AUTOMATIC PNEUMATIC BRAKING AND BUMPER SYSTEM

Submitted in partial fulfillment of the requirement for the award of

DIPLOMA

IN

MECHANICAL ENGINEERING

BY

Under the guidance of ------------------------

2005-2006

DEPARTMENT OF MECHANICAL ENGINEERING

CERTIFICATE

Register number: _________________________

This is to certify that the project report titled “PNEUMATIC BUMPER FOR FOUR WHEELER” submitted by the following students for the award of Diploma engineering is record of bonafide work carried out by them.

Done byMr. /Ms._______________________________

In partial fulfillment of the requirement for the award of

Diploma in Mechanical Engineering During the Year – (2004-2005)

_________________ _______________Head of Department Guide

Coimbatore –641651.Date:

Submitted for the university examination held on ___________

_________________ ________________ Internal Examiner External Examiner

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ACKNOWLEDGEMENT---------------------------------------------------------------------------------

ACKNOWLEDGEMENT

At this pleasing moment of having successfully

completed our project, we wish to convey our

sincere thanks and gratitude to the management

of our college and our beloved chairman

…………………………………………………, who provided all

the facilities to us.

We would like to express our sincere thanks to

our principal ………………………………………, for

forwarding us to do our project and offering

adequate duration in completing our project.

We are also grateful to the Head of

Department Prof. …………………………………….., for

her constructive suggestions & encouragement

during our project.

With deep sense of gratitude, we extend our

earnest & sincere thanks to our guide

…………………………………………………….., Department

of Mechanical for her kind guidance &

encouragement during this project.

We also express our indebt thanks to our

TEACHING and NON TEACHING staffs of

MECHANICAL ENGINEERING DEPARTMENT,

……………………….(COLLEGE NAME).

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PNEUMATIC BUMPER FOR FOUR WHEELER

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CONTENTS---------------------------------------------------------------------------------

CONTENTS

ADKNOWLEDGEMENT

1. SYNOPSIS

2. INTRODUCTION

3. LITERATURE SURVEY

4. TYPES OF BRAKING

5. IR SENSOR

6. PROXIMITY SENSOR

7. COMPONENTS AND DESCRIPTION

8. BLOCK DIAGRAM

9. WORKING PROCEDURE

10. PROGRAM

11. APPLICATION AND ADVANTAGES

12. LIST OF MATERIAL

13. COST ESTIMATION

14. CONCLUSION

BIBLIOGRAPHY

PHOTOGRAPHY

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Chapter-1

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SYNOPSIS---------------------------------------------------------------------------------

CHAPTER-1

SYNOPSIS

The technology of pneumatics has gained tremendous importance in the field of

workplace rationalization and automation from old-fashioned timber works and coal

mines to modern machine shops and space robots. It is therefore important that

technicians and engineers should have a good knowledge of pneumatic system, air

operated valves and accessories.

The aim is to design and develop a control system based an

intelligent electronically controlled automotive bumper activation

system is called “AUTOMATIC PNEUMATIC BRAKING AND BUMPER

SYSTEM”. This system is consists of IR transmitter and Receiver circuit, Control Unit,

Pneumatic bumper system. The IR sensor is used to detect the obstacle. There is any

obstacle closer to the vehicle (with in 4 feet), the control signal is given to the bumper

activation system.

The pneumatic bumper system is used to product the man and vehicle. This

bumper activation system is only activated the vehicle speed above 40-50 km per hour.

This vehicle speed is sensed by the proximity sensor and this signal is given to the control

unit and pneumatic bumper activation system.

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Chapter-2---------------------------------------------------------------------------------------

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INTRODUCTION---------------------------------------------------------------------------------

CHAPTER-2

INTRODUCTION

We have pleasure in introducing our new project “AUTOMATIC

PNEUMATIC BUMPER”, which is fully equipped by IR sensors circuit and Pneumatic

bumper activation circuit. It is a genuine project which is fully equipped and designed for

Automobile vehicles. This forms an integral part of best quality. This product underwent

strenuous test in our Automobile vehicles and it is good.

NEED FOR AUTOMATION:

Automation can be achieved through computers, hydraulics, pneumatics, robotics,

etc., of these sources, pneumatics form an attractive medium for low cost automation.

The main advantages of all pneumatic systems are economy and simplicity. Automation

plays an important role in mass production.

For mass production of the product, the machining operations decide the

sequence of machining. The machines designed for producing a particular product are

called transfer machines. The components must be moved automatically from the bins to

various machines sequentially and the final component can be placed separately for

packaging. Materials can also be repeatedly transferred from the moving conveyors to the

work place and vice versa.

Nowadays almost all the manufacturing process is being atomized in order to

deliver the products at a faster rate. The manufacturing operation is being atomized for

the following reasons.

To achieve mass production

To reduce man power

To increase the efficiency of the plant

To reduce the work load

To reduce the production cost

To reduce the production time

To reduce the material handling

To reduce the fatigue of workers

To achieve good product quality

Less Maintenance

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Chapter-3---------------------------------------------------------------------------------------

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LIERATURE SURVEY---------------------------------------------------------------------------------

CHAPTER-3

LITERATURE SURVEY

SAFETY SYSTEM:

The aim is to design and develop a control system based on pneumatic breaking

system of an intelligent electronically controlled automotive braking system. Based on

this model, control strategies such as an 'antilock braking system' (ABS) and improved

maneuverability via individual wheel braking are to be developed and evaluated.

There have been considerable advances in modern vehicle braking systems in

recent years. For example, electronically controlled ABS for emergency braking,

electronically controlled hydraulically actuated individual brake-by-wire (BBW) systems

for saloon cars and electronically controlled pneumatically actuated systems for heavy

goods vehicles. The work of recent years shall form the basis of a system design

approach to be implemented. The novelty of the proposed research programmed shall lie

in the design and evaluation of control systems for achieving individual wheel motion

control facilitated by BBW. In the case of BBW the brake pedal is detached from the

hydraulic system and replaced by a 'brake pedal simulator'. The simulator provides an

electrical signal for the electronic control system.

