input voltage / supplied voltage to DC motors connected
through Phoenix connector. It ranges from 9V to 24V with maximum current consumption up to
1Amp. Generally User just need to connect +12V pin as +5V and GND can be get through FRC.
3.11 Temperature Sensor
The importance of temperature sensors in many thermal systems is virtually ignored. Within that
ignorance lays tremendous opportunities for you to make yourself valuable to your customers!
This study guide begins opening up those opportunities for you. We explore the four basic types
of sensors Watlow Gordon and Watlow Infrared offer. We discover how they work and learn
about some of each sensor’s unique features and advantages (as well as disadvantages).
Fig 3.19 Temperature Sensor

3.11.1 Temperature Range
Obviously, the operating temperature of a thermal system will dictate what thermocouple we can
choose. If the operating temperature is 700˚F (370˚C), for example, what thermocouples can we
use? Looking at Figure 7 or 8, we can use any thermocouple, except Type T. Most likely, we will
use Type J or Type K.
3.11.2 Accuracy of Temperature Sensor
Accuracy is defined as the amount of error which exists in a temperature measurement. It
indicates how close measured values are to the true temperature value. This is also called
“tolerance” or “error.” A chart called “Initial Calibration Tolerances” in Figure 8 tells us what
accuracy or “tolerance” we can expect from a given thermo couple. When a thermocouple is
connected with reversed polarity, it tricks the temperature controller into thinking that the
temperature is decreasing, when it is really increasing. The controller automatically corrects or
“compensates” for the reference junction temperature. It does this by using a small temperature
sensor to measure the reference junction temperature. Then the controller electronically “adds
in” a reference junction temperature adjustment. That is why it displays the correct temperature.
For example, a controller measures a reference junction temperature of 20˚C (68˚F). If a Type J
thermocouple is used, the controller automatically adds 1.019 milli volts to any signal it receives
from the thermocouple. If the measuring junction is also at 68˚F, the controller receives 0 mV.
The total then is 1.019 milli volts. The controller will then display 20˚C (or 68˚F).
3.11.3 Thermistor
The thermistor is a semiconductor used as a temperature sensor. It is manufactured from a
mixture of metal oxides pressed into a bead, wafer or other shape. The bead is heated under
pressure at high temperatures and then encapsulated with epoxy or glass (Figure). Beads can be
very small, less than 1 mm in some cases. The result is a temperature sensing device that displays a
very distinct non-linear resistance versus temperature relationship (Figure). The resistance decreases as
temperature increases. This is called a negative temperature coefficient (NTC) thermistor.

(A) Poxy Coated Thermistor Bead. (B) Glass Coated Thermistor Bead.
Fig 3.20 Types of Thermistor Bead
Another type of thermistor is a silistor, a thermally sensitive silicon resistor. Silistor employ
silicon as the semi conductive component material. Unlike ceramic PTC thermistors, silistor
have an almost linear resistance-temperature characteristic. Barium titanate thermistors can be
used as self-controlled heaters; for a given voltage, the ceramic will heat to a certain temperature,
but the power used will depend on the heat loss from the ceramic. The dynamics of PTC
thermistors being powered also is extremely useful. When first connected to a voltage source, a
large current corresponding to the low, cold, resistance flows, but as the thermistor self-heats, the
current is reduced until a limiting current (and corresponding peak device temperature) is
reached. The current-limiting effect can replace fuses. They are also used in
the degaussing circuits of many CRT monitors and televisions where the degaussing coil only
has to be connected in series with an appropriately chosen thermistor; a particular advantage is
that the current decrease is smooth, producing optimum degaussing effect. Improved degaussing
circuits haveauxiliary heating elements to heat the thermistor further (and reduce the final
current) or timed relays to disconnect the degaussing circuit entirely after it has operated.
Another type of PTC thermistor is the polymer PTC, which is sold under brand names such as
"Polyswitch” "Semi fuse", and "Multi fuse". This consists of plastic with carbon grains
embedded in it. When the plastic is cool, the carbon grains are all in contact with each other,
forming a conductive path through the device. When the plastic heats up, it expands, forcing the
carbon grains apart, and causing the resistance of the device to rise, which then causes increased
heating and rapid resistance increase. Like the BaTiO3 thermistor, this device has a highly
nonlinear resistance/temperature response useful for thermal or circuit control, not for
temperature. .

