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
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.
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 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.