Aim of this project is control the unmanned rail gate automatically using FPGA platform. Today often we see news papers very often about the railway accidents happening at un- attended railway gates. Present project is designed to avoid such accidents if implemented in spirit.
This project utilizes two powerful IR transmitter and two receivers,one pair of transmitter and receiver is fixed at upside (from the train comes) at a levelhigher than human being in exact alignment and similarly other pair is fixed at 1Km away from gate to detect train depature.IR sensor activation time is so adjusted by calculating the time taken at a certain speed to cross at least one compartment of standard minimum size of theIndian railway, normally 5 seconds.
The sensors are fixed at 5000 meters on foreside and 1000 meters on aft side, wecall fore side sensor pair for common towards gate train, and aft side sensors for the train just Crosses the gate. When train cross the fore side sensor it gives signal to the gate receiver to close the gate. The buzzer is activated to clear the gate area for drivers .Gate motor is turned on in one direction and gate is closed, and stay closed till train crosses the gate and reaches aft side sensors when aft side receiver get activated motor turns in opposite direction and gate opens and motor stops . If there is any problem in the gate means it will operate red signal on both side for the driver indication.
Train arrival and departure sensing can be achieved by means of IR Sensor ,when the train cuts the IR rays placed at 5km before the gate, sensor get activated and this acts as a signal to the FPGA kit indicating train arrival. RED signal appears for the road user .A buzzer is made on as a pre cautionary measure for the road users.The LASER and LDR circuit is used to monitor the obstacle in between the gates,the laser source is made to fall on LDR continuously when there is an obstacle laser light falling on LDR breaks indicated by high output of led

INTRODUCTION
Present project is designed using FPGA to avoid railway accidents happening at unattended railway gates, if implemented in spirit. This project utilizes two powerful IR transmitters and two receivers; one pair of transmitter and receiver is fixed at up side (from where the train comes) at a level higher than ahuman being in exact alignment and similarly the other pair is fixed at other side of the train direction. Sensor activation time is so adjusted by calculating the time taken at a certain speed to cross at least one compartment of standard minimum size of the Indianrailway. We have considered 5 seconds for this project. Sensors are fixed at on bothsides of the gate. We call the sensor along the train direction as ‘foreside sensor’ which is placed at 5Km before the gate and the other as ‘aft side sensor placed 1Km after the gate.Initially road signals are made green and train signals are made red When foreside receiver gets activated, Buzzer will immediately sound at the fore side receiver activation and gate will close after 5 seconds, so giving time to drivers to clear gate area in order to avoid trapping between the gates ,the motor is turned on in one direction and the gate is closed the train signal changes from red to green and road signal from green to red and gate stays closed until the train crosses the gate and reaches aft side sensors. When aft side receiver gets activated motor turns in opposite direction and gate opens and motor stops and signals are resetted. In case if there is any obstacle in between the gates after the gate has closed , the signal kept at 2km is made red indicating train driver to slow down the train and during this time period the obstacle is cleared and this is indicated by signal placed at 180m as green if obstacle is cleared if not it is maintained red

Gate Control:
Railways being the cheapest mode of transportation are preferred over all the other means .When we go through the daily newspapers we come across many railway accidents occurring at unmanned railway crossings. This is mainly due to the carelessness in manual operations or lack of workers. We, in this project has come up with a solution for the same. Using simple electronic components we have tried to automate the control of railway gates. As a train approaches the railway crossing from either side, the sensors placed at a certain distance from the gate detects the approaching train and accordingly controls the operation of the gate. Also an indicator light has been provided to alert the motorists about the approaching train.
Scope of project:
This project is developed in order to help the INDIAN RAILWAYS in making its present working system a better one, by eliminating some of the loop holes existing in it.
Based on the responses and reports obtained as a result of the significant development in the working system of INDIAN RAILWAYS, this project can be further extended to meet the demands according to situation.
This can be further implemented to have control room to regulate the working of the system. Thus becomes the user friendliness.
 Additional modules can be added with out affecting the remaining modules. This allows the flexibility and easy maintenance of the developed system.
This system consists of following features over manual system
There is no time lag to operate the device.
Accuracy

Contents of the Thesis:

Chapter 2 describes the block diagram and operation of different units with block diagrams.

Chapter 3 describes power supply part that we used in this project, with different parts of it, with ratings.

Chapter 4 presents stepper motor interfacing and explanation for program written.

Chapter 5 presents detailed explanation about infrared sensors and its parts with circuit diagrams.

