DESIGN AND FABRICATION COMPUTER CONTROLLED WIRELESS ROPOT WITH WIRELESS CAMERA

DESIGN AND FABRICATION OF AUTOMATIC ULTRASONIC SENSOR OPERATED PNEUMATIC BRAKING SYSTEM

DESIGN AND FABRICATION OF AUTOMATIC ULTRASONIC SENSOR OPERATED PNEUMATIC BRAKING SYSTEM

ANNA UNIVERSITY CHENNI 600 025 BONAFIDE CERTIFICATE Certified that this project DESIGN AND FABRICATION OFAUTOMATIC ULTRASONIC SENSOR OPERATED PNEUMATIC BRAKING SYSTEM is the bonafide work of N.RAJA who carried out the project work under my supervision SIGNTURE SIGNTURE Mr.S.BENJAMENLAZARUS ME.,(Ph.D) Mr.N.RANJITH .ME HEAD OF THE DEPARTMENT Assistant professor Associate professor Department of mechanical enggDepartment of Mechanical Engg The Kavery Engineering collegeThe kavery Engineering college Submitted for the University Viva-voce Examination held on____________________INTERNAL EXAMINER EXTERNAL EXAMINER CONTENTS

CHAPTER 1SYNOPSIS The brake system on a tractor-trailer is an "S-Cam Air Brake." It's a drum brake system. Drum brakes have a big advantage over drum brakes on a big truck--there's more friction surface on a drum brake than there is on a disc brake. 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 air is compressed in an air compressor and from the compressor plant the flow medium is transmitted to the pneumatic cylinder through a well laid pipe line system. To maintain optimum efficiency of pneumatic system. CHAPTER -2 INTRODUCTION All drum brakes work the same way. The tire and wheel assembly is bolted to a cast-iron drum, which looks like a bowl (and, of course, which is used as one once it wears out--every repair shop owner in the world has one of these on his desk, which he throws pens, paper clips or whatever in). and two brake shoes fit inside the drum. When you step on the brakes, or pull the parking brake handle, the shoes are forced against the inside of the drum. As they rub the drum, the kinetic energy of the rotating wheel is converted into heat energy through friction, and the vehicle stops. A recent typical BS is composed of a central electronic unit, four speed sensors (one for each wheel), and two or more hydraulic valves on the brake circuit. The electronic unit constantly monitors the rotation speed of each wheel. When it senses that one or more wheel is rotating slower than the others (a condition that will bring it to lock), moves the valves to decrease thepressure on the braking circuit, effectively reducing the braking force on that wheel.

On high-traction surfaces such as bitumen, whether wet or dry, most IBS-equipped cars are able to attain braking distances better (i.e. shorter) than those that would be possible without the benefit of ABS. A moderately-skilled driver without ABS might be able, through the use of cadence-braking, to match the performance of a novice driver with an ABS-equipped vehicle. However, for a significant number of drivers, ABS will improve their braking distances in a wide variety of conditions. The recommended technique for non-expert drivers in an IBS-equipped car, in a typical full-braking emergency, is to press the brake pedal as firmly as possible and, where appropriate, to steer around obstructions. In such situations, IBS will significantly reduce the chances of a skid and subsequent loss of control - particularly with heavy vehicles. In gravel and snow, ABS tends to increases braking distances. On these surfaces, locked wheels dig in and stop the vehicle more quickly. IBS prevents this from occurring. Some IBS controllers reduce this problem by slowing the cycling time, thus letting the wheels repeatedly, briefly, to lock and then unlock again.

CHAPTER 3LITRESERY SURVEY

There are three ways to move the brake shoes. The first is with a cable. Every car has cable-actuated parking brakes. (They're officially called "emergency brakes," but the only car I know of where the "emergency brakes" will actually stop the car in an emergency is a Saab, because the brake cables on a Saab are hooked to the FRONT brakes. Evere else hooks the brake cables to the rear brakes, and those will kinda slow you down.) The service brakes on a car are hydraulic brakes. The system is full of mineral oil, and the brake pedal is connected to a piston. When you step on the brakes, the piston pushes down on the fluid. Fluid is essentially incompressible--you CAN compress fluid, but it takes more force than most people can muster to do it--so it has to go somewhere

