If you have some RC gear and a few bits of GPS electronics this project that iforce2d built might be worth a look.  Have a look at it in action at 2:40.  The user has a GPS module and the car has a GPS module, the module with the person sends its position to the car and the car goes to that location, issue with GPS is that it isn’t very precise so following tight corners is quite challenging. This would perform great in a field though, I would like to see this connected to some farm equipment in the field. There is some code here that will help you build your own.Â