So, I'm looking to build an autonomous robot of a sort and want to know what sensors / MCU packages would be good for dealing with lined boundaries?
These would be similar to how dog collars work. Lay a ground line beneath the ground, power it up, and use a sensor (magnet?) of some sort to detect the boundary.
Another way could be to use wireless beaming of a kind (above ground) but would have to work without LOS (Line of Sight).
What are my options? Any suggestions would be helpful too.
Some options explored or being thought about:
Hall effect sensor:
What is a low voltage (approx 5v) hall sensor that could detect up to 8".
I came across: A3144 but spec says it's a discontinued product since 2005.
Inductive sensor.
The few that I could find were around $3 but could only provide up to about 4mm of distance.
AM radio and receiver:
After more research perhaps the best way to go about this would be using a similar setup of how dog collars work. From what I understand the ground line basically acts as a small AM frequency antenna and the receiver (on the bot) picks up that signal when it gets close. By fine tuning the power going to the antenna / receiver, you can have a fairly accurate type of boundary system.
Now only to find what kind of MCU/receiver would be best for the job.
Another part of the problem that I forgot to mention is that there will be a 9DOF MPU-9150 package onboard (or something similar, Perhaps GY-271 HMC5883L). How will the magnetic field affect this? I imagine it's possible to fine tune the ground boundary wire to output as minimal of a field as possible.
Best Answer
A few suggestions:
Lets assume that there is only a wire/ metal strip buried beneath the ground (not very deep) as the 'invisible' boundary.
(1) The wire/strip has a direct current passing through it.
You could detect the magnetic field around the wire with a Hall sensor.
(2) The wire/strip has a low frequency alternating current.
Hall sensor or pick up coil (detecting AC 'hum')
(3) The wire/strip has a high frequency alternating current
Tuned LC circuit - probably with a ferrite rod to localize signal.
(4) The wire/strip is carrying a pulse signal (e.g. output of a square wave generator)
as per solution (3) but doesn't need to be tuned (detects wideband 'noise') - similar to electric cable detector in walls.
(5) The wire/strip is not connected to anything
Some form of metal detector.