I do not know if this post belongs here, but it does deal with electronics. I am building a car about 30cm long and 20cm wide. This car has to go a specified distance and must stop as closely as possible to this distance. I have built previous vehicle and found out that there are only two things to consider; 1) the car moving left and right, 2) and stopping +/- 2 cm to the correct spot. For the new car, i want to use some electronic device that can give me some data, so that the car can adjust itself while moving. The first car is has 4 wheels with a microprocessor that is programmed to run a stepper motor on the left and right back wheels. With the data from the electronic device i want to be able to calculate the speed the opposite wheels should be moving at, so that the car compensates on its own. I also want something else to be able to make sure the car stops at the right distance. If anyone knows of a device that can give me this type of data, please let me know. Thanks. If there is a better place for this post, let me know and i will post it there.