I want to build a small wheeled detecting platform — what parts might run into problems in real-world use?

[halle monkey]

I’m working on a small personal prototype and would really appreciate criticism from experienced detectorists.
The idea is a low, slow-moving wheeled platform that carries a detector coil at a steady height over open ground. I’m not trying to replace normal detecting, and I’m not selling anything here. I’m mainly trying to understand whether this idea would be useful in real conditions or whether it creates more problems than it solves.
The use case I’m thinking about is beaches, flat fields, or large open areas where consistent coverage matters.
A few things I’m unsure about:
- Would motor or battery interference make this impractical?
- Does a coil need the normal hand swing motion to work well?
- Would fixed coil height be a problem on uneven ground?
- Is it harder to pinpoint targets if the coil is on a cart?
- Would pushing it by hand make more sense than remote control?
- Are there any detecting situations where this would actually help?
I’d especially like to hear the deal-breakers before I spend more time building it.

 

[pepperj]

to the concept of the whole idea.

 

[SD51]

Welcome to T Net. If your prototype doesn't move the coil side to side and then index the platform about six inches forward and repeat the coil movement, it would take way too much time to cover a ten-by-ten foot area on a beach vs you manually detecting the same area.

 

[halle monkey]

to the concept of the whole idea.

My idea is to put a metal detector on an RC car.

 

[k0bgalan]

You're not the first to think about this, but the truth is, the actual practicality isn't there.

I started getting into metal detecting when I was still a teenager, due to an article in Popular Science—if you remember the publication? Nowadays, I still do it to keep in shape. It must be working, because I'll be 87 years old soon.

 

[3RDLIFE]

I never say impossible or undoable in electronics, only undone so far or impractical for now.

Already done at a much larger scale with GPR, sonar, proton magnetometers and other ground sensing equipment. From human powered carts, vehicles, boats and planes.
I used software to stitch together underwater side scan data I collected into maps. Resolution was <2 feet on a swath that was up to 700 feet wide. All under $2000


Just some considerations.
The coil area would need to be large enough to make up for coverage that would be lost from not being swung, possibly losing accuracy and resolution.
Without precise positioning, time would be lost refinding any hits.
Costs in development time and money would be high on a single one off DIY version.
EMI shielding for the motor and other electronics may be problematic.
Detectors are designed with human motion in mind so it's likey never going to be any faster than doing it manually.
Much of the area being detected is not very suitable for small vehicles.
Probably some more issues I haven't mentioned.

My starting point would be an robotic electric mower with precise positioning measurement, use single/multiple already available detectors and integrate the headphone output into a GPS to mark potential hits for later pinpointing and digging. It would likely be a " dig them all " proposition.

 

[pepperj]

I never say impossible or undoable in electronics, only undone so far or impractical for now.

Already done at a much larger scale with GPR, sonar, proton magnetometers and other ground sensing equipment. From human powered carts, vehicles, boats and planes.
I used software to stitch together underwater side scan data I collected into maps. Resolution was <2 feet on a swath that was up to 700 feet wide. All under $2000


Just some considerations.
The coil area would need to be large enough to make up for coverage that would be lost from not being swung, possibly losing accuracy and resolution.
Without precise positioning, time would be lost refinding any hits.
Costs in development time and money would be high on a single one off DIY version.
EMI shielding for the motor and other electronics may be problematic.
Detectors are designed with human motion in mind so it's likey never going to be any faster than doing it manually.
Much of the area being detected is not very suitable for small vehicles.
Probably some more issues I haven't mentioned.

My starting point would be an robotic electric mower with precise positioning measurement, use single/multiple already available detectors and integrate the headphone output into a GPS to mark potential hits for later pinpointing and digging. It would likely be a " dig them all " proposition.

I'm thinking of my go to machine (DEUS II)
The headphones are good for 30ft away, meaning I can still hear the coil.
The machine has one of the fastest processors on the market.
But here's the thing on very open areas, where targets are well separated-GREAT!
Swing fast (4 ft per sec.) and it's going to sound off.

But it has limitations on what that sounds will produce in accuracy.
Slower Swing will be very accurate.
A chirp swinging fast might produce either a lower or a high signal.

Now get into a heavy targeted site. (Iron patches)
The speed of the coil is now 1 foot per second.
So you might as well park the remote car.
Use your arm as the extension of the machine as the machine was designed for.
As for detecting? Personally I prefer the K.I.S.S method.

 

[Ism]

I thought of doing the robot detector some years ago. The coil doesn't need to swing back and forth. Just go in a straight line with a DD coil mounted sideways. A rough location could be marked with something like sports field striping paint.
At the end of the run, the robot would move over a determined distance and go back the other way gridding the area. Meteorite hunters do similar with a 4-wheeler and special PI detector coil drug behind it.
A target rich area would be a problem for marking. There would be a lot of programming and interfacing all the components. If you have the knowhow, it might be a fun project but not quite practical.

