Dynamic Speed Governor

CONTENTS 

INTRODUCTION

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OBJECTIVES

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BLOCK SCHEMATIC OF THE TRANSMITTER SECTION

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BLOCK DESCRIPTION

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SCHEMATIC EXPLANATION OF THE PROJECT

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DIGITAL TACHOMETER TACHOMETER SECTION  CONCLUSION

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REFERENCES

DYNAMIC SPEED GOVERNOR  ABSTRACT: The Dynamic Speed Governor is a system that can be implemented effectively for an efficient and perfectly controlled traffic system. This system can limit the speed of a moving vehicle over an area where the speed has to be restricted and retained within a  predetermined value. The Dynamic Speed Governor consists of mainly two parts, the Transmitter section and the Receiver section. The transmitter section is mounted on the signal board, on which the speed limit over that area is indicated. Receiver section is kept inside the vehicle. The radio frequency signal from the transmitter is transmitted and the receiver receives it. f the speed of the vehicle is greater than the speed limit proposed for  that particular area, which in turn is transmitted by the transmitter section, the speed governor comes into action and restricts the driver from going beyond that rated speed. f  the system detects that the speed of the vehicle has gone beyond the speed limit, a signal is generated from the dynamic speed governor circuit. This signal in turn is used to drive the mechanical part of the vehicle, which closes the fuel no!!le of the vehicle thereby restricting the vehicle from going beyond that speed. n this particular reproduction of  the system, to indicate the signal produced, the signal output from the circuit is used to trigger a mono"stable multi"vibrator, which in turn sounds a bu!!er.

INTRODUCTION The proposed mini pro#ect work is a Dynamic S!!" G#$!%n#%. Dynamic speed governor is designed with the aim of dynamically limiting the speed of the vehicle to a  preset value, when the driver drives through an area that has a preset speed limit, thereby encouraging safe driving and preventing accidents. The main idea is to transmit the speed limit for the area to the vehicle, as it approaches an area that has speed restriction, so that the driver can be warned and the speed of the vehicle is automatically reduced. The system is implemented with the help of a R$ transmitter that transmits a speed limit to the approaching vehicle, and an R$ receiver inside the vehicle that accepts the incoming signal and then feeds the speed limit as one of the inputs to a comparator. The other input of the comparator comes from a digital tachometer. %hen the comparator detects an input speed that is greater than the speed limit received by the R$ receiver, it will trigger  off a chain of reactions that induce the mechanical functioning of the vehicle to automatically bring down the speed of the vehicle to a range in tandem with the preset value and thus the desired results are obtained from the system.

OBJECTIVES The primary design criteria for this pro#ect work were as follows&

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ncorporate easily available components

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'se cheap and easily worked materials platform

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(inimi!e the weight of the unit

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(aintain a level of robustness

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)ring about solid design and construction features

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*imit the consumption of energy

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(odular design

BLOCK SCHEMATIC OF THE TRANSMITTER  SECTION The block diagram of R$ Transmitter section is as shown below& C-a)) ( R!/!%!nc! S!!"

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Fi&'%! (: RF T%an)mi**!% S!c*i#n

BLOCK SCHEMATIC OF THE RECIEVER + TACHOMETER  SECTION The block diagram of R$ receiver and digital tachometer section is as shown below&

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R sensor  unit

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Shaft

A-a%m S!c*i#n  Timin& ci%c'i*

BLOCK DESCRIPTION +. R$ Transmitter 'nit The R$ Transmitter consists of& a Reference Speed Setting -ircuit& "t allows the authori!ed body to set the reference speed limit  b Display Section& t will display the speed limit set by the authori!ed body. c arallel to Serial /ncoder& t will encode the parallel input data to serial data. d R$ Transmitter (odule& " t will transmit the encoded data. 0. R$ Receiver 'nit t consists of& a R$ Receiver& " which will receive the data sent by the R$ Transmitter.  b Serial to arallel Decoder& "which will decode the serial encoded data. c Display 'nit& which will display the reference speed sent by the R$ transmitter. 1. Digital tachometer  t consists of& a 2 white dot on the shaft of the vehicle.  b Sensor 'nit&This consists of R transmitter and R receiver. t will sense the number of times the white spot reflects the transmitted R. c -ounter& This will count the number of times the white spot has been detected in a time interval. d Timing circuit& %hich will provide a preset time limit over which the counter counts the number of times white spot is detected by the sensor. e -onverter 'nit& This will convert the pulses counted over a time period to speed 3km4h and send this speed to the comparator for comparing it with the received reference speed limit and also to a display unit to display the speed of the vehicle. f Display 'nit& This will display the speed of the vehicle. 5. -omparator& t produces the speed governing signal that is fed to the mechanical drive of the vehicle and subsequently reduces the speed to the preset limit.

