7/30/2019 Robo Gyan.pdf http://slidepdf.com/reader/full/robo-gyanpdf 1/74 ROBOGYANSTUDY MATERIAL FOR CERTIFICATE TRAINING ON EMBEDDED SYSTEMS AND ROBOTICS THE INFORMATION CONTAINED IN THIS BOOK HAS BEEN COMPILED FROM VARIOUS SOURCES FOR CLASSROOM DISCUSSIONS ONLY. WE ACKNOWLEDGE RESPECTIVE SOURCES. NOT FOR SALE. www.roboticwares.com LEARNICS
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 1/74
ROBOGYAN
STUDY MATERIAL FOR CERTIFICATE TRAINING ON EMBEDDED SYSTEMS AND ROBOTICS
THE INFORMATION CONTAINED IN THIS BOOK HAS BEEN COMPILED FROM VARIOUS SOURCES
FOR CLASSROOM DISCUSSIONS ONLY. WE ACKNOWLEDGE RESPECTIVE SOURCES.
NOT FOR SALE.
www.roboticwares.com
LEARNICS
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 2/74
www.roboticwares.com | www.learnics.in
LEAR NICSI M P A R T I N G S K I L L S
E M P O W E R I NG P E R F O R M A N C E
PUBLISHED BY KUSHAL NAHATA ON BEHALF OF ROBOTICWARES PVT. LTD.
COPYRIGHT 2009 ROBOTICWARES PVT LTD
PRINTED AT-
3rd
REVISED EDITION: 2010; 5000 COPIES
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 3/74
www.roboticwares.com | www.learnics.in
LEAR NICSI M P A R T I N G S K I L L S
E M P O W E R I NG P E R F O R M A N C E
Gratitude
The RoboticWares publication department while working on this book drew their inspiration
from the great visionaries like Dr A P J Abdul Kalam, Ratan Tata and A Samanta who have
played an instrumental role in putting India on the path of economic, social, and technical
development. We intend to keep up the good work done by them and contribute in making
India a true technology giant that will help us in accomplishment of VISION 2020.
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 4/74
www.roboticwares.com | www.learnics.in
LEAR NICSI M P A R T I N G S K I L L S
E M P O W E R I NG P E R F O R M A N C E
The Third Edition 2010
This book is basically the result of 4000 hours of teaching the material to engineering students.
Some of the "students" have also been faculty and post-docs. I am very grateful to them for their patience and tolerance as it progressed from crude notes to its present form. The materialowes its existence to many conversations and collaborations.
The topic of "Robotics" has become more than a technical subject to me. As a trainer, I see thedistinction in the different reactions of my students to the material, and more importantly, the
approach. Hence this book seems very appropriately located. There is no need to elaborate
further on this theme here, since it has been woven into the fabric of the book. It has deeper
implications for the future of Robotics Technology. The subject matter of this book dwells onhow that can be done. If this point is understood, a world of constructive engineering research
lies in front of anyone willing to take it seriously. I hope enough students see this to make it
happen. If this book contributes in any small way to that future progress, it will have served its purpose.
The material in the book is written for persons at a number of levels. Much of it is introductory
for an engineer, but serves to link various engineering principles. For that reason, it needs to bestudied with some care. To the average student, much of it will be easy going and hopefully
quite rewarding too if mastered.
I would be remiss if I failed to thank Mr. Gautam Kumar who suffered through my initial few
successes and many failures while doing his research with me. He was gracious enough to
forgive me for the many times I had initially rejected what turned out to be some of the most
crucial ideas now used in the design and development of Embedded Systems. Among manyothers, I wish to thank Mr. Gaurav Srivastava and Mr. Ashutosh Kumar for significant
contributions. Particular gratitude is due to the people who have made the computer work
possible. My thanks to the editorial and publishing staff of RoboticWares for their patience withme. I kept them waiting much longer than I care to mention, partially because of some the part
of university life we all wish we could find a way to do away with and partially because I am
always very unrealistic about the magnitude of the tasks to which I commit myself.