Preliminary modeling and simulation work considers a quarter cars initially

followed by a natural progression to the half car and full four wheel station cases. The

model is to be constructed in modular form thus allowing the replacement / interchange

of the various blocks and their associated technologies. Upon completion of the full

vehicle braking model, sensitivity analyses will be carried out. Once the preliminary

simulation model has been thoroughly benchmarked and existing control system

strategies evaluated, an audit of the technology used is to take place and this will provide

a basis for comparison of iterative technologies / techniques.

The final phase of the new modern vehicle shall include:

Development of improved ABS control systems

Development and assessment of an electro-hydraulic-BBW (EH-BBW) system

Individual wheel braking combined with traction control

Assessing sensor failure and fault tolerant control system design

Preliminary studies into an electrically actuated system

Re-engineering using simplified models.

PNEUMATICS

The word ‘pneuma’ comes from Greek and means breather wind. The word

pneumatics is the study of air movement and its phenomena is derived from the word

pneuma. Today pneumatics is mainly understood to means the application of air as a

working medium in industry especially the driving and controlling of machines and

equipment.

Pneumatics has for some considerable time between used for carrying out the

simplest mechanical tasks in more recent times has played a more important role in the

development of pneumatic technology for automation.

Pneumatic systems operate on a supply of compressed air which must be made

available in sufficient quantity and at a pressure to suit the capacity of the system. When

the pneumatic system is being adopted for the first time, however it wills indeed the

necessary to deal with the question of compressed air supply.

The key part of any facility for supply of compressed air is by means using

reciprocating compressor. A compressor is a machine that takes in air, gas at a certain

pressure and delivered the air at a high pressure.

Compressor capacity is the actual quantity of air compressed and delivered and the

volume expressed is that of the air at intake conditions namely at atmosphere pressure

and normal ambient temperature.

The compressibility of the air was first investigated by Robert Boyle in 1962 and

that found that the product of pressure and volume of a particular quantity of gas.

The usual written as

PV = C (or) PıVı = P2V2

In this equation the pressure is the absolute pressured which for free is about 14.7

Psi and is of courage capable of maintaining a column of mercury, nearly 30 inches high

in an ordinary barometer. Any gas can be used in pneumatic system but air is the mostly

used system now a days.

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Chapter-4---------------------------------------------------------------------------------------

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TYPES OF BRAKING---------------------------------------------------------------------------------

CHAPTER-4

TYPES OF BRAKING

The brakes for automotive use may be classified according the following considerations.

1. PURPOSE

2. LOCATION

3. CONSTRUCTION

4. METHOD OF ACTUATION

5. EXTRA BRAKING EFFORT

Based on the above considerations, brakes are classified with respect to following

factors.

1. With respect to application,

a. Foot brake

b. Hand brake

2. With respect to the number of wheels,

a. Two wheel brakes

b. Four wheel brakes

3. With respect to the method of braking contact

a. Internal expanding brakes

b. External contracting brakes

4. With respect to the method of applying the braking force.

a. Single acting brake

b. Double acting brakes.

5. With respect to the brake gear,

a. Mechanical brake

b. Power brakes

6. With respect to the nature of power employed

a. Vacuum brake

b. Air brake

c. Hydraulic brake

d. Hydrostatic brake

e. Electric brake

7. With respect to power transmission,

a. Direct acting brakes

b. Geared brakes

8. With respect to power unit,

a. Cylinder brakes

b. Diaphragm brake

The foot brake or service brake is always applied by a pedal, while the parking

brake is applied by a hand lever. The parking brake is intended chiefly to hold the car in

position. The parking brake can be set in the “ON” position by means of a latch while

the service brake remains on only as long as the driver presses down on the pedal.

The hand brake is normally used only after the driver has stopped the car by using

the foot brake. Its other use is as an emergency brake to stop the car if the foot braked

system should fail. The hand or parking brakes operates on a pair of wheels, frequently

the rear wheels. When drum type rear brakes are used, the same shoes can be used for

both hand and foot control.

The drum type of brake may either be a band brake or a shoe brake. Both band

brakes and shoe brakes may be either external or internal. The band brakes generally are

external and shoe brakes internal. In drum brakes the drum is attached to the wheel and

revolves with it. Friction to slow the drum is applied from inside by the shoes which do

not rotate but are mounted on a stationary metal back plate. There are different types of

drum brakes such as a two leading shoe arrangement – which gives an augmented

response to pedal effort because of its self applying arrangement. A leading-trailing shoe

is a cheaper and better alternative as it is equally effective whether the car is going

forward or backwards.

Manufacturers design drum brakes so that rain, show or ice or grit cannot get

inside and decrease braking efficiency for moisture greatly reduces the friction between

the linings and the drum.

The dissipate quickly the considerable amount of heat generated when braking a

fast moving heavy car large brake drums would be required. Disc brakes do the job more

efficiently, for the cooling air can get to the rubbing between each piston and the disc,

there is a friction pad held in position by retaining pins, spring plates etc. Passages are

drilled in the caliper for the fluid to enter or leave the each housing. These passages are

also connected to another one for bleeding. Each cylinder contains a rubber selling ring

between the cylinder and the piston.

The brakes are applied, hydraulically actuated piston move the friction pads into

contact with the disc, applying equal and opposite forces on the later. On releasing the

brakes, the rubber sealing rings act as return springs and retract the pistons and the

friction pads away from the disc.

Now let us see in detail about different braking systems in automobiles.

MECHANICAL BRAKE:

In a motor vehicle, the wheel is attached to an auxiliary wheel called drum. The

brake shoes are made to contact this drum. In most designs, two shoes are used with each

drum to form a complete brake mechanism at each wheel. The brake shoes have bake

linings on their outer surfaces. Each brake shoe is hinged at one end by on anchor pin;

the other end is operated by some means so that the brake shoe expands outwards. The

brake linings come into contact with the drum. Retracting spring keeps the brake shoe

into position when the brakes are not applied. The drum encloses the entire mechanism

to keep out dust and moisture. The wheel attaching bolts on the drum are used to contact

wheel and drum. The braking plate completes the brake enclosure, holds the assembly to

car axie, and acts the base for fastening the brake shoes and operating mechanism. The

shoes are generally mounted to rub against the inside surface of the drum to form as

internal expanding brake as shown in the figure.

