Fuzzy Based Traffic Light Con Troll Err

8/3/2019 Fuzzy Based Traffic Light Con Troll Err

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FUZZY BASED SMART TRAFFIC LIGHT

Submitted By:


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INTRODUCTION

As the number of vehicles and the needs for greater transportation has grown in recent years, city

streets and highways frequently face serious road traffic congestion problems. Due to this factor,

traffic signals now become a common feature of cities controlling heavy traffic. Careful planning

of these signals is important to increase the efficiency of traffic flow on road. Controlling traffic

on oversaturated intersections is a big issue.

Conventional methods for traffic signal control based precise models fail to deal efficiently with

the complex and varying traffic situations. They are modeled based on the preset cycle time to

change the signal without any analysis of traffic situation. Due to fixed cycle time, such systems

do not consider that which intersection has more load of traffic, so should kept green more or

should terminate earlier then complete cycle time. In case of intersections, conventional control

systems only consider waiting time of signals on different directions but not the vehicle

directions. Such situations can be seen in various areas of Delhi and NCR where traffic flow

varies in different hours and heavy traffic flows in morning and evening timings because of large

number of offices on that route. Also, in different intersections, traffic flow abruptly changes in

schools timings then other daily hours. Preset Cycle Time Controllers fail in such scenarios

because they could not get complete information of vehicles earlier.

Fuzzy based controllers are proved to be well manager of traffic system in such scenarios. Fuzzy

Logic based controllers have the ability to take decision even with incomplete information. More

and more sophisticated controllers are being developed for traffic control.

These algorithms are continually improving the safety and efficiency by reducing the waiting

delay of vehicles on signals. This increases the tempo of travel and thus makes signals moreeffective and traffic flow smooth. The key motivation towards Fuzzy Logic in traffic signal

control is the existence of uncertainties in signal control. Decisions are taken based on imprecise

information and the effect of evaluation is not well known.

METHODOLOGY:

The fuzzy logic controller determines whether to extend or terminate the current green phase

based on a set of fuzzy rules. The fuzzy rules compare traffic conditions with the current green

phase and traffic conditions with the next candidate green phase. The flow diagram of a

controller is shown in figure 1.


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FIG 1. Fuzzy Traffic Signal Control

Fuzzy

Interference

System

Fuzzification Defuzzi-fication

Traffic

Situatio

n

Model

Signal

Control

Action

Detection Traffic Situation

Signal

Status


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A BRIEF INTRODUCTION TO 8051 MICROCONTROLLER:

When we have to learn about a new computer we have to familiarize about the

machine capability we are using, and we can do it by studying the internal hardware design

(devices architecture), and also to know about the size, number and the size of the registers.

A microcontroller is a single chip that contains the processor (the CPU), non-volatile memory for

the program (ROM or flash), volatile memory for input and output (RAM), a clock and an I/O

control unit. Also called a "computer on a chip," billions of microcontroller units (MCUs) are

embedded each year in a myriad of products from toys to appliances to automobiles. For

example, a single vehicle can use 70 or more microcontrollers. The following picture describes a

general block diagram of microcontroller.

89s52: The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with

8K bytes of in-system programmable Flash memory. The device is manufactured using Atmels

high-density nonvolatile memory technology and is compatible with the industry-standard 80C51instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed

in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit

CPU with in-system programmable Flash on a monolithic chip, the Atmel's AT89S52 is a

powerful microcontroller which provides a highly-flexible and cost-effective solution to many

embedded control applications. The AT89S52 provides the following standard features: 8K bytes

of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit

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

oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for

operation down to zero frequency and supports two software selectable power saving modes. The

Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt

system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the

oscillator, disabling all other chip functions until the next interrupt


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The hardware is driven by a set of program instructions, or software. Once familiar with

hardware and software, the user can then apply the microcontroller to the problems easily.


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The pin diagram of the 8051 shows all of the input/output pins unique to microcontrollers:

The following are some of the capabilities of 8051 microcontroller.

