NUMI V4: AUTONOMOUS AI COIN SORTING

Numi v3 (left), v4 (right)

After gathering feedback from dealers and collectors at seminars last summer, I've spent the past twelve months rebuilding my automated coin-sorting robot from the ground up. Here's a walkthrough of the new system, from dumping a handful of coins to full AI analysis and automated sorting.

While v4 isn't perfect, it's a massive leap forward. Numi v3 was a bulky Raspberry Pi rig on a flex-prone LEGO chassis with two cameras.

For v4, I completely tore it down. The LEGOs are gone, replaced with a custom 3D-printed frame. The Raspberry Pi is gone too, replaced by a microcontroller running C++ directly to the hardware.

How It Works: One Coin's Journey

The Hopper: A laser rangefinder monitors the distance of the coin stack, automatically starting and stopping the feed.

The Pusher: A motor pushes the bottom coin onto a small stage lit by a 19-LED ring, then resets its position against a hard wall.

The Flip: A mechanical flipper arm turns the coin over so the single 5MP camera can capture both sides.

AI Analysis: Both photos are sent to Google Gemini Flash with a set of plain-English instructions. Instead of complex code, I simply write rules like "Save: Silver, Key Dates" or "Inspect: Variety Candidates." The AI extracts the series, year, mint mark, tags, and sorting decision, then sends it all to a dashboard.

Sorting Carousel: A web browser tab runs the master control loop. It reads the AI's verdict and directs the machine to drop the coin into one of five bins (Dump, Save, Inspect, Misc, Retry).

Numi now processes about 250 coins an hour at a cost of roughly $0.25 per thousand coins. It's a massive