When I first learn Arduino, I wanted to build this. I first saw something like this when I was browsing pyroelectro.com. Surprisingly the website is still up after all these years. I was going to link it to my YouTube video but can no longer find the project. So back then I attempted to make this with 4 IR sensors and 4 DC motors that are designed for spinning up CD, that's right, I tried to build a robot with the small wimpy bluray spinning engine. Eventually it didn't work because the motor has so little torque. Now, years later I tried to make this project yet again, this time armed with more knowledge. I use 3D Printed parts, a proper motor and 4 pairs of IR emitter, receiver. There is a problem with IR sensors that I can't fix, and that is they are very sensitive to sunlight. That's because sunlight has infrared in it's composition, thus you might notice that when I operate the robot, I never do it when it's bright outside. I also changed the 3D printed parts after finding out that the quality is unacceptable. I could have made it larger but I was limited to the capability of the 3D Printers at my makerspace. But the makerspace recently purchase two Ultimakers which allow me to make projects more than twice as large. So I used that to my advantage and continue making this project. It was fun while it lasted!