CHAPTER 4 WORKING PRINCIPLE In an air brake system there is no fluid. It's operated by compressed air. An air brake system has the brake drum and brake shoes. One end of the shoes is connected to an axle, so it can pivot. The other end of each shoe has a little roller on it, and the roller rides on a rotating cam. It's called an S-cam because it's shaped like an S. They stick the cam at the end of a big steel bar, which allows it to turn. Next comes the slack adjuster. It connects the S-cam rod to the brake chamber rod, and it's called an adjuster because...well, it gets longer to compensate for the brake shoes wearing down with use. (There are manual slack adjusters and automatic slack adjusters. If you have manual slack adjusters you have to go under the truck every so often and set the slack with a wrench. I don't think it's legal to sell manual slack adjusters any more--automatic ones are just safer because they're always in good adjustment.) And finally, there is the brake chamber, where the air goes in. The brake chamber has a rod sticking out of it, which connects to the slack adjuster, and either one or three devices to move it. The first device is the service brake chamber. It is connected to the service air circuits, of which you normally have two unless your truck is ancient. When you step on the brakes, air flows into the service circuits and presses against the diaphragm in the service chamber. This pulls on the rod, which pulls the slack adjuster, which turns the S-cam and makes you stop. The other two devices are parts of the spring brake system. There are never spring brakes on the front wheels--these can activate automatically, and if your front wheels lock up when you don't want them to you couldn't steer the truck. That would be very bad. The first device is a huge spring, which will pull on the rod. The other is the spring override chamber, which pushes against the spring to allow the brakes to release. If the air system pressure drops below 20psi on your tractor, or 40psi on your trailer, or you use the buttons on your tractor's dashboard to shut the air off by hand, there won't be enough air in the system to push the spring back and the spring brakes will come on. Now for some free advice from a Class A CDL holder to people getting ready to get one... You are going to take several written tests at the DMV to get your learner's permit. The one you are most likely to fail is Air Brakes, because of the way it's written.10 parking brakes and emergency brakes are all the same brake. A spring brake stops, or holds, the truck when there's no air pressure. It becomes an emergency brake if something happens to make your truck lose air pressure. It is a parking brake if you use the control valve on the dashboard (the one for the tractor is yellow, the one for the trailer is red) to turn the air off. If you can remember you have two brake systems on your truck--the service brake, which works by stepping on the brake pedal, and the spring brake, which is called three things--spring, parking and emergency--you'll pass with flying colors. Quote 'The brake system on a tractor-trailer is an "S-Cam Air Brake." It's a drum brake system. Drum brakes have a big advantage over drum brakes on a big truck--there's more friction surface on a drum brake than Wrong. The disc brake is a far more effective brake under all circumstances. Simply because it offers better cooling under heavy use and its far more effective to have two brake pads grab a brake disc than to have brake shoes pushing against a brake drum. Brake drums have been known to shatter after a very short life span Most European trucks nowadays have disc brakes fitted as standard, as well as trailers.

BLOCK DIAGRAM AND DESCRIPTIONDESCRIPTION

The message to be communicated has to be first converted into an electrical signal by the help of a suitable transducer. The electrical signal so obtained has to be suitable processed and amplified before being fed to the channel. The information signal called the modulating signal is used to modulate a high frequency sine wave signal. The type of modulation depends on the requirements. The carrier signal generated by the oscillator goes to the RF output power amplifiers through the buffer and RF amplifiers. The RF amplifier sends the signal containing all bands of frequencies.

INTERNAL BLOCK DIAGRAM OF ULTRASONIC DISTANCE METER:

DESCRIPTION

Practically all receivers today are super heterodyne. The RF amplifier is tuned to the required incoming frequency. The output of the RFA is combined with the local oscillator voltage and normally converted into a signal of lower fixed frequency. This IF signal contains the same modulation as the original carrier. It is then amplified and detected to obtain information. A fixed frequency difference is maintained between the local oscillator and RF frequency with the help of capacitance tuning. IF stage is consists of a number of transformers which provides a large gain. The characteristics of the IFA are kept independent of the frequency to which the receiver is tuned, so that the sensitivity of the super heterodyne remains fairly uniform throughout its tuning range. The various blocks of super heterodyne receiver is explained as follows. Safety Valve A safety relief valve is installed in the first tank the air compressor pumps air to. The safety valve protects the tank and the rest of the system from too much pressure. The valve is usually set to open at 150 psi. If the safety valve releases air, something is wrong. Have the fault fixed by a mechanic.

