This Robot use two motors control  rear wheels and the single front wheel is free. It has 4-infrared sensors on the bottom for detect black tracking tape, when the sensors detected black color, output of  comparator, LM324 is low logic and the other the output is high.
Microcontrollor AT89C2051 and H-Bridge driver L293D were used  [...]

8951 Microcontroller Robotic car Project Blog diagram
Robotic Car is a miniature ancestor car powered by batteries whose assorted movements can be ascendancy either manually or automatically, or the aggregate of both. Here the command is accustomed through keyboard; it would accept been bigger if we acclimated IR alien ascendancy or article of that affectionate rather [...]