HYDRAULIC BRAKES:

The hydraulic brakes are applied by the liquid pressure. The pedal force is

transmitted to the brake shoe by means of a confined liquid through a system of force

transmission.

The force applied to the pedal is multiplied and transmitted to brake shoes by a

force transmission system. This system is based upon Pascal’s principle, which states

that “The confined liquids transmit pressure without loss equally in all directions”.

It essentially consists of two main components – master cylinder and wheel

cylinder the master cylinder is connected by the wheel cylinders at each of the four

wheels. The system is filled with the liquid under light pressure when the brakes are not

in operation. The liquid is known as brake fluid, and is usually a mixture of glycerin and

alcohol or caster-oil, denatured alcohol and some additives Spring pressure, and thus the

fluid pressure in the entire system drops to its original low valve, which allows retracting

spring on wheel brakes to pull the brake shoes out of contact with the brake drums into

their original positions. This causes the wheel cylinder piston also to come back to its

original inward position. Thus, the brakes are released.

AIR BRAKE:

Air brakes are widely used in heavy vehicle like buses and trucks which require a

heavier braking effort that can be applied by the driver’s foot. Air brakes are applied by

the pressure of compressed air, instead of foot pressure, acting against flexible

diaphragms in brake chamber. The diaphragms are connected to the wheel brakes. These

diaphragms are controlled through a hand or foot operated valve. The brake valve

controls brake operation by directing the flow of air from a reservoir against diaphragms

in the brake chamber when the brakes are applied and from brake chambers to tube

atmosphere when the brakes are released. The air compressor, driven by the engine

furnishes compressed air to the reservoir fall below a set valve.

ELECTRIC BRAKE:

Electric Brakes are also used in some motor vehicles, although these are not very

popular. Warner electric brake is one of the examples of such brakes. An electric brake

essentially consists of an electromagnet within the brake drum. The current from the

battery is utilized to energize the electromagnet, which actuates the mechanism to expand

the brake shoe against the brake drum, thus applying the brakes. The severity of braking

is controlled by means of a rheostat, which is operated by the driver through the foot

pedal.

Electric brakes are simpler. These brakes do not require complicated operating

linkage. Only cable is required to take current from the battery to the electromagnet.

Also, these are very quick in action as compared to other types of brakes.

VACUUM BRAKES / SERVO BRAKES:

A serve mechanism fitted to the braking system reduces the physical effort the

driver has to use on the brake pedal most servo mechanisms are of the vacuum assistance

type. A pressure differential can be established by subjecting one side of the piston to

atmospheric pressure and the other side to a pressure below atmospheric pressure by

exhausting air from the corresponding end of the servo cylinder.

REGENERATIVE BRAKING:

Electricity powered vehicles use regenerative braking for stopping the vehicle.

With regenerative braking pressing the brake pedal does not necessarily activate a

conventional friction brake. The motor controller controlling the vehicle is treated as a

generator which slows the vehicle and simultaneously provides an output for charging the

battery. The effectiveness of regenerative braking falls of with vehicle speed. Electric

vehicles will have to be fitted with conventional hydraulic friction brakes as well as with

regenerative systems.

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Chapter-5---------------------------------------------------------------------------------------

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IR SENSOR---------------------------------------------------------------------------------

CHAPTER-5

IR SENSOR

SENSORS

A sensor is a transducer used to make a measurement of a physical variable. Any

sensor requires calibration in order to be useful as a measuring device. Calibration is the

procedure by which the relationship between the measured variable and the converted

output signal is established.

Care should be taken in the choice of sensory devices for particular tasks. The

operating characteristics of each device should be closely matched to the task for which it

is being utilized. Different sensors can be used in different ways to sense same

conditions and the same sensors can be used in different ways to sense different

conditions.

TYPES OF SENSOR:

Passive sensors detect the reflected or emitted electro-magnetic radiation from

natural sources, while active sensors detect reflected responses from objects which are

irradiated from artificially generated energy sources, such as radar. Each is divided

further in to non-scanning and scanning systems.

A sensor classified as a combination of passive, non-scanning and non-imaging

method is a type of profile recorder, for example a microwave radiometer. A sensor

classified as passive, non-scanning and imaging method, is a camera, such as an aerial

survey camera or a space camera, for example on board the Russian COSMOS satellite.

Sensors classified as a combination of passive, scanning and imaging are classified

further into image plane scanning sensors, such as TV cameras and solid state scanners,

and object plane scanning sensors, such as multi-spectral scanners (optical-mechanical

scanner) and scanning microwave radiometers.

An example of an active, non-scanning and non-imaging sensor is a profile

recorder such as a laser spectrometer and laser altimeter. An active, scanning and imaging

sensor is radar, for example synthetic aperture radar (SAR), which can produce high

resolution, imagery, day or night, even under cloud cover.

The most popular sensors used in remote sensing are the camera, solid state

scanner, such as the CCD (charge coupled device) images, the multi-spectral scanner and

in the future the passive synthetic aperture radar.

Laser sensors have recently begun to be used more frequently for monitoring air

pollution by laser spectrometers and for measurement of distance by laser altimeters.

CHARACTERISTICS OF OPTICAL SENSOR:

Optical sensors are characterized specified by spectral, radiometric and geometric

performance

The spectral characteristics are spectral band and band width, the central

wavelength, response sensitivity at the edges of band, spectral sensitivity at outer

wavelengths and sensitivity of polarization.

Sensors using film are characterized by the sensitivity of film and the

transmittance of the filter, and nature of the lens. Scanner type sensors are specified by

the spectral characteristics of the detector and the spectral splitter. In addition, chromatic

aberration is an influential factor. The radiometric characteristics of optical sensors are

specified by the change of electro-magnetic radiation which passes through an optical

system. They are radiometry of the sensor, sensitivity in noise equivalent power,

dynamic range, signal to noise ratio (S/N ratio) and other noises, including

quantification noise.

