25-08-2017, 09:32 PM
AUTOMATIC VEHICLE SPEED MANAGEMENT SYSTEM A PROJECT REPORT
AUTOMATIC VEHICLE.doc (Size: 1.22 MB / Downloads: 62)
ABSTRACT
The objective of this project is to control speed of the vehicle automatically with the help RF technology.
This project is very useful to traffic police department. If the speed of the vehicle is over than limit value, the speed is automatically controlled. So this project is used to prevent the accident.
INTRODUCTION
This project is designed with RF transmitter and Receiver, Microcontroller, Encoder, Decoder, Proximity sensor, signal conditioning unit and Relay driver circuit with relay.
Many RF transmitters is placed in the emergency road and traffic rush areas. These RF transmitters are transmitting the speed limit value through the RF transmitter. The transmitter section consists of key pad encoder and RF transmitter. The key pad is used to set the speed limit value. Then the set value is given to encoder to encoded the signal and given to RF transmitter block in which the encoded signal is modulated with carrier frequency and transmitted through RF transmitter.
The receiver section consists of microcontroller RF receiver, Decoder, Proximity sensor and driver circuit for relay. The receiver section is attached in the vehicle. The proximity sensor is fixed in the vehicle wheel to monitor the speed. Proximity sensor is used detect the metals. The metal rod is fixed in vehicle. So whenever the rod is crossed the sensor it generates the pulse given to microcontroller. The microcontroller count that pulse and displayed on the LCD display which is equal to speed of the vehicle. The RF receiver is used to receive the speed limit value. The value is given to microcontroller through decoder. The RF receiver removes the carrier frequency and decoder is used to decode the signal then given to microcontroller.
In microcontroller the received speed limited value is compared with obtained speed. If the speed is higher then limits value it activates the relay through relay driver circuit. The relay output is connected petrol valve. So it controls the petrol flow to engine. Through this way the vehicle speed is automatically limited to speed level set the by traffic police department
BLOCK DIAGRAM DESCRIPTION
MICROCONTROLLER
A microcontroller is a complete microprocessor system built on a single IC. Microcontrollers were developed to meet a need for microprocessors to be put into low cost products. Building a complete microprocessor system on a single chip substantially reduces the cost of building simple products, which use the microprocessor's power to implement their function, because the microprocessor is a natural way to implement many products. This means the idea of using a microprocessor for low cost products comes up often. But the typical 8-bit microprocessor based system, such as one using a Z80 and 8085 is expensive. Both 8085 and Z80 system need some additional circuits to make a microprocessor system. Each part carries costs of money. Even though a product design may require only very simple system, the parts needed to make this system as a low cost product.
LIQUID CRYSTAL DISPLAY (LCD)
Liquid crystal displays (LCD’s) have materials, which combine the properties of both liquids and crystals. Rather than having a melting point, they have a temperature range within which the molecules are almost as mobile as they would be in a liquid, but are grouped together in an ordered form similar to a crystal.
An LCD consists of two glass panels, with the liquid crystal material sand witched in between them. The inner surface of the glass plates are coated with transparent electrodes which define the character, symbols or patterns to be displayed polymeric layers are present in between the electrodes and the liquid crystal, which makes the liquid crystal molecules to maintain a defined orientation angle.
One each polarizes are pasted outside the two glass panels. These polarizes would rotate the light rays passing through them to a definite angle, in a particular direction. When the LCD is in the off state, light rays are rotated by the two polarizes and the liquid crystal, such that the light rays come out of the LCD without any orientation, and hence the LCD appears transparent.
OVERALL CIRCUIT DIAGRAM DESCRIPTION
POWER SUPPLY DESCRIPTION
The ac voltage, typically 220V rms, is connected to a transformer, which steps that ac voltage down to the level of the desired dc output. A diode rectifier then provides a full-wave rectified voltage that is initially filtered by a simple capacitor filter to produce a dc voltage. This resulting dc voltage usually has some ripple or ac voltage variation.
A regulator circuit removes the ripples and also remains the same dc value even if the input dc voltage varies, or the load connected to the output dc voltage changes. This voltage regulation is usually obtained using one of the popular voltage regulator IC units.
Working principle
Transformer
The transformer will step down the power supply voltage (0-230V) to (0-6V) level. Then the secondary of the potential transformer will be connected to the precision rectifier, which is constructed with the help of op–amp. The advantages of using precision rectifier are it will give peak voltage output as DC; rest of the circuits will give only RMS output.
Bridge rectifier
When four diodes are connected as shown in figure, the circuit is called as bridge rectifier. The input to the circuit is applied to the diagonally opposite corners of the network, and the output is taken from the remaining two corners.
Let us assume that the transformer is working properly and there is a positive potential, at point A and a negative potential at point B. the positive potential at point A will forward bias D3 and reverse bias D4.
The negative potential at point B will forward bias D1 and reverse D2. At this time D3 and D1 are forward biased and will allow current flow to pass through them; D4 and D2 are reverse biased and will block current flow.
The path for current flow is from point B through D1, up through RL, through D3, through the secondary of the transformer back to point B. this path is indicated by the solid arrows. Waveforms (1) and (2) can be observed across D1 and D3.
One-half cycle later the polarity across the secondary of the transformer reverse, forward biasing D2 and D4 and reverse biasing D1 and D3. Current flow will now be from point A through D4, up through RL, through D2, through the secondary of T1, and back to point A. This path is indicated by the broken arrows. Waveforms (3) and (4) can be observed across D2 and D4. The current flow through RL is always in the same direction. In flowing through RL this current develops a voltage corresponding to that shown waveform (5). Since current flows through the load (RL) during both half cycles of the applied voltage, this bridge rectifier is a full-wave rectifier.
IC voltage regulators
Voltage regulators comprise a class of widely used ICs. Regulator IC units contain the circuitry for reference source, comparator amplifier, control device, and overload protection all in a single IC. IC units provide regulation of either a fixed positive voltage, a fixed negative voltage, or an adjustably set voltage. The regulators can be selected for operation with load currents from hundreds of milli amperes to tens of amperes, corresponding to power ratings from milli watts to tens of watts.
RF Receiver:
The RF receiver is used to receive the encoded data which is transmitted by the RF transmitter. Then the received data is given to transistor which acts as amplifier. Then the amplified signal is given to carrier demodulator section in which transistor Q1 is turn on and turn off conducting depends on the signal. Due to this the capacitor C14 is charged and discharged so carrier signal is removed and saw tooth signal is appears across the capacitor. Then this saw tooth signal is given to comparator. The comparator circuit is constructed by LM558. The comparator is used to convert the saw tooth signal to exact square pulse. Then the encoded signal is given to decoder in order to get the decoded original signal.
Decoder:
In this circuit HT648 is used as decoder. The 318 decoder are a series of CMOS LSIs for remote control system application. They are paired with 318 series of encoders. For proper operation a pair of encoder/decoder pair with the same number of address and data format should be selected. The 318 series of decoder receives serial address and data from that series of encoders that are transmitted by a carrier using an RF or an IR transmission medium.
It then compares the serial input data twice continuously with its local address. If no errors or unmatched codes are encountered, the input data codes are decoded and then transferred to the output pins. The VT pin also goes high to indicate a valid transmission.