WELCOME

AUTOMATIC LEVEL CROSSING

SUBMITTED BY LENIN C

INTRODUCTION

• Railways - cheapest mode of transportation .• Aims to avoid accidents. • Using simple electronic components- automate the control of

railway gates.

• Indicator light - alert the motorists about approaching train. 

BLOCK DIAGRAM

PIC 16F877A

MICROCONTROLLER

POWER SUPPLY UNIT

TRANSMITTER RECEIVER

UNIT

GATE CONTROL UNIT

BLOCK DIAGRAM DESCRIPTION

1.POWER SUPPLY UNIT

• Consists of transformer, Bridge rectifier & regulator.• Power supply -230V ac single phase .• Output - rectifier circuit.• Regulator 7805 provide 5V –microcontroller operation.

2. TRANSMITTER RECEIVER UNIT

2 powerful IR transmitters and two receivers.IR LED Fixed at 2 KM.Sensor along the train direction -‘foreside sensor’ , other - ‘aft side sensor’.

3.GATE CONTROL UNIT

Consists of motor driver, H Bridge and DC motor.Major components used - PIC microcontroller 16F877A, ULN

2803 and 30 rpm geared DC motor.DC motor controls gate opening and closing.Driver IC 2803 decodes the coding - conveys necessary data to

DC motor. 

START

GATE OPENS, GREEN SIGNAL FOR ROAD USERS

IF TRAIN REACHES SENSOR1

GATE CLOSES, BUZZER SOUNDS RED SIGNAL FOR ROAD USERS

YES

NO

IF TRAIN REACHES SENSOR2

GATE OPENS, BUZZER STOPS, GREEN LIGHT FOR ROAD USERS

STOP

FLOWCHART

YES

NO

SCHEMATIC DIAGRAM FOR GATE CONTROL UNIT

CIRCUIT DIAGRAM

CIRCUIT DIAGRAM DESCRIPTION

1.POWER SUPPLY UNIT

Step down transformer-reduce high voltage. Rectifier -ac to dc . Regulator -regulates output , avoid fluctuations.

Input filter -remove harmonics and ripples.Output filter –remove ripples in output.

2. IR TRANSMITTER

 

•IR LED series with resistor. •IR LED- detection. •IR led - constantly emits light.•Power consuming.•Optimized for low ranges.

3. IR RECEIVER

Detects transmitted IR pulses . • Train crosses sensor, output transits

to low state. • IR light falls , emitter to collector

voltage increases. • More light intensity - more voltage

drop. • As voltage drop increases- output of

op-amp high.

4.PIC MICROCONTROLLER

• PIC 16F877A- 40 pin IC• Crystal oscillator- 16 MHz• Input pins - RA0 & RA1• Output - port B pins• RA0 low – outputs 0 1 0 1 sequence – rotate motor

clockwise.• RA1 low – RA1 high – outputs 1 0 1 0 sequence – rotate

motor anticlockwise.

PIC DESCRIPTION

5. DC MOTOR

•30 RPM geared DC motor. •Simple electromagnetism.•DC motor – clockwise direction – gate closes.•DC motor – anticlockwise direction – gate opens.•Forward and reverse operation - changing the direction of current.

6.ULN - 2803

•Motor driver IC.•No VCC pin.•Decodes coding - conveys data to DC motor•Port B drives DC motor through ULN2803.•PIC outputs 0 1 0 1- ULN outputs 1 0 1 0 - one terminal of DC motor to VCC- other terminal to gnd -DC motor rotates clockwise and viceversa.

OPERATION

Two pairs of IR sensors .Gate operated by DC motor.DC motor interfaced to ULN2803. Train arrives sensor1- DC motor rotates forward – gate closes-

red signal glow-buzzer beeps. Train reaches sensor2- DCmotor rotates reverse- gate opens -

green signal glow-buzzer stops.

START

INITIALIZE RA0 & RA1

RED LIGHT GLOWS, BUZZER STARTS, GATE CLOSED

IF RA0=

0

IF RA1=

0

GREEN LIGHT GLOWS, BUZZER STOPS , GATE OPENS

IF RA1=1

STOP

1

1

PROGRAM FLOWCHART

YES

YES YES

NO

NO

NO

ADVANTAGES

Accidents are avoided.High accuracy.No time lag.

DISADVANTAGES

Regular assessment of safety performance.Motor requires 223v ac power supply. REMEDY: Using solar cell batteries.

SCOPE OF PROJECT

Better working of INDIAN RAILWAY. User friendly. Can be expanded according to demand. Additional modules can be added .

CONCLUSION

Improving safety level crossings. Priority of safety enhancement .

REFERENCES

SITESwww.scribd.comwww.google.com

THANK YOU