pipe inspection

PIPE INSPECTION ROBOT

MGMCET 2013-14 Page 1

CHAPTER 01

INTRODUCTION

1.1 DEFINATION OF ROBOT

A robot is a mechanical or virtual artificial agent, usually an electro-mechanical

machine that is guided by a computer program or electronic circuitry.

1.2 PIPE INSPECTION

In the world, millions of miles of pipeline carrying everything from water to crude oil.

The pipe is vulnerable to attack by internal and external corrosion, cracking, third party

damage and manufacturing flaws. If pipeline carrying water springs a leak bursts, it can

be a problem but it usually doesn't harm the environment. However, if a petroleum or

chemical pipeline leaks, it can be a environmental disaster.

When a pipeline is built, inspection personnel may use visual, X-ray, magnetic particle,

ultrasonic and other inspection methods to evaluate the welds and ensure that they are of

high quality. These inspections are performed as the pipeline is being constructed so

gaining access the inspection area is not a problem. In some sections of pipeline are left

above ground like but in most areas they get buried. Once the pipe is buried, it is

undesirable to dig it up for any reason.

1.3 GENERAL FAILURE OF PIPE

1.3.1 Scaling of pipe:

In most cases, pipe scale is the material that builds up on the inside of pipes. This

material makes the inner area of the pipe smaller, which will either decrease the volume

or increase the pressure of the liquid flowing through the system. In addition, this makes

machinery based on flowing water work harder to gain the amount of liquid they need.



Pipe scale is also the term used to describe the musical resonance of a specific pipe on a

pipe organ.

Pipe scale mostly consists of minerals present in the liquid flowing through the pipe. In

water, this generally means calcium and magnesium. As water flows, small irregularities

in the pipe's surface will catch impurities. These impurities will continue to catch on

these rough spots, causing them to grow. This is similar to how the formations in caves

are made, just much faster.

The buildup of pipe scale has several direct impacts on the liquid in the pipe. As the inner

surface of the pipe becomes smaller, the liquid must change its flow patterns to

compensate. If the system allows for quantity variations, the volume of water transferred

by the system will begin to decrease. If the system transfers a set volume of liquid, then

the pressure and speed will build up in the pipe. This could cause problems if there are

weak or leaky joints in the system.

1.3.2 Corrosion of pipe:

Pipes used to distribute drinking water are made of plastic, concrete, or metal (e.g., steel,

galvanized steel, ductile iron, copper, or aluminum). Plastic and concrete pipes tend to be

resistant to corrosion. Metal pipe corrosion is a continuous and variable process of ion

release from the pipe into the water. Under certain environmental conditions, metal pipes

can become corroded based on the properties of the pipe, the soil surrounding the pipe,

the water properties, and stray electric currents. When metal pipe corrosion occurs, it is a

result of the electrochemical electron exchange resulting from the differential galvanic

properties between metals, the ionic influences of solutions, aquatic buffering, or the

solution pH.



1.3.3 Cracking in pipe:

Low alloy steel welded pipes buried in the ground were sent for failure analysis

investigation. Failure of steel pipes was not caused by tensile ductile overload but

resulted from low ductility fracture in the area of the weld, which also contains multiple

intergranular secondary cracks. The failure is most probably attributed to intergranular

cracking initiating from the outer surface in the weld heat affected zone and propagated

through the wall thickness. Random surface cracks or folds were found around the pipe.

In some cases cracks are emanating from the tip of these discontinuities.

1.4 PIPE LINE INSPECTION ROBOT

This is a robot which inspects the pipe line inner surface by travelling through pipe and

does visual video inspection and providing the surface inspection to the user or inspector

who can obtain the result easily at outside of the pipeline.

1.5 OBJECTIVE OF PROJECT

1.5.1 Monitoring of inner surface:

The robot must easily inspect the inner surface of the pipe line without any trouble and

gives proper live images to the inspector.

1.5.2 Low cost with high quality:

It must have a low cost with effective functions and high durability with high quality.



1.5.2 Unskilled labor:

For general inspection no need of skilled person. An unskilled labor cal easily inspects

the pipe.

1.5.3 All inspection points with maximum efficiency:

It can inspect the pipe with maximum accuracy with high grade result.

1.5.4 Easy for transport:

It must be easy for traveling purpose with zero damage.

1.5.5 900 turn & sufficiently work against gravity:

It must take turn in 900 bend (elbow) and it must work against the gravity not fully

vertical but at least inclined position up to 450.

1.5.6 Mumbai water pipe lines, our robot can locate the exact location where the

crack is present:

This is our main objective of our project. It will be explain in next chapter PROBLEM

DEFINITION

1.6 CONCLUSION

In this chapter we discussed about just of our project topic & its definition and objectives

of our project.



CHAPTER 02

PROBLEM DEFINITION

2.1 MUMBAI WATER PIPE LINES

Mumbai! The city of 1.5 crore people.

The water supply to Mumbai from various sources is about 563 million gallons per day

(MGD). The monsoon precipitation is collected in six lakes and supplied to the city

through the year. 460 MGD are treated at the Bhandup Water Treatment Plant, the largest

in Asia. The BMC manages to supply between 70 and 75% of the city's water needs.

The water distribution system in Bombay is about 100 years old. Water is brought into

the city from the lakes after treatment, and stored in 23 service reservoirs. Since two of

the major sources, Tansa and Lower Vaitarna, are at a higher level than the city, not

much power is required to pump the water.

The service reservoirs are mainly situated on hills. Some of them are located at Malabar

Hill, Worli Hill, Raoli, Pali Hill, Malad, Powai and Bhandup. Timings of water supply to

different parts of the city vary between 2 and 5 hours.

2.2NEED

2.2.1 Water pipe lines in MUMBAI:

The pipeline from main source has diameter about 3 to 4 meters after that it has

branches to supply water in different areas.

The big diameters pipelines are easily inspected by manually inspection. But

small diameter pipes which are in branches which has diameter up to 25 inch

which is critical to inspect.



Most of the branches of pipelined are situated parallel to the gutter lines and most

of them are in buried into the earth.

Almost all pipelines are 25 years old and its life is almost affected because of

continuous digging the road, gutter lines and buildings construction.

If crack present in the pipelines which results the gutter drainage water mixed

with drinking water which affects our health.

Also there is a scaling and corrosion because of long year services.

If any problem occurred with pipeline results the decrease in pressure of water

and to obtain the previous supply of water to maintain the force of water BMC dig

the whole path of pipe line & then repair the crack or replace which is more

costly.

It means waste on money and time hence it is too difficult though it is small

diameter pipe line.

2.2.2 Boiler steam carrying pipe lines:

In MIDC areas most of small scale industries uses the boiler.

Boiler is the most sensitive part which must be inspected periodically

During the inspection of steam carrying pipe line they uses outer source which is

increased in maintenance cost.

If they neglect the inspection of steam carrying pipe lines then it results in major

accidents.

2.3 OUR OBJECTIVES RELATED WITH PROBLEM DEFINITION

Design a robot in that way which can easily inspect the water pipelines and trace

out the location where crack is present.

