Kapil Project

8/3/2019 Kapil Project

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OBSTACLE DETECTOR AND AVOIDER WITH DTMF

CONTROL

A PROJECT

SUBMITTED IN FULFILMENT OF REQUIREMENTS FOR THE

INDUSTRIAL TRAINING

BACHELOR OF TECHNOLOGY

(ELECTRONICS AND COMMUNICATION)

BY

KAPIL RANA (0951312808)

UNDER THE GUIDANCE OF MR. PRAVEEN

TO

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

GURU PREMSUKH MEMORIAL COLLEGE OF ENGINEERING

BUDHPUR, DELHI-110036

AUGUST 2011


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ACKNOWLEDGEMENT

The success of this project can be attributed to a number of people. Firstly

we would like to thank our Mr. PRAVEEN(PROJECT LEADER) for his

support and valuable technical advice during the course of the project.

I am thankful to our LAB supervisor who helped us a lot in the

implementation phase of our project.

A warm thanks goes to our family and friends who had provided support

during the challenges, and understanding of our many hours spending duringthe project.

KAPIL RANA (0951312808)


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CERTIFICATE

It is certify that the project has been carried out by PANKAJ

CHOUDHARY a student of 4th semester under our guidance. The report

covers all the aspects of the work done ( including H/W & S/W, Coding etc.)

The project report is complete in all respects and I have understood the

entire software. It shall be possible for the next batch of the students to take

up further work after consulting this report.

(Signatures)/ Date

Mr. B.P ARUN

(DIRECTOR)


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CONTENTS

1) INTRODUCTION

2) OBJECTIVE

3) METHODOLOGY

4) DETAILS - The Differential Steering System

- Mechanical and Structural Actuators

- DC Motor

- H- Bridge Motor Control

- Design and Implementation- Coding

5) LIMITATIONS

6) APPLICATIONS

7) RESULTS AND CONCLUSIONS

8) BIBLIOGRAPHY


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INTRODUCTION

An Autonomous obstacle avoider is a robot which while its journey, avoids the

obstacles itself. Before striking any obstacle, it changes its direction. The basic

aim behind making the obstacle avoider is to apply the principle in the new

generation cars which moves in autopilot mode. New generation of automobiles

will use the technology for obstacle avoidance in a different manner, for instance

the sensor may be used to slow down the vehicle instead of changing direction of

motion or control the direction wirily or wirelessly (i.e. using DTMF). Many

industrial applications are there undone. This project also aims at giving a newdirection to autopilot modes of airplanes and helipads. For further clarifications of

project we need to understand some basic components and the basic principle as

well.

The word "robot" originates from the Czech word for forced labor or serf. Robots

are electronic devices intended to perform a desired function. Many refer to them

as "machines", however, a drill press is a machine, yet it requires an operator to

perform its function, where robots can be programmed to do it themselves. Robots

have the potential to change our economy, our health, our standard of living, our

knowledge and the world in which we live. As the technology progresses, we are

finding new ways to use robots. Each new use brings new hope and possibilities,

but also potential dangers and risks. Robotics is not only a science, but it is also

an art. The bots we build reflect the ideas and personalities we portray. There are

many different versions of robots that can be made. From turtle bots to vehicles

like the Mars rovers to rovers like R2-D2. From walkers that have anywhere from

1 to 10 legs to robotic arms to androids. Whatever you can dream, you can create.


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The level of expertise you want your robot to have and how much learning and

research you want to do is up to you. We have seen how ants always travel in a

line, following an invisible route in search of food, or back home. How on roads

we follow lanes to avoid accidents and traffic jams. Ever thought about a robot

which follows line? A perfect or near perfect mimic of mother-nature?

In the age of ubiquitous systems it is important to be able to control robots

everywhere. Although many methods to remotely control robots have been

devised, the methods have the problems such as the need for special devices or

software to control the robots. This paper suggests a method for robotic control

using the DTMF tone generated when the user pushes mobile phone keypad

buttons or when connected with a remote mobile robot.

Conventionally, Wireless-controlled robots use rf circuits, which have the

drawbacks of limited working range, limited frequency range and the limited

control. Use of a mobile phone for robotic control can overcome these limitations.

It provides the advantage of robust control, working range as large as the

coverage area of the service provider, no interference with other controllers andup to twelve controlles.

Although the appearance and the capabilities of robots vary vastly, all robots

share the feature of a mechanical, movable structure under some form of control.

The Control of robot involves three distinct phases: perception, processing and

action. Generally, the preceptors are sensors mounted on the robot, processing is

done by the on-board microcontroller or processor, and the task is performed

using motors or with some other actuators.


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OBJECTIVE

To build a car that will detect the object and hence avoid it follow the

instructions viz moving straight in backward, forward, rightward or leftward

directions or to stop, made by the controller via a Bluetooth enabled mobile

phone.


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DETAILS

1) THE DIFFERENTIAL STEERING SYSTEM

(LOCOMOTION)

The differential steering system is familiar from ordinary life because it is the

arrangement used in a wheelchair. Two wheels mounted on a single axis are

independently powered and controlled, thus providing both drive and steering.

Additional passive wheels (usually casters) are provided for support. Most of us

have an intuitive grasp of the basic behavior of a differential steering system. If

both drive wheels turn in tandem, the robot moves in a straight line. If one wheel

turns faster than the other, the robot follows a curved path. If the wheels turn at

equal speed, but in opposite directions, the robot pivots.For motion with turns, we

need at least three wheels

2 fixed, motor driven wheels

1 free motion caster wheel

1(a) Forward Motion


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1(b) backward motion

1(c) Left turn


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1(d) Right turn

Figure 1: The Differential steering model


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2) MECHANICAL AND STRUCTURAL ACTUATORS-

MECHANICAL HARDWARE USED-

1. Caster - 1

2. Screw for Caster - 4

3. Hexagonal Nut for Caster - 4

4. Wheels - 2

STRUCTURAL ACTUATORS USED-

D C Geared motors (12 volts, 150 rpm) - 2


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CASTER

The picture of caster wheel is shown below..