The Brake Pedal You put on the brakes by pushing down the brake pedal. (It is also called the foot valve or treadle valve.) Pushing the pedal down harder applies more air pressure. Letting up on the brake pedal reduces the air pressure and releases the brakes. Releasing the brakes lets some compressed air go out of the system, so the air pressure in the tanks is reduced. It must be made up by the air compressor. Pressing and releasing the pedal unnecessarily can let air out faster than the compressor can replace it. If the pressure gets too low, the brakes won't work.Foundation Brake inside Foundation brakes are used at each wheel. The most common type is the s-cam drum brake. The parts of the brake are discussed below. Brake Drums, Shoes, and Linings. Brake drums are located on each end of the vehicle's axles. The wheels are bolted to the drums. The braking mechanism is inside the drum. To stop, the brake shoes and linings are pushed against the of the drum. This causes friction, which slows the vehicle (and creates heat). The heat a drum can take without damage depends on how hard and how long the brakes are used. Too much heat can make the brakes stop working.

Stop Light Switch Drivers behind you must be warned when you put your brakes on. The air brake system does this with an electric switch that works by air pressure. The switch turns on the brake lights when you put on the air brakes.Front Brake Limiting Valve Some older vehicles (made before 1975) have a front brake limiting valve and a control in the cab. The control is usually marked "normal" and "slippery." When you put the control in the "slippery" position, the limiting valve cuts the "normal" air pressure to the front brakes by half. Limiting valves were used to reduce the chance of the front wheels skidding on slippery surfaces. However, they actually reduce the stopping power of the vehicle. Front wheel braking is good under all conditions. Tests have shown front wheel skids from braking are not likely even on ice. Make sure the control is in the "normal" position to have normal stopping power.Many vehicles have automatic front wheel limiting valves. They reduce the air to the front brakes except when the brakes are put on very hard (60 psi or more application pressure). These valves cannot be controlled by the driver

Spring Brakes All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. They must be held on by mechanical force (because air pressure can eventually leak away). Spring brakes are usually used to meet these needs. When driving, powerful springs are held back by air pressure. If the air pressure is removed, the springs put on the brakes. A parking brake control in the cab allows the driver to let the air out of the spring brakes. This lets the springs put the brakes on. A leak in the air brake system, which causes all the air to be lost, will also cause the springs to put on the brakes. Tractor and straight truck spring brakes will come fully on when air pressure drops to a range of 20 to 45 psi (typically 20 to 30 psi). Do not wait for the brakes to come on automatically. When the low air pressure warning light and buzzer first come on, bring the vehicle to a safe stop right away, while you can still control the brakes.The braking power of spring brakes depends on the brakes being in adjustment. If the brakes are not adjusted properly, neither the regular brakes nor the emergency/parking brakes will work right.

Parking Brake Controls In newer vehicles with air brakes, you put on the parking brakes using a diamond-shaped, yellow, push-pull control knob. You pull the knob out to put the parking brakes (spring brakes) on, and push it in to release them. On older vehicles, the parking brakes may be controlled by a lever. Use the parking brakes whenever you park. Caution. Never push the brake pedal down when the spring brakes are on. If you do, the brakes could be damaged by the combined forces of the springs and the air pressure. Many brake systems are designed so this will not happen. But not all systems are set up that way, and those that are may not always work. It is much better to develop the habit of not pushing the brake pedal down when the spring brakes are on. Modulating Control Valves. In some vehicles a control handle on the dash board may be used to apply the spring brakes gradually. This is called a modulating valve. It is spring-loaded so you have a feel for the braking action. The more you move the control lever, the harder the spring brakes come on. They work this way so you can control the spring brakes if the service brakes fail. When parking a vehicle with a modulating control valve, move the lever as far as it will go and hold it in place with the locking device.