Internal ROM and RAM

I/O ports with programmable pins

Timers and counters

Serial data communication

The 8051 architecture consists of these specific features:


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16 bit PC &data pointer (DPTR)

8 bit program status word (PSW)

8 bit stack pointer (SP)

Internal ROM 4k

Internal RAM of 128 bytes.

4 register banks, each containing 8 registers

80 bits of general purpose data memory

32 input/output pins arranged as four 8 bit ports:P0-P3

Two 16 bit timer/counters: T0-T1

Two external and three internal interrupt sources

Oscillator and clock circuits

For any electronics project the power supply plays a very important role in its properfunctioning.

In this project we are using external A.C supply (220 v) as input , this high voltage is

converted into 12 Volts A.C by step down transformer , then we use voltage regulators and

filters with bridge rectifier to convert the A.C into D.C voltage .

For voltage regulation we are using LM 7805 and 7812 to produce ripple free 5 and 12 volts

D.C constant supply.


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IR SENSOR

INFRARED LED'S:-

Gallium arsenide is a direct-gap semiconductor with an energy gap of 1.4eV at room

temperature. A typical GaPs LED is made by solid-state impurity diffusion with zinc as the p-

type impurity diffused into an n-type substate doped with tin, tellurium or silicon. The external

efficiency at room temperature is typically 5 percent.

A GaAs diode can also be fabricated by liquid-phase epitaxy with silicon as both its n and

p dopants. If a silicon atom replaces a Ga atom, it provides one additional electron, thus the

resulting GaAs in as n-type. If a silicon atom replaces arsenic atoms, an electron is missing and

the resulting GaAs is a p-type. In Si doped GaAs diode, the emission peak shifts down to

1.32eV. Since the emission is in infrared region, GaAs light sources are suitable for application

such as the optical isolator. The high switching speed, with a recovery time between 2 and 10ns,

makes them ideal for data transmission.

The disadvantages of the GaAs emitter are emitted wavelength and the associated

attenuation an dispersion. A critical issue of using an LED for the fibre optics is the coupling oflight from the semiconductor to the fibre. Because of the larger refractive index of GaAs relative

to air, the internal efficiency of LED can be quite low.

PHOTO SEMICONDUCTOR


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A Germanium or silicon diode or transistor, which has a transparent encasing, can serve

as a photodiode or transistor because the light photons can initiate conduction in the p-n-

junction region. Early devices such as the OCP 71 were Ge-devices. Later, silicon types became

available with lower leakage current and better light sensitivity. In a phototransistor, the base

lead is not used; but, if a resistor is connected form base to emitter it reduced the light sensitivity.

Darlington connected photo transistors (two transistors together in one case) such as the 2N5777

are very sensitive with a hFE of 2.5K, a dark current of 100nA and a light current of 0.5-2.0mA

for light flux density H=2mW/cm2. The device is rated 200mW and voltage of 25V maximum.

SCRs with a light window are also available, called as LASCR, which are very sensitive

and can turn mains power ON and OFF, with light.

The switching speed of phototransistors far exceeds those of LDRs, made of CdS. The

rise time for the 2N5777 is 75 s and fall time is 50 s. Maximum switching speed is 1KHz.

Photo devices are useful in optical encoding, intrusion alarms, tape readers, level control,

character recognition etc.

Nowadays packing containing an LED and a photodiode, called opto-coupler is used for

switching on power or control circuits. Because the light source (LED) and photodiode are

physically kept separated (with 2mm) in the package, isolation upto 2500V can be had.

555 timer

The buffer circuit's input has a very high impedance (about 1M ) so it requires only a few A,

but the output can sink or source up to 200mA. This enables a high impedance signal source

(such as an LDR) to switch a low impedance output transducer (such as a lamp). It is an

inverting buffer or NOT gate because the output logic state (low/high) is the inverse of the input

state:

Input low (< 1/3 Vs) makes output high, +Vs

Input high (> 2/3 Vs) makes output low, 0V

When the input voltage is between 1/3 and2/3 Vs the output remains in its present state. This

intermediate input region is a deadspace where there is no response, a property called hysteresis,it is like backlash in a mechanical linkage. This type of circuit is called a Schmitt trigger.