6.2larm 'nit& t will alert the driver if the speed of the vehicle is greater than the reference speed

SCHEMATIC EXPLANATION OF THE PROJECT The main sections of the dynamic speed governor are& + R$ Transmitter 'nit 0 R$ Receiver 'nit 1 Digital Tachometer 'nit 5 -omparator 'nit 6 2larm 'nit

RF TRANSMITTER UNIT

Transmitter is divided into two sections. .

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SENSOR UNIT

The circuit diagram of the sensor unit is shown below in $igure1.

 Fi&'%! 2: S!n)#% 'ni*

The first section consists of a sensor, a monostable multi"vibrator and an astable multi"vibrator. The main aim of the sensor unit is to sense the presence of a vehicle using R sensor The sensor  unit requires that the *DR impedance should be high 3099k Ω when there is no vehicle and its impedance should be low 3+: Ω when the sensor is cut.

The sensor is actually a combination of photodiode and a *DR 3*ight Detector Resistor. %hen light falls on *DR, its resistance will be appro;imately +k Ω. %hen light is not falling, resistance will be greater than 099k Ω. %hen light falls, the impedance of the *DR becomes low. Thus, a voltage drop occurs. This voltage drop will be greater than +41< cc.2t that time, the monostable is triggered.

%hen a vehicle approaches, it cuts the light beam, at that time t he output at the third pin of the monostable will become high. This output is given to the R -87ence 7 p B 07r C E Cr Ca.  7 p47r  B 0 E CrCa.

 %e take 7 p47r  B + i.e. no scaling which means that sensor output is directly coupled to counter.

 Therefore, + B 0E CrCa a B +4 30E Cr.

>ere we take the radius of the wheel as, 00.6cm B 00.6C+9 "6km. ence measuring time B 3+4a hr   

B1@99sec4=9=.= B6.9A sec

Therefore the measuring time is appro;imately taken as 6 seconds

Fi&'%! 6: Di&i*a- Tac.#m!*!% Uni*

n the steady state conditions motor will not rotate, high impedance occurs and the voltage drop  becomes greater than +41ere this 666 timer is designed for 59>!. Therefore the noise signals, which is in k>!, can be avoided.

The output pulse from the666 timer will act as a clock for the dual counter -D56+A. -D56+A will count the rotation of the shaft.++, +0, +1, +5 pins act as lower section of the counting and 1, 5, 6, @ pins act as upper section of counting. =,+6 are the reset pins. $or the counter -D 56+A to work, the reset pins ie.= and +6 should be in low state. The clock signal to the pin 0 is taken from  pin +5.The output from -D 56+A is connected to the = th pin of -D59+=.-D 59+= is a Hohnson ring counter.

Fi&'%! 7: Di)-ay Uni*

(easured values from -D56+A are first displayed. Then it should remain there sometime. $or that a low bit should be given at 6 th pin for latch enabling. %e give this from the output of 78T gate. 7ow to measure and store the new speed value 3as the vehicle is moving continuously we need to reset the counter -D 56+A.The new value is measured, stored and reseted, and the  process continuous.

COMPARATOR UNIT

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Fi&'%! (81C#ma%a*#% S!c*i#n

2 comparator unit compares the received set reference speed or the speed set for that particular  !one with the actual speed of the user vehicle. f the speed of the user vehicle is greater than that of the reference speed received, the comparator pin +1 outputs goes high and this high output is used to trigger the alarm section. The comparator unit is reali!ed by using -D 56A6, which is a 5"  bit comparator. >owever the speed of the vehicle and the received speed limit e;ceeds 5 bits when converted into the binary system. >ence two -D 56A6 comparator -?s are cascaded so as to implement an A"bit comparator. -omparator -?s in 0 steps does comparison. The st compares the most significant output and the output from the st is then fed to the 0 nd-.The 0nd - then compares the lower 5 bits and the output from this - is used to drive the alarm unit. 2 high in pin +1 indicates 2J), high in pin 1 indicates 2B), and 2K), when pin +0is high.

4 ALARM UNIT

Fi&'%! ((1A-a%m S!c*i#n

The aim of the pro#ect is to warn the user when he

is e;ceeding the speed limit of the !one.

>ere, we make use of a bu!!er that will sound an alarm when the user vehicle is e;ceeding the set speed limit. The output from the comparator pin received set speed limit. This output is then given to a 666 timer - that is connected in the monostable mode of operation through a =595 378T gate.

%henever the output from the comparator is low the input to the 666 will be high and hence it out operate. >owever when the output at the comparator - goes high it will appear as a !ero at the pin0 of the 666 timer - i.e., les s than +41