CHAPTER 4
SOFTWARE DESCRIPTION
4.1 Embedded C
Embedded C is a set of language extensions for the C Programming language by the C Standards
committee to address commonality issues that exist between C extensions for different embedded
systems. Historically, embedded C programming requires nonstandard extensions to the C
language in order to support exotic features such as fixed-point arithmetic, multiple distinct
memory banks, and basic I/O operations.
In 2008, the C Standards Committee extended the C language to address these issues by
providing a common standard for all implementations to adhere to. It includes a number of
features not available in normal C, such as, fixed-point arithmetic, named address spaces, and
basic I/O hardware addressing. Embedded C uses most of the syntax and semantics of standard
C, e.g., main () function, variable definition, data-type declaration, conditional statements (if,
switch, case), loops (while, for), functions, arrays and strings, structures and union, bit
operations, macros, etc.
As assembly language programs are specific to a processor, assembly language didn’t offer
portability across systems. To overcome this disadvantage, several high level languages,
including C, came up. Some other languages like PLM, Modula-2, Pascal, etc. also came but
couldn’t find wide acceptance. Amongst those, C got wide acceptance for not only embedded
systems, but also for desktop applications. Due to the wide acceptance of C in the embedded
systems, various kinds of support tools like compilers & cross-compilers, ICE, etc. came up and
all this facilitated development of embedded systems using C. Assembly language seems to be
an obvious choice for programming embedded devices. However, use of assembly language is
restricted to developing efficient codes in terms of size and speed. Also, assembly codes lead to
higher software development costs and code portability is not there. Developing small codes are
not much of a problem, but large programs/projects become increasingly difficult to manage in

assembly language. Finding good assembly programmers has also become difficult nowadays.
Hence high level languages are preferred for embedded systems programming. Compared to
other high level languages, C offers more flexibility because C is relatively small, structured
language; it supports low-level bit-wise data manipulation. Compared to assembly language, C
Code written is more reliable and scalable, more portable between different platforms (with some
changes). Moreover, programs developed in C are much easier to understand, maintain and
debug. Also, as they can be developed more quickly, codes written in C offers better
productivity. C is based on the philosophy ‘programmers know what they are doing’; only the
intentions are to be stated explicitly. It is easier to write good code in C & convert it to an
efficient assembly code (using high quality compilers) rather than writing an efficient code in
assembly itself. Benefits of assembly language programming over C are negligible when we
compare the ease with which C programs are developed by programmers. Efficient embedded C
programs must be kept small and efficient; they must be optimized for code speed and code size.
Good understanding of processor architecture embedded C programming and debugging tools
facilitate this. Embedded C is used for Microcontroller applications. Embedded C has to be used
with limited resources (RAM, ROM I/O’s) on an embedded processor. Thus, program code must fit
into the available program memory. If code exceeds the limit, the system is likely to crash. Compilers
for C (ANSI C) typically generate OS dependant executable. Embedded C requires compilers to
create files to be downloaded to the microcontrollers/microprocessors where it needs to run.
Embedded compilers give access to all resources which is not provided in compilers for desktop
computer applications. Embedded systems often have the real-time constraints, which is usually
not there with desktop computer applications. Embedded systems often do not have a console,
which is available in case of desktop applications.
4.1.1 Advantages of Embedded C
 It is small and simpler to learn, understand, program and debug.
 Compared to assembly language, C code written is more reliable and scalable, more portable
between different platforms.
 It is fairly efficient.
 C compilers are available for almost all embedded devices in use today.

