MICROCONTROLLER

BASED

AUTOMATIC RAILWAY

GATE CONTROL

Submitted by, P.NAVEEN S.SUDHAKAR

ARULMIGU KALASALINGAM COLLEGE OF ENGINEERING KRISHNANKOVIL

Email id: sudhakar_mani87@yahoo.co.in Naveensree007@rediffmail.com

ABSTRACT:

The objective of this paper is to provide an automatic railway gate at a

levelcrossing replacing the gates operated by the gatekeeper. It deals with two things.

Firstly, it deals with the reduction of time for which the gate is being kept closed. And

secondly, to provide safety to the road users by reducing the accidents.

By the presently existing system once the train leaves the station, the

stationmaster informs the gatekeeper about the arrival of the train through the

telephone. Once the gatekeeper receives the information,he closes the gate depending

on the timing at which the train arrives. Hence, if the train is late due to certain

reasons,then gate remain closed for a long time causing traffic near the gates.

By employing the automatic railway gate control at the level crossing the

arrival of the train is detected by the sensor placed near to the gate. Hence, the time

for which it is closed is less compared to the manually operated gates and also reduces

the human labour. This type of gates can be employed in an unmanned level crossing

where the chances of accidents are higher and reliable operation is required. Since, the

operation is automatic, error due to manual operation is prevented .

Automatic railway gate control is highly economical microcontroller based

arrangement, designed for use in almost all the unmanned level crossings in the

country.

INTRODUCTION:

In this paper we are concerned of providing an automatic railway gate

control at unmanned level crossings replacing the gates operated by gate keepers and

also the semiautomatically operated gates. It deals with two things. Firstly, it deals

with the reduction of time for which the gate is being kept closed. And secondly, to

provide safety to the road users by reducing the accidents that usually occur due to

carelessness of road users and at times errors made by the gatekeepers.

By employing the automatic railway gate control at the level crossing

the arrival of train is detected by the sensor placed on either side of the gate at about

5km from the level crossing. Once the arrival is sensed , the sensed signal is sent to

the microcontroller and it checks for possible presence of vehicle between the gates,

again using sensors. Subsequently, buzzer indication and light signals on either side

are provided to the road users indicating the closure of gates. Once, no vehicle is

sensed in between the gate the motor is activated and the gates are closed. But, for the

worst case if any obstacle is sensed it is indicated to the train driver by signals(RED)

placed at about 2km and 180m,so as to bring it to halt well before the level crossing.

When no obstacle is

sensed GREEN light is indicated, and the train is to free to move.

The departure of the train is detected by sensors placed at about 1km

from the gate. The signal about the departure is sent to the microcontroller, which in

turn operates the motor and opens the gate. Thus, the time for which the gate is closed

is less compared to the manually operated gates since the gate is closed depending

upon the telephone call from the previous station. Also reliability is high as it is not

subjected to manual errors.

R1 & R2 Sensors on the track, placed at about 5 km from the gate to detect the train arrival on either directions.

R3 & R4 Sensors on the track, placed at about 1 km from the gate to detect the train departure on either directions.

SG1,SG2,SG3 & SG4 Signals placed by the side of the track to indicate the train driver about the closing of the gate.

B Buzzer, an audio signal to warn the road user about theapproach of train.

M Motor for gate operation.

L Light signal to warn the road user.

LEVELCROSSING

89C51CONTROLLER

MICRO

R1 R4 R3 R2

M

M

SG1 SG2 SG4 SG3

L

L

B

B

RAILWAY GATE CONTROL

railtrack

road

The detailed description of the working of the above model can be explained

under various heads.

i) Initial Signal Display:

Signals SG1,SG2,SG3 and SG4 are placed near the gate each at a specified

distance. SG1 and SG4 are placed at 2Km on either side of the gate whereas SG2 and

SG3 are placed at 180m from the gate. The train may be approaching the gate in

either direction. So all four signals are made RED initially to indicate that gate is open

and vehicles are passing through the gate.

The road user signals are made GREEN so that they can freely move through

the gate buzzer is made ‘OFF’ since there is no approach of train and road users need

not be warned.

ii) Train Arrival Detection:

IR transmitter

IR receiver

Comparator

~

Transistor switch

+V

Detection of a train approaching the gate can be sensed by means of sensors

R1,R2,R3 and R4 placed on either side of the gate. In a particular direction of

approach,R1 is used to sense the arrival while R3 senses the departure of train. In the

same way,R4 senses the approach and R2 the departure respectively in the other

direction of train arrival.