Advantage

In current method they dig whole pipe line which is too costly as

discussed in earlier chapter but due to our pipe inspection robot



they can easily trace problem and dig the pipe where actual

problem occurs.

This can saves lot of time and money of BMC.

It must directly give the live images to the inspector to its device and its control

must be easy.

Advantage

Unskilled labor can easily inspect and can generate the report

quickly

No need of high skilled engineers

The robot can easily inspect the boiler steam carrying pipe lines..

Advantage

No need to small scale industries to use outsource

Saves money of industries

Pipe inspection robot can be used for general purpose.

o Ex. In Case of central ac plant duct inspection

Advantage

This robot can be easily used for general purpose where the use of

pipe is present.

We will try to provide different sensors for general inspection. Ex.

Temperature sensor poisons gas sensor, moisture quantity

measurement sensor.

2.4 CONCLUSION

In this chapter we highlighted problem definition and try to bold our solution and clarify

the path of our aims related with project.



CHAPTER 03

LITERATURE SURVEY

3.1 INTRODUCTION

Pipeline video inspection' is a form of telepresence used to visually inspect the

interiors of pipelines. A common application is to determine the condition of small

diameter sewer lines and household connection pipes.

Older sewer lines of small diameter, typically 6-inch (150 mm), are made by the

union of a number of short 3 feet (0.91 m) sections. The pipe segments may be made

of cast iron, with 12 feet (3.7 m) to 20 feet (6.1 m) sections, but are more often made

of vitrified clay pipe (VCP), a ceramic material, in 3 feet (0.91 m), 4 feet (1.2 m) & 6 feet

(1.8 m) sections. Each iron or clay segment will have an enlargement (a "bell") on one

end to receive the end of the adjacent segment. Roots from trees and vegetation may

work into the joins between segments and can be forceful enough to break open a larger

opening in terra cotta or corroded cast iron. Eventually a root ball will form that will

impede the flow and this may cleaned out by a cutter mechanism and subsequently

inhibited by use of a chemical foam - a rooticide.

With modern video equipment the interior of the pipe may be inspected - this is a

form of non-destructive testing. A small diameter collector pipe will typically have a

cleanout access at the far end and will be several hundred feet long, terminating at

a manhole. Additional collector pipes may discharge at this manhole and a pipe (perhaps

of larger diameter) will carry the effluent to the next manhole, and so forth to a pump

station or treatment plant.



3.2 TYPES OF INSPECTION PROCESS

3.2.1 Camera tractor:

A run to be inspected will either start from an access pipe leading at an angle

down to the sewer and then run downstream to a manhole, or will run between

manholes.

The service truck is parked above the access point of the pipe. The camera tractor,

with a flexible cable attached to the rear, is then lowered into the pipeline. The

tractor is moved forward so that it is barely inside of the pipeline.

A "down-hole roller" is set up between the camera tractor and the cable reel in

the service truck, preventing cable damage from rubbing the top of the pipeline.

The operator then retires to the inside of the truck and begins the inspection,

remotely operating the camera tractor from the truck.

When the inspection is complete or the camera cable is fully extended, the camera

tractor is put in reverse gear and the cable is wound up simultaneously.

When the camera tractor is near the original access point, the down hole roller is

pulled up and the camera tractor is moved into the access point and pulled up to

the service truck.

A tractor may be used to inspect a complete blockage or collapse that would

prevent using a fish and rope as described below.

Pulling the camera backwards

For small diameter pipes there may not be enough room for the tractor

mechanism. Instead, a somewhat rigid "fish" is pushed through the pipe and

attached to a rope at the access point near the truck. The fish is then pulled to

place the rope along the pipe. The rope is then used to pull the inspection pig and

cable through the pipe. Detaching the rope, the cable is then used to pull the pig

backwards as the pipe is inspected on the monitor (this is the method shown in the

illustrations below).



3.2.2 Analysis of video footage:

Much of the analysis of what was viewed in the pipeline is conducted at the time

of the inspection by the camera operator, but the entire inspection is always

recorded and saved for review.

Using software you can easily record digital video and simplify the analysis

process, here are some samples of different applications available on the market:

The early detection and identification of cracks, leakage points, blockages or intrusions

allows for the adequate repair or replacement of pipeline to be undertaken.

With pipeline infrastructure ageing, the urban sprawl widening and the population

growing, demand is continually increasing on our water and sewer mains.

The development of teleinspection technology equipment has opened up a new world for

the maintenance, repair, replacement and construction of pipelines, allowing greater

consultation ahead of any excavation work.

Teleinspection technology allows pipe inspection without any digging, allowing

inspectors to save the unnecessary cost of excavation around a pipe which might still be

in a robust and safe condition and not in need of replacement or even repair.

Major developments and improvements over the years in the design of equipment now

allows for improved results when determining the most appropriate method or product

equipment to be used to complete any scheduled work

Robotic CCTV crawlers, pushrod portable systems, laser profiling and sonar profiling are

just some of the inspection technology systems now being utilized during regular

inspection of water and sewer mains. These systems allow for comprehensive

information on the condition of the underground infrastructure to be collated, allowing a

planned maintenance program to be developed.

CCTV robotic crawlers/tractors and pushrod manual systems allow for condition

reporting and surveying of an asset, giving early warning of failures and allowing for

economical repair under no-crisis conditions.



CCTV is used in a variety of methods. The camera is placed in the pipeline and is either

winched through or self propelled. Crawlers are electronically powered, with the power

supply for the camera coming from a connection at the rear. The picture and control

signals are transferred to a monitor control centre managed by an operator working to

detect and determine what condition work or repairs are recommended.

3.2.3 Robotic crawlers:

Robotic crawlers first appeared in the 1950s and the 1990s saw the coming of the age of

this equipment in Australia. A greater range of products and equipment now allows

inspections to be completed in areas once deemed inaccessible, providing vision that

could previously not be seen in small, large or restrictive locations.

Specialist robotic crawling tractor systems are now produced to inspect pipes ranging

from 100 mm up to larger pipes in excess of 2 m in diameter.

Crawlers systems can be fitted with a fixed forward view camera head, a pan & tilt

camera head, or even a zoom pan & tilt camera head fitted with laser for crack width

measurement detection. Some crawlers are fitted with an elevator lift to allow greater

camera height and vision while working in a larger size pipe. Others are steerable to give

directional control if working in larger pipes or box culvert pipe.

Recent developments have led to the introduction of lateral inspection systems, with the

system entering the service connection line from the main using remote control functions

and allowing vision from a pan & tilt camera head. Lateral inspection systems can be

deployed in 150 mm mainline pipe upwards. Introduction of the camera into laterals is

aided by a motorised driven guide device and monitoring camera.

The new 3D Optoscanner, Panoramo, is the latest inspection system to be released to the

Australian market, capturing images of the pipeline and its condition through the use of

two high resolution digital photo cameras. The two 186 wide-angled camera lenses are

integrated in the front and rear section of the housing. Pipes are inspected at a speed of 35

cm (14 inches) per second.

During inspection, xenon flashing lights are triggered at the same position in the pipe.