 Unlike assembly, C has advantage of processor-independence and is not specific to any
particular microprocessor/microcontroller or any system. This makes it convenient for a user
to develop programs that can run on most of the systems.
 As C combines functionality of assembly language and features of high level languages, C is
treated as a ‘middle-level computer language’ or ‘high level assembly language’.
 It supports access to I/O and provides ease of management of large embedded projects.
 Java is also used in many embedded systems but Java programs require the Java Virtual
Machine (JVM), which consumes a lot of resources. Hence it is not used for smaller
embedded devices.
Fig 4.1 Names of the window

CHAPTER 5
SYSTEM DESIGN
5.1 Block Diagram
Fig 5.1 Block Diagram

5.2 Description of the Block Diagram
5.2.1 Voice recognition unit
Voice or speech recognition is the ability of a machine or program to receive and interpret
dictation, or to understand and carry out spoken commands. This unit recognizes the voice
command from the voice reception unit. IC HM2007P is the main component of this Voice
Recognition circuit. This IC can recognize 20 voice different commands. This Voice Recognition
circuit produces an 8-bit digital output for each voice commands. People with disabilities can
benefit from speech recognition programs. For individuals that are Deaf or Hard of Hearing,
speech recognition software is used to automatically generate a closed-captioning of
conversations such as discussions in conference rooms, classroom lectures, and/or religious
services. Speech recognition is also very useful for people who have difficulty using their hands,
ranging from mild repetitive stress injuries to involve disabilities that preclude using
conventional computer input devices. In fact, people who used the keyboard a lot and
developed RSI became an urgent early market for speech recognition. Speech recognition is used
in deaf telephony, such as voicemail to text, relay services, and captioned telephone. Individuals
with learning disabilities who have problems with thought-to-paper communication (essentially
they think of an idea but it is processed incorrectly causing it to end up differently on paper) can
possibly benefit from the software but the technology is not bug proof. Also the whole idea of
speak to text can be hard for intellectually disabled person's due to the fact that it is rare that
anyone tries to learn the technology to teach the person with the disability. This type of
technology can help those with dyslexia but other disabilities are still in question. The
effectiveness of the product is the problem that is hindering it being effective.
5.2.2 Microcontroller
The 8- bit digital output obtained from the voice recognition circuit is used to drive a
microcontroller based control circuit. ATMEL atmega 328 microcontroller is used in this circuit.
The microcontroller is programming such away to produce the required outputs for
corresponding voice command. The high-performance Atmel 8-bit AVR RISC-based

microcontroller combines 32KB ISP flash memory with read-while-write capabilities, 1KB
EEPROM, 2KB SRAM, 23 general purpose I/O lines, 32 general purpose working registers,
three flexible timer/counters with compare modes, internal and external interrupts, serial
programmable USART, a byte-oriented 2-wire serial interface, SPI serial port, 6-channel 10-bit
A/D converter (8-channels in TQFP and QFN/MLF packages), programmable watchdog timer
with internal oscillator, and five software selectable power saving modes. The device operates
between 1.8-5.5 volts. By executing powerful instructions in a single clock cycle, the device
achieves throughputs approaching 1 MIPS per MHz, balancing power consumption and
processing speed.
5.2.3 Android Mobile
Any an android mobile can be used. It is used as input device it receives the touch screen
command by the handicapped user and transfers this as text to Bluetooth module with the help of
Bluetooth wirelessly.
5.2.4 Motor Driver circuit
The drives used in the wheelchairs are DC motors. Two motors are used to drive the wheelchair.
They are 12V, 12A brushed DC motor.
5.2.5 Bluetooth Module
Bluetooth is a type of wireless communication protocol used to send and receive date between
two devices. It is free to use wireless communication protocol. Although its range it lower than
other wireless communication protocols like Wi-Fi and ZigBee. But it is still suitable for many
low range applications. Bluetooth wireless protocol lies in the same range of frequency of Wi-Fi
and ZigBee. It operates on 2.41 GHz frequency. Bluetooth module is used to transfer data from
an android mobile to the Microcontroller PIC 16F877 wirelessly. Bluetooth module is work as
master or slave. There are many Bluetooth modules available in market which is either