This list is incomplete and I apologize to anyone I omitted. One omission cannot be permitted,
however. I owe a special note of thanks to so many colleagues who, for various reasons, were(and may still be) skeptical of the approach. Without that skepticism and close scrutiny, there
would be far more weaknesses and errors in this and related works. Those who know me knowthat I love a good argument, often to the point of becoming very excited. I hope that trait is
never construed as a lack of appreciation for opposition to one of my pet ideas. For that reason,this acknowledgement to those who were willing to try to get me to see... is especially heartfelt.
We are a very special community in that without the dialectic; we would be so much less that
we are. I hope we never lose that quality. In the same spirit, I hope this book provokes somestrong reactions, positive and negative!
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 5/74
www.roboticwares.com | www.learnics.in
LEAR NICSI M P A R T I N G S K I L L S
E M P O W E R I NG P E R F O R M A N C E
Preface to the Second Edition
In this revised edition, opportunity has been taken to update completely all information as
there have been changes in our methodology of teaching Robotics in a more practical oriented
and application based manner.
This popular book has become a standard book of reference not only for students but also for
teachers and research fellows.
This edition of the book consists of new chapters, each of them thoroughly revised and
enlarged to meet the requirement. The present edition meets the needs of robotic enthusiasts
from the various backgrounds.
The complete material has been newly organized and strengthened.
Many of our colleagues and friends helped us by giving their valuable suggestions on the
structure and content of this text, which were instrumental in improving the quality and
presentation of this book in this new edition. We wish to express our profound gratitude and
appreciation to all of them.
We are also thankful to our trainees for their high appreciation, acceptance and use of the
book.
Critical views and suggestions for improving the contents would be warmly welcomed.
Publication Team
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 6/74
www.roboticwares.com | www.learnics.in
LEAR NICSI M P A R T I N G S K I L L S
E M P O W E R I NG P E R F O R M A N C E
SESSION 1
Resistance:
A resistor is a two-terminal electronic component that produces a voltage across
its terminals that is proportional to the electric current through it in accordance with
Ohm's law:
V = IR
Fig 1.1 Colour coding of resistance (Fixed Resistor)
Types of resistance:
Basically resistors are of two types, fixed resistor and Variable resistor.
Fixed Resistors: - This short of resistors has fixed value of resistance. Like 220Ω, 10KΩ.
(e.g.: as shown above.)
Variable Resistors: - Resistors having variable value of the resistance by maintaining
some physical changes comes under this category. This is also known as potentiometer or
A capacitor is used to store charge. Like resistors there is fixed as well as variable
capacitor also. But we mostly use fixed capacitor in robotics; variable capacitors are
mainly used in analog communication. There are capacitors with no polarity and polarity.
Ceramic and Mica capacitors available are of no-polarity, but electrolytic capacitors are of
polarity. There is a variation in their symbols also.
Fig 1.3 Different type of capacitors and their symbols.DIODES:
Diodes are two terminal devices which conduct electricity in one direction. Current flows
from anode to cathode when the diode is forward biased. In a normal forward biased
diode, energy is dissipated as heat in the junction, but in LED's energy dissipated as visible
light. In robotics we use normal diodes as freewheeling diodes or to make power supply.
LED's are of two types - IR led and normal LED. IR LED emits Infra Red radiations while
normal LED emits visible light. So first talk about a normal diode. Mostly we us 1N4001 or
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 8/74
www.roboticwares.com | www.learnics.in
LEAR NICSI M P A R T I N G S K I L L S
E M P O W E R I NG P E R F O R M A N C E
1N4007 as freewheeling diodes for motors or relays, used in H-bridge also.
Fig 1.4 Symbol of a diode.
ZENER DIODE:
A zener diode works in reverse biased region. In reverse biased it gives fixed output
voltage.
Fig 1.5 Symol for zener diode.