The hemispherical pictures are scanned together to form 360 spherical images. During



the scanning process, which is possible in both forward and reverse direction, the data is

transferred digitally to the inspection vehicle and is immediately available to the operator

for orientation purposes and to locate any obstructions.

The data is stored in the form of film and removable onto hard disks or DVDs as storage

media. This unique method of inspection captures a complete inspection of the pipe

surface allowing you to rotate and also pan & tilt the camera image at any position in the

pipe whilst reviewing the data film.

An unfolded 2D view of the inner pipe surface allows rapid viewing of the pipe condition

and permits computer-aided measurement of the position and size of objects. For further

analysis and

3.2.4 Laser profiling:

The ability to detect and measure changes in pipe shape or bore clearance, be it due to

deformation, siltation, corrosion or erosion, is difficult at the best of times, especially

when using conventional CCTV camera systems.

This is further exasperated by the fact that the video footage produced by the camera is

without calibration or a reference point from which to take accurate measurements of any

kind it is all guesswork.

Any conventional CCTV survey thereby runs the risk of missing subtle, but relevant,

changes in the pipes shape as observations are dependent on the keenness of the

operators eye.

Rigid pipes, such as vitrified clay, present less of a problem as these tend to crack or

collapse rather than deform and the results are rather obvious. However, even in

circumstances where deformation is obvious it can still be difficult to determine the exact

extent of the deformation or if the deformation has got worse over time.

To address this problem, recent advances in pipeline inspection technology have seen the

refinement and development of state-of-the-art profiling systems that have enabled the

range of applications and degree of accuracy of traditional survey delivery systems to be

enhanced dramatically.



These new systems are all geared towards the elimination of human error, increased

reliability of technology and, ultimately, accuracy of information.

Laser profiling incorporates cutting edge, split laser technology that allows for pipe

profiling to be carried out under normal light conditions. This means that profiling and

conventional CCTV imaging can be carried out in tandem without interfering with the

quality of the survey results.

The laser profiler allows you accurately determination of amount of damage contained

within a pipe asset. The attachment shows the actual shape of the pipe while the software

can predetermine the correct pipe shape and calculate the difference between the two.

The aim of projecting a bright line onto the internal pipe wall is to define a plane on the

video image where measurements on the image can be translated in the real dimensions

of objects observed through the camera.

The system is calibrated by using two fixed points with a known separation on the radial

light plane, established with small marker pins that are illuminated by the laser light.

These act as calibration points on the video image to identify the scale of the image

where it is illuminated by the red laser light. The laser intensity is sufficient to make the

generated red line on the pipe bright enough to see clearly on the video image under

normal light conditions. Calibrating the video image allows measurement to be carried

out after the video has been recorded and does not slow the rate at which the video can be

recorded.

The software measurement tools provide the ability to accurately determine the amount

of flow loss caused by a wide variety of pipe faults. Combining the laser profiler and the

measurement tools makes obtaining the actual degradation of the pipe a reality.

Analysing this data determines whether pipe refurbishment is necessary.

3.2.5 Sonar pipe profiling:

The sonar system was specifically designed for the inspection of submerged and semi-

submerged pipelines. It uses high resolution/short range sonar and only works

underwater. The system itself is capable of inspecting pipelines from 225 mm in diameter

to conduits in excess of 5 m in diameter.



The head of the sonar, its transducer, looks sideways at right angles to the direction of the

motion through the pipe, resulting in a cross sectional view of the pipe in real time.

As the speed of inspection is critical for the longitudinal resolution, the general guideline

for the speed of inspection is approximately 100 mm per second. The sonar uses a color

display to indicate the type of surface the sonar is sweeping, denoted by red for a hard

surface and blue for a softer surface.

As with the CCTV system, the method of propulsion would either be self propelled or

floated, dependent upon known circumstances in the pipeline or the size of the pipe. If

heavy silt is expected then pipelines above 600 mm would be surveyed by floating the

sonar along the crown of the pipe.

If the pipeline were less than 600 mm then either the self-propelled or winch assisted self-

propelled method would be used. The level of deformation and/or silt levels can easily

and accurately be measured by the site software.

3.2.6 Visual:

The visual portion of the inspection consists of observing visible features and

cracks that indicate potential distress.

This inspection requires experienced staff to know which cracks are normal and

which are indicative of a problem. It also requires a thorough understanding of the

width and length of cracks that are normally produced during the production of

pipe as opposed to those that might indicate lack of prestressing, or distress, in the

pipe.

The visual inspection will also include an examination of the joints as well as the

width of joints or the amount of pull the pipeline was subjected to in order to

maintain line and grade. All anomalies will be noted with the distance and

location from known features. In many instances closure pieces, adapters, shorts,

and other specials are inserted in pipelines to make station on outlets and other

tie-in features.



3.3 ASSESSMENT OF EXISTING PIPE INSPECTION ROBOTS

Although there have been many robots designed for the purpose of pipe

inspection, most of these focus on operation in empty pipes and do not take into account

the effects of pressurized fluid on the motion and stability of the robot. Existing pipe

inspection robots can be categorized by their different locomotion methods: wheeled,

inchworm, snake and legged.

3.3.1 Wheeled Robots

Wheeled robots are widely used in this application due to their simple design and

control methodologies, energy efficiency.The simplest of these behave similar to regular

wheeled vehicles in that they rely on their own weight to maintain contact between their

wheels and the pipe wall.

Although these robots have no theoretical upper limit on the diameter of pipe they

can navigate, they can only travel through horizontal or near horizontal pipe networks,

with limitations on the maximum incline that they can traverse. Such robots would not be

able to navigate vertical pipe sections and would not be capable of operating in pipes

with high rates of fluid flow as they would be swept away. In order to overcome these

problems, some wheeled pipe inspection robots have attempted to use an active method

of attracting the wheels to the pipe wall.

Although the design of both these robots means that they are not restricted by pipe

diameter, their use of magnets limits their operational environment to those which are

constructed primarily of ferrous materials. Other wheeled pipe inspection robots operate

by pressing their wheels against the pipe surface through passive means (e.g. springs), or

active means (e.g. linear Actuators), or a combination of both.

Although these robots each have distinctive designs, they all follow the same

general principle of pushing their wheels against the pipe wall and using them to propel

down the pipe. Of particular note is Explorer, a segmented robot that is used for the

inspection of gas pipelines. Unlike other pipe robots, Explorer was designed to operate in

pressurised, active gas pipes. Each segment of the robot is designed to protect the internal



workings from the high pressure inside the pipe and the shape of the robot is designed to

provide minimum resistance to the flow of gas .Despite their mechanical simplicity, the

efficiency of wheeled robots whilst climbing is not optimal, as the force used to push the

wheels against the pipe wall acts against the actuators trying to drive the wheels.

3.3.2 Inchworm Robots

Inchworm-type robots, like wheeled robots, are relatively simple to control and

allow the robot to navigate the various features inside the pipe

Each of these robots uses a vibration source as the main driving force, coupled

with a passive mechanical system pressing against the pipe wall. The simple nature of

these robots means that they are easy to control and usually have very few parts, but are

incapable of navigating junctions. Other inchworm robots have used an active method of

pressing against the pipe wall. Although they are more complex than their passive

variants, they have more control over their movement and can more easily change

direction.