master/slave or both. Master Bluetooth module can send or receive data from other Bluetooth
modules. But slave Bluetooth can only listen to master Bluetooth module. It depends on your
application which Bluetooth module you need for your project. This module enables to wireless
transmit and receive serial data. This module is having 10 meters range. Operate on 5v supply.
Easily interface with Microcontroller.
APPLICATIONS OF BLUETOOTH:
The major applications of Bluetooth module are given below:
 In mobiles, computers, laptops and all other smart computers.
 wireless Audio and video controllers
 wireless mouse and keyboards
 Wireless head phones and Microphones
5.2.6 IR Module
This is used to detect an obstacle in the path of wheel chair and if an obstacle is detected then it
will send a signal to Microcontroller and wheel chair will be stop. It detects the larger obstacle in
the range of 40 cm.
5.2.7 L293D (Driver IC)
It’s a high voltage and high current dual full bridge driver IC having 16 pin. This is used to drive
the DC motors. It operates on 12V power supply. It provides DC current up to 4A. The operating
supply voltage is up to 24V. L293D is a typical Motor Driver or Motor Driver IC which allows
DC motor to drive on either direction. L293D is a 16-pin IC which can control a set of two DC
motors simultaneously in any direction. It means that you can control two DC motor with a
single L293D IC. It is a dual H-bridge Motor Driver Integrated Circuit (IC). It works on the
concept of H-bridge. H-bridge is a circuit which allows the voltage to be flown in either
direction. As we know that the voltage needs to change its direction for being able to rotate the
motor in clockwise or anticlockwise direction. Hence H-bridge IC is ideal for driving a DC
motor. In a single L293D chip there are two H-bridge circuit inside the IC which can rotate two

DC motor independently. Due to its size, it is very much used in robotic application for
controlling DC motors. There are two Enable pins on l293d. Pin 1 and pin 9, for being able to
drive the motor, the pin 1 and 9 need to be high. For driving the motor with left H-bridge you
need to enable pin 1 to high. And for right H-Bridge you need to make the pin 9 to high. If
anyone of the either pin1 or pin9 goes low then the motor in the corresponding section will
suspend working. It’s like a switch
5.2.8 DC Motors
A direct current, or DC, motor is the most common type of motor. DC motors normally have
just two leads, one positive and one negative. If you connect these two leads directly to a
battery, the motor will rotate. If you switch the leads, the motor will rotate in the
opposite direction. To control the direction of the spin of DC motor, without changing the way
that the leads are connected, you can use a circuit called an H-Bridge. An H bridge is an
electronic circuit that can drive the motor in both directions. H-bridges are used in many
different applications, one of the most common being to control motors in robots. It is called
an H-bridge because it uses four transistors connected in such a way that the schematic
diagram looks like an "H." You can use discrete transistors to make this circuit, but for this
tutorial, we will be using the L298 H-Bridge IC. The L298 can control the speed and direction
of DC motors and stepper motors and can control two motors simultaneously. Its current rating
is 2A for each motor. At these currents, however, you will need to use heat sinks. Two DC
motors are used for the movement of the wheel chair in Forward, Reverse, Left, and Right
Direction. These motors are controlled from the Microcontroller. L298 is a dual bridge driver
IC is used for driving the DC motors.
5.2.9 Power Supply Section
This section is consisting of a rechargeable battery. This section deals with the power
requirements of the wheel chair for DC motors, Microcontroller and other Section. Battery is
used to provide the power supply to L293D driver IC (12V supply) which drives the DC motors,

