I'm an irrigation farmer and I use several machines called irrigation pivots to water my land. These machines consist of several sections called spans that range in length from 100 to 215 feet (30 to 65.5m), the overall machines range from 100 to 2600 feet (30 to 800m) long. The first span is attached to a pivot point in the center of the field and has a set of legs, wheels, driveline and electric motor at the other end called a tower. The next span is attached to the first using a flexible coupling and the next to it and so on. [login to view URL]
We've always had problems keeping long units straight, because of the way each tower's movent is controlled long units with more than ten towers will develop curves and can be stressed enough to cause structural failure. The problem has been addressed using several mechanical methods but the problem has never been resolved. Basically the only solution is to monitor these machines and adjust them periodically. We actually have to shut down these machines during high winds and local storm conditions as well.
I'm trying to figure out a way to align one or more center towers with the pivot point and last tower using laser, radar, radio waves etc. There must be a way to use triangulation or something to keep these units in alignment. GPS might be an option but it may be prohibitably expensive as I would have to use RTK.
So I'm putting this out there to see if anyone has any ideas.