The geometric characteristics are specified by those geometric factors such as field

of view (FOV), instantaneous field of news (IFOV), band to band registration, MTF,

geometric distortion and alignment of optical elements.

IFOV is defined as the angle contained by the minimum area that can be detected

by a scanner type sensor. For example in the case of an IFOV of 2.5 milli radians, the

detected area on the ground will be 2.5 meters x 2.5 meters, if the altitude of sensor is

1,000 m above ground.

In our project IR transmitter and IR receiver are used to detect the obstacle. These

sensors are fitted at the front side of the vehicle.

IR TRANSMITTER:

The IR transmitting circuit is used in many projects. The IR transmitter sends 40

kHz (frequency can be adjusted) carrier under 555 timer control. IR carriers at around 40

kHz carrier frequencies are widely used in TV remote controlling and ICs for receiving

these signals are quite easily available.

IR RECEIVER:

The transmitted signal reflected by the obstacle and the IR receiver circuit receives

the signal and giving control signal to the control unit. The control unit activates the

pneumatic breaking system, so that break was applied.

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Chapter-6---------------------------------------------------------------------------------------

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COMPONENTS AND DESCRIPTION -----------------------------------------------------------------------------------------

CHAPTER-6

PROXIMITY SENSORS

Infrared proximity sensors

Infrared proximity sensors work by sending out a beam of IR light, and then

computing the distance to any nearby objects from characteristics of the returned

(reflected) signal. There are a number of ways to do this, each with its own advantages

and disadvantages:

Reflected IR strength

You could build a simple IR proximity sensor out of essentially just an IR LED

and IR photodiode. This simple sensor, though, would be prey to background light

(i.e., your IR "receiver" would be responding to naturally present IR as well as

reflected IR).

Modulated IR signal

A better solution would be to modulate your transmitted IR (i.e., to send out a

rapidly-varying IR signal), and then have the receive circuitry only respond to the

level of the received, matching, modulated IR signal (i.e., to ignore the DC

component of the received signal, and only trigger off the AC component). This

method, though, is still at the mercy of the characteristics (in particular, IR

reflectance) of the obstacle you're trying to sense.

Triangulation

The best way to use IR to sense an obstacle is to sense the angle at which the

reflected IR is returned to your sensor. By use of a bit of trigonometry, you can

then compute distance, knowing the location of your transmit and receive

elements. Needless to say, this isn't a simple sensor to build yourself.

You're probably money ahead by just buying an IR proximity sensor with this logic built

in. One I particularly like is the Sharp GP2D15 IR Ranger. It has a built-in detection

range of 24 cm (this keeps its cost, and the complexity of your interface circuitry down),

is reasonably priced, and is available from Acroname. Acroname also has an interesting

article covering the operation and utilization of all the impressive Sharp IR sensors here.

The GP2D15 interface is 3-wire with power, ground and the output voltage (the sensor

outputs Vcc when it sees something at 24 cm distance); it requires 4.5 - 5.5 V power for

operation, and eats about 50 mA of current as long as it is powered. So its advantages are

(1) its simple interface, and (2) easy, reliable sensing of obstacles at a distance. Its

disadvantages are (1) its requirement for 5 V power, and (2) its requirement for 50 mA of

current regardless of whether anything is being sensed (neither of these recommend this

sensor for solar-powered 'bots).

If your BEAMbot's circuitry has provision for a "touch-switch" contact sensor, the

GP2D15 can easily be used instead, with the addition of an NPN transistor:

Acoustic proximity sensors

One oft-used method (at least on larger, pricier 'bots) of avoiding hazards is via sonar

ranging. Here, acoustic signals ("ping"s) are sent out, with the time of echo return being a

measure of distance to an obstacle. This does, unfortunately, require fairly accurate

timing circuitry -- so acoustic sensors really require a processor of some sort to drive

them. Also note that acoustic sensing essentially requires the use of commercial sensors,

there's no real way to "homebrew" something from scratch.

The most common acoustic proximity sensor is the kind used in polaroid cameras. For

details on these, I'll refer you to the Acroname site's "Polaroid Sonar Ranging Primer."

There's now also a "new kid on the block" -- the Devantech SRF04 UltraSonic Ranger.

Acroname sells it (see their page on it here), and "Tech Geek" has a review on it here.

This guy costs about twice what the Sharp IR sensors cost, but has a much wider range of

sensing; it costs far less than the Polaroid acoustic rangers, is easier to interface, and

draws less power.

Capacitive proximity sensors

Your 'bot can also sense its distance to objects by detecting changes in capacitance

around it. When power is applied to the sensor, an electrostatic field is generated and

reacts to changes in capacitance cause by the presence of a target. The main disadvantage

to this sensor (often called a capaciflector) is that its usefulness is dependent on

properties of the obstacles it is sensing (namely, their dialectric constant). The higher the

dielectric constant (say, water), the more sensitive a capacitive sensor is to that target.

The sensing distance depends on the dielectric constant of the target and the surface areas

of the probe and the target.

Inductive proximity sensors

Another method for sensing distance to objects is through the use of induced magnetic

fields. The primary problem with this method is that it is largely confined to sensing

metallic objects.

Contact sensors (as their name implies) require physical contact with some other object in

order to "trigger."

While this is sometimes a bit inconvenient for your 'bot (unlike proximity sensors,

contact sensors won't help a 'bot avoid an obstacle before it is within "arm's reach"), it has

two big advantages:

Contact sensors are very easy to build at home from various bits & pieces you probably

already have lying around.

Contact sensors don't draw power until contact is made.

Obstacle avoidance contact sensors

Contact sensors for obstacle avoidance are essentially the electronic version of a

cat's "whiskers." In most designs, a whisker is attached to one electrical contact, and this

contact gets pushed into another one if the whisker touches something. You can also just

mount a "whisker" to a small pushbutton switch (you can salvage some nice "soft" ones

from floppy drives).