Transistor:
When we talk of transistor in robotics, we talk about the cut off and saturation region
only, while in your course you study transistor in active region. So here I am talking about
transistor as a switch. When we say transistor as a switch, we talk of cut off or not
because the typical cut off voltage is around .5V and the saturation voltage (vbe) is around
.8V. There
is regions between them. Let's start with transistor to glow an LED.
Fig 1.6 Transisor Circuit to glow an led
Connect this circuit and see. Connect multimeter at the base of the transistor and see thevoltage. In this circuit we can see that Ve=Vbe. For the transistor to be switched ON
Ve=.5V. Vary the potentiometer to make Vbe=.5V, you can see that LED starts glowing (but
it is less brightness). Vary the potentiometer to make Vbe to around .8V; you can see that
the LED brightness increases. This is because when Vbe=.5V it starts with cut off and
when Vbe=.7V in active and Vbe=.8V it become saturation region. Transistor is a current
controlled device. In active region Ic=hfe Ib and in saturation region Ic>hfeIb. That is why
the brightness of the LED changes.
7/30/2019 Robo Gyan.pdf
http://slidepdf.com/reader/full/robo-gyanpdf 9/74
www.roboticwares.com | www.learnics.in
LEAR NICSI M P A R T I N G S K I L L S
E M P O W E R I NG P E R F O R M A N C E
SESSION 2
OPAMP (IC741, LM324):
As the name implies it is an operational amplifier. It performs mathematical operations
like addition, subtraction, log, antilog etc. The main reason for OPAMPS used over
transistors is that transistor can only amplify AC while OPAMPS can amplify AC and DC.
You can get good amplifier gain in OPAMPS. The most commonly used OPAMPS are 741
and 324. IC741 is used in close loop configuration and LM324 in open loop configuration.
i.e LM324 mainly used as comparator while 741 for amplification, addition etc.
COMPARATOR (LM324):
Comparator is a digital IC. The difference between the analog IC and digital IC is that in
digital IC the output has only two states, while in analog IC it has more than two states.
IC7404, it has two states LOGIC HIGH and LOGIC LOW, IC555 is also digital IC. IC741 is an
analog IC because it has output voltage vary from -12v to 12V.
Comparator has only two states +vcc or –vcc. But LM324 we normally apply Vcc=5V and -
vcc=0. So output will have only 5V and 0V. But LM324 output LOGIC HIGH will be
aroundVcc-1.5V and LOGIC LOW around .2V. So if you use Vcc=5V then LOGIC HIGH=3.5V
and LOGIC LOW=0V. But LOGIC HIGH for a digital circuit is a voltage greater than 2.4V and
LOGIC LOW is less than .8V
Fig 2.1 Symbol of OPAMP
Above figure shows the general circuit diagram of a general comparator. If V1>V2 then
Vout=+Vcc and if V1<V2 then Vout=-Vcc. Suppose if V1=V2, then output will be +vcc or -
vcc
theoretically. But practically no such condition exist, because an operational amplifier has
coupling capacitors are used for good regulation. But there is no need for it in normal
case( I never used these capacitors). But if you are using 7805 in analog circuit you
should use capacitor, otherwise the noise in the output voltage will be high.The mainly
available 78xx IC's are 7805,7809,7812,7815,7824.
NEGATIVE VOLTAGE REGULATORS
Mostly available -ve voltage regulators are of 79xx family. You will use -ve voltage if you
use IC741. For IC741 +12v and -12v will be enough, even though in most circuits we use
+15v and -15v.
VARIABLE VOLTAGE REGULATORS
Most commonly variable voltage regulator is LM317 although other variable voltageregulators are available. The advantage of variable voltage regulator is that you can get a
variable voltage supply by just varying the resistance only.
Fig 3.12 Circuit diagram for using LM317.