A caster (or castor) is an un-driven, single, double, or compound wheel mounted

on an object to make movement easier. Found on shopping carts , office chairs


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and material handling equipment, casters may be fixed to roll in one direction, or

mounted on a pivot, such that the wheel will automatically swivel, aligning itself

to the direction in which it is moving. Swivelling casters are sometimes

themselves attached to handles, so users can turn the caster into the desired

direction.

Casters are used in many industrial applications. Heavy duty and high capacity

casters are used on platform trucks, carts, assemblies, and tow lines in plants.

DESIGNS AND APPLICATIONS

A caster is defined as a wheel mounted to a fork, but has an additional offset

steering joint. The steering joint allows the wheel to rotate freely in 360. This

allows for easy turning of objects without changing the direction of the chassis

that the casters are mounted to. The angle and distance of the wheel axles and

steering joint can be adjusted for different types of caster performance.

Casters are typically used on carts and furniture and are mounted underneath these

platforms. Casters are advantageous for moving vehicles or platforms in both

straight and turning motions. Casters are commonly used on supermarket

shopping cart.

During straightforward motion, the swivel caster will tend to rotate parallel to the

direction of travel. This can be seen on a shopping cart when the caster rotates

backwards during forward motion down an aisle. A benefit of this caster rotation

is the vehicle naturally tends to travel in a straight direction. Precise steering is

not required because the casters tend to maintain straight motion.

This is also true during turning. The caster rotates again parallel to the turning

radius and provides a smooth turn. The can be seen on a shopping cart as the


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wheels rotate differently depending on how tight a turn is made. Because of these

two qualities, casters are often used on dollies, office chairs, and wheelchairs.

Casters can be designed in many different sizes and materials depending on

application. Generally, they are made from rubber, plastic, nylon, aluminum, or

stainless steel. Generally, casters operate well on smooth and flat surfaces.

WHEELS:

The wheels connected to geared motors are shown below.

The basic purpose of wheels connected to geared motors is to convert the

rotational torque of shaft (which moves due to the rotation of gears), to linear

motion for the car. Positioning and alignment of wheels is necessary for the

smooth motion of car.


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Also, they are to be fixed on the shaft in such a manner that they rotate only on

the movement of shaft and unlike caster are not free to rotate as such.

Wheels are the most important part for any car for its linear motion and so

knowledge about their proper use is necessary for any person related to the field.

GEAR MECHANISM IN MOTORS-

A gear is a component within a transmission device that transmits rotational

torque by applying a force to the teeth of another gear or device. A gear is

different from a pulley in that a gear is a round wheel that has linkages ("teeth" or

"cogs") that mesh with other gear teeth, allowing force to be fully transferred

without slippage. Depending on their construction and arrangement, geared

devices can transmit forces at different speeds, torques, or in a different direction,

from the power source. The most common situation is for a gear to mesh with

another gear, but a gear can mesh with any device having compatible teeth, such

as linear moving racks.

The gear's most important feature is that gears of unequal sizes (diameters) can be

combined to produce a mechanical advantage, so that the rotational speed and

torque of the second gear are different from those of the first. In the context of a

particular machine, the term "gear" also refers to one particular arrangement of

gears among other arrangements (such as "first gear"). Such arrangements are

often given as a ratio, using the number of teeth or gear diameter as units.


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(3)D.C. MOTORS

DC motors are widely used, inexpensive, small and powerful for their size.

Reduction gearboxes are often required to reduce the speed and increase the

torque output of the motor. Unfortunately more sophisticated control algorithms

are required to achieve accurate control over the axial rotation of these motors.

Although recent developments in stepper motor technologies have come a long

way, the benefits offered by smooth control and high levels of acceleration with

DC motors far outweigh any disadvantages.

Several characteristics are important when selecting DC motors and these can be

split into two specific categories. The first category is associated with the input

ratings of the motor and specifies its electrical requirements, like operating

voltage and current. The second category is related to the motor's output

characteristics and specifies the physical limitations of the motor in terms of

speed, torque and power.

Example specifications of the motors used are given below:

CHARACTERISTICS VALUE

Operating voltage - 6V to 12V

Operating current - 2A MAX.

Speed - 2400 rpm

Torque - 30 gm-cm


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As noticed, the torque provided can hardly move 30gm of weight around with

wheel diameter of about 2cm. This is a fairly a huge drawback as the robot could

easily weigh about a kg. This is accomplished by gears which reduce the speed

(2400 rpm is highly impractical) and effectively increase the torque. If the speed

is reduced by using a gear system by a factor of then the torque is increased by

the same factor. For example, if the speed is reduced from 2400 rpm, to 30 rpm,

then the torque is increased by a factor of (2400/30 = 80) in other words the

torque becomes 30x80=2400 gm-cm or 2.4 kg-cm which is more than sufficient.

(4) H-BRIDGE MOTOR CONTROL

DC motors are generally bi-directional motors. That is, their direction of rotation

can be changed by just reversing the polarity. But once the motors are fixed,

control becomes tricky. This is done using the H-Bridge. The figure is given

below.


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Figure 4: The H-Bridge Using Relays.

The Explanation is simple, If A & D are turned on, then the current flows in the

direction shown in the figure below.