Ian Bernstein's site has an excellent tutorial for one contact sensor design here.

Ground contact sensors

Some BEAMbots may want to know when a leg touches the ground. Here, you'll

need some sort of a foot contact sensor. Again, you can use a "soft" pushbutton switch

(preferably salvaged) for this job. You can also build a fairly simple ground contact

sensor of your own.

Clifford Boerema, Jr. posted a nice design for a foot contact sensor.

Field (electric, capacitance) sensors

Field sensors aren't used much in BEAMbots yet (principally because of the power

and complexity some designs require). A couple, though, has been put forward to date

(bear in mind that I haven't built either, so you're on your own here...):

Wilf Rigter's E-sensor

The incomparable Wilf Rigter came up with an E-field detector (well, two variant designs

actually) that your bot can use, Either of these (and just on a hunch, I'd suspect the

2N7000 version is easier to get parts for) should work equally well; note that the human

body is a good absorber of stray RF fields, so this sensor should be a good people-

detector.

Rich Caudle's capaciflector

There's more info on the capaciflector here, and a brief abstract on it here.

State sensors

State sensors tell your 'bot something about its condition -- tilt, temperature, and

the like. These can be used to change your 'bot's behavior in ways (ideally) that help it

protect itself and get around.

Tilt switches pix/tilt_switches.jpg pix/tilt_switches.jpg pix/tilt_switches.jpg (1/4" grid)

A number of types of tilt switches are commercially available -- all use some sort of

moving contact (in some cases a blob of mercury, in others a metal ball) to short out

various contacts. You can use these to cause your 'bot to do something special if...

Your BEAMbot has flipped "upside down"

Your BEAMbot is on a "dangerous" slope, and needs to turn in order to avoid

rolling

Your BEAMbot is attempting to climb up / down a slope that is beyond its

capabilities, and needs to reverse

'Most any of these will work for you; personally, I try to avoid tilt switches containing

mercury since its toxic, and generally contained in glass vials that are fairly easy to

accidentally break open.

Temperature sensors

Thermister, other goodies...

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Chapter-7---------------------------------------------------------------------------------------

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COMPONENTS AND DESCRIPTION -----------------------------------------------------------------------------------------

CHAPTER-7

COMPONENTS AND DESCRIPTION

SELECTION OF PNEUMATICS:

Mechanization is broadly defined as the replacement of manual effort by

mechanical power. Pneumatics is an attractive medium for low cost mechanization

particularly for sequential or repetitive operations. Many factories and plants already

have a compressed air system, which is capable of providing both the power or energy

requirements and the control system (although equally pneumatic control systems may be

economic and can be advantageously applied to other forms of power).

The main advantages of an all-pneumatic system are usually economy and

simplicity, the latter reducing maintenance to a low level. It can also have out standing

advantages in terms of safety.

PNEUMATIC COMPONENTS AND ITS DESCRIPTION

The pneumatic bearing press consists of the following components to fulfill the

requirements of complete operation of the machine.

1) PNEUMATIC SINGLE ACTING CYCLINDER

2) SOLENOID VALVE

3) FLOW CONTROL VALVE

4) IR SENSOR UNIT

5) WHEEL AND BRAKE ARRANGEMENT

6) PU CONNECTOR, REDUCER, HOSE COLLAR

7) STAND

8) SINGLE PHASE INDUCTION MOTOR

1) PNEUMATIC SINGLE ACTING CYLINDER:

Pneumatic cylinder consist of

A) PISTON B) CYLINDER

The cylinder is a Single acting cylinder one, which means that the air pressure

operates forward and spring returns backward. The air from the compressor is passed

through the regulator which controls the pressure to required amount by adjusting its

knob.

A pressure gauge is attached to the regulator for showing the line pressure.

Then the compressed air is passed through the single acting 3/2 solenoid valve for

supplying the air to one side of the cylinder.

One hose take the output of the directional Control (Solenoid) valve and they are

attached to one end of the cylinder by means of connectors. One of the outputs from the

directional control valve is taken to the flow control valve from taken to the cylinder. The

hose is attached to each component of pneumatic system only by connectors.

CYLINDER TECHNICAL DATA:

Piston Rod:

M.S. hard Chrome plated

Seals:

Nitrile (Buna – N) Elastomer

End Covers:

Cast iron graded fine grained from 25mm to 300mm

Piston:

-Aluminium.

Media:

-Air.

Temperature Range:

0^c to 85^c

Parts of Pneumatic Cylinder

Piston:

The piston is a cylindrical member of certain length which reciprocates inside the

cylinder. The diameter of the piston is slightly less than that of the cylinder bore

diameter and it is fitted to the top of the piston rod. It is one of the important parts which

convert the pressure energy into mechanical power.

The piston is equipped with a ring suitably proportioned and it is relatively soft

rubber which is capable of providing good sealing with low friction at the operating

pressure. The purpose of piston is to provide means of conveying the pressure of air

inside the cylinder to the piston of the oil cylinder.

Generally piston is made up of

Aluminium alloy-light and medium work.

Brass or bronze or CI-Heavy duty.

The piston is single acting spring returned type. The piston moves forward when

the high-pressure air is turned from the right side of cylinder.

The piston moves backward when the solenoid valve is in OFF condition. The

piston should be as strong and rigid as possible. The efficiency and economy of the

machine primarily depends on the working of the piston. It must operate in the cylinder

with a minimum of friction and should be able to withstand the high compressor force

developed in the cylinder and also the shock load during operation.

The piston should posses the following qualities.

a. The movement of the piston not creates much noise.

b. It should be frictionless.

c. It should withstand high pressure.

Piston Rod

The piston rod is circular in cross section. It connects piston with piston of other

cylinder. The piston rod is made of mild steel ground and polished. A high finish is

essential on the outer rod surface to minimize wear on the rod seals. The piston rod is

connected to the piston by mechanical fastening. The piston and the piston rod can be

separated if necessary.

