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



affordable in the longer run. The wheelchair can be mapped with a particular route for access to

known or important localities. Such implementation will have a smart platform of sensors to

assist the mapping process along with use of image processing. A definite route maybe

programmed to the controller so that the wheelchair can move in specified path.



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