Based on the vibration of the track as the train approaches the sensor works.

The sensor comprises of an IR transmitter, IR receiver, a comparator and a transistor

switch. IR transmitter gives IR rays whose wavelength depends upon the vibration of

track that corresponds to the input frequency . If frequency increases its wavelength

increases and thus reduces the resistance of the IR receiver. It reduces voltage drop

across the receiver. Its output voltage is the difference between this voltage drop and

input voltage to the sensor.

This is fed to the comparator whose reference voltage is based on the

threshold frequency which is minimum frequency caused by a slow train. Thus, the

comparator produces -12V saturation when it senses a train and +12V if not.

Correspondingly, a transistor switch produces +5V and 0V respectively. This is

transmitted employing FM to the microcontroller.

iii) Warning For Road Users:

At the moment the train arrival is sensed on either side of the gate, road users

are warned about the train approach by RED signals placed to caution the road users

passing through the gate. RED signal appears for the road user once the train cuts the

relay sensor placed 5Km before the gate. A buzzer is made ON as a precautionary

measure for the road user and that nobody should enter the gate at that moment.

iv) Sensing For Vehicles:

Laser light is used as a source and LDR as a tool for sensing purpose. When

light strokes on LDR its resistance decreases and when light does not strike LDR its

resistance remains at normal value. This change of resistance of LDR is used for

sensing by the micro controller 89C51 by the use of compensation.

If there is no vehicle in between or beneath the gates, then the laser light from

the source falls on the LDR since there is no obstacle. Since there is no vehicle or

obstacle, signal is made GREEN for the train to pass through the gate. The same is

applied for in the other direction and SG3 and SG4 are made GREEN and gates are

closed.

Due to some unavoidable circumstances, if there is a sudden breakdown of a

vehicle between the gate, then the light from laser source does not fall on LDR. It

indicates the presence of vehicle and the signal for train should be made RED in order

to slow down the train to avoid collision. Then the obstacle should be warned to clear

the path.

v) Gate Closing Operation:

Once the microcontroller senses that there is no vehicle inside, then it

automatically produces the signal to operate the motor through relay circuit and hence

close the gate for the passage of train.

When any presence of obstacle is sensed, 89C51 gives signal for obstacle to

clear the path and once the path is cleaned, motor is operated to close the gate.

Actually rotary motion occurs in a motor. This rotary motion is converted to linear

motion of the gate using a gear.

vi) Signal For Train:

When the path is clear inside the gate, GREEN signal is produced for the train

when there is any obstacle, signal is made RED for the train in order to slow down its

speed before 5 Km from the gate. Another signal placed at 180 m before the gate,

when it is still RED when train approaches if then provisions if then provisions should

be stop the train.

vi)Train Departure Detection:

Detection of train departure is also done using relay technique as explained

under the head of train arrival detection. Train departure sensing is done by sensors

R3 and R2 respectively considering the directions of train approach.

viii) Gate Opening:

When the train departure is sensed by the sensors, signal is given to the

Microcontroller which operates the motor in reverse direction and the gates are

opened. Once the gate is opened signal for road users are made GREEN so that the

vehicles can pass through the gate.

ALGORITHM:

STEP 1: Start.

STEP 2: Set the variables.

STEP 3: Make initial settings of the signals for the train and road users.

STEP 4: Check for the arrival of the train in either direction by the sensors. If the train is sensed go to STEP 5. Otherwise repeat STEP 4.

STEP 5: Make the warning signal for the road users and set the signal for the train.

STEP 6: Check for the presence of the obstacle using sensors. If there is no obstacle go to STEP 7. Otherwise repeat STEP 6.

STEP 7: Close the gate and stop the buzzer warning.

STEP 8: Change the signal for the train.

STEP 9: Check for the train departure by the sensors. If the train sensed go to next STEP. Otherwise repeat STEP 9.

STEP 10: Open the gate.

STEP 11: Go to STEP 3.

STEP 12: Stop.

