I am very new to arduino so I am reaching out for help from those far more knowedgeable than I. I want to creat something that will trigger an electric pulse from the arduino whenever 2 objects pass eachother. While not exactly what I want it for ; as an example, lets just assuming i have a wheel with a sensor on the outside. This wheel is free rotating within a slightly larger wheel with a sensor on the inside, also free rotating in the opposite direction. Could it be possible to program arduino to activate each time the sensors pass eachother? How fast could these be going before it surpasses the capabilities of the arduino? Are there any systems better suited for high accuracy and highly regulated pulses?