Figure 4.1: Clockwise rotation


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If B & C are turned on, then the motor rotates in counter clockwise direction.

Figure 4.2: Counter-Clockwise rotation

If you turn on the two upper circuits, the motor resists turning, so you effectively

have a breaking mechanism. The same is true if you turn on both of the lower

circuits. This is because the motor is a generator and when it turns it generates a

voltage. If the terminals of the motor are connected (shorted), then the voltage

generated counteracts the motors freedom to turn. It is as if you are applying a

similar but opposite voltage to the one generated by the motor being turned. In

other words, it acts like a brake. Any other state like A & C = ON or B & D = ON

will cause a direct path to ground causing a very high current to pass through the

relays thus causing a burnt fuse (if it exists).


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The following figure shows an H-Bridge using only transistors. The same theory

applies

.

Figure 4.3: H-Bridge using transistors.

Usually, the above circuitry can be used only for direction control. The Existing

H-Bridge is further modified to include another transistor, now making speed

control possible too. This is shown in the figure below.


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Figure 4.4: Enhanced H-Bridge

The same direction rules apply, but now the motor will behave as per the direction

control only when a 1 is given to the EN input. Speed control is usually done bygiving a PWM signal, and the duty cycle is varied to vary the speed of the motor.

Usually protection diodes are also incorporated across the transistors to catch the

back voltage that is generated by the motor's coil when the power is switched on

and off. This fly-back voltage can be many times higher than the supply voltage!

If diodes are not used, the transistors have a good chance to get burnt.


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(5)DESIGN & IMPLEMENTATION

The block diagram of circuit is given below. It consists of mainly four parts:-

1. Microcontroller Unit

2. DTMF Unit

3. H-Bridge Circuit

4. IR Sensor

Figure 5: BLOCK DIAGRAM

Microcontroller

Unit

Module

DTMF

Unit

H-Bridge

Circuit

IRSensor


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5.1 MICRO-

CONTROLLER UNIT MODULE

2

.

8

.

5

.

6.


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1. Atmel AT89S52 Microcontroller chip - 1

2. Connection for Adapter - 1

3. Pins according to AT89S52 configuration - 40

4. Resistor(1 K) - 1

5. Diodes (1N4007) - 4

6. Electrolytic Capacitor(1000 F) - 1

7. Voltage Regulator 7805(5 V) - 1

8. Capacitor(10 F) - 2

7

.

4

.

9

.

3

.

1

0

1.

1

.


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9. Crystal Oscillator(11.0592Mhz) - 1

10. 10 k sip - 1

5.1.1 AT89S52 MICROCONTROLLER:

(a)DESCRIPTION:

The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller

with 8K bytes of in-system programmable Flash memory. The device is

manufactured using Atmels high-density non-volatile memory technology and is

compatible with the industry-standard 80C51 instruction set and pin-out. The on-

chip Flash allows the program memory to be reprogrammed in-system or by a

conventional non-volatile memory programmer. By combining a versatile 8-bit

CPU with in-system programmable Flash on a monolithic chip, the Atmel

AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-

effective solution to many embedded control applications. The AT89S52 provides

the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O

lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector

two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and

clock circuitry. In addition, the AT89S52 is designed with static logic for

operation down to zero frequency and supports two software selectable power

saving modes. The Idle Mode stops the CPU while allowing the RAM,

timer/counters, serial port, and interrupt system to continue functioning. The

Power-down mode saves the RAM con-tents but freezes the oscillator, disabling

all other chip functions until the next interrupt or hardware reset.


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(b)PIN CONFIGURATION:

123456

78910111213141516

17181920

403938373635

34333231302928272625

24232221

P1.0P1.1P1.2P1.3P1.4P1.5

P1.6P1.7RST

(RXD)P3.0(TXD)P3.1

(T0)P3.4(T1)P3.5

XTAL2XTAL1

GND

(INT0)P3.2

(INT1)P3.3

(RD)P3.7

(WR)P3.6

VccP0.0(AD0)P0.1(AD1)

P0.2(AD2)P0.3(AD3)P0.4(AD4)

P0.5(AD5)P0.6(AD6)P0.7(AD7)

EA/VPPALE/PROG

PSENP2.7(A15)

P2.6(A14)P2.5(A13)P2.4(A12)

P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)

8051

(8031)

ATMEL

89S52


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(d)PIN DESCRIPTION

1)VCC-Supply voltage.2) GND- Ground.

3) Port 0 - Port 0 is an 8-bit open drain bidirectional I/O port. As an output port,

each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins

can be used as high-impedance inputs. Port 0 can also be configured to be the

multiplexed low-order address/data bus during accesses to external program and

data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code

bytes during Flash programming and outputs the code bytes during program

verification. External pull-ups are required during program verification.

4) Port 1 - Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port

1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1

pins, they are pulled high by the internal pull-ups and can be used as inputs. As

inputs, Port 1 pins that are externally being pulled low will source current (IIL)

because of the internal pull-ups. In addition, P1.0 and P1.1 can be configured to

be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2

trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 1

also receives the low-order address bytes during Flash programming and

verification.

5) Port 2 - Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port

2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2

pins, they are pulled high by the internal pull-ups and can be used as inputs. As

inputs, Port 2 pins that are externally being pulled low will source current (IIL)

because of the internal pull-ups. Port 2 emits the high-order address byte during

fetches from external program memory and during accesses to external data


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memory that uses 16-bit addresses (MOVX @ DPTR). In this application, Port 2

uses strong internal pull-ups when emitting 1s. During accesses to external data

memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the

P2 Special Function Register. Port 2 also receives the high-order address bits and

some control signals during Flash programming and verification.