FLOW CHART:

Make the initial settings for train & road users

If arrival of train in either of directions

Buzzers & signal warnings to road users

Stop warning & close the gate

Set the signal for train

If train departure

Open the gate

If obstacles

SOURCE CODE :ASM PROGRAMME FOR AUTOMATIC RAILWAY GATE CONTROL:

gateon .reg p3.0gateoff .reg p3.1ce .reg p1.2sig1r .reg p0.2sig1g .reg p0.3sig2r .reg p0.0sig2g .reg p0.1sig3r .reg p2.3sig3g .reg p2.4sig4r .reg p0.5sig4g .reg p0.4rsg5r .reg p2.2rsg5g .reg p2.7rsg6r .reg p2.5rsg6g .reg p2.6ldr1 .reg p3.2ldr1 .reg p3.3ldr3 .reg p2.1ldr4 .reg p2.0rlysens1 .reg p3.7rlysens2 .reg p3.6rlysens3 .reg p3.5rlysens4 .reg p3.4buzzer .reg p1.0laser .reg p1.1count .reg 23hcount2 .reg 24h

org 0000hjmp startorg 0003hretiorg 000bhretiorg 0013hretiorg 001bhretiorg 0023hreti

start: clr cemov p0,#00hmov p2,#03h

clr buzzerclr laser clr gateon

clr gateoffgon: mov count1,#ffhloop15: mov count2,#ffhloop2: djnz count2,loop2

djnz count1,loop15call dly

mn: setb sig1rsetb sig2rsetb sig4rsetb sig3rsetb rsg5gsetb rsg6gclr buzzerclr laser

main: jnb rlysens1,loop1jb rlysens4,mainclr sig4gsetb buzzersetb lasersetb rsg5rclr rsg5gsetb rsg6rclr rsg6gjnb ldr1,loop20jnb ldr2,loop20jnb ldr3,loop20jnb ldr3,loop20jnb ldr4,loop20

loop2a: call gateclsclr buzzerclr laserclr sig3rclr sig4rsetb sig4gsetb sib3g

loop5: jb rlysens2,loop5loop6: jnb rlysens2,loop6

clr sig3gsetb sig3rclr sig4gsetb sig4rclr rsg5rclr rsg6r setb rsg5gsetb rsg6gcall delaycall gateopencall delayclr rsg5r clr rsg6r

setb rsg5gsetb rsg6gcall delaycall delayjmp mn

loop20: setb buzzersetb lasersetb sig3rsetb sig2r

loop21: jnb ldr1,loop21jnb ldr2,loop21jnb ldr3,loop21jnb ldr4,loop21clr buzzerclr laserjmp loop2a

loop1: setb sig2rclr sig1gsetb buzzersetb lasersetb rsg5rclr rsg5gsetb rsg6rclr rsg6gjnb ldr1,loop23jnb ldr2,loop23jnb ldr3,loop23jnb ldr4,loop23

loop24: call gateclsclr buzzerclr lasersetb sig1gclr sig1rsetb sig2gclr sig2rcall delaysetb rsg5rsetb rsg6r

loop9: jb rlysens3,loop9loop10: jnb rlysens3.loop10

call delaycall gateopenclr buzzerclr laserclr sig1gclr sig2gsetb sig1rsetb sig2rclr rsg5rclr rsg6r

setb rsg5gsetb rsg6gcall delaycall delayjmp mn

loop23: setb buzzersetb sig3rsetb sig2r

loop26: jnb ldr1,loop26jnb ldr2,loop26jnb ldr3,loop26jnb ldr4,loop26clr buzzerjmp loop24

gateopen: setb gateonclr gateoffcall delayclr gateonret

gatecls: setb gateoffclr gateoncall delayclr gateoffret

delay: mov 50h,#04hji: mov 51h,#f0hbala: mov 52h,#ffhriju: djnz 52h,riju

djnz 51h,baladjnz 50h,jiret

dly: mov 53H,#50Hkr: djnz 53h,kr

ret

FUTURE ENHANCEMENT:

This paper has satisfactorily fulfilled the basic things such as

prevention of accidents inside the gate and the unnecessity of a gatekeeper. But still

the power supply for the motor operation and signal lights. It can be avoided and a

battery charged by means of a solar cell. It can be used directly during the daytime

and by charging the battery during night. Hence this arrangement can be used in

remote areas where the power supply can’t be expected. The obstacle detection part

can be implemented using Fuzzy logic. As it thinks in different angles or aspects, the

system works still more efficiently.

THE LAST WORD…

The idea of automating the process of railway gate operation in level

crossings has been undertaken. As the system is completely automated, it avoids

manual errors and thus provides ultimate safety to road users. By this mechanism,

presence of a gatekeeper is not necessary and automatic operation of the gate through

the motor action is achieved. Microcontroller 89C51 performs the complete operation

i.e., sensing ,gate closing and opening operation is done by software coding written

for the controller. The mechanism works on a simple principle and there is not much

of complexity needed in the circuit.

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