These robots all use a form of linear actuation for propulsion, coupled with full

control over the extension and retraction of their limbs, which allows them to easily move

forwards and backwards along the pipe. Examples of such robots have been demonstrated

to navigate straight Pipe sections and bends. Unlike wheeled robots, inchworm robots

cannot continuously move forwards, but rather move forward in steps, which can make

them slower than their wheeled counterparts. However, they are likely to be more

efficient during climbing as the force pushing the robots feet against the pipe wall acts

perpendicular to the robots direction of motion and thus does not hinder it.

3.3.3 Snake and Legged Robots

Snake and legged robots both have many degrees of freedom, which permit them

a wide range of different motions. However, these results in robots using more actuators

and having more complex control systems than those found in robots using other

locomotion types.



These capable of navigating bends and junctions in a pipe. Similarly, snake robots used

for pipe inspection can be seen. These robots consist of several modules connected

together using actuated joints.

Movement is primarily achieved through the use of travelling wave locomotion.

The serial nature of both these locomotion types means that they require high power

actuators and have limited payload capacity .The nature of travelling wave locomotion in

snake robots can make it difficult for sensors to take stable readings of their environment

.As pipelines are generally uniform and structured environments, the complexity of

legged and snake robots may not be required for this application, especially since robots

with simpler locomotion methods have demonstrated their ability to navigate the various

features in pipelines.

3.4 CONCLUSION

In this chapter we discussed about the different technology used for pipe inspection &

different types of robot used in pipe inspection.



CHAPTER 04

WORKING PRINCIPLE OF PIPE INSPECTION ROBOT

4.1 MECHANICAL WORKING PRINCIPLE

Refer given figure

Note: Here we decide about only one set of links. In project there are 3 set of links

situated at an interval of 1200. Also there is a similar part which is connected by

plate joint.

4.1.1DESCRIPTION OF DIFFERENT MECHANICAL PARTS:

4.1.1.1 Wheel:

Wheels are used for the purpose for to run travel the whole mechanism.

4.1.1.2Motor:

Motor is used for them to give motion to the wheel and to open and close the robot

position to adjust the self position according to inner diameter of pipe.

There are total 8 motors. Out of which 6 motors are used for to travel the

mechanism and remaining two motors are used for to maintain open and closed position

with the help of screw.

4.1.1.3 Screw or shaft:

Screw or shaft is run by motor and collar is mounted on it and it works as a nut.



4.1.1.4 Collar no 1:

Collar is moves horizontally as shown in figure and link no 1 is welded on it.

4.1.1.5 Link no 1

This one part of the mechanism and it welded to the collar as shown in figure and it

moves with collar in horizontal position. It joins with link no 2. The joint is not fixed. It

is movable for the purpose of open and close motion.

4.1.1.6 Link no 2

This is one part of the mechanism which joints between link no 1 & 3.

4.1.1.7 Link no 3

This is one part of the mechanism which is supported by the link no 2 & 4. This is

important link because motor and wheel are mounted on it as shown in figure.

4.1.1.8 Link no 4

This is fixing link on collar no 2 by welding. During motion transfer it is in fixed

position. It supports to the link no 3.

4.1.1.9 Collar no 2:

This is only used for to support the screw and link no 4



4.1.1.10 Round ring:

Round ring is used for to support C channel, collar no 2 and link no 4. It also supports

to the motor.

4.1.1 .11 C channel

C channel is important part because it supports almost whole assembly. The purpose of

this is to make a connection between second similar part of the assembly.

4.1.1.12 Plate joint:

It works a knuckle joint to join two parts.

4.1.1.13 Nut bolts joints:

Nut bolted joints are used in to make a joint between links.

4.1.2 WORKING PRINCIPLE OF ROBOT (MECHANICAL)

1. Consider first the robot is totally in closed position means it has minimum pipe

diameter inspection range.

2. When we insert it in pipe for the purpose of inspection then by rotating motor

which is fixed in C channel we adjust the pipe inner diameter surface range.

3. At that time when motor rotates the collar no 1 works as a nut and it moves

horizontally as shown in figure.

4. When it moves that time link 1 also moves it results link 2 & 3 moves or change

its original position.

5. When link 1 moves horizontally the motion transfers to the link 2 which is in

between link 1 & 3.



6. The movement of link 2 causes the movement of link 3 up or down as motion

direction of collar.

7. If collar moves towards right link 3 go up and vice versa.

8. The wheel and motor are mounted at the end of the link no 3. When this motor

runs it causes the forward or reverse motion of robot.

9. The electrical system is provided to run the motors and camera with LED lights,

temperature sensor and poisons gas sensor.

10. Camera or cam system provided live pictures to the inspector.

11. Temperature sensor give live reading of temperature present inside the pipe and

gas sensor measures the PPM of pipe inside air.

4.2 ELECTRICAL WORKING PRINCIPLE

4.2.1 DIFFERENT ELECTRICAL AND ELECTRONICS PARTS:

1. Microcontroller 89s51

2. Relays

3. Analog to digital converter

4. DC motor

5. Battery

6. Transistor

7. Transformer

8. LCD

9. Crystal

4.2.2 WORKING PRINCIPAL OF ROBOT (ELECTRICAL)

1. 12 volts dc reduction gear motor

2. In front vga camera

3. Two sensors: gas sensor(MQ6), Temperature sensor/Thermistor (ntc)



4. Sensors output will go to ADC (analog to digital convertor). ADC gives data to

microcontroller 89s51. Controller through serial cables will give data to computer.

5. computers trigger signal will be received by controller

6. Controller will give output to relay contactor.

7. Controller output is logic signal. Logic signal is received by transistor (name-

npnvc 549) .signal is amplified and relay coil is magnetized.

8. Relay is electro mechanical switch. First relay is closed motor will move forward.

if second relay is close it will move reverse.

9. power supply-

A. For power supply

B. Two lead acid battery. Battery output goes to filter capacitor than to voltage

regulator.

C. Battery output of 12v is converted to 5v. as voltage requirement for adc and

microcontroller is 5v.

D. Through regulator 5v is given to microcontroller and batteries 12v to motor

through relay.

E. We have LCD display to see the incoming outgoing data.

F. Temperature and gas value will be displayed in LCD.

10. Crystal clock: To execute the program in microcontroller.

11. IC 7414 is used to give signal to ADC. Thereby analog signal is converted to

digital.

4.3 CONCLUSION

Here we learned the different parts of robot their construction and working principal.



CHAPTER 05

DESCRIPTION OF ELECTRICAL COMPONENTS

5.1 MICROCONTROLLER 89S51

5.1.1 Description:

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller

with 4K bytes of In System Programmable Flash memory. The device is manufactured

using Atmels high-density nonvolatile 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 nonvolatile

memory programmer. By combining a versatile 8-bit CPU with In-System Programmable

Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which

provides a highly-flexible and cost-effective solution to many embedded control

applications.