RELAYS
You have seen controlling home equipments such as light, fans and equipments that run
on 230V using parallel port of computer or a microcontroller or any other digital IC’s. This
is possible through relays. Relay is an electromagnetic device which works on magneticfield. If you apply proper low voltage on one side the metal will get contacted.
SESSION 4
SENSORS
Temperature sensor: Commonly available temperature sensors are LM35,
DS1621,thermistor. Thermistor gives resistance proportional to the temperature. But
For a small distance measurement we can use a photo diode or photo transistor, but only
distance up to 5-7cm. You just connect the output to ADC or any comparator to
measurement. Suppose if we use one LM324 for distance measurement, you can measure
1cm, 2cm, 3cm and 4cm. You just connect a 330 ohm in series with IR LED. At the other
end use a photo diode in reverse region.
If you want a good distance then you should use 38Khz modulated IR with TSOP1738
detector. Use IC555 to generate 38 Khz square wave. You can get range about 1 Meter. If
you want to measure various distances then you should vary R2 of the IC555. Suppose if you want to measure distance from a fixed point, then you have to vary the frequency of
IC555. You can get range about 1 Meter. If you want to measure various distances then
you should vary Ra of the IC555. Suppose if you want to measure distance from a fixed
point, then you have to vary the frequency of IC555. You can do it fixing Rb>Ra and vary
Ra so that frequency will vary slightly from some 36Khz to 40Khz and find corresponding
reading. You can do it by using the following technique
As a beginner we mostly use DC motors, stepper motor and servo motor will come later.
As everybody knows DC motor has two leads. If we apply +ve to one lead and ground to
another motor will rotate in one direction, if we reverse the connection the motor will
rotate in opposite direction. If we keep both leads open or both leads ground it will not
rotate(but some inertia will be there). If we apply +ve voltage to both leads then braking
will occurs. You can test this, first without applying any voltage you rotate the shaft of the
motor, then apply ground on both lead and try to rotate the shaft. Both will almost remainsame, but if we apply both lead +ve voltage(+12V) and try to rotate the shaft, you can feel
the difference between the previous one. You have to apply more force to rotate the same
rotation in previous connection. So we take this condition as braking, because if we want
to stop the motor suddenly then this is the better way which is easily possible. There are
methods to brake motor fastly, like shorting two leads, applying negative polarity exists,
but we won't use this in robotics. We apply (1,1) condition to break the motor fastly(see
H-bridge section for more about it).
The main things about a DC motor are Voltage rating, current rating, Torque, Speed.
Remember Torque is inversely proportional to speed. So we had to get a good speed
motor to get good torque because we can operate the good speed motor in slow speed toget good torque. So maximum speed of the motor should be as high as possible.
Then the transistor continuously switch ON and OFF and the effective voltage across the
motor become voltage across motor= (Ton/Ttotal) *Vcc in PWM case Ttotal remains
same, only Ton will vary which makes a varying voltage across the motor. PWM can be
easily generated by any digital circuit (microcontroller used mostly). In PWM switchingspeed is comparatively slow because we continuously switch ON and OFF motor. A motor
is basically an induction; it takes some time to charge and discharge. So if the quality of
motor is good, then you can get a good PWM response. The inductance of the motor limits
the selection of T total. I used T total=10ms for the 2kgcms motor and it gave a good
response.
Generation of PWM:
PWM can be generated using IC555 or using microcontroller or computer parallel port.
Now you try to generate PWM using IC555, remember that T total should remain
Pronounced risk, and stands for Reduced Instruction Set Computer. RISC chips evolved
around the mid-1980 as a reaction at CISC chips. The philosophy behind it is that almost
no one uses complex assembly language instructions as used by CISC, and people mostlyuse compilers which never use complex instructions. Apple for instance uses RISC chips.
Therefore fewer, simpler and faster instructions would be better, than the large, complex
and slower CISC instructions. However, more instructions are needed to accomplish a
task.
An other advantage of RISC is that - in theory - because of the more simple instructions,
RISC chips require fewer transistors, which makes them easier to design and cheaper to
produce.