One end of the piston rod is connected to the bottom of the piston. The other end

of the piston rod is connected to the other piston rod by means of coupling. The piston

transmits the working force to the oil cylinder through the piston rod. The piston rod is

designed to withstand the high compressive force. It should avoid bending and withstand

shock loads caused by the cutting force. The piston moves inside the rod seal fixed in the

bottom cover plate of the cylinder. The sealing arrangements prevent the leakage of air

from the bottom of the cylinder while the rod reciprocates through it.

Cylinder Cover Plates

The cylinder should be enclosed to get the applied pressure from the compressor

and act on the pinion. The cylinder is thus closed by the cover plates on both the ends

such that there is no leakage of air. An inlet port is provided on the top cover plate and

an outlet ports on the bottom cover plate. There is also a hole drilled for the movement

of the piston.

The cylinder cover plate protects the cylinder from dust and other particle and

maintains the same pressure that is taken from the compressor. The flange has to hold

the piston in both of its extreme positions. The piston hits the top plat during the return

stroke and hits the bottom plate during end of forward stroke. So the cover plates must

be strong enough to withstand the load.

Cylinder Mounting Plates:

It is attached to the cylinder cover plates and also to the carriage with the help of

‘L’ bends and bolts.

2. SOLENOID VALVE WITH CONTROL UNIT:

The directional valve is one of the important parts of a pneumatic system.

Commonly known as DCV, this valve is used to control the direction of air flow in the

pneumatic system. The directional valve does this by changing the position of its internal

movable parts.

This valve was selected for speedy operation and to reduce the manual effort and

also for the modification of the machine into automatic machine by means of using a

solenoid valve. A solenoid is an electrical device that converts electrical energy into

straight line motion and force. These are also used to operate a mechanical operation

which in turn operates the valve mechanism. Solenoids may be push type or pull type.

The push type solenoid is one in which the plunger is pushed when the solenoid is

energized electrically. The pull type solenoid is one is which the plunger is pulled when

the solenoid is energized.

The name of the parts of the solenoid should be learned so that they can be

recognized when called upon to make repairs, to do service work or to install them.

Parts of a Solenoid Valve

1. Coil

The solenoid coil is made of copper wire. The layers of wire are separated by

insulating layer. The entire solenoid coil is covered with an varnish that is not affected

by solvents, moisture, cutting oil or often fluids. Coils are rated in various voltages such

as 115 volts AC, 230 volts AC, 460 volts AC, 575 Volts AC, 6 Volts DC, 12 Volts DC,

24 Volts DC, 115 Volts DC & 230 Volts DC. They are designed for such frequencies as

50 Hz to 60 Hz.

2. Frame

The solenoid frame serves several purposes. Since it is made of laminated sheets,

it is magnetized when the current passes through the coil. The magnetized coil attracts

the metal plunger to move. The frame has provisions for attaching the mounting. They

are usually bolted or welded to the frame. The frame has provisions for receivers, the

plunger. The wear strips are mounted to the solenoid frame, and are made of materials

such as metal or impregnated less fiber cloth.

3. Solenoid Plunger

The Solenoid plunger is the mover mechanism of the solenoid. The plunger is

made of steel laminations which are riveted together under high pressure, so that there

will be no movement of the lamination with respect to one another. At the top of the

plunger a pin hole is placed for making a connection to some device. The solenoid

plunger is moved by a magnetic force in one direction and is usually returned by spring

action. Solenoid operated valves are usually provided with cover over either the solenoid

or the entire valve. This protects the solenoid from dirt and other foreign matter, and

protects the actuator. In many applications it is necessary to use explosion proof

solenoids.

WORKING OF 3/2 SINGLE ACTING SOLENOID (OR) CUT OFF VALVE:

The control valve is used to control the flow direction is called cut off valve or

solenoid valve. This solenoid cut off valve is controlled by the emergency push button.

The 3/2 Single acting solenoid valve is having one inlet port, one outlet port and one

exhaust port. The solenoid valve consists of electromagnetic coil, stem and spring. The

air enters to the pneumatic single acting solenoid valve when the push button is in ON

position.

Technical Data:

Size : ¼”

Pressure : 0 to 7 kg / cm2

Media : Air

Type : 3/2

Applied Voltage : 230V A.C

Frequency : 50 Hz

3. FLOW CONTROL VALVE:

1. Technical Data:

Size : ¼”

Pressure : 0 to 10 kg / cm2

Media : Air

(b) Purpose:

This valve is used to speed up the piston movement and also it acts as an one – way

restriction valve which means that the air can pass through only one way and it can’t

return back. By using this valve the time consumption is reduced because of the faster

movement of the piston.

1 8

2 7 IC 5553 6

4 5

4. IR SENSOR UNIT:-

The IR transmitter and IR receiver circuit is used to sense the obstacle. It is fixed

to the back side of the frame stand with a suitable arrangement. The pneumatic cylinder is

controlled by the flow control valve, single acting solenoid valve and control unit.

IR TRANSMITTER CIRCUIT:

+Vcc

R4 (47Ω) T1 (BD140) 150K 3 1 2 C3 (100µ/25V) R1 R2 (47Ω) 1.5K R5 4.7Ω L1 IR LED C2 C1 0.01pF 0.1pF

IR RECEIVER CIRCUIT:

1K

+12V

RELAY R12 (680Ω) R1 (4.7K) RL1 L1 (IR SENSOR) D2 R10 C3 (100µ) C2 (100µ) L2 (IR SENSOR) L3 (LED) 1N4007 4.7K R3 R2 R7 (100K) 4.7K 4.7K

D1 (1N 4007) T3 C4 (0.1pF) C1 (0.01 pF) T5 (BC547B) R9 (4.7K) R8 BC 557

T4 (BC 547B) T2 (BC549C) R13 120Ω C8 (47 pF) 120Ω

R5 T1 (BC 549C)

R11 C7 22µF (50V) R6

22K 2.2K C5 (0.1pF)

AT NORMAL CONDITION:

The IR transmitter sensor is transmitting the infrared rays with the help of 555 IC

timer circuit. These infrared rays are received by the IR receiver sensor. The Transistor

T1, T2 and T3 are used as an amplifier section. At normal condition Transistor T5 is OFF

condition. At that time relay is OFF, so that the vehicle running continuously.

