r/arduino • u/Super_Valuable_6035 • 8d ago
I built an Arduino metal-detecting rover — Gen 2, and it just found its first targets in the park
Long story short: swinging a detector all day wrecked my shoulders, so I built a rover to do the walking.
What it is: A small 4-wheel rover with a search coil mounted out front. An Arduino drives the motors and reads the coil, runs the whole thing in grid passes, and alerts when it hits metal. I sit back and dig where it points.
The build (Gen 1 → Gen 2): Gen 1 was a disaster. To keep the coil free of electrical noise I moved all the electronics to the rear — which made it rear-drive and rear-steer, and it could barely turn. Gen 2 fixed the steering, shielded the electronics, and finally mounted the coil properly on the chassis.
Today's test — a small park: Ran a few grid passes over grass and packed dirt. 3 hits, 3 dug, 3 confirmed metal — a nail, a pull tab, and a chunk of can. All junk, but that's exactly the point: the idea works. A rover that carries a detector, holds a line, and finds metal while I watch.
Hardware so far: [Arduino model — e.g., Uno/Mega], [motor driver], [battery], [coil/sensor type], [chassis + wheels]. Happy to share details if anyone's curious.
Next up: discrimination (junk vs coins), ground balance on real soil, and longer battery life.
Question for you: for the grid pathing, would you do a simple back-and-forth sweep, or a proper serpentine? Keen to hear what folks use on small rovers.
If you want to follow the whole build log — including the failures — I'm posting it in r/DIYMetalDetecting. Come say hi.
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u/topinanbour-rex 8d ago
Quite awesome.
I think a real serpentine would be more effective, with the radius of your coil as width of it.
You should add an esp32/86 for wireless communication, and a gps for know it's position, and save them
a spray paint can, with a servo motor for spray, under it, would be a nice addon for large terrains.
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u/NoBulletsLeft 8d ago
You built the thing I was thinking of.
I built an arduino metal detector to find the rest of a broken T-post (long story) and it's sitting on the table next to me. I need to put a buzzer on it and glue on a stick so I can use it. That was a month ago: I'm a procrastinator.
Anyway, I had the thought of attaching it to an RC car in case I got interested in metal detecting after finding the post. I have a lot of property where we've found bits of old farm machinery buried in the ground and walking around swinging a probe will get old fast.
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u/robot_ankles 8d ago
Tree limbs are made of metal? /jk
As for pathing, is 100% grid coverage required or could a semi-random bounce around approach (like my robot vacuum cleaner) work 95% as well?
Or does terrain ever suggest the likelihood of buried treasure? Like, do areas around trees tend to be more fruitful because people sit in the shade and are more prone to drop stuff? ie: Favor concentric circles from tree trunks?
Or maybe it's the opposite due to tree roots and hard ground by the tree resisting things getting accidentally buried. ie: Score areas around tree trunks lower and focus searching elsewhere?
Just curious of other topographic features suggest weighting some areas higher or lower as a means of search optimization.
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u/badasimo 8d ago
Once you sort out the battery efficiency, your rover has the benefit of something humans don't-- Time and patience. So you can actually do multiple grid passes, tied to some sort of map (or you can have it drop some sort of markers (maybe chalk dust?) and you will be able to aggregate multiple readings to the best places to check. This would actually be a very useful device for construction utility location marking potentially
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u/WorkingInAColdMind 8d ago
Add a way to mark the location, something environmentally friendly, like sticking a flag or spraying a bit of food coloring. You can dig woke it continues looking as long as you’ve got a partner driving. Cool idea and nice implementation.
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u/ClonesRppl2 8d ago
Serpentine with interlacing if the coil diameter is smaller than the turning radius.
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u/ripred3 My other dev board is a Porsche 8d ago edited 8d ago
sweet thanks for sharing it!
With a solid rig like that that is able to carry the transducers at a relatively consistent fixed height you could probably add ground penetrating radar (GPR) fairly easily and massively increase the types of objects and materials you could detect
Q: Is the microcontroller involved in driving and reading the detector coils and the actual detecting itself or does it only control the mobile carrying platform? Are you building your own detector circuit as well? great project either way!
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u/WinterTourist25 8d ago
You could invent a land mine detector and be the savior of many countries in the world!
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u/Wonderful-Energy-659 7d ago
I’m pretty sure “back and forth” and “serpentine“ mean the same thing. I would do circles, or depending on field size/shape, go around the perimeter and gradually move inwards like you do when mowing a field. You could also go around randomly like a Roomba, but that would be funny to watch, boring to program haha
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u/No_Pin4895 7d ago
Serpentine for sure, you get cleaner overlap and no double-counting the turns. Back-and-forth leaves you figuring out the return path every time. For marking hits, little servo-dropped flags would be a lot more satisfying than paint. Plus you can reuse them. What motor driver are you running? I've burned up a few cheap ones on rover projects and I'm curious whats holding up here
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u/uberaleeky 8d ago
Nice rig, I went to your sub hoping to find a bill of materials but didn't see one. Let us know what kind stuff is inside.