Finally, it's easier to write powerful optimized compilers, since fewer instructions exist.
RISC Vs CISC
There is still considerable controversy among experts about which architecture is better.
Some say that RISC is cheaper and faster and therefore the architecture of the future.
Others note that by making the hardware simpler, RISC puts a greater burden on the
software. Software needs to become more complex. Software developers need to write
more lines for the same tasks.
Therefore they argue that RISC is not the architecture of the future, since conventional
CISC chips are becoming faster and cheaper anyway.
RISC has now existed more than 10 years and hasn't been able to kick CISC out of the
market. If we forget about the embedded market and mainly look at the market for PC's,
workstations and servers I guess a least 75% of the processors are based on the CISC
architecture. Most of them the x86 standard (Intel, AMD, etc.), but even in the mainframeterritory CISC is dominant via the IBM/390 chip. Looks like CISC is here to stay …
Is RISC than really not better? The answer isn't quite that simple. RISC and CISC
architectures are becoming more and more alike. Many of today's RISC chips support just
as many instructions as yesterday's CISC chips. The PowerPC 601, for example, supports
more instructions than the Pentium. Yet the 601 is considered a RISC chip, while the
voltage on the AREF pin minus 1 LSB. Optionally, AVCC or an internal 2.56V reference voltage may
be connected to the AREF pin by writing to the REFSn bits in the ADMUX Register. The internal
voltage reference may thus be decoupled by an external capacitor at the AREF pin to improve
noise immunity.
The ADC is enabled by setting the ADC Enable bit, ADEN in ADCSRA. Voltage reference and input
channel selections will not go into effect until ADEN is set. The ADC does not consume power
when ADEN is cleared, so it is recommended to switch off the ADC before entering power saving
sleep modes. The ADC generates a 10-bit result which is presented in the ADC Data Registers,
ADCH and ADCL. By default, the result is presented right adjusted, but can optionally be presented
left adjusted by setting the ADLAR bit in ADMUX.
If the result is left adjusted and no more than 8-bit precision is required, it is sufficient to read
ADCH. Otherwise, ADCL must be read first, then ADCH, to ensure that the content of the Data
Registers belongs to the same conversion. Once ADCL is read, ADC access to Data Registers isblocked. This means that if ADCL has been read, and a conversion completes before ADCH is read,
neither register is updated and the result from the con version is lost. When ADCH is read, ADC
access to the ADCH and ADCL Registers is reenabled.
A single conversion is started by writing a logical one to the ADC Start Conversion bit, ADSC. This
bit stays high as long as the conversion is in progress and will be cleared by hardware when the
conversion is completed. If a different data channel is selected while a conversion is in progress,
the ADC will finish the current conversion before performing the channel change. Alternatively, a
conversion can be triggered automatically by various sources. Auto Triggering is enabled by
setting the ADC Auto Trigger Enable bit, ADATE in ADCSRA. The trigger source is selected bysetting the ADC Trigger Select bits, ADTS in SFIOR (see
description of the ADTS bits for a list of the trigger sources). When a positive edge occurs on the
selected trigger signal, the ADC prescaler is reset and a conversion is started. This provides a
method of starting conversions at fixed intervals. If the trigger signal still is set when the
conversion completes, a new conversion will not be started. If another positive edge occurs on the
trigger signal during conversion, the edge will be ignored.
By default, the successive approximation circuitry requires an input clock frequency between 50
kHz and 200 kHz to get maximum resolution. If a lower resolution than 10 bits is needed, the input
clock frequency to the ADC can be higher than 200 kHz to get a higher sample rate.
The ADC module contains a prescaler, which generates an acceptable ADC clock frequency from
any CPU frequency above 100 kHz. The prescaling is set by the ADPS bits in ADCSRA. The
prescaler starts counting from the moment the ADC is switched on by setting the ADEN bit inADCSRA. The prescaler keeps running for as long as the ADEN bit is set, and is continuously reset
when ADEN is low. When initiating a single ended conversion by setting the ADSC bit in ADCSRA,
the conversion starts at the following rising edge of the ADC clock cycle.