AT OBSTACLE CONDITION:

At Obstacle conditions the IR transmitter and IR receiver, the resistance across the

Transmitter and receiver is high due to the non-conductivity of the IR waves. So the

output of transistor T5 goes from OFF condition to ON stage. In that time the relay is ON

position. In that time, the solenoid valve is on so that the vehicle stops.

5. WHEEL AND BRAKING ARRANGEMENT:

The simple wheel and braking arrangement is fixed to the frame stand. Near the

brake drum, the pneumatic cylinder piston is fixed.

6. PU CONNECTIORS, REDUCER AND HOSECOLLAR:

In our pneumatic system there are two types of connectors used; one is the hose

connector and the other is the reducer. Hose connectors normally comprise an adapter

(connector) hose nipple and cap nut. These types of connectors are made up of brass or

Aluminium or hardened steel. Reducers are used to provide inter connection between two

pipes or hoses of different sizes. They may be fitted straight, tee, “V” or other

configurations. These reducers are made up of gunmetal or other materials like hardened

steel etc.

7. STAND:

This is a supporting frame and made up of mild steel.

8. SINGLE PHASE INDUCTION MOTOR:-

It is found to drive the roller shaft which fixed on the end of the frame structure.

The free end of the shaft in the motor a large pulley is found around which the belt runs.

The other specification about the motor is discussed in design part of the machine.

Single-Phase Theory

Because it has but a single alternating current source, a single-phase motor can

only produce an alternating field: one that pulls first in one direction, then in the opposite

as the polarity of the field switches. A squirrel-cage rotor placed in this field would

merely twitch, since there would be no moment upon it. If pushed in one direction,

however, it would spin.

The major distinction between the different types of single-phase AC motors is

how they go about starting the rotor in a particular direction such that the alternating field

will produce rotary motion in the desired direction. This is usually done by some device

that introduces a phase-shifted magnetic field on one side of the rotor.

The figure the performance curves of the four major types of single-phase AC

motors. They are described below.

1. Split-Phase Motors:

The split phase motor achieves its starting capability by having two separate

windings wound in the stator. The two windings are separated from each other. One

winding is used only for starting and it is wound with a smaller wire size having higher

electrical resistance than the main windings. From the rotor's point of view, this time

delay coupled with the physical location of the starting winding produces a field that

appears to rotate. The apparent rotation causes the motor to start.

A centrifugal switch is used to disconnect the starting winding when the motor

reaches approximately 75% of rated speed. The motor then continues to run on the basis

of normal induction motor principles.

2. Capacitor-Start Motors

Capacitor start motors form the largest single grouping of general purpose single

phase motors. These motors are available in a range of sizes from fractional through 3HP.

The winding and centrifugal switch arrangement is very similar to that used in a

split phase motor. The main difference being that the starting winding does not have to

have high resistance. In the case of a capacitor start motor, a specialized capacitor is

utilized in a series with the starting winding.

The addition of this capacitor produces a slight time delay between the

magnetization of starting poles and the running poles. Thus the appearance of a rotating

field exists. When the motor approaches running speed, the starting switch opens and the

motor continues to run in the normal induction motor mode.

This moderately priced motor produces relatively high starting torque, 225 to

400% of full load torque. The capacitor start motor is ideally suited for hard to start loads

such as conveyors, air compressors and refrigeration compressors. Due to its general

overall desirable characteristics, it also is used for many applications where high starting

torque may not be required.

The capacitor start motor can usually be recognized by the bulbous protrusion on

the frame where the starting capacitor is located.

Permanent-Split Capacitor Motors

The capacitor of this motor is left in series with the starting winding during normal

operation. The starting torque is quite low, roughly 40% of full-load, so low-inertia loads

such as fans and blowers make common applications.

Running

performance

and speed

regulation can

be tailored by

selecting an

appropriate

capacitor value. No centrifugal switch is required.

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Chapter-8---------------------------------------------------------------------------------------

---------------------------------------------------------------------------------

BLOCK DIAGRAM---------------------------------------------------------------------------------

CHAPTER-8

BLOCK DIAGRAM

POWER SUPPLY

CONTROL UNIT

IR TRANSMITTER

PNEUMATIC CYLINDER

SOLINOID VALVE

BUMPER ANGEMENT

IR RECEIVER

FLOW CONTROL VANVE

AIR TANK(COMPRESSOR)

WHEEL SPEED SENSING ARRANGEMENT

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Chapter-9---------------------------------------------------------------------------------------

---------------------------------------------------------------------------------

WORKING OPERATION---------------------------------------------------------------------------------

CHAPTER-9

WORKING OPERATION

The impartant components of our project are,

IR transmitter

IR receiver

Control Unit with Power supply

Solenoid Valve

Flow control Valve

Air Tank (Compressor)

The IR TRANSMITTER circuit is to transmite the Infra-Red rays. If any

obstacle is there in a path, the Infra-Red rays reflected. This reflected Infra-Red rays are

received by the receiver circuit is called “IR RECEIVER”.

The IR receiver circuir receives the reflected IR rays and giving the control signal

to the control circuit. The control circuit is used to activate the solenoid valve. The

operating principle of solenoid valve is already explained in the above chapter.

If the solenoid valve is activated, the compressed air passes to the Single Acting

Pneumatic Cylinder. The compressed air activate the pneumatic cylinder and moves the

piston rod.

If the piston moves forward, then the breaking arrangement activated. The

breaking arrangement is used to break the wheel gradually or suddenly due to the pistion

movement. The breaking speed is varied by adjesting the valve is called “FLOW

CONTROL VALVE”.

In our project, we have to apply this breaking arrangement in one wheel as a

model. The compressed air drawn from the compressor in our project. The compressed

air floe through the Polyurethene tube to the flow control valve. The flow control valve is

connected to the solenoid valve as mentioned in the block diagram.