The AT89S51 provides the following standard features: 4K bytes of Flash, 128

bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit

timer/counters, a Five-vector two-level interrupt architecture, a full duplex serial port, on-

chip oscillator, and clock circuitry. In addition, the AT89S51 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 contents but freezes the oscillator, disabling all other chip functions until the next

external interrupt or hardware reset.

5.1.2 Features:

Compatible with MCS-51 Products

4K Bytes of In-System Programmable (ISP) Flash Memory

Endurance: 10,000 Write/Erase Cycles



4.0V to 5.5V Operating Range

Fully Static Operation: 0 Hz to 33 MHz

Three-level Program Memory Lock

128 x 8-bit Internal RAM

32 Programmable I/O Lines

Two 16-bit Timer/Counters

Six Interrupt Sources

Full Duplex UART Serial Channel

Low-power Idle and Power-down Modes

Interrupt Recovery from Power-down Mode

Watchdog Timer

Dual Data Pointer

Power-off Flag

Fast Programming Time

Flexible ISP Programming (Byte and Page Mode)

Green (Pb/Halide-free) Packaging Option



5.1.3 Pin diagram:



5.1.4 Block diagram



5.1.5 Pin Description:

5.1.5.1 VCC

Supply voltage.

5.1.5.2GND

Ground.

5.1.5.3 Port 0

Port 0 is an 8-bit open drain bi-directional 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.

5.1.5.4 Port 1

Port 1 is an 8-bit bi-directional 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. Port 1 also

receives the low-order address bytes during Flash programming and verification.



5.1.5.5 Port 2


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 memory that use 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 use 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.

5.1.5.6 Port 3


can

sink/ source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by

the inter-

Port Pin Alternate Functions

P1.5 MOSI (used for In-System Programming)

P1.6 MISO (used for In-System Programming)



P1.7 SCK (used for In-System Programming)

nal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being

pulled low

Will source current (IIL) because of the pull-ups.

Port 3 receives some control signals for Flash programming and verification.

Port 3 also serves the functions of various special features of the AT89S51, as shown in

the following

Table.

5.1.5.7 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 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.

5.1.5.8 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.

5.1.5.9 PSEN

Program Store Enable (PSEN) is the read strobe to external program memory. When the

AT89S51 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.

5.1.5.10 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.



5.1.5.11 XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

5.1.5.12 XTAL2

Output from the inverting oscillator amplifier

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier that

can be

Configured for use as an on-chip oscillator, as shown in Figure 11-1. Either a quartz

crystal or

Ceramic resonator may be used. To drive the device from an external clock source,

XTAL2

Should be left unconnected while XTAL1 is driven, as shown in Figure 11-2. There are

no

Requirements on the duty cycle of the external clock signal, since the input to the internal

clocking

Circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high

and low

Time specifications must be observed.

Figure shows Oscillator Connections

C2



XTAL2

GND

XTAL1

C1

Basic Reset Ckt.

5.1.6 For 89c51 and 89s51 Memory Organization

MCS-51 devices have a separate address space for Program and Data Memory. Up to

64K

Bytes each of external Program and Data Memory can be addressed.

Program Memory

If the EA pin is connected to GND, all program fetches are directed to external memory.

On the AT89S51, if EA is connected to VCC, program fetches to addresses 0000H

through FFFH are directed to internal memory and fetches to addresses 1000H through

FFFFH are directed to external memory.

Data Memory

The AT89S51 implements 128 bytes of on-chip RAM. The 128 bytes are accessible via

direct

and indirect addressing modes. Stack operations are examples of indirect addressing, so

the 128 bytes of data RAM are available as stack space.



5.2 RELAY

5.2.1 Introduction:

A relay is an electrically operated switch. Many relays use an electromagnet to

operate a switching mechanism, but other operating principles are also used. Relays find

applications where it is necessary to control a circuit by a low-power signal, or where

several circuits must be controlled by one signal. The first relays were used in long

distance telegraph circuits, repeating the signal coming in from one circuit and re-

transmitting it to another. Relays found extensive use in telephone exchanges and early

computers to perform logical operations. A type of relay that can handle the high power

required to directly drive an electric motor is called a contactor. Solid-state relays control

power circuits with no moving parts, instead using a semiconductor device to perform

switching. Relays with calibrated operating characteristics and sometimes multiple

operating coils are used to protect electrical circuits from overload or faults; in modern

electric power systems these functions are performed by digital instruments still called

"protection relays

5.2.2 Basic design and operation:

A simple electromagnetic relay consists of a coil of wire surrounding a soft iron

core, an iron yoke, which provides a low reluctance path for magnetic flux, a movable

iron armature, and a set, or sets, of contacts; two in the relay pictured. The armature is

hinged to the yoke and mechanically linked to a moving contact or contacts. It is held in

place by a spring so that when the relay is de-energized there is an air gap in the magnetic

circuit. In this condition, one of the two sets of contacts in the relay pictured is closed,

and the other set is open. Other relays may have more or fewer sets of contacts depending

on their function. The relay in the picture also has a wire connecting the armature to the

yoke. This ensures continuity of the circuit between the moving contacts on the armature,

and the circuit track on the printed circuit board (PCB) via the yoke, which is soldered to

the PCB.



When an electric current is passed through the coil, the resulting magnetic field

attracts the armature, and the consequent movement of the movable contact or contacts

either makes or breaks a connection with a fixed contact. If the set of contacts was closed

when the relay was de-energized, then the movement opens the contacts and breaks the

connection, and vice versa if the contacts were open. When the current to the coil is

switched off, the armature is returned by a force, approximately half as strong as the

magnetic force, to its relaxed position. Usually this force is provided by a spring, but

gravity is also used commonly in industrial motor starters. Most relays are manufactured

to operate quickly. In a low voltage application, this is to reduce noise. In a high voltage

or high current application, this is to reduce arcing.

When the coil is energized with direct current, a diode is often placed across the

coil to dissipate the energy from the collapsing magnetic field at deactivation, which

would otherwise generate a voltage spike dangerous to circuit components. Some

automotive relays already include a diode inside the relay case. Alternatively a contact

protection network, consisting of a capacitor and resistor in series, may absorb the surge.

If the coil is designed to be energized with alternating current (AC), a small copper ring

can be crimped to the end of the solenoid. This "shading ring" creates a small out-of-

phase current, which increases the minimum pull on the armature during the AC cycle.

By analogy with functions of the original electromagnetic device, a solid-state

relay is made with a thyristor or other solid-state switching device. To achieve electrical

isolation an optocoupler can be used which is a light-emitting diode (LED) coupled with

a photo transistor.

5.2.3 Types:

5.2.3.1 Latching relay:

Latching relay, dust cover removed, showing pawl and ratchet mechanism. The

ratchet operates a cam, which raises and lowers the moving contact arm, seen edge-on

just below it. The moving and fixed contacts are visible at the left side of the image.



