AUTOMATIC DISTANCE MEASURMENT AND BRAKING SYSTEM USING ULTRASONIC SENSOR SYNOPSIS
Until Until well well into into the twenti twentieth eth centu century ry,, most most devic devices es develo developed ped for measur measuring ing distan distance ce worke worked d on the same same princi principle ple.. The measur measured ed distan distance ce is compar compared ed with with a standard unit of length. Other means are available. One of these is the measurement of time taken by the sound wave to cover a certain distance. This sound normally lies beyond human hearing. The ultrasonic sensor is used to measure the distance in digital form and also automatically braking the vehicle when the obstacle closer to the vehicle.
The aim is to design and develop a control system based an
‘ULTRASONIC NIC DISTANCE DISTANCE METER” METER” is suit In our our proj projec ectt of ‘ULTRASO suitab able le for for
measuring distances between 25 cm and about 6 m. The measured distance is shown on a 3-digit liquid crystal display (LCD).
The low current drawn by the unit makes battery operation possible: ‘LO BAT’ reading on the LCD indicates when the battery needs to be replaced. The block diagram of this meter is shown in figurer. This is having the four major parts of the meter
•
A sender and A Receiver
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Timing and time reference section
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A counter with display
The technology of pneumatics has gained tremendous importance in the field of
fully equipped by ultrasonic and IR sensors circuit and Pneumatic breaking 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.
The “PNEUMATIC BRAKEING CIRCUIT ” can stop the vehicle within 2 to 3 seconds running at a speed of 50 KM. The pneumatic breaking system is a fully automation project. This is an era of automation where it is broadly defined as replacement of manual effort by mechanical power in all degrees of automation. The operation remains an essential part of the system although with changing demands on physical input as the degree of mechanization is increased. Degrees of automation are of two types, viz.
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.
To reduce man power
To increase the efficiency of the vehicle
To reduce the work load
To reduce the fatigue of workers
To achieve good product quality
Less Maintenance To reduce the accident
SENSORS
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
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.
1. ULTRASONIC SENSOR:-
In comparison to X-Rays, ultrasonic encompasses a region where the frequency is
1. MAGNETOSTRICTION EFFECT:
The magnetostriction effect is the phenomenon of expansion or contraction which takes place in a rod of ferromagnetic material (such as iron or nickel) when placed in a magnetic field parallel to its axis. The change in the length is a function of the magnitude of the field and nature of the material.
It is independent of the sign of the field. If the applied magnetic field is alternating in nature then the rod or tube placed in the field will contract and expand alternately with the frequency which is twice the frequency of the applied magnetic field. The longitudinal expansions and contractions produce ultrasonic frequencies. The frequency of vibration is a function of the dimensions of the magnetostrictive material and the mode of vibration.
The figure shows an iron bar which is clamped at the middle and placed inside two coaxial coils. By suitable choice of the value of the condenser C, high frequency oscillation currents are set up in the circuit coil A. The high frequency current flowing in coil results in a periodically varying magnetic field this produces alternate compression and extension of the bar. An induced e.m.f. is now set up in coil B due to the alternate
Piezoelectric Effect:
By the term piezoelectric effect, we mean production of a potential difference across the opposite faces of a substance, crystalline or ceramic, due to contraction or expansion between the opposite faces. This voltage appears due to the crystal lattice deformation. The application of force to a crystal of quartz or Rochellesalt produces a voltage across the crystal. Conversely, application of an electric field may cause the crystal or expand or contract in certain directions. The piezoelectric deformations are directly proportional to the electric field and changes sign when the field is reversed. Piezoelectric effect is possible only in crystals that do not posses a centre of symmetry.
Detection of Ultrasonics:
Characteristics of Ultrasonics:
The important characteristics of ultrasonic signals are that (i)
Ultrasonic signals exhibit very negligible diffraction due to their small λ values. They can thus be transmitted over long distances without appreciable attenuation or loss.
(ii)
The speed of propagation of ultrasonic signals depends on their frequency, i.e. the speed decreases with decrease of frequency.
(iii)
Ultrasound is highly energetic.
(iv)
If an ultrasonic wave is transmitted through a liquid, stationary wave patterns are generated due to the reflection of the wave from the other end. The liquid density thus changes from layer to layer along the propagation direction. A plane diffraction grating can thus be formed which can diffract light.
(iv)
Cleaning and clearing
(v)
Direction signaling
(vi)
Coagulation and crystallization
(vii)
Degassing of liquids by ultrasonic waves
(viii) Metallurgical applications Ultrasonic in medicine.
COMPONENTS AND DESCRIPTION
SELECTION OF PNEUMATICS:
Mechanization is broadly defined as the replacement of manual effort by
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) ULTRASONIC SENSOR UNIT 5) WHEEL AND BRAKE ARRANGEMENT 6) PU CONNECTOR, REDUCER, HOSE COLLAR
In our project cut of solenoid valve is used for flow direction of braking cylinder. It is used to flow the air from air tank to the single acting cylinder.
Single acting cylinder
Single acting cylinder is only capable of performing an operating medium in only one direction. Single acting cylinders equipped with one inlet for the operating air pressure, can be production in several fundamentally different designs. Single cylinders develop power in one direction only.
Therefore no heavy control equipment should be attached to them, which requires to be moved on the piston return stoke single action cylinder requires only about half the air volume consumed by a double acting for one operating cycle.
APPLICATIONS AND ADVANTAGES
APPLICATION:
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For automobile application
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Industrial application
ADVANTAGES
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Brake cost will be less.
SPECIFICATION 1. Single acting pneumatic cylinder
Technical Data
Stroke length
:
Cylinder stoker length 170 mm
Quantity
:
2
Seals
:
Nitride (Buna-N) Elastomer
End cones
:
Cast iron
Piston
:
EN – 8
Media
:
Air
Temperature
:
0-80 º C
Applied Voltage
: 230V A.C
Frequency
: 50 Hz
3. Flow control Valve Technical Data
Port size
:
0.635 x 10 ²ֿ m
Pressure
:
0-8 x 10 ⁵ N/m²
Media
:
Air
Quantity
:
1
4. Connectors Technical data
Max working pressure
:
10 x 10 ⁵ N/m²
Inner diameter
:
3.5 mm = 3.5 x 10 ˉ ³m
IMPORTANT FEATURES •
Distance measurement upto 6 meter
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Fast pick-up
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Low maintenance expenditure
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Good efficiency
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LCD is used to measure the distance in meter..
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Microcontroller IC 89C51 has large memory capacities.
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Simple, easy to construct.
Battery low indication is provided in the LCD display for weak battery replacement •
BLOCK DIAGRAM
CONTROL POWER SUPPLY
ULTRASONIC TRANSMITTER
UNIT ULTRASONIC RE
INTERNAL BLOCK DIAGRAM OF ULTRASONIC DISTANCE METER:-
SENDER
CENTRAL TIMING RECEIVER
Height Measurement.
Automobile Application
DISADVANTAGES
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This circuit only measures the distance bellow 6 meter.
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This circuit doesn’t senses fast moving obstacle distance.
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Cost of the sensor is very high when compared to other sensors.