The AVR atmega16 supports pulse width modulation (PWM) on all three timer counters. Initiallywe will use the 8 bit timer 0 to implement this function. The AVR supports normal PWM or so
called fast PWM. Normal PWM involves starting a counter which counts up to it’s maximum value
and then reverses, counts back to zero and then repeats. In order to create output pulses whose
mark:space ratio changes the output compare register (Ref ) is loaded with a value so that when the
after a reset to indicate that the transmitter is ready.
FE: Frame Error:
This bit is set if the next character in the receive buffer had a Frame Error when received.
i.e., when the first stop bit of the next character in the receive buffer is zero. This bit isvalid until the receive buffer (UDR) is read. The FE bit is zero when the stop bit of received
data is one. Always set this bit to zero when writing to UCSRA.
DOR: Data OverRun:
This bit is set if a Data OverRun condition is detected. A Data OverRun occurs when the
receive buffer is full (two characters), it is a new character waiting in the receive Shift
Register, and a new start bit is detected. This bit is valid until the receive buffer (UDR) is
read. Always set this bit to zero when writing to UCSRA.
PE: Parity Error:
This bit is set if the next character in the receive buffer had a Parity Error when received
and the parity checking was enabled at that point (UPM1 = 1). This bit is valid until the
receive buffer (UDR) is read. Always set this bit to zero when writing to UCSRA.
U2X: Double the USART Transmission Speed:
This bit only has effect for the asynchronous operation. Write this bit to zero when using
synchronous operation.
Writing this bit to one will reduce the divisor of the baud rate divider from 16 to 8
effectively doubling the transfer rate for asynchronous communication.
MPCM: Multi-processor Communication Mode:
This bit enables the Multi-processor Communication mode. When the MPCM bit is written
to one, all the incoming frames received by the USART receiver that do not contain
address information will be ignored.
UCSRB: USART Control And Status Register B
RXCIE: Receive Complete Interrupt Enable - When this bit is written one the the RXC
based flag interrupt is enabled.
TXCIE: Transmit Complete Interrupt Enable - When this bit is written one the theinterrupt based on TXC flag is enabled.
• Bit 0 – UCPOL: Clock PolarityThis bit is used for Synchronous mode only. Write this bit to zero when Asynchronous
mode is used. The UCPOL bit sets the relationship between data output change and data
input sample, and the synchronous clock (XCK).
USART Baud Rate Registers – UBRRL and UBRRH
System Operation and Programming:
The basic activities of the USART system consist of initialization, transmission, andreception. These activities are summarized in Figure given below. Both the transmitter
and receiver must be initialized
with the same communication parameters for proper data transmission. The transmission
and reception activities are similar except for the direction of data flow. In transmission
,we monitor for
the UDRE flag to set, indicating the data register is empty. We then load the data for
transmission into the UDR register. For reception, we monitor for the RXC bit to set,
indicating there are unread data in the UDR register. We then retrieve the data from the
The basic line follower is one in which consist of two motors. For taking turn we stop one motorand run the other motor. This makes the robot to take a turn. You should keep the sensors with
LED to sense dark and white. The sensor and LED should be covered properly to produce sharp
sensing.
Use LED+LDR combination or IR LED + Photo diode (photo transistor) or 38Khz modulated
IR+TSOP1738 to sense white and black strip.
SOME IMPORTANT THINGS ABOUT LINE FOLLOWERS WITH TWO SENSORS
1. The above circuits use switching OFF and ON the motor. This is not a good method because
motor is basically an inductor. The time taken for the motor to attain full speed from OFFcondition is too much (ie in milliseconds depends on quality of motor). Suppose if we use two
sensor for each side and when first sensor goes into black then motor speed will be 50% then the
time required for a motor to charge to full speed=time required to charge to 100% speed -time
required to charge to 50%. But in the previous robots it is the time required to charge up to 100%
speed. But this time is always in 10ms or more for charging up to 100% speed. I don't remember
the charging and discharging equation of inductor. Do some calculation and see the difference. So
the difference is above 10ms. This is a good time we are wasting.