If high sensitivity is required the hysteresis is a problem, but in many circuits it is a helpful

property. It gives the input a high immunity to noise because once the circuit output has switched

high or low the input must change back by at least 1/3 Vs to make the output switch back.


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LIGHT EMITTING DIODE

Light emitting diode (LED) is basically a P-N junction semiconductor diode particularly

designed to emit visible light. There are infrared emitting LEDs which emit invisible light. The

LEDs are now available in many colours red, green and yellow. A normal LED emits at 2.4V

and consumes MA of current. The LEDs are made in the form of flat tiny P-N junction enclosed

in a semi-spherical dome made up of clear coloured epoxy resin. The dome of a LED acts as a

lens and diffuser of light. The diameter of the base is less than a quarter of an inch. The actual

diameter varies somewhat with different makes. The common circuit symbols for the LED are

shown in Fig. It is similar to the conventional rectifier diode symbol with two arrows pointing

out. There are two leads- one for anode and the other for cathode.

LEDs often have leads of dissimilar length and the shorter one is the cathode. All

manufacturers do not strictly adhere this to. Sometimes the cathode side has a flat base. If there

is doubt, the polarity of the diode should be identified. A simple bench method is to use the

ohmmeter incorporating 3-volt cells for ohmmeter function. When connected with the ohmmeter:

one way there will be no deflection and when connected the other way round there will be a large

deflection of a pointer. When this occurs the anode lead is connected to the negative of test lead

and cathode to the positive test lead of the ohmmeter.


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If low range (Rxl) of the ohmmeter is used the LED would light up in most cases because

the low range of ohmmeter can pass sufficient current to light up the LED.

Another safe method is to connect the test circuit shown in Fig. 2. Use any two dry cells

in series with a current limiting resistor of 68 to 100 ohms. The resistor limits the forward diode

current of the LED under test to a safe value. When the LED under test is connected to the testterminals in any way: if it does not light up, reverse the test leads. The LED will now light up.

The anode of the LED is that which is connected to the A terminal (positive pole of the

battery). This method is safe, as reverse voltage can never exceed 3 volts in this test.

ELECTRICAL CHARACTERISTICS OF LEDS: -

Electrically, a LED is similar to the conventional diode in that it has relatively low

forward voltage threshold. Once this is exceeded the junction has a low slope resistance and

conducts current readily. An external resistor must limit this current. Forward voltage drew

across red LED is nominally 1.6 V but spread with commercial diodes, it may be as high as 2

volts or so, while the Green LED drops 2.4V. This difference accounts for use of lower limiting

resistor used with the Green LED.

Another important parameter of the LED is its maximum reverse voltage rating. For typical Red

device it is of the order of 3 volts. But for Green LED it is somewhat higher- 5 to 10 volts.

The LED produces light only when a d.c. current is passed in the forward direction and the

amount of light emitted by a LED is proportional to the forward current over a broad range. It

means that light intensity increases in an approximately linear manner with increasing current.

BLOCK DIGRAM:


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As shown in the circuit a microcontroller is programmed to automatically ON and OFF the

LEDs (traffic light). The crystal oscillator provides the necessary clocking for the

microcontroller to work properly. The four traffic lights, shown as 4 groups of 3 LEDs (Red,

Green, Yellow), is actually installed at each of the four roads.

The necessary stabilized power source is designed by the use of LM7805, as shown above (in the

lower figure). The whole circuit will be implemented on a zero PCB. The programming of the

Microcontroller can be done either in C or in Assembly, using a programmer.

8051MAX

232

Tx

Rx

RS232

PORT1

PORT2

Sensor Input

MATLAB PROGRAM

RUNNING ON COMPUTER

Fuzzy Based Traffic Light Con Troll Err

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