I want to build a small car that is about 200 grams. I want it to run the following course and stop at exactly or about the the finish line. I can't use any controlling devices or electronics.
I've an idea to count the number of revolution the wheels make to pass the finish line and the next time I stop it when it hit's it last wheel revolution.
Is there a device that can stop a wheel after a certain amount of turns? It must be mechanical and it doesn't have to be supplied by Lego either.