Chapter 6: gives detailed presentation of all hardware components that we use in this project

Chapter 7 gives the conclusions and future scope of this project 1. Power supply unit
2. Gate control unit
3. Signalling
This project uses FPGA for programming and operation. And
The Block diagram consists of the power supply, which is of single-phase230V ac. This should be given to step down transformer to reduce the 230V ac voltage to lower value. i.e., to 9V or 18V ac this value depends on the transformer inner winding .The output of the transformer is given to the rectifier circuit. This rectifier converts ac voltage to dc voltage. But the voltage may consist of ripples or harmonics.
To avoid these ripples, the output of the rectifier is connected to filter. The filter thus removes the harmonics. This is the exact dc voltage of the given specification. But the controller operates at 5V dc and the relays and driver operates at 12V dc voltage. So the regulator is required to reduce the voltage. Regulator 7805 produces 5V dc and regulator 7812 produces 12V dc. Both are positive voltages.
The supply from 7805 regulator is used for the purpose of whichconsists of a stepper motor . The supply of12v is given to drive the stepper motor for the purpose of gate control.

Operation:
Infrared sensor circuit consists of IC555 timer C 555 is used to construct an astable multivibrator which has two quasi-stable states. It generates a square wave offrequency 38 kHz and amplitude 5Volts. It is required to switch ‘ON’ the IR LED.
A stepper motor is a widely used device that translates electrical pulses into mechanical movement. They function as their name suggests - they “step” a little bit at a time.
The software is written verilg coding and is dumped to the FPGA kit to run the project.
Operation of this project can be explained through three units:
1. Gate control unit
2. signalling

Railways being the cheapest mode of transportation are preferred over all theother means .When we go through the daily newspapers we come across many railwayaccidents occurring at unmanned railway crossings. This is mainly due to the carelessnessin manual operations or lack of workers. We, in this project have come up with a solutionfor the same. Using simple electronic components we have tried to automate the controlof railway gates. As a train approaches the railway crossing from either side, the sensorsplaced at a certain distance from the gate detects the approaching train and accordinglycontrols the operation of the gate. Also an indicator light has been provided to alert the motorists about the approaching train.
The above figure shows the gate controlling unit block diagram. Its operation can be explained through that.
As the figure shows it consists of two pairs of infrared sensors placed at twosides of gate. They should keep at a distance of 5km (2km in usual case) from the gate.and a stepper motor is used for the purpose of the gate closing and opening. Interfaced through FPGA kit
When train reaches the sensor, it is detected by IR sensors placed 5Km before thestation and led in the sensor will glow because the 555 timer works into quasi state ofoperation. such that the IR LED should glow till the timer works in quasi state i.e., whentrain passes away the sensors it again into normal state then it receives 5v at terminals that pin at the FPGA terminal goes high which enables the power to the stepper motor torotate in steps which drives gate to close similarly when it reaches the second pair of sensors it senses and send the signal to the FPGA to enable the current driver to open the gate by rotating the stepper motor in steps to get back in to original position

Train arrival detection::
Detection of train approaching the gate can be sensed by means of sensorsR1, R2, R3&R4 placed on either side of the gate. In particular direction of approach, R1is used to sense the arrival; R3 is used to sense the departure of the train. In the same wayR4&R2 senses arrival and departure in the other direction. Train arrival and departure sensing can be achieved by means of relay technique.when thetrain cuts the IR rays sensor get activated this acts as a signal to microcontroller (89C51) indicating train arrival. The train detection in the other directionis done in the same way by the sensors R1 & R4. These sensors are placed five kilometers before the gate. warning for road users: At that moment the train arrival is sensed on either of the gate, road users are warned about the train approach by Buzzer is made ON and RED signal placed to caution

GREEN so that they freely move through gate. Buzzer is OFF since there is no approach of train and users need not be warned.

INFRARED SENSOR introduction:
This infrared sensor also called as IR sensors, consists of two parts:
1. IR transmitter circuit
2. IR receiver unit
The transmitter unit consists of an infrared LED and its associated circuitry

The transmitter circuit consists of the following components:
1. IC 555
2. Resistors
3. Capacitors

. IR LEDThe IR LED emitting infrared light is put on in the transmitting unit. To generate IR signal, 555 IC based astable multivibrator is used. Infrared LED is driven through transistor BC 548.
IC 555 is used to construct an astable multivibrator which has twoquasi-stable states. It generates a square wave of frequency 38kHz and amplitude 5Volts.It is required to switch ‘ON’ the IR LED.

The receiver circuit consists of the following components:
1.TSOP1738 (sensor)
2. IC 555
3. Resistors
4. Capacitors
The receiver unit consists of a sensor and its associated circuitry.In receiver section, thefirst part is a sensor, which detects IR pulses transmitted by IR-LED. Whenever a traincrosses the sensor, the output of IR sensor momentarily transits through a low state. As aresult the monostable is triggered and a short pulse is applied to the port pin of FPGA kit. On receiving a pulse from the sensor circuit, the controller activates thecircuitry required for closing and opening of the gates