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Chapter-10---------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

PROGRAM-------------------------------------------------------------------------------------

CHAPTER-10

PROGRAM

//#include <REGX51.H>

#include <reg52.H>#include<lcd-max.h>sbit input=P1^3;sbit output=P2^0;sbit output1=P3^2;void del();void ser_init();void ser_out(unsigned char); void ser_dis(unsigned char*da,unsigned char no);void mob_init();void sms_rec();void msg_send();void speed();void ex_int();unsigned char c,v[30],s,j,a,start,msec,dac,CON;unsigned int s_spd,spd,diff,kk,var,cou,R1,R2,R3,R4,CON1,siv;bit b;void main()P2=0X00; j=1; CON=0; CON1=0; lcd_init(); ser_init(); read(0x01); read(0x80); lcd_disp(" PNUEMATIC ",16); read(0xc0); lcd_disp(" PUMBER ",16); del();del(); read(0x80); lcd_disp("SPEED: ",16); TMOD=0X21; TH0=TL0=0X00; EA=1; ET0=1;

TR0=1; siv=0; b=0; dac=150; while(1) if(input==1&&b==0) b=1; if(input==0&&b==1)

b=0; cou++;

speed();

void timer0_intr() interrupt 1 TR0=0; msec++; TR0=1;

void speed() if(msec>=45) TR0=0; msec=0;

spd=cou*60; spd=spd/2;

read(0x86); write(spd/1000+0x30); R1=(spd/1000+0x30); write(spd%1000/100+0x30); R2=(spd%1000/100+0x30); write('.'); write(spd%100/10+0x30); R3=(spd%100/10+0x30); write(spd%10+0x30); R4=(spd%10+0x30); write('K'); write('M'); cou=0;

siv++;TH0=TL0=0x00; TR0=1;

if(spd>0150)

output=1;

void ser_init()TH1=0xfd; ////TH1=0xFd; 9600 baud rate 12MhzTMOD=0x20;TR1=1;delay(200);SCON=0x58;

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Chapter-11---------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------

APPLICATIONS AND ADVANTAGES

-------------------------------------------------------------------------------------

CHAPTER-11

APPLICATIONS AND ADVANTAGES

APPLICATIONS

For automobile application

Industrial application

ADVANTAGES

Free from wear adjustment.

Less power consumption

It gives simplified very operation.

Installation is simplified very much

DISADVANTAGES

Additional cost is required to install this arrangement in the

vehicle .

---------------------------------------------------------------------------------------

Chapter-12---------------------------------------------------------------------------------------

---------------------------------------------------------------------------------

LIST OF MATERIALS

---------------------------------------------------------------------------------

CHAPTER-12

LIST OF MATERIALS

Sl. No. PARTS Qty.

i. Single Acting Pneumatic Cylinder 1

ii. Flow Control Valve 1

iii. Wheel 1

iv. Solenoid Valve 1

v. Single Phase induction motor 1

vi. Sensor Unit 1

vii. Pulley 2

viii. Polyethylene Tube -

ix. Hose Collar and Reducer -

x Stand (Frame) 1

---------------------------------------------------------------------------------------

Chapter-13---------------------------------------------------------------------------------------

---------------------------------------------------------------------------------

COST ESTIMATION---------------------------------------------------------------------------------

CHAPTER-13

COST ESTIMATION

1. MATERIAL COST:

Sl. No. PARTS Qty. Amount (Rs)

i. Single Acting Pneumatic Cylinder 1

ii. Flow Control Valve 1

iii. Wheel 1

iv. Solenoid Valve 1

v. Single Phase induction motor 1

vi. Sensor Unit 1

vii. Pulley 2

viii. Polyethylene Tube -

ix. Hose Collar and Reducer -

x Stand (Frame) 1

2. LABOUR COST

LATHE, DRILLING, WELDING, GRINDING, POWER HACKSAW, GAS CUTTING:

Cost =

3. OVERHEAD CHARGES

The overhead charges are arrived by “Manufacturing cost”

Manufacturing Cost = Material Cost + Labour cost

=

=

Overhead Charges = 20% of the manufacturing cost

=

TOTAL COST

Total cost = Material Cost + Labour cost + Overhead Charges

=

=

Total cost for this project =

---------------------------------------------------------------------------------------

Chapter-14---------------------------------------------------------------------------------------

---------------------------------------------------------------------------------

CONCLUSION---------------------------------------------------------------------------------

CHAPTER-14

CONCLUSION

This project work has provided us an excellent opportunity and experience, to use

our limited knowledge. We gained a lot of practical knowledge regarding, planning,

purchasing, assembling and machining while doing this project work. We feel that the

project work is a good solution to bridge the gates between institution and industries.

We are proud that we have completed the work with the limited time successfully.

The AUTOMATIC PNEUMATIC BRAKING AND BUMPER SYSTEM is working

with satisfactory conditions. We are able to understand the difficulties in maintaining the

tolerances and also quality. We have done to our ability and skill making maximum use

of available facilities.

In conclusion remarks of our project work, let us add a few more lines about our

impression project work. Thus we have developed an “AUTOMATIC PNEUMATIC

BRAKING AND BUMPER SYSTEM” which helps to know how to achieve low cost

automation. The application of pneumatics produces smooth operation. By using more

techniques, they can be modified and developed according to the applications.

---------------------------------------------------------------------------------

BIBLIOGRAPHY---------------------------------------------------------------------------------

BIBLIOGRAPHY

1. G.B.S. Narang, “Automobile Engineering”, Khanna Publishers, Delhi, 1991,

pp 671.

2. William H. Crowse, “Automobile Engineering”.

3. Donald. L. Anglin, “Automobile Engineering”.

4. Pneumatic Control System----Stroll & Bernaud, Tata Mc Graw Hill

Publications, 1999.

5. Pneumatic System----Majumdhar, New Age India International (P) Ltd

Publishers, 1997.

Web sites:

www. Profc.udec.cl/~gabriel/tutorials.com

www.carsdirect.com/features/safetyflatures

www.hwysafety.org

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PHOTOGRAPHY---------------------------------------------------------------------------------

PHOTOGRAPHY