I would like to make a simple line follower robot that runs along a trail between two farm barns on the property. This is an out door path through the woods so i plan to use a shallow burried magnetic wire. I was wondering if anyone had any experience with this idea? What hall effect sensors to use, etc? I searched on the internet but there does not seem to be much for this specific idea (out door burried wire in the woods to guide a shuttle robot).
Thank you.
Have a look at the technology used for 'pet fences'. It's essentially a buried wire with a 7 kHz transmitter on one end (or loop). The wire acts an antenna and the signal can be detected a few cm either side of the wire using a portable receiver.
All the robot has to do is keep moving in a direction that keeps the signal strength high. If it loses the signal then it knows it's gone off course.
Sounds like you're after this sort of thing: Automated Tugger [New Products] | Material Handling and Logistics. A search on 'agv' will bring results.
The types I'm familiar with didn't use magnets but rather two coils tuned to the frequency of an oscillator driving the signal into a length of stranded ~14ga. wire buried ~1/2" below the surface of a concrete floor a la mikb55's pet fence. Essentially the same concept, from a guidance standpoint, as the optical line followers.
There are safety issues. What does the cart do if it loses the signal, encounters an obstacle? How does it 'know' when to stop?
I built s similar robot to mow the lawn. Bury a wire with a signal running a few hundred milliamps. On the robot I had sets of two, non-shielded inductors tuned to the freq. ( I had several sets spread across the front so only needed one wire for several passes ) You only would need two, one right and one left. Compare the signal strength ( L & R ) and you have what is needed for guidance. Remember not to have two wires running together, or the magnetic signal will cancel. Good luck