Dual Parking Control Valves. When main air pressure is lost, the spring brakes come on. Some vehicles, such as buses, have a separate air tank which can be used to release the spring brakes. This is so you can move the vehicle in an emergency. One of the valves is a push-pull type and is used to put on the spring brakes for parking. The other valve is spring loaded in the "out" position. When you push the control in, air from the separate air tank releases the spring brakes so you can move. When you release the button, the spring brakes come on again. There is only enough air in the separate tank to do this a few times. Therefore, plan carefully when moving. Otherwise, you may be stopped in a dangerous location when the separate air supply runs out. Antilock Braking Systems (ABS) Truck tractors with air brakes built on or after March 1, 1997, and other air brakes vehicles, (trucks, buses, trailers, and converter dollies) built on or after March 1, 1998, are required to be equipped with antilock brakes. Many commercial vehicles built before these dates have been voluntarily equipped with ABS. Check the certification label for the date of manufacture to determine if your vehicle is equipped with ABS. ABS is a computerized system that keeps your wheels from locking up during hard brake applications.

Vehicles with ABS have yellow malfunction lamps to tell you if something isn't working. Tractors, trucks, and buses will have yellow ABS malfunction lamps on the instrument panel.Trailers will have yellow ABS malfunction lamps on the left side, either on the front or rear corner. Dollies manufactured on or after March 1, 1998 are required to have a lamp on the left side.On newer vehicles, the malfunction lamp comes on at start-up for a bulb check, and then goes out quickly. On older systems, the lamp could stay on until you are driving over five mph. If the lamp stays on after the bulb check, or goes on once you are under way, you may have lost ABS control at one or more wheels. In the case of towed units manufactured before it was required by the Department of Transportation, it may be difficult to tell if the unit is equipped with ABS. Look under the vehicle for the electronic control unit (ECU) and wheel speed sensor wires coming from the back of the brakes.

CHAPTER-5 CONCLUSION In the present work. a prototype of an ultrasonic ACC for low speed and short distances typical of urban traffic, where the systems available on the market do not work, has been designed, built and experimentally tested. An ultrasonic sensor, cheaper and less demanding of hardware then other types of sensor currently used ,such as those based on radar or computer vision , is used to measure the distance between vehicles. The relative speed is estimated using consecutive samples of this distance. These two quantities are used by the control system to calculate the actions on both the accelerator and the brake , and to adjust the speed in order to maintain the safety distance. As ultrasonic sensors can detect any kind of obstacle, this system can also prevent collision with pedestrians, or at least reduce the injuries sustained. CHAPTER-6 REFERENCE1.onieva E., Milanes V., Gonzalez C., de pedro T., perez J. throttle and brake pedals automation for populated areas. Robotic. 2010 2.kinsler L.E., Frey A.R., Coopens A.B., Sanders J.V. Fundamentals of Acoustics. 4thed. Wiley; New York, NY, USA:20003.Alonso L., Perez-Oria J.M., Fernandez M., Arce J., Ibarra M., Ordonez V. Artificial Neural Networks ICANN20104.Autopia. Available online: http:// www.iai.csic.es/users /autopia/programa_en.html (accessed on September 15, 2010)5.Short M., pont M.J., Huang Q. simulation of vehicle longitudinal dynamics. Embedded systems Laboratory, university of Leicester; Leicester,UK:2014 CHAPTER 7LIST OF MATERIALSSl. No.PARTSQty.Material1Pneumatic Cylinder1Aluminium25/2 DC Valve1Aluminium3Electronic Control Unit1Electronic4Pedal arrangement1Mild Steel 5Flow Control Valve1Aluminium6Connecting Tube-Polyurethene7Hose Collar and Reducer-Brass8Stand (Frame)1Mild steelCHAPTER-8 COST ESTIMATION

Sl. No.PARTSQty.Amount (Rs)i.Pneumatic Cylinder1550.00ii.5/2 DC Valve1300.00iii.Electronic Control Unit1400.00v.Pedal arrangement1200.00vi.Flow Control Valve1300.00viii.Connecting Tube-250.00ix.Hose Collar and Reducer-200.00XStand (Frame)1600.00 TOTAL2800.00 CHAPTER-9 ANALYSIS OF ERROR An insufficiently high threshold level causes the detection of false echoes produced by turbulences and irregularities in the road, making the control system act on the brakes unnecessarily. In contrast, if the threshold is too high detection failures can occur, meaning that no objects are detected when they are there and there fore causing possible collisions. To adjust the threshold level, 100 echoes were recorded in the range of 11m, with The sensor at rest and no obstacles in front. The threshold has been reduced slowly, Ntil at a final value of 2*10^-4 a false echo has been detected.