A latching relay has two relaxed states (bistable). These are also called "impulse",

"keep", or "stay" relays. When the current is switched off, the relay remains in its last

state. This is achieved with a solenoid operating a ratchet and cam mechanism, or by

having two opposing coils with an over-center spring or permanent magnet to hold the

armature and contacts in position while the coil is relaxed, or with a remanent core. In the

ratchet and cam example, the first pulse to the coil turns the relay on and the second pulse

turns it off. In the two coil example, a pulse to one coil turns the relay on and a pulse to

the opposite coil turns the relay off. This type of relay has the advantage that it consumes

power only for an instant, while it is being switched, and it retains its last setting across a

power outage. A remanent core latching relay requires a current pulse of opposite polarity

to make it change state.

5.2.3.2 Reed relay:

A reed relay has a set of contacts inside a vacuum or inert gas filled glass tube,

which protects the contacts against atmospheric corrosion. The contacts are closed by a

magnetic field generated when current passes through a coil around the glass tube. Reed

relays are capable of faster switching speeds than larger types of relays, but have low

switch current and voltage ratings.

5.2.3.3 Mercury-wetted relay:

A mercury-wetted reed relay is a form of reed relay in which the contacts are

wetted with mercury. Such relays are used to switch low-voltage signals (one volt or less)

because of their low contact resistance, or for high-speed counting and timing

applications where the mercury eliminates contact bounce. Mercury wetted relays are

position-sensitive and must be mounted vertically to work properly. Because of the

toxicity and expense of liquid mercury, these relays are rarely specified for new

equipment. See also mercury switch.



5.2.3.4 Polarized relay:

A polarized relay placed the armature between the poles of a permanent magnet to

increase sensitivity. Polarized relays were used in middle 20th Century telephone

exchanges to detect faint pulses and correct telegraphic distortion. The poles were on

screws, so a technician could first adjust them for maximum sensitivity and then apply a

bias spring to set the critical current that would operate the relay.

5.2.3.5 Machine tool relay:

A machine tool relay is a type standardized for industrial control of machine tools,

transfer machines, and other sequential control. They are characterized by a large number

of contacts (sometimes extendable in the field) which are easily converted from

normally-open to normally-closed status, easily replaceable coils, and a form factor that

allows compactly installing many relays in a control panel. Although such relays once

were the backbone of automation in such industries as automobile assembly, the

programmable logic controller (PLC) mostly displaced the machine tool relay from

sequential control applications.

5.2.3.6 Contactor relay:

A contactor is a very heavy-duty relay used for switching electric motors and

lighting loads, although contactors are not generally called relays. Continuous current

ratings for common contactors range from 10 amps to several hundred amps. High-

current contacts are made with alloys containing silver. The unavoidable arcing causes

the contacts to oxidize; however, silver oxide is still a good conductor.[2]

Such devices are

often used for motor starters. A motor starter is a contactor with overload protection

devices attached. The overload sensing devices are a form of heat operated relay where a

coil heats a bi-metal strip, or where a solder pot melts, releasing a spring to operate

auxiliary contacts. These auxiliary contacts are in series with the coil. If the overload



senses excess current in the load, the coil is de-energized. Contactor relays can be

extremely loud to operate, making them unfit for use where noise is a

5.2.3.7 Solid-state relay:

A solid state relay (SSR) is a solid state electronic component that provides a

similar function to an electromechanical relay but does not have any moving components,

increasing long-term reliability. With early SSR's, the tradeoff came from the fact that

every transistor has a small voltage drop across it. This voltage drop limited the amount

of current a given SSR could handle. As transistors improved, higher current SSR's, able

to handle 100 to 1,200 Amperes, have become commercially available. Compared to

electromagnetic relays, they may be falsely triggered by transients.

5.2.3.8 Solid state contactor relay:

A solid state contactor is a very heavy-duty solid state relay, including the

necessary heat sink, used for switching electric heaters, small electric motors and lighting

loads; where frequent on/off cycles are required. There are no moving parts to wear out

and there is no contact bounce due to vibration. They are activated by AC control signals

or DC control signals from Programmable logic controller (PLCs), PCs, Transistor-

transistor logic (TTL) sources, or other microprocessor and microcontroller controls.

5.2.3.9 Buchholz relay:

A Buchholz relay is a safety device sensing the accumulation of gas in large oil-

filled transformers, which will alarm on slow accumulation of gas or shut down the

transformer if

5.2.3.10 Forced-guided contacts relay:

A forced-guided contacts relay has relay contacts that are mechanically linked

together, so that when the relay coil is energized or de-energized, all of the linked



contacts move together. If one set of contacts in the relay becomes immobilized, no other

contact of the same relay will be able to move. The function of forced-guided contacts is

to enable the safety circuit to check the status of the relay. Forced-guided contacts are

also known as "positive-guided contacts", "captive contacts", "locked contacts", or

"safety relays".

5.2.3.11 Overload protection relay:

Electric motors need over current protection to prevent damage from over-loading

the motor, or to protect against short circuits in connecting cables or internal faults in the

motor windings.[3]

One type of electric motor overload protection relay is operated by a

heating element in series with the electric motor. The heat generated by the motor current

heats a bimetallic strip or melts solder, releasing a spring to operate contacts. Where the

overload relay is exposed to the same environment as the motor, a useful though crude

compensation for motor ambient temperature is provided.

5.2.4 Applications:

Relays are used to and for:

Control a high-voltage circuit with a low-voltage signal, as in some types of

modems or audio amplifiers,

Control a high-current circuit with a low-current signal, as in the starter solenoid

of an automobile,

Detect and isolate faults on transmission and distribution lines by opening and

closing circuit breakers (protection relays),



5.2.5 Selection of an appropriate relay for a particular application requires

evaluation of many different factors:

Number and type of contacts normally open, normally closed, (double-throw)

Contact sequence "Make before Break" or "Break before Make". For example,

the old style telephone exchanges required Make-before-break so that the

connection didn't get dropped while dialing the number.

Rating of contacts small relays switch a few amperes, large contactors are rated

for up to 3000 amperes, alternating or direct current

Voltage rating of contacts typical control relays rated 300 VAC or 600 VAC,

automotive types to 50 VDC, special high-voltage relays to about 15 000 V

Coil voltage machine-tool relays usually 24 VAC, 120 or 250 VAC, relays for

switchgear may have 125 V or 250 VDC coils, "sensitive" relays operate on a few

mill amperes

Coil current

Package/enclosure open, touch-safe, double-voltage for isolation between

circuits, explosion proof, outdoor, oil and splash resistant, washable for printed

circuit board assembly

Assembly Some relays feature a sticker that keeps the enclosure sealed to allow

PCB post soldering cleaning, which is removed once assembly is complete.

Mounting sockets, plug board, rail mount, panel mount, through-panel mount,

enclosure for mounting on walls or equipment

Switching time where high speed is required

"Dry" contacts when switching very low level signals, special contact materials

may be needed such as gold-plated contacts

Contact protection suppress arcing in very inductive circuits

Coil protection suppress the surge voltage produced when switching the coil

current

Isolation between coil circuit and contacts

Aerospace or radiation-resistant testing, special quality assurance



Expected mechanical loads due to acceleration some relays used in aerospace

applications are designed to function in shock loads of 50 g or more

Accessories such as timers, auxiliary contacts, pilot lamps, test buttons

Regulatory approvals

Stray magnetic linkage between coils of adjacent relays on a printed circuit board.