My thought is that the humanoid robot would be a great start to a project like this. It's the most practical application I can think of for the current iteration of humanoid robots.
Interfacing would be a problem because the humanoid robot companies (mostly Chinese) don't want the user to have that kind of access to modify their hardware/software. Battery life is an issue also.
Once again, you would have to be there to dig the targets and protect the robot from idiots. However, it sure would be fun to see the looks on people's faces when they see a robot detecting.

 

[Digger54]

In the future they will design wireless coils in the soles of shoes communicating with belt size control boxes and hearing aid type headphones. Everyone will be dancing while detecting. I will probably be fish food before that happens.

 

[AU Seeker]

In the future they will design wireless coils in the soles of shoes communicating with belt size control boxes and hearing aid type headphones. Everyone will be dancing while detecting. I will probably be fish food before that happens.

Someone already trying to market a pair.

 

[Digger54]

Someone already trying to market a pair.

View attachment 2261101

I might be interested in a not so noticeable street shoe version.

 

[WoodsDigger]

Put the coil on a spring loaded pendulum so swings itself as the spring unwinds. Just like a wind up clock you could adjust shaft length to fine tune the timing or distance of the swing.

 

[Carl-NC]

- Would motor or battery interference make this impractical?

Battery, no. Motor, possibly, especially a stepper motor. Distance and orientation matter.

- Does a coil need the normal hand swing motion to work well?

If you are using a motion VLF detector, then the coil needs to be in motion, about 1m/s. If you are using a static mode detector (unlikely) or one that has an exceptionally slow retune speed, then forward motion is enough.

- Would fixed coil height be a problem on uneven ground?

No more so than regular metal detecting.

- Is it harder to pinpoint targets if the coil is on a cart?

I would expect so

- Would pushing it by hand make more sense than remote control?

I would start with this to prove the concept and the motion parameters, then see if it makes sense to roboticize it.

- Are there any detecting situations where this would actually help?

Most of the ones I've seen are used in beach or desert/field (meteorites) hunting.

Here are some examples:

This guy is actually riding a bike with a detector mounted.

Similar, but on a push cart.

Tow-behind drag coil, probably looking for big deep nuggets. Also common with meteorite hunters.

Another tow coil.

Coils mounted to the front of a pick-up truck. (Treasure Search, April 1982)

Somewhere I have 1 more pic but cannot find it. It shows a guy at the beach pushing a cart, and the cart has 2 coils mounted on swing arms driven by a windshield wiper motor such that the coils swing back and forth in unison.

 

[LUE-Hawn]

I’m working on a small personal prototype and would really appreciate criticism from experienced detectorists.
The idea is a low, slow-moving wheeled platform that carries a detector coil at a steady height over open ground. I’m not trying to replace normal detecting, and I’m not selling anything here. I’m mainly trying to understand whether this idea would be useful in real conditions or whether it creates more problems than it solves.
The use case I’m thinking about is beaches, flat fields, or large open areas where consistent coverage matters.
A few things I’m unsure about:
- Would motor or battery interference make this impractical?
- Does a coil need the normal hand swing motion to work well?
- Would fixed coil height be a problem on uneven ground?
- Is it harder to pinpoint targets if the coil is on a cart?
- Would pushing it by hand make more sense than remote control?
- Are there any detecting situations where this would actually help?
I’d especially like to hear the deal-breakers before I spend more time building it.

The NOKTA DEEPHUNTER PRO has a large two person coil. That can be used to hunt for deep targets and I am sure it can be modified to find shallow objects as well. It could be adapted to be pulled behind a cart or wagon by one person in order to keep it off the ground at a continual height as not to run into rocks or branches. I was able to find that coil new on fleabay for less then $250.00.

https://modernmetaldetectors.com/products/nokta-makro-24-x-39-t100-search-coil-deephunter-3d

This might get your foot in the door if you can modify the above said coil.

Hope this helps

Bests in Treasure

LUE-Hawn

 

[LUE-Hawn]

In the future they will design wireless coils in the soles of shoes communicating with belt size control boxes and hearing aid type headphones. Everyone will be dancing while detecting. I will probably be fish food before that happens.

Semper Fi Jarhead. Thank you for your service.

USMC/USMCR. 1972-1979

Bests in Treasure

LUE-Hawn

 

[Digger54]

Semper Fi Jarhead. Thank you for your service.

USMC/USMCR. 1972-1979

Bests in Treasure

LUE-Hawn

Your service as well Devil Dog. I did a tour at 4th MAW at NSA NOLA 96-99 and got to work with a lot of ARs and SMCRs, made a lot of friends there.