We know that the railway network of India is the biggest in south Asia and perhaps the most complicated in all over the world. There are so many different types of trains local, fast, super fast, passenger, goods…. etc. and their so many multiple routs. Although the time table is perfect it is not at all possible to maintain it. And that’s why the train accidents are becoming more and more usual. So why not we add a kind of intelligence to the train engines itself so that it tries to avoid accidents.
The idea is whenever any engine observes a red signal on its track it will start decreasing its speed gradually and stops automatically at some distance from the signal pole. After then when it gets green signal the driver can manually start the train and go on. In the mean time when train has not stopped yet and a red signal becomes green then it crosses the signal pole with low speed and then driver can slowly increase the speed.
So now before the driver observes the red signal the engine itself observes it and automatically starts decreasing speed and then stops. The driver can feel relax in driving because he doesn’t have to take care about red signal. Even if he forgets to take any action on red signal then also we can avoid accidents by the implementation of this idea.
What we have to do is we have to attach a transmitter with signal pole which will start transmitting signals only when the red light is on. If there is green light no transmission. The engine has a receiver which catches these transmitted signals and takes desire actions.
Both the transmitter and receiver are of RF type with minimum range of 2 Km. so that train can get enough time to decrease its speed and stop before the signal pole with minimum swapping distance of 100-200 mt.
Here in our project we have used IR transmitter and receiver instead of RF for demo purpose. But same idea can be easily implemented with RF also with a little more cost.
Lets first discuss the demonstration model.
The train engine runs on 24V DC motor so that we can easily vary its speed by varying applied voltage. The switching voltage is applied in step of 18 V, 15 V, 12 V and 9 V (min speed). The 230 VAC is step-down to 24 VAC by 12-0-12, 2 Ampere step down transformer. As shown in figure this 24 VAC line runs parallel with track at the top of the train. Movable tapping are taken from this line and fed to the internal circuit of engine. These tapping slides as the train runs on the track and give continuous supply to circuit. The IR sensor is placed at the top of the engine, senses the signals transmitted by IR transmitter attached to signal pole. Train track is straight and 20 ft long. Signal pole is placed at the end of track and train starts from farther end.
- TSOP will detect the 38 KHz IR beam and gives the interrupt to 89C51.
- 89C51 will indicate the interrupt event on first (green) LED and energizes only one particular relay through ULN chip.
- When any of the four relay get energized the motor will get supply from it and it will start running
- As voltage is less it will run with less speed
- So now its the function of microcontroller to receive signal from IR sensor, decrease the speed of train gradually in four steps and then stop it. And this is done by software embedded in to 89C51.
How the project works?
- Initially when you switch on the supply 89C51 will switch all the relays RL1- RL4 one by one. So motor will get 9-12-15-18 V supply in steps and gradually increases its speed reaches max speed indicated by first red LED (P0.0).
- Now if the signal is green then train will cross the pole with same pole
- But if signal becomes red in between then IR sensor will detect IR beam and interrupts the 89C51
- Getting first interrupt 89C51 will switch off RL4 and switch on RL3 so now motor will get 15 V supply and its speed will be decreased. That’s indicated by second red LED (P0.1)
Now 89C51 will wait for some time (2 to 3 sec) and train goes on with same speed. Again if still red signal is on 89C51 will be interrupted and this time it will