Autonomous Line Follower (Simplest IR Module Based)

graphics-click-here-688974Click here to get all components required to build this robot

Today world are very advance in the field of robotics. Still the term robotics it very advance but the hobbyist made it easy as to cope up with their lazy style of working. In this we talk the simplest circuit ever you encounter for the line follower robot.

Components Required:

  • DC geared motor (2 sets)
  • Wheels (2 sets)
  • caster wheel
  • PCB
  • Ribbon wire
  • IR LED (2 sets)
  • Phototransistor (2 sets)
  • 100K-Ohm Variable resistance (2 sets)
  • 330 ohm(3 sets)
  • Power transistor (4 sets)
  • Battery  9V DC
  • Battery connector
  • robotic base
  • Ribbon wire
    To get all the componentsgraphics-click-here-688974 Click here.

Design & Working:



for the design the first part is the sensor module and for that we use the  infrared module, first we take an IR LED and get it glow via a 330 Ohm resistance on the 9 Volt grid as shown in figure-1 (Always keep in mind that the Positive lead having longer terminal of IR LED), then comes our sensor part for that we’ll use a Phototransistor that is a very good sensor having immunity to the visible range light and hence very good for indoor robotic event as if will not malfunction due to the environmental lights which is present in the case of LDR based circuits. As far as the Phototransistor is concern always keep in mind that the longer terminal is emitter and shorter terminal is collector so when it connected to the circuit as per the  design is looks like you connected oppositely as we normally see in case of LED that we always connect the small terminal to the ground. but remember the Phototransistor is not the LED so instead it looks like we are connecting in opposite way as LED but the connection is correct. then we connect the variable resistance from the collector and the positive bus of 9 Volt grid (Use of variable resistance instead of fixed resistance has its own advantage as we can always has a facility to tune and adjust our sensor as per the requirement by just varying the variable resistance). there after we connect he middle point of PT(Phototransistor ) and variable resistance to the base of another NPN Power transistor which having a 330 Ohm resistance on its collector terminal having its other terminal to the positive but of the 9Volt grid. then the final connection is made via the collector terminal of 1st Power transistor is being connected to the base of second stage power transistor  which having a motor to its collector terminal. Yeah!!! it’s a quite good question why we are using two transistor, is it possible to use a single transistor instead? the answer is yeah, but in that case the tuning of the variable resistance should be precise and any deviation in the environmental IR light required another tuning, So to increase the circuit performance we like to employed 2 instead of one. Moreover it can work Black Line follower and White line follower both we have to just swap the position of PT and variable resistance or can put the sensor inside and outside the track.

Ohhhh….. The actual design has some more adventure then we see here in the circuit since we have to put the sensor module at the track level so make a sensor module by taking the circuit component out of main circuit as the shaded part shown in Figure-2 into the path sensor module and the terminal connected back to the circuit via a hard wire.

Now here are few tips over the mechanical arrangement of the setup. for the optimal dynamics control of the Robot always keep your sensor module in the direction of the motion at the half of the distance between wheels  in front of the wheels axis. So here is we are finally now take your Robot and do some artwork on it….. :) :):):)

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