I am using an IR sensor which detects the obstacle. My question is how does 2 robots stops on a finish line which is an object higher that the height of the car robot if i am using IR, comparator(LM741),Relay, bjt, diode And Hbridge (L293d) ? How to detect the egde? If detected what it does ? How to detect obstacle ? And how to detect the finish line which is the an object higher in height?