Line Following Robot detects Obstacles and spins 180°

Thread Starter


Joined Dec 1, 2016
I'm building a robot that would follow a white line on the floor, then detect obstacles on its path, spin 180° and go in the other direction.
I already have the first part of the circuit working, with two IR emitters/detectors pairs on each side of the robots connected to the respective op-amps and then to an H-bridge.
I am now working on the obstacle detection and rotation: I need to use a IR proximity sensor, which I think should be connected to a 555 timer monostable circuit. This would then give a high output voltage which is connected to pins 4A (through an inverter) and 3A of the H bridge. The fact that 4A has an inverter before makes the output to 4A low and the output for 3A high, causing a change in direction.
However, I need to time it properly (maybe through values of resistor and capacitor in the 555 monostable circuit??) and particularly I need to switch off the white line detector part of the circuit which otherwise would not allow the robot to spin 180°!

Can anyone help?