2. Here we are stopping motor completely for a simple turn, so the time lost will be high. Think of
a train going at 100kmph, which had to stop at a station for a 2sec. The time lost in its run will be
around 7-
10sec, if it had stopped at a station compared to normal running of train. The same case with a
robot motor stopped completely. So we should avoid this.
3. There is some switching time with power transistor, relays. The switching time of power
transistor is around .1ms while that of relay is about 100ms (not accurate, but greater than 10ms).
So the time will be lost in the switching time of these components. So it is better not to use relays
your robot looses the way in crossings and cuttings and no way exist to bring back the robot back
to the track. If you want to do this then you had to add extra circuits and complexity of circuit
increase with the path. But if you use a microcontroller then this problem will be solved and the
requirement of processing circuits also avoided.
A microcontroller circuit can trace back the path which it followed. It can avoid the situation of
external light. If we use ADC for the LDR readings then the external light problem will be avoided.
External light affect the readings almost equally in all sensors, so it equally in ADC reading. We can
subtract the reading to avoid this problem. Suppose if we use 4 sensors on each side. Then from
the following circuit diagram you can use PWM to control the H-bridge by connecting PWM output
to enable of H-bridge. Then the PWM can be controlled by the following way. If ADC1 readings
increase then PWM will be reduced from 100% to 90%.Assuming that ADC1 reading is the front
LDR (ldr1). Suppose if ldr1 crosses line then we can detect it and we can reduce pwm to 80%. But
in analog case this was not possible. We can determine the instant position of the ldr's and takeappropriate decision while that is not possible in analog circuits. This makes the robot to get a
proper movement.
Suppose if we use microcontroller just like a parallel port and the sensor readings are inputted to
the microcontroller and LM317 circuit is connected to another port. You can see that there are 2^4
combinations of voltage are possible with that circuit, but with the analog circuit we are
able to use only about 4 voltages. We can use 16 different voltages using a microcontroller. This 16
different voltages are applied to the motor using the ADC readings of the sensor(1-4). Thus we can
get voltages from 1.25 to 12V with 1V difference and better control is possible and we can
determine the position of sensors, so that we can get a robot with good speed by adjusting voltagewith better precision.
Robotics in INDIA is still at its infancy. But we are pretty confident that some of us can certainly play avital role in propelling INDIA to come out of this situation and become a technology solutions giant in thetime to come.
We believe that our efforts if based on the following three aspects will deliver the maximum results.
1. Sharing of knowledge:
The gap between science fiction and science fact is closing. With recent advances in robotic softwareand computer hardware, new levels of robotic intelligence are now available. For education, roboticsoffers an exciting, enjoyable means for students to learn and to apply useful transferable skills. Roboticsprovides a multidisciplinary learning tool for fundamentals, such as mathematics, physics, and science
Our academicians should understand this fact and act accordingly to include robotic in syllabus rightfrom secondary schools to higher studies.
2. A competitive environment for growth:
We need more and more Robotic clubs, robotic contests, seminars and workshops to be organized andconducted to cultivate a competitive environment.
3. Sharing of Resources:
Knowledge base and raw materials are equally important for the development of a technology like
robotics. One should practice and understand this science.
“Excellent, it met my expectations.” Suhas Rohit Pal, NIT Surathkal
“ They gave us the idea and how to implement them in day to day life.”
Debesh kumar, NIT Rourkela
“The workshop was the best I have ever witnessed. I am not so good at electronic circuits, but the manner in which everything was explained could be understood even by a beginner.”
Akash Kumar, NIT Allahabad
“It was very knowledgeable and helpful in terms of i ll d l d h l i ”