Line Follower Robot – without using Microcontroller

Line Follower Robot – without using Microcontroller

After a long time I am presenting my new project Line Follower Robot without using Microcontroller.
It is a simple circuit with a LM358 op-amp and is able to operate from 9v to 12V. The LM358 contains two op amps which are wired as comparators. Thus when the voltage at the non-inverting terminal (+) is higher than inverting terminal (-) its output will be high and when the voltage at the inverting terminal (-) is higher than non-inverting terminal (+) the output will be low. Outputs of the op-amp comparators are given to transistors which are wired as switch to drive the motors. Diodes D3 and D4 are provided to cancel the negative voltages produced due to the back emf of the motor.

Line Follower Robot Circuit - without using Microcontroller

Line Follower Robot Circuit – without using Microcontroller

When a sensor is on white color, LED light will be reflected to the corresponding LDR. As a result, resistances of LDR decreases and the voltage at non-inverting terminal (+) of the op-amp will increase. Thus op-amp output goes high and turns on the transistor, which rotates the motor. When a sensor is on black color, LED light will not be reflected to LDR, thus the output of the op-amp will be low and the motor will be off.

Thus when the both sensor are on white color, it will run both motors forward and when any of them on black color it will stop the corresponding motor. Thus the robot turns in corresponding direction since one motor is running.

The sensitivity of the LDR can be adjusted by using the 10K pot. For more accuracy, cover the sensor-LED pairs in a black wrapper through sides in such a way that only the reflected light falls on the LDR. The Line Follower can trace path drawn with black ink on a white chart and the width of the black track should be a litte less than the width between sensors.


Line Follower Robot - Construction

Line Follower Robot – Construction

Note : Use Geared DC Motor

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85 Comments on "Line Follower Robot – without using Microcontroller"

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Sudhanshu
Guest

great yaar……….

Shiv Thakur
Guest

nice yaar

prinil das
Guest

very easy circuit

Ligo George
Guest

Your motor might require more current, than BC547 transistor can safely handle…
Replace BC547 transistors with BC107..

shree
Guest

i have connected darlington pair at the o/p of both opamp and to which i have connected relay and motor but when both o/p is high my one relay goes off so the motor. please suggest the solution..
thank you.

Ligo George
Guest

I think you might have some problem with one relay or darlington pair… check it by turning on separately..

shree
Guest

Thanks, i have checked my relay module separately it work perfect. but when it connected to the op amp then shows problem.
any other solution???
can u tell me which is perfect transistor combination for darlington pair which gives me more than 200ma current rather than bc574.

Ligo George
Guest

What about the output of opamps… does it correct?

shree
Guest

it shows output on led but fluctuate in relay motor combination.

i think there is the problem of current. but i cant figure out what exactly going on there.. what about transistor ???

Ligo George
Guest

reduce the base resistor of transistors..

Daff
Guest

hi, what should I do if I want to make the robot to follow a white line on a black surface

Ligo George
Guest

Just interchange the + and – pins of opamp comparator.

Ahmed_yassin
Guest

how can I do this robot with PIC16f877a ,,,, shall i connect the LDR to the analog pins ,,or as pull up resistor ,,please help me with the code by micro c pro
Also I want to make a robot with ultrasonic sensor I found the interface with microcontroller what should I do to make this robot ,, thank you sir

Darpan Patel
Guest

hello,
say me about motors,,what is difference between simple DC motor and geared DC motor? what effect it will make if i use simple DC motor? Also describe, which LED,LDR pair will be better for sensor? It will be great if you will show me circuit analysis (i mean how values of resistance and current detail)
thanks

kishore
Guest

I have a small question.how can we select the components for our projects..I mean where to start..how to select those resistors and specific transistors and all the others…

Ligo George
Guest

Geared DC motor has gears attached to simple DC motor to increase torque..
Select the color of LED depending on the surface color .. or use white led..

Ligo George
Guest

Use IR sensor pair.. you can use comparators with presets to adjust sensitivity of each sensor..
Output of each comparator (digital o/p) can be connected to pic..

Ligo George
Guest

It is a difficult question to answer..
Choose resistors depending on the required resistance value and power rating..
choose transistors using max voltage, current and current gain required. .
Each components has its own way..

asad
Guest

sir can you please tell me what current and voltage, motors required to run ?

asad
Guest

sir motors are running both in light and dark. please guide me

Pratim
Guest

Sir, i have a problem, my left motor is working perfectly fine but right side motor is working both in light and dark. I have checked the circuit many times there is no fault in the circuit.. please help me..

Ligo George
Guest

You can use two 12V 40RPM geared dc motors..

Ligo George
Guest

Try adjusting sensitivity using presets..

Ligo George
Guest

Try adjusting the sensitivity using preset..

Pratim
Guest

Thank you for your reply, I’m still stuck with the same problem, I have triple checked the circuit and tried changing the IC and the BC547, the pot doesn’t have any effect(I’ve tried changing the pot also). The motor which is controlled by 5,6,7 pin of the ic, works like charm.. but the motor controlled by the pin 1,2,3 doesn.t work at all… please help!!

Ligo George
Guest

It should work.. try replacing the LDR..

asad
Guest

sir .. will this circuit work, if i use only half of the circuit that is .. if i want to run only one motor using ldr.. will this circuit work ?

Ligo George
Guest

Yes it will but… it can’t be used as a Line tracer..

asad
Guest

sir i have checked my circuit , several times .. but still it is not working. help me !

Madhura
Guest

do we need only one LM358N IC know?

Ligo George
Guest

Yes, only one IC is required…

Madhura
Guest

you are saying,we can use BC107 transistor for the BC547 transistor know?

Ligo George
Guest

Yes you can use BC107..

Ligo George
Guest

Are you using 12V dc motor with 9V supply.
That 9v battery might not be able to drive DC Motors, you should use a good battery having more Ah capacity.

Madhura
Guest

yes,i used dvd rom motors.and 9v battery.

Ligo George
Guest

Your motors should not have enough torque.. You should use geared dc motors.

Madhura
Guest

If i use this motor,it will work know.

Madhura
Guest

what kind of mAh power should i used to run this motors with 9V?

Ligo George
Guest

Yes, it should work… limited by the total weight..

Ligo George
Guest

It will depend on how much time your robot should work…
mAh => milliampere per hour…
eg : if the battery is 1.2Ah, 12V >> it can give 1.2A current with 12V for 1 hour…
if you are drawing 600mA it will work for 2 hours..

Madhura
Guest

if i use 12V with 1800mah,will it work? no any harm to the circuit?

sakthi nandhan
Guest

i am new to this i want simple circuit diagram to do line follower robot or video how to do line follower by stepby step

ssss
Guest

the above diagram is the simplest circuit diagram you’ll find

Ligo George
Guest

Sorry, we haven’t any video of above project..

Ligo George
Guest

Yes, it should work..

Madhura
Guest

I completed this line follower.thank you Ligo George.It`s working perfectly.

Ligo George
Guest

Thanks for the feedback .. 🙂

bony
Guest

how much lm358n should we use

Ligo George
Guest

Only 1

sahil
Guest

sir what is RV1 & RV2