6) Port 3 - This does not need any pull-up resistors since it already has

Pull-up resistors internally. Although port 3 is configured as an output port upon

reset, this is not the way it is most commonly used.

Port 3 has the additional function of providing signals.This can be seen from thenext table.

PORT 3 Table of functions

7) RST - Reset input. A high on this pin for two machine cycles while the

oscillator is running resets the device. This pin drives high for 98 oscillator


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periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address

8EH) can be used to disable this feature. In the default state of bit DISRTO, the

RESET HIGH out feature is enabled.

8) ALE/PROG - Address Latch Enable (ALE) is an output pulse for latching the

low byte of the address during accesses to external memory. This pin is also the

program pulse input (PROG) during Flash programming. In normal operation,

ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used

for external timing or clocking purposes. Note, however, that one ALE pulse is

skipped during each access to external data memory. If desired, ALE operation

can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is

active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly

pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in

external execution mode.

9) PSEN - Program Store Enable (PSEN) is the read strobe to external program

memory. When the AT89S52 is executing code from external program memory,

PSEN is activated twice each machine cycle, except that two PSEN activations

are skipped during each access to external data memory.

10) EA/VPP - External Access Enable. EA must be strapped to GND in order to

enable the device to fetch code from external program memory locations starting

at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will

be internally latched on reset. EA should be strapped to VCC for internal program

executions. This pin also receives the 12-volt programming enable voltage (VPP)

during Flash programming.

11) XTAL1 - Input to the inverting oscillator amplifier and input to the internal

clock operating circuit.

12) XTAL2 - Output from the inverting oscillator amplifier.


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5.1.2 FUNCTION OF OTHER PARTS:

1. CONSTANT VOLTAGE SUPPLY (POWER SUPPLY UNIT)7805

KA7805/KA7805A (3-Terminal 1A Positive Voltage Regulator)

As clear from its name, the function of voltage regulator 7805 is , basically to

regulate the voltage. By this, we mean to ensure a constant supply at a level of 5

volts compared to ground. This is essential as the Micro-controller works on

voltage levels 5V and ground.

Figure 5.1: A typical 7805 voltage regulator IC

Features

Output Current up to 1A.

Output Voltage of 5V.

Thermal Overload Protection.

Short Circuit Protection.

Output Transistor Safe Operating Area Protection.

Input voltage(Vi)

for Vo= 5 to 18 V - 35V

for Vo= 24 V - 40V


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Operating Temperature up to ~ +125 degree Celcius

Description

The KA7805/KA7805A series of three-terminal positive regulator are available in

the TO-220/D-PAK package and with several fixed output voltages, making them

useful in a wide range of applications. Each type employs internal current

limiting, thermal shut down and safe operating area protection, making it

essentially indestructible. If adequate heat sinking is provided, they can deliver

over 1A output current. Although designed primarily as fixed voltage regulators,

these devices can be used with external components to obtain adjustable voltages

and currents.

Figure 5.2: Internal Block diagram of a 7805 voltage regulator IC

2. Capacitors (10 F)

The capacitor (10 F) connected at the left side is for reset of the circuit and the

one at the right side is to smoothen the output load.


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3. Electrolytic Capacitors (1000 F) and Diodes

These form the bridge rectifier circuit for the micro-controller unit module. This

circuit is responsible for fact that the car will run on both ac and dc. In case of dc,

the rectifier circuit will not come into account but in case of ac, the circuit will

convert the ac into dc. This is essential as the micro-controller runs on dc.

4.10 k sip

This 10 k sip is a register network. Its function is to give active-low on Port P0.

So, what happens is that all the 8 pins of P0 have 5 volts on them and so are

disabled. Only when they are made 0 do the pins become enabled.

5. Crystal (11.0592 MHz)

This is a Quartz crystal. Its function is to provide for the pins XTAL1 and

XTAL2. The crystal provides for the internal operating clock and also is the input

to the inverting oscillating amplifiers in the internal structure of the AT89S52

micro-controller.


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5.2 H-BRIDGE CIRCUIT

5.2.1 H-BRIDGE (Transistor Circuit)

As can be seen from the numbers listed on the diagram, the components are:

1. Opto-Couplers (PC 817) - 4

2. Resistors (1 K ) - 16

3. Transistors (BC 557) - 8

4. Transistors (NPN , TIP 112) - 4

5. Transistors (PNP , TIP 127) - 4

6. Connections with Motors - 2

7. Diodes (1N4007, 1 Ampere) - 8

3

.

5

4

1

5

2

6

7


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FUNCTIONS OF INDIVIDUAL PARTS-

1. PC 817 OPTO-COUPLER-

Its function is isolation of the voltage levels of the DC motor and the micro-

controller. The micro-controller works on 5 volts but the DC motor works on 12

volts. As these two are different voltage levels, there is a need of isolation and the

four-legged PC 817 device is used here.

2. BC 557 TRANSISTORS-

The function of BC 557 transistors is to perform the EX-OR operation in the

module. This leads to the fact that the DC motor will work either on 10 or 01

logic levels coming from the micro-controller to the input signal position in the

H-Bridge module. So, the DC motor is saved from damage. This is because if 00

or 11 are supplied to the motors, they will be shorted as explained i the theory

about H-Bridges.


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3. TIP 112 and TIP 127-There are 8 transistors connected in the H-Bridge

module other than BC 557. Of them, 4 are TIP 112 and 4 are TIP 127. The former

are NPN transistors and the latter are PNP transistors. They make up in total 4

Darlington Pairs.

A Darlington Pair is a circuit consisting of transistors which is responsible for

current amplification. Eventually, this current is supplied to the DC motors to

make them run.

