Line Follower Robot Without Using Microcontroller

We are required to do a project in the second year of our college, but we are not allowed to use any type of microcontroller. Therefore, I wanted to do an exciting project so I started researching on the internet.

Suddenly, I got the idea to make a line follower robot without using a microcontroller. After that, I started researching this topic but can't find any proper guidance. So I started simulating and building logic for each functionality, such as forwarding direction, reverse direction, left turn, right turn, and stop.

Supplies

IR receiver x2
IR transmitter x2
Resistors(220ohm,1K) x2
Capacitor(0.1uF,10uF,100uF)
LM7805
LM358
Potentiometer
Hex inverter (74HC04)
Quad nand I.C (74HC00)
Motor Driver (L293D)
Batteries(Li-ion/9v)

*To buy electronics components at the cheapest online click here

Step 1: IR Proximity Sensor

First I decided to buy the module then, I thought I should make the sensor on my own.

IR transmitter is used to emit IR light which is connected via a 220-ohm resistor.

I used a dual comparator to compare the reference voltage at inverting input, set reference voltage using a potentiometer, and varying voltage at the voltage divider node of the IR receiver(opposite polarity) and 1K resistor.

*Refer to the elonics video for a better understanding of the IR sensor working

*To learn more about comparators refer to my inscrutable

Step 2: Motor Driving

Motor needs alternating polarity for clockwise and counterclockwise rotation and a high current signal to drive, but the opamp output can deliver 20 mA max.

so first the output of the opamp is inverted using a hex inverter then, both signal is connected to the inputs of the motor driver respectively.

Step 3: Stopping Logic

To stop the robot at the black line, both sensors read one, if anyone's sensors read zero or both sensors read zero, it should give zero, and the output pin connects to both enable pins of l293d.