5.3 DC MOTOR

5.3.1 Introduction & working principle:

A DC motor relies on the fact that like magnet poles repels and unlike magnetic

poles attracts each other. A coil of wire with a current running through it generates

a electromagnetic field aligned with the center of the coil. By switching the current on or

off in a coil its magnet field can be switched on or off or by switching the direction of the

current in the coil the direction of the generated magnetic field can be switched 180. A

simple DC motor typically has a stationary set of magnets in the stator and an

armature with a series of two or more windings of wire wrapped in insulated stack slots

around iron pole pieces (called stack teeth) with the ends of the wires terminating on

a commutator. The armature includes the mounting bearings that keep it in the center of

the motor and the power shaft of the motor and the commutator connections. The

winding in the armature continues to loop all the way around the armature and uses either

single or parallel conductors (wires), and can circle several times around the stack teeth.

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.

The sequence of turning a particular coil on or off dictates what direction the

effective electromagnetic fields are pointed. By turning on and off coils in sequence a

rotating magnetic field can be created. These rotating magnetic fields interact with the

magnetic fields of the magnets (permanent or electromagnets) in the stationary part of the

motor (stator) to create a force on the armature which causes it to rotate. In some DC

motor designs the stator fields use electromagnets to create their magnetic fields which



allow greater control over the motor. At high po wer levels, DC motors are almost always

cooled using forced air.

The commutator allows each armature coil to be activated in turn. The current in

the coil is typically supplied via two brushes that make moving contact with the

commutator. Now, some brushless DC motors have electronics that switch the DC

current to each coil on and off and have no brushes to wear out or create sparks.

Different number of stator and armature fields as well as how they are connected

provides different inherent speed/torque regulation characteristics. The speed of a DC

motor can be controlled by changing the voltage applied to the armature. The

introduction of variable resistance in the armature circuit or field circuit allowed speed

control. Modern DC motors are often controlled by power electronics systems which

adjust the voltage by "chopping" the DC current into on and off cycles which have an

effective lower voltage.

Since the series-wound DC motor develops its highest torque at low speed, it is

often used in traction applications such as electric. 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.

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.

5.3.2 Types of dc motor:

5.3.2.1 Brush type:

A brushed DC electric motor generating torque from DC power supply by using

an internal mechanical commutation. Stationary permanent magnets form the stator field.

Torque is produced by the principle that any current-carrying conductor placed within an

external magnetic field experiences a force, known as Lorentz force. In a motor, the

magnitude of this Lorentz force (a vector represented by the green arrow), and thus the

output torque, is a function for rotor angle, leading to a phenomenon known as torque

ripple) Since this is a single phase two-pole motor, the commutator consists of a split

ring, so that the current reverses each half turn ( 180 degrees).

The brushed DC electric motor generates torque directly from DC power supplied

to the motor by using internal commutation, stationary magnets

(permanent or electromagnets), and rotating electrical magnets.

Advantages of a brushed DC motor include low initial cost, high reliability, and

simple control of motor speed. Disadvantages are high maintenance and low life-span for

high intensity uses. Maintenance involves regularly replacing the carbon brushes and

springs which carry the electric current, as well as cleaning or replacing the commutator.

These components are necessary for transferring electrical power from outside the motor

to the spinning wire windings of the rotor inside the motor. Brushes consist of

conductors.

5.3.2.2 Brushless type:

Typical brushless DC motors use a rotating permanent magnet in the rotor, and

stationary electrical current/coil magnets on the motor housing for the stator, but the

symmetrical opposite is also possible. A motor controller converts DC to AC. This design

is simpler than that of brushed motors because it eliminates the complication of



transferring power from outside the motor to the spinning rotor. Advantages of brushless

motors include long life span, little or no maintenance, and high efficiency.

Disadvantages include high initial cost, and more complicated motor speed controllers.

Some such brushless motors are sometimes referred to as "synchronous motors" although

they have no external power supply to be synchronized with, as would be the case with

normal AC synchronous motors.

5.4 BATTERY (LEAD ACID BATTERY)

5.4.1 Introduction

The leadacid battery was invented in 1859 by French physicist Gaston

Plant and is the oldest type of rechargeable. Despite having a very low energy-to-weight

ratio and a low energy-to-volume ratio, its ability to supply high surge currents means

that the cells have a relatively large power-to-weight ratio. These features, along with

their low cost, make it attractive for use in motor vehicles to provide the high current

required by automobile starter motors.

As they are inexpensive compared to newer technologies, lead-acid batteries are

widely used even when surge current is not important and other designs could provide

higher energy densities. Large-format lead-acid designs are widely used for storage in

backup power supplies in cell phone towers, high-availability settings like hospitals,

and stand-alone power systems. For these roles, modified versions of the standard cell

may be used to improve storage times and reduce maintenance requirements.

This battery provides 6V in our project. We want 12 volt requirement. So, we

connected two batteries in series.



5.5 TRANSISTOR

A transistor is a semiconductor device used

to amplify and switch electronic signals and electrical power. It is composed of

semiconductor material with at least three terminals for connection to an external circuit.

A voltage or current applied to one pair of the transistor's terminals changes the current

through another pair of terminals. Because the controlled (output) power can be higher

than the controlling (input) power, a transistor can amplify a signal. Today, some

transistors are packaged individually, but many more are found embedded in integrated

circuits.

The transistor is the fundamental building block of modern electronic devices, and

is ubiquitous in modern electronic systems. Following its development in 1947 by John

Bardeen, Walter Brattain, and William Shockley, the transistor revolutionized the field of

electronics, and paved the way for smaller and cheaper radios, calculators,

and computers, among other things. The transistor is on the list of IEEE milestones in

electronics, and the inventors were jointly awarded the 1956 Nobel Prize in Physics for

their achievement.

5.6 CRYSTAL

5.6.1 Description:

Crystals are commonly used to provide a stable clock source for micro-

controllers. This has a freq. tolerance of +-50ppm, temperature stability of +-50ppm, and

load capacitance of 18pF. It's slightly more than 1/8" tall.

5.6.2 More information and instructions:

Spec sheet: here (ABL type)



Here are 22pF ceramic disc capacitors commonly used with this crystal to provide a clock

source to micro-controllers.

When installing, be sure that the case does not make contact with any other conductors;

ie, don't push it all the way flush with the board.

+-5ppm (parts per million) per year aging drift.

About crystals: There are several different ways to provide a clock source, including

crystals, oscillators, RC circuits, and resonators; this article gives a good comparison.

Crystals offer a good compromise of low cost, high accuracy, good temperature stability,

and low power use.

They are typically used in what's called a "Pierce circuit" with microcontrollers that has

two other capacitors tied to ground on either side of the crystal. The value of the

capacitors affects the circuit's frequency. Crystals manufactured for use in this type of

circuit are parallel crystals and come pre-compensated for a certain "capacitive load." The

formula that relates the crystal's capacitive load and the capacitors used in the circuit is:

CL = (C1*C2)/(C1+C2) + Cs (stray capacitance in leads and circuit board). Many guides

suggest Cs is usually around 5 pF, but the Microchip spec sheets seem to assume it's

12.5pF.