4. Diodes-

There are 8 diodes used here. Their number is 1N4007 and of 1 ampere currentrating. They are used to prevent back e.m.f. This back e.m.f can cause damage to

the DC motor.

5.2.2 H-BRIDGE IC (L298)

The L298 is a Dual Full Bridge driver that can drive up to 2Amps per bridge with

supply voltage up to 46V. It can drive DC motors, stepper motors, relays,

solenoids, etc. The device is TTL compatible. Two H bridges of L298 can be

connected in parallel to increase its current capacity to 4 Amp. It can be used in

conjunction with stepper motor controller for driving one/two phase stepper

motor. The device is available in 15- lead Multi watt package.


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PIN CONFIGURATION

APPLICATIONS

DC and stepper motor drives.

Position and velocity servomechanisms.

Computer printers and plotters.

5.3 DTMF UNIT MODULE


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The parts in this module

are

1. IC MT8870 - 1

2. Red LEDs - 5

3. White LEDS - 1

4. Resistors

1 kohm - 7

3

.

4

.

1

.

5

.

2

.

6

.

7.


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10 kohm - 1

22 kohm - 3

100 kohm - 1

330 kohm - 1

5. Crystal (3.5791) - 1

6. Capacitors (22pF) - 4

7. Connector - 1

5.3.2 DTMF SIGNALLING


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Dual-tone multi-frequency signaling (DTMF) is used for telecommunication

signaling over analog telephone lines in the voice-frequency band between

telephone handsets and other communications devices and the switching center.

The version of DTMF that is used in push-button telephones for tone dialing is

known as Touch-Tone, first used by AT&T in commerce as a registered

trademark, and is standardized by ITU-T Recommendation Q.23. It is also known

in the UK as MF4.

It is a tone consisting of two frequencies superimposed. Individual frequencies

are chosen such that it is easy to design filters and easy to transmit the tones

through a telephone line having bandwidth of approximately 3.5 kHz. DTMF was

not intended to be used for data transfer, it was meant to be used for sending the

control signals along the telephone line. With standard decoders it is possible to

send 10 beeps per second i.e., five bits per second. DTMF standard specifies

50ms tones and 600ms duration between two successive tones. The multiple tones

are the reason for calling the system multi frequency.

Note that the last column is not commonly seen in the telephones that we used,

but telephone exchanges use them quite often. Nowadays, DTMF is used for
http://en.wikipedia.org/wiki/Signalling_(telecommunications)http://en.wikipedia.org/wiki/Signalling_(telecommunications)http://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Automatic_telephone_exchangehttp://en.wikipedia.org/wiki/Push-button_telephonehttp://en.wikipedia.org/wiki/Push-button_telephonehttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/Q.23http://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Automatic_telephone_exchangehttp://en.wikipedia.org/wiki/Push-button_telephonehttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/Q.23http://en.wikipedia.org/wiki/Signalling_(telecommunications)http://en.wikipedia.org/wiki/Signalling_(telecommunications)


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dialing the numbers in telephones, configuring telephone exchanges etc. A CB

transceiver of 2.7 MHz is normally used to send floating codes. DTMF was

designed to be able to send the codes using microphone. Each beep (or digit you

dial on the telephone) is composed of two concurrent frequencies, which are

superimposed on amplitude. The higher of the two frequencies is normally aloud

by 4dB, and this shift is termed as twist. If the twist is equal to 4dB, the higher

frequency is loud by 4dB. If the lower frequency is loud, then the twist is said to

be negative.

GeneratingDTMF

DTMF signals can be generated through dedicated ICs or by using RC networks

connected to a microprocessor. MT8880 is an example of a dedicated IC. But

getting the latter method work is a bit difficult if high accuracy is needed. The

crystal frequency needs to be sacrificed for a non standard cycle length. Hence

this method is used for simple applications. Most often, a PIC micro could be

used for the above purpose.

DecodingDTMFDetecting DTMF with satisfactory precision is a hard thing. Often, a dedicated IC

such as MT8870 is used for this purpose. It uses two 6th order band-pass filters

using switched capacitor filters and it suppresses any harmonics. Hence they can

produce pretty good sine waves from distorted input. Hence it is preferred. Again

microprocessors can also be used, but their application is limited.

5.3.3FUNCTIONING OF IC MT8870


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FUNCTIONAL DESCRIPTION

The CAMD MT8870/70C DTMF Integrated Receiver provides the design

engineer with not only low power consumption, but high performance in a small

18-pin DIP, SOIC, or 20-pin PLCC package configuration. The CM8870/70Cs

internal architecture consists of a band-split filter section which separates the high

and low tones of the received pair, followed by a digital decode (counting) section

which verifies both the frequency and duration of the received tones before

passing the resultant 4-bit code to the output bus.

DECODER SECTION

The MT8870/70C decoder uses a digital counting technique to determine the

frequencies of the limited tones and to verify that these tones correspond to

standard DTMF frequencies. A complex averaging algorithm is used to protect

against tone simulation by extraneous signals (such as voice) while providing

tolerance to small frequency variations. The averaging algorithm has been

developed to ensure an optimum combination of immunity to talk-off and

tolerance to the presence of interfering signals (third tones) and noise. When the

detector recognizes the simultaneous presence of two valid tones (known as

signal condition), it raises the Early Steering flag (ESt). Any subsequent loss

of signal condition will cause ESt to fall.

5.4BLUETOOTH WIRELESS HEADSETS


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A headset is a headphone combined with a microphone. Headsets provide the

equivalent functionality of a telephone handset with hands-free operation.