Microcontroller and IR section operates on 5V supply which is provided with the help of L293D
which is a 5V regulator IC by converting 12V into 5V.
5.3 Flow Chart of the Voice and Gesture Based Wheelchair
In this project, we have made use of touch screen and voice recognition technology to control the
locomotion of wheelchair. Both these modules are controlled by a Atmel atmega 328 which also
controls the Heart rate monitor, Ultrasonic sensor, GSM which are integrated together to enable
to user for the navigation of wheelchair. Using the touch screen and voice recognition we able to
control the movement of the wheelchair. The figure shows the data transfer between the Micro
Controller and the External device. We have selected either touch screen (or) voice recognition
by using the control switch. The UV Sensor are used to detect the obstacle on the pathway, It is
used to monitor distance from the obstacle and also display the range.
The GSM has a inter linked with the heart rate sensor, if the heart rate reached the abnormal
values the message (sms) will be sent to the caretaker (or) nearby hospital.
Here input is taken from the android mobile; speech signal is converted into the text with the
help of an android application. This text is transfer to the Microcontroller which controls the
movement and direction of wheel chair via a Bluetooth module wirelessly. Microcontroller
decides the operation of the two DC motors depending on the text received.L298 is a dual full
bridge driver IC which is used for driving purpose of DC motors.

Fig 5.2 Flowchart of voice and touchscreen based wheelchair

5.4 Testing
The testing of the direction keys and the working of sensors with motors is done. As seen in the
photograph the following connections are made. The program is dumped into the arm controller
using the RS232. The software used for dumping is Philips Flash Utility. The programming
language used is embedded C which is written in Kiel version 4. After dumping the code into the
ARM processor the reset button should be pressed to run the program.
5.4.1 Testing of the Motor and Obstacle Detection using Sensors
Fig 5.3 Initial condition when no obstacle is detected
The Figure 5.3 shows the initial condition where the motor driver, motor and the sensors are
interfaced with the ARM processor. Here the motor is running in the normal speed until any
obstacle is detected.

Fig 5.4 Indicating the condition of speed reduction
Here the first sensor is sensing the obstacle and the speed of the motor is reduced. This is
depicted in the Figure 5.4. Now the prototype will still continue to move in that direction but the
speed is reduced to the half of the original speed.
Fig 5.5 Indicating the condition where the motor stops
Here in the Figure 5.5 the obstacle is closer which is detected by the second sensor which is
tuned for lesser range and the motor stops.

5.5 PROTOTYPE
The Figure 5.6 shows the photographs of the completed prototype. The prototype is a two level
structure where the complete prototype is built using the acrylic plate. In the lower layer all the
components such as battery, Arm controller, RF receiver, motor drivers etc are placed. The
higher layer acts as the seat of the prototype. The back panel is attached to the rear end of the
higher layer and the front panel is attached to the front end of the prototype. Where both are
made of acrylic plate, which can be moved in any inclination as desired by the user. For this
purpose separate keys are provided in the key pad.
These sensors are used for obstacle detection such as wall. The sensor S5 is used for sensing the
presence of any hollow such as staircase which is placed on the lower end of the front panel.
This increases the security by ceasing the motion of the prototype. Also in the photograph, motor
M3 is seen this is placed on the front end of the prototype. This motor is used for the movement
of the front panel. In the rear view as seen, the sensor S6 and S7 are placed. The sensor S6 is
connected in the rear end which is used for obstacle detection such as wall in the backward
direction. The sensor S7 which is placed in the lower rear end is used to detect the variations in
the depth in the backward direction. The motors M1, M2, M4 can be seen. M1 and M2 are used
to drive each of the wheels. The motor M4, used in the rear end of the prototype. This motor is
used for the movement of the back panel.

