Easy Way to Design an Automatic Driverless Train - LEKULE BLOG


Sunday, 21 August 2016

Easy Way to Design an Automatic Driverless Train

Designing and Controlling a Automatic Train Prototype
Designing and Controlling a Automatic Train Prototype 

Every one in the metro cities like Kolkata, Delhi enjoying the luxuries of the metro train ever spared a thought about the train? No, then let me give you a brief idea about the driverless automatic driven and controlled train. But before that let us have a brief recall about types of metro automation.
The Driver Controlled Mode: In conventional modes, it’s the manual driver who drives the train and controls the train motion using the stationary light signals.

The Partially Automatic Mode: In this mode, the driver drives the train while an external control system is used to constantly monitor the speed and acceleration of the train and provide required feedback to the driver.

Driverless Mode: The whole operation and maintenance of the train is done automatically without any human intervention. The train stops and starts automatically and the doors are closed and opened automatically.

So, now let us fix our attention to the last mode i.e. The Driverless Mode
In a fully automatic driverless train, the control is done through a Communication based train control where a trackside computer is used to monitor the train running on the assigned line and convey this information to the centralized computer. The train is controlled by the automatic train control system.

Designing a Basic Prototype of a Automatic Driverless Train
The design will include the following components:
  • A rectangular body which holds all the other robotic components like the control circuit, the door etc.
  • A sliding door prototype
  • A couple of IR LED and photodiode arrangement
  • A control circuitry using a Microcontroller

Working of the Basic Prototype:

So let us see how our basic prototype works does:
  • The Automatic platform sensing and Door control system: It consists of an IR LED and a photodiode system. When the sensor senses the coming of the station, the motor driver automatically drives the motor such that the train comes to a halt and the door is opened when a person is sensed.

  • Passenger counter system: The train is also equipped with a passenger counter system which counts the number of passengers entering the train and when the count reaches a certain limit the door is closed automatically and the train will start moving after a certain time limit.

How to controls the Train Prototype:

  • Controlling the movement of the train: Normally when the train is moving, the IR LED-photodiode arrangement is placed such that both are placed parallel to each other and thus as the photodiode doesn’t gets the light pulses, it doesn’t conducts and as a result the microcontroller will get a high signal. Now as the train approaches a station, the IR light from the IR LED gets reflected by any object (suppose the station signal) and the reflected light falls on the photodiode, causing it to conduct and thus an interrupt low signal is given to the microcontroller through the transistor. The microcontroller is programmed so as to send signals to the motor driver to stop the motors. The operation of the motor is driven by the motor drive IC; here two stations are connected to the microcontroller through the motor drive.
    Block Diagram Showing Train Movement Control
    Block Diagram Showing Train Movement Control 
  • Controlling the opening and closing of doors: As the train stops, i.e. the microcontroller sends an interrupt signal to the motor driver to stop the motors; the microcontroller also sends a high signal to the door motor driver such that it drives the motor to open the door, for the passengers to get in. The microcontroller is programmed such that the door is opened till the number of passengers entering reach a limit and then the microcontroller is programmed to signal the motor driver to rotate the motor so as to close the door. The microcontroller stores the code which is written in an assemble language. So to dump this coded program into a microcontroller IC we need a device which is known as burner or programmer. A programmer is a hardware device with software which reads the content of the hex file which is stored on a pc or laptops. It’s read the hex file data serial or USB cable and transfer the data to the memory of the microcontroller. The programmers and compilers are different for different microcontroller which is for different companies like the 8051 microcontroller “flash magic” is used to program the microcontroller and AT89C51 microcontroller “programmer” used to program the microcontroller. This is way how we are programming code in a microcontroller with a burner or programmer.

Block Diagram Showing Door Opening and Closing Control
Block Diagram Showing Door Opening and Closing Control 
  • Controlling the count of number of passengers entering and leaving the train: This is done using a passenger counter system. This again consists of an IR LED-Photodiode arrangement – one at the door and another a little distance away. When a person enters the door, there is an interrupt between the IR LED and the photodiode and accordingly the corresponding transistor sends a logic high signal to the microcontroller. As the person leaves the area and goes further inside interrupting the second IR LED-Photodiode arrangement, the 1st IR LED-Photodiode arrangement comes back to its normal operation and a low signal is send from the corresponding transistor to the microcontroller. This transition from high to low of the microcontroller pin causes an increase in the number display of the 7 segment display programmatically. When the count reaches a maximum, the microcontroller is programmed so as to trigger a buzzer alarm. Similarly when an interrupt is sensed between the 2nd IRLED-Photodiode arrangements, the transition from high to low signal of the microcontroller causes a decrease in the number count of the second 7 segment display.
Block Diagram Showing Counting System Control
Block Diagram Showing Counting System Control

Advantages of automatic train control system:
  • Easy way of transport from and to remote area
  • Fully air conditioning trains
  • By using the automatic train systems we can travel  a safe journey
  • High speed technology
  • Modernity
  • Accessibility
Disadvantages of automatic train control system:
  • Expensive
  • Disturbance
  • Loss of control

So, now I have given a basic prototype design, just spare a thought for how the actual automatic metros trains in our country are controlled?
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