PPM (Parts per Million): This is like a percent error (1000 PPM = .1% error), and is

convenient for calculating error with crystals. 5ppm on a 4MHz crystal = 5*4 = 20Hz

possible error. Most microcontroller applications don't require too much accuracy,

100ppm is fine. If the parallel capacitors don't match the crystal's capacitive load exactly,

they will pull the frequency, but not much. This offers more info about pullability and

crystals in general. It seems to indicate that on a 20pF CL crystal, you may get 16ppm/pF

error between the anticipated load and actual.

A Microchip application note that talks about crystal design considerations for

microcontrollers.



5.7 TRANSFORMER

5.7.1 Working principal:

A transformer is an electrical device that transfers energy between two circuits

through electromagnetic induction. A transformer may be used as a safe and

efficient voltage converter to change the AC voltage at its input to a higher or lower

voltage at its output. Other uses include current conversion, isolation with or without

changing voltage and impedance conversion.

A transformer most commonly consists of two windings of wire that are wound

around a common core to provide tight electromagnetic coupling between the windings.

The core material is often a laminated iron core. The coil that receives the electrical input

energy is referred to as the primary winding, while the output coil is called the secondary

winding.

An alternating electric current flowing through the primary winding (coil) of a

transformer generates a varying electromagnetic field in its surroundings which causes a

varying magnetic flux in the core of the transformer. The varying electromagnetic field in

the vicinity of the secondary winding induces an electromotive force in the secondary

winding, which appears a voltage across the output terminals. If a load impedance is

connected across the secondary winding, a current flows through the secondary winding

drawing power from the primary winding and its power source.

A transformer cannot operate with direct current; although, when it is connected

to a DC source, a transformer typically produces a short output pulse as the current rises.

5.7.2 Applications:

Transformers perform voltage conversion; isolation protection; and impedance

matching. In terms of voltage conversion, transformers can step-up voltage/step-down

current from generators to high-voltage transmission lines, and step-down voltage/step-up

current to local distribution circuits or industrial customers. The step-up transformer is

used to increase the secondary voltage relative to the primary voltage, whereas the step-

down transformer is used to decrease the secondary voltage relative to the primary



voltage. Transformers range in size from thumbnail-sized used in microphones to units

weighing hundreds of tons interconnecting the power grid. A broad range of transformer

designs are used in electronic and electric power applications, including miniature, audio,

isolation, high-frequency, power conversion transformers, etc.

5.7.3 Basic principles:

The functioning of a transformer is based on two principles of the laws of

electromagnetic induction: An electric current through a conductor, such as a wire,

produces a magnetic field surrounding the wire, and a changing magnetic field in the

vicinity of a wire induces a voltage across the ends of that wire.

The magnetic field excited in the primary coil gives rise to self-induction as well

as mutual induction between coils. This self-induction counters the excited field to such a

degree that the resulting current through the primary winding is very small when no load

draws power from the secondary winding.

The physical principles of the inductive behavior of the transformer are most

readily understood and formalized when making some assumptions to construct a simple

model which is called the ideal transformer. This model differs from real transformers by

assuming that the transformer is perfectly constructed and by neglecting that electrical or

magnetic losses occur in the materials used to construct the device.

5.8 ANALOG TO DIGITAL CONVERTER

An analog-to-digital converter (abbreviated ADC, A/D or A to D) is a device that

converts a continuous physical quantity (usually voltage) to a digital number that

represents the quantity's amplitude.

5.9 CONCLUSION

In this chapter we discussed about different type of electrical components which we used

in our academic project.



CHAPTER 06

SENSOR

6.1 INTRODUCTION

In our project we used two sensors for general purpose use of our robot. First one

is gas sensor and another is temperature sensor.

A sensor is a physical device or biological organ that detects, or senses, a signal or

physical condition and chemical compounds.

6.2 OVERVIEW

Most sensors are electrical or electronic, although other types exist. A sensor is a

type of transducer. Sensors are either direct indicating (e.g. a mercury thermometer or

electrical meter) or are paired with an indicator (perhaps indirectly through an analog to

digital converter, a computer and a display) so that the value sensed becomes human

readable. In addition to other applications, sensors are heavily used in medicine, industry

and robotics. Technical progress allows more and more sensors to be manufactured with

MEMS technology. In most cases this offers the potential to reach a much higher

sensitivity. See also MEMS sensor generations.

6.3 TYPES OF SENSORS

Since a significant change involves an exchange of energy, sensors can be classified

according to the type of energy transfer that they detect.



6.3.1 Thermal sensors:

Temperature sensors:

Thermometers, thermocouples, temperature sensitive resistors (thermistors and

resistance temperature detectors), bi-metal thermometers and thermostats

Heat sensors:

Bolometer, calorimeter

6.3.2 Electromagnetic sensors:

electrical resistance sensors: ohmmeter, multimeter

electrical current sensors: galvanometer, ammeter

electrical voltage sensors: leaf electroscope, voltmeter

electrical power sensors: watt-hour meters

magnetism sensors: magnetic compass, fluxgate compass, magnetometer, Hall

effect device,

metal detectors

6.3.3 Mechanical sensors:

pressure sensors: altimeter, barometer, barograph, pressure gauge, air speed

indicator, rate of climb indicator, variometer

gas and liquid flow sensors: flow sensor, anemometer, flow meter, gas meter,

water meter, mass flow sensor

mechanical sensors: acceleration sensor, position sensor, selsyn, switch, strain

gauge

6.3.4 Chemical sensors:

Chemical sensors detect the presence of specific chemicals or classes of

chemicals. Examples include oxygen sensors, also known as lambda sensors, ion-

selective electrodes, pH glass electrodes, and redox electrodes.



6.3.5 Optical and radiation sensors:

Electromagnetic time-of-flight. Generate an electromagnetic impulse, broadcast it,

then measure the time a reflected pulse takes to return. Commonly known as -

RADAR (Radio Detection And Ranging) are now accompanied by the analogous

LIDAR (Light Detection And Ranging. See following line), all being

electromagnetic waves. Acoustic sensors are a special case in that a pressure

transducer is used to generate a compression wave in a fluid medium (air or

water)

light time-of-flight. Used in modern surveying equipment, a short pulse of light is

emitted and returned by a retroreflector. The return time of the pulse is

proportional to the distance and is related to atmospheric density in a predictable

way.

6.4 TEMPERATURE SENSOR (THERMISTOR)

6.4.1 Introduction:

A thermistor is a type of resistor whose resistance varies significantly

with temperature, more so than in standard resistors. The word is

a portmanteau of thermal and resistor. Thermistors are widely used as inrush current

limiters, temperature sensors, self-resetting over current protectors, and self-

regulating heating elements.

Thermistors differ from resistance temperature detectors (RTD) in that the

material used in a thermistor is generally a ceramic or polymer, while RTDs use pure

metals. The temperature response is also different; RTDs are useful over larger

temperature ranges, while thermistors typically achieve a higher precision within a

limited temperature range, typically 90 C to 130 C.

Thermistors are thermally sensitive resistors produced

Documents

pipe inspection