Fig 5.6 Prototype System

CHAPTER 6
APPLICATION, ADVANTAGES AND LIMITATIONS
6.1 Applications
Since our project deals with designing a system that allows the user to interact with the smart
wheelchair at different levels of control for obstacle detection and collision avoidance providing
efficient risk management and an additional feature where the smart wheelchair can be converted
into a bed, it greatly reduces the dependency on caretakers or family members. This provides
independent mobility to the users thereby increasing the educational and vocational
opportunities. The wheelchair provides safety by adopting features such as obstacle detection for
collision avoidance and hollow detection to avoid danger which they might encounter in their
day to day life such as stairs, potholes, etc. A buzzer is also provided to help during emergencies.
6.2 Advantages
The designed prototype provides independent movement of the wheelchair by the user with just
the help of simple switches. The switches are provided separately for both direction control and
sleep mode operation. This makes the wheelchair very easy to operate. The main advantage of
using this wheelchair is that it has the ability to provide sufficient risk management. The
obstacles in the way of the wheelchair are detected and avoided correspondingly using IR
sensors which are mounted on the wheelchair. The IR sensor used here are of low cost which
makes the system cost effective. This fully functional smart wheelchair prototype can be
transformed into a bed whenever necessary. Additional keys for this purpose are provided on the
armrest of the wheelchair. There are separate keys for both back panel and the front panel; pair
of keys for single operation is provided. The angle of inclination of the backrest and the front
panel can be adjusted accordingly. During this operation the direction keys are disabled to
further increase the safety.

The keypad is made portable by providing wireless transmission between the transmitter side and
the receiver side. To further increase the safety, additional features such as buzzer is provided so
that the user can alert the people around him during emergencies. The switch for the buzzer is
mounted on the armrest of the wheelchair for easy access. Also, LED is mounted on the
wheelchair to provide light source which helps the user to navigate in dark surroundings.
6.3 Limitations
Since we are doing a cost effective project we are using IR sensors. The range of these sensors is
less and so in our prototype it can detect an obstacle within 0.5m to increase the range ultrasonic
sensor can be used. Our prototype cannot be used by all classes of disabled such as blind people
and people who are completely paralyzed as they encounter difficulty in operating the keypad.
Since the mode of input we are using is a switch it might not be feasible to all classes of
disabled. Instead of keypad other input modes such as voice recognition, head or neck
movement, and eye ball movement can be used.

CHAPTER 7
CONCLUSION AND FUTURE SCOPE
The designed smart wheelchair enables the movement of wheelchair in any desired direction
(forward, backward, right, and left) with the help of a keypad. The keypad is mounted on the arm
rest. This keypad is made portable fort better usage. The recumbent smart wheelchair can be
transformed into the bed through separate keys that are provided in the keypad. The back panel’s
and the front panel’s angle can be adjusted depending on the user’s requirement. This greatly
decreases the dependency on the family members and the care-takers. The wheelchair also
provides efficient risk management by obstacle detection and obstacle avoidance. To provide
further safety to the disabled the wheelchair has a LED to provide light when the surrounding
environment is dark. During any emergencies that is when the disabled have to alert any of the
care-takers around him he/she can easily do this with the help of a buzzer that is placed on the
wheelchair.
The future scope is to make the present touch screen feasible to all classes of disabled,
particularly for the blind, the touch screen can be made Braille so that the blind person can feel
the touch pad and operate the wheelchair accordingly. The touch screen in the present prototype
has keys as the input mode. Also, the wheelchair can be controlled by the user himself through
voice recognition. The range of sensing can be further increased by using high accuracy
ultrasonic sensors. To save energy, the energy from the motion of the wheels can stored in a
battery and made use whenever necessary. The wheelchair can be GSM based, where the patient
sitting on the wheelchair can have access to additional features. If the patient on the wheelchair
feels uncomfortable or will have some issue regarding health, he/she can send message to his/her
relatives or friends indicating the need for help. Thereby creating a much more stable and
reliable platform for the patient. The wheelchair can be source powered by solar power which is
free of cost and is renewable source. Presently, this wheelchair operates on DC battery source
but in future it can be operated by solar power which can be stored for day-night usage. Only the
initial cost for such implementation has to be taken into consideration, but will be relatively

Voice and touchscreen operated wheelchair report.

Voice and touchscreen operated wheelchair report.

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