Headsets typically have only one speaker like a telephone, but also come with

speakers for both ears. They have many uses including in call centers and other

telephone-intensive jobs and for personal use at the computer to facilitate

comfortable simultaneous conversation and typing.

TYPES OF HEADSET

Headsets can come in single-earpiece and double-earpiece designs. Single-

earpiece headsets are known as monaural headsets. However, double-earpiece

headsets come in both stereo type (two channels of audio signal, one for each

earpiece) orbinauraltype (the same audio channel for both ear-pieces).

Professional users may choose to wear monaural headsets because they free up

one ear, so they can be more conscious of their work surroundings. Telephone

headsets come in only monaural type for double-earpiece designs because

telephone offers only single-channel input and output, so all double-earpiece

telephone headsets are binaural.

However, for computer or other audio applications, where the sources offer two-

channel output, stereo headsets are the norm. Telephone headsets generally use

150-ohm loudspeakers with a narrower frequency range, so sound outside the

voice band is less audible to reduce background noise. Stereo computer headsets,

on the other hand, use 32-ohm loudspeakers which have a much broader

frequency range, and is more suitable of music listening.
http://en.wikipedia.org/wiki/Headphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Call_centershttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Stereohttp://en.wikipedia.org/wiki/Binaural_recordinghttp://en.wikipedia.org/wiki/Binaural_recordinghttp://en.wikipedia.org/wiki/Loudspeakershttp://en.wikipedia.org/wiki/Frequency_rangehttp://en.wikipedia.org/wiki/Voice_bandhttp://en.wikipedia.org/wiki/Headphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Call_centershttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Stereohttp://en.wikipedia.org/wiki/Binaural_recordinghttp://en.wikipedia.org/wiki/Loudspeakershttp://en.wikipedia.org/wiki/Frequency_rangehttp://en.wikipedia.org/wiki/Voice_band


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A Typical Bluetooth Headset

Most users have heard about Bluetooth, and although this technology was

designed originally for a much wider application, it has today become largely for

voice transmission (a notable exception to this would be the use of Bluetooth in

the Nintendo Wiimote). The reason for this general exclusivity is because of the

power/range settings of Bluetooth. Bluetooth uses 2.4 GHz RF, similar to WLAN

or Wi-Fi; however, by default it is set for a very close proximity usage for power

consumption benefits. This deficiency for a longer-range coverage made

bluetooth technology un-desirable for data transmission. As nowadays, more and

more mobile phones come equipped with bluetooth, this technology has become acommon wireless profile for wireless mobile phone headsets only.


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A Stereo Bluetooth Headset

When choosing a Bluetooth headset users should be aware that bluetooth headsets

come in different types as well. Standard bluetooth headset's using version 1.0 or

1.1 are often a single-side monaural earpiece, which can only access the

Headset/handsfree profile of Bluetooth. Depending on the phone's operating

system, this type of headset will either play music at a very low quality (because

the phone is converting it into a voice signal) or will be unable to play music at all

(because the phone cannot perform such a conversion). Users who need a stereo-

music playing Bluetooth headset should look for a headset with the A2DP profile.

Users should note that some A2DP-equipped headsets will automatically de-

activate the microphone function during music-listening, so if these headsets are

paired to a computer via bluetooth connection, the headset may either disable the

stereo function or the microphone function.
http://en.wikipedia.org/wiki/A2DPhttp://en.wikipedia.org/wiki/A2DP


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Bluetooth Wireless Desktop Solutions

Some developers have offered complete desktop solutions using Bluetooth

technology. With a base-station that connects via cables to the fixed-line

telephone and also the computer via soundcard, users with any bluetooth headset

can pair their headset to the base-station, hence enabling them to use a single

headset for both fixed-line telephone and computer VoIP communication. This

type of solution, when used together with a multiple-point bluetooth headset

enables user to use a single bluetooth headset to communicate in

Telephone/Computer/Mobile.

There are now Bluetooth office headsets that incorporate Class 1 Bluetooth into

the base station so that when using with a Class 1 Bluetooth headset, the user can

get a greater distance from the phone or computer; generally around 100 feet

compared to the 33 feet of Class 2 Bluetooth, which is what most Bluetooth

headsets run on. The headsets that come with these base stations connect to cell

phones via Class 2 Bluetooth, so you still get the same 33 foot range from your

cell phone.


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5.5 SENSOR MODULE

The sensor is an array of 3 IR LED-Photodiode pairs arranged in the form of aninverted V. The output of each sensor is fed into an analog comparator with the

threshold voltage (used to calibrate the intensity level difference of the line with

respect to the surface). These 3 signals (from each photo-reflective sensor) is

given to a comparator, the output of which goes to the microcontroller.

This sensor can be used for most indoor applications where no important ambient

light is present. For simplicity, this sensor doesn't provide ambient light

immunity, but a more complicated, ambient light ignoring sensor should bediscussed in a coming article. However, this sensor can be used to measure the

speed of object moving at a very high speed, like in industry or in tachometers. In

such applications, ambient light ignoring sensor, which rely on sending 40 KHz

pulsed signals cannot be used because there are time gaps between the pulses

where the sensor is 'blind'...

The solution proposed doesn't contain any special components, like photo-diodes,

photo-transistors, or IR receiver ICs, only a couple if IR leds, an Op amp, a

transistor and a couple of resistors. In need, as the title says, a standard IR led is

used for the purpose of detection. Due to that fact, the circuit is extremely simple,

and any novice electronics hobbyist can easily understand and build it.

5.5.1OBJECT DETECTION USING IR LIGHT

It is the same principle in ALL Infra-Red proximity sensors. The basic idea is to

send infra red light through IR-LEDs, which is then reflected by any object in

front of the sensor.

Then all you have to do is to pick-up the reflected IR light. For detecting the


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reflected IR light, we are going to use a very original technique:we are going to use another IR-LED, to detect the IR light that was emitted from

another led of the exact same type.

This is an electrical property of Light Emitting Diodes (LEDs) which is the fact that a

led Produce a voltage difference across its leads when it is subjected to light. As if it

was a photo-cell, but with much lower output current. In other words, the voltage

generated by the leds can't be - in any way - used to generate electrical power from

light, It can barely be detected. Thats why as you will notice in the schematic we are

going to use a Op-Amp (operational Amplifier) to accurately detect very small

voltage changes.

5.5.2 SENSOR CIRCUIT

The resistance of the sensor decreases when IR light falls on it. A good sensor will

have near zero resistance in presence of light and a very large resistance in absence of

light. We have used this property of the sensor to form a potential divider.

The potential at point 2 is Rsensor / (Rsensor + R1). Again, a good sensor circuit

should give maximum change in potential at point 2 for no-light and bright-light

conditions. This is especially important if you plan to use an ADC in place of the


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comparator. To get a good voltage swing , the value of R1 must be carefully chosen.

If we assume Rsensor = a, when no light falls on it and Rsensor = b, when light

falls on it. The difference in the two potentials is: Vcc * { a/(a+R1) - b/(b+R1) }

Relative Voltage Swing = Actual Voltage Swing / Vcc

= Vcc * { a/(a+R1) - b/(b+R1) } / Vcc

= a/(a+R1) - b/(b+R1)

Figure 5.3: Schematic of a single sensor

5.6 WIRELESS CAMERA


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A wireless camera is a type of video camera that does not require the use of cables or

external wires for connection to related equipment. Wireless cameras offerconvenience when the placement of such cables would be difficult or even

impossible. Some wireless cameras use batteries, making them totally independent of

power outlets as well. Furthermore, they are portable and can be moved from location

to location quite easily.

Wireless cameras function similarly to other types of wireless devices. The exception

to the similarity, however, is that they send radio signals that are decoded into video

data. Wireless cameras are often used for surveillance, though some people purchase

them just for fun. Some wireless cameras are compatible with personal computers

(PCs) and are used to serve data streams tocomputerapplications or the Internet.

A wireless camera may be a good choice for video surveillance. This type of camera

can be used for both home and business, providing good surveillance coverage while

offering easy installation. Keep in mind, however, that some wireless cameras still

require connection to a power outlet. If connecting to a power outlet isnt convenient

or will give away the location of a camera you want hidden, consider purchasing a

battery-powered wireless camera instead.

Wireless cameras are also popular for web camming. Used for this purpose, a wireless

camera owner can allow another Internet user to both see and hear him or her using

Internet technology. Many individuals use wireless cameras to catch up with long-

distance relatives and friends, chat over the Internet with just about anyone, and even

participate in the online datingscene.

5.6.1 WIRELESS AV CAMERA
http://www.wisegeek.com/what-are-personal-computers.htmhttp://www.wisegeek.com/what-is-pcs.htmhttp://www.wisegeek.com/what-is-a-computer.htmhttp://www.wisegeek.com/what-is-a-computer.htmhttp://www.wisegeek.com/what-should-i-know-about-online-dating.htmhttp://www.wisegeek.com/what-should-i-know-about-online-dating.htmhttp://www.wisegeek.com/what-are-personal-computers.htmhttp://www.wisegeek.com/what-is-pcs.htmhttp://www.wisegeek.com/what-is-a-computer.htmhttp://www.wisegeek.com/what-should-i-know-about-online-dating.htm


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BASIC

ANTENNA

INTERFACE

DC INPUT

PLUG

VIDEO

OUTPUT

AUDIO

OUTPUT

FREQUENCY

CONTROLLER

POWER

INDICATORY

LIGHT


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SPECIFICATION PARAMETERS

VIDEO OUTPUT : 75 / 1 Vp-p

AUDIO OUTPUT : 10k / 200 M Vp-p

POWER CONSUMPTION : LESS THAN 2W

WORK TEMPERATURE : 0 ~ 40C

SIZE : 115 X 60 X 20 mm

WEIGHT : 150 g

RANGE : 60 m

OPERATING INSTRUCTIONS

CAMERA TRANSMITTER

1. Install the camera transmitter toward the direction you need to monitor.

2. Insert the DC8V500mA power adaptor into the inter flow power plug, and

insert its DC output plug into the DC input plug of the camera transmitter to

put through the circuit.

RECEIVER

1. Insert the antenna into the antenna interface of the receiver and fasten it.

2. Use AV line to connect the audio and video output interface of the receiver

with the audio and video input interface of the TV set or monitor.

3. Insert the DC9V/12V 500mA power adaptor into the interflow power plug, and

insert its DC output plug into the DC input plug of the receiver to put through


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the circuit, and at the moment the power indicatory light shines.

4. Adjust the frequency controller of the receiver to the sending frequency of the

corresponding camera transmitter with hands and you can get the picture and

sound by the TV set. Adjust the supervision position of the camera transmitter

to the supervision object, and you can make effective supervision.

THE MATTER NEEDS PAYING ATTENTION TO

1. The two kinds of power adaptors of DC9V/12V500mA and DC8V500mA must

not be mix-used, in order to avoid to cause the circuit damage of the camera

transmitter.

APPLICATIONS

This product is suitable for supervision of the places such as supermarkets,

department stores, homes, workshops, hospitals, and so on.

(6)CODING


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ORG 00H

OBS: MOV P0, #1111 0101B

JNB P0.2, ST

AJMP OBS

ST: MOV P0, #1111 1111B

MOV A, P1

CJNE A, #1111 1100B, OBS

AJMP DTMF

DTMF: MOV A, P1

FW: CJNE A, #11110010B, BK

MOV P0, #11110101B

AJMP DTMF

BK: CJNE A, #11111000B, RT

MOV P0, #11111010B

AJMP DTMF

RT: CJNE A, #11110110B, LT


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MOV P0, #11111001B

AJMP DTMF

LT: CJNE A, #11110100B, STP

MOV P0, #11110110B

AJMP DTMF

STP: CJNE A, #11110101B, CHECK

MOV P0, #11111111B

AJMP DTMF

CHECK: CJNE A, #1111 1011B, DTMF

AJMP OBS

LIMITATIONS


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Different DTMF characters have different level of effectiveness in

transmission, i.e., one DTMF tone may have a larger effective

communication area than the other. Therefore, in estimating the effectiveness

region of the whole DTMF character set, communication is considered failed

when two or more tones out of 16 are not transmitted successfully

Choice of Sensors sensitivity is made in the hardware abstraction and cannot

be changed by software.

Calibration is difficult, and it is not easy to set a perfect value.

The steering mechanism is not easily implemented in huge vehicles and

impossible for non-electric vehicles (petrol powered).

Lack of a four wheel drive, makes it not suitable for a rough terrain.

Use of IR sensors makes it difficult for robot to sense during day light, it

senses the Infrared from sunlight as well as IR use makes it hard to debug a

faulty sensor.

Lack of speed control makes the robot unstable at times.

APPLICATIONS


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Industrial automated equipment carriers.

Entertainment and small household applications.

Automated cars.

Tour guides in museums and other similar applications.

Second wave robotic reconnaissance operations.

Autopilot modes of airplanes and helipads

Spy robots in surveillance system

RESULT AND CONCLUSION


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The Obstacle Avoider robot was finally completed. After detecting the object

movement of car is as desired by bluetooth enable mobile phone. A lot of effort

was put into the design, implementation and days of toil in front of the computer,

writing and debugging the code. The robot was finally running with a few glitches

here and there which were sorted in the later revisions of the firmware. The

Obstacle Avoiding robot still has a few shortcomings but achieves most of the

objectives.

We earned a lot of knowledge on micro-controllers, a deeper & clearer view of

the architecture, ports & all other functional blocks was achieved. Did a lot of

research on robotics. Had a peek look at all simple functional parts of the project

like the crystal oscillator, logic gates and the works. Well, these were the topics

that we have already dealt with, but we must be honest and admit that there were

various practical issues which one would learn only during a project. Theres a lot

of learning & yet not the end, learning is a continuous never ending process but is

definitely fun.

BIBLIOGRAPHY


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1) WEBSITES REFERRED

www.google.com

All others are searched through GOOGLE.

The Seattle Robotics Society Encoder library of robotics articles:

http://www.seattlerobotics.org/encoder/library.html

Dallas Personal Robotics Group. Most of these tutorials and articles were

referred:

http://www.dprg.org/articles/index.html

http://www.dprg.org/tutorials/index.html

Go Robotics.NET, this page has many useful links to robotics articles.

http://www.gorobotics.net/articles/index.php

this site provides all information regarding components used in robotics

http://www.ikalogic.com

2) BOOKS

The 8051 microcontroller and Embedded System
http://www.google.com/http://www.seattlerobotics.org/encoder/library.htmlhttp://www.dprg.org/articles/index.htmlhttp://www.dprg.org/tutorials/index.htmlhttp://www.gorobotics.net/articles/index.phphttp://www.google.com/http://www.seattlerobotics.org/encoder/library.htmlhttp://www.dprg.org/articles/index.htmlhttp://www.dprg.org/tutorials/index.htmlhttp://www.gorobotics.net/articles/index.php


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by Muhammad Ali Mazidi second edition-PEARSON Education

Programming and Customizing the AVR microcontroller

by Myke Predko Second edition McGraw Hill

AVRmicro Mid-Range ATmega Family Reference Manual

by ATMEL

Design with AVR ATmega-16 microcontrollers

by John B. Peatman PEARSON Education

PIC Robotics, A beginners guide to robotics projects using the PICmicro

by John Iovine McGraw Hill

Digital logic and computer design

by M. Morris Mano - Prentice Hall of India PVT limited

Digital Systems Principles & applications

by Ronald J. Tocci Sixth Edition - Prentice Hall of India PVT limited

METHODOLOGY


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The first idea was to use optical imaging (CCD cameras) to see the obstacle. This

was later given up due to various reasons including complexity and unavailability

of components. Later a choice was made to use an array of sensors which solved

most of the problems pertaining to complexity. Also to enhance efficiency in

detecting obstacle we use wireless camera.

The resistor values used in the sensor array were experimentally determined

rather than theoretical mathematical design calculations. This was done as the

data sheets of the proximity sensor was not available anywhere and most of the

parameters had to be determined experimentally.

The L298 chip is used as it was a much better option than forming an H-Bridge

out of discrete transistors, which would make the design unstable and prone to

risk of damage.

The 8051microcontroller was used as it is the only device I have a full practical

knowledge about, and most of all a RISC processor which are better suited for

realtime operations. Thus the midrange devices were chosen.

Software was coded day and night, deciding on a few algorithms and few tiny

details which gradually got the robot to do what was required.

The first idea to control the robots was to use RF circuits but due to certain

limitations we use DTMF technology which provides the robust control and large

working areas.

The project was entirely designed, created, soldered, tested and coded by us. For

which we are thankful for, as I have learnt much more in the processes and not to

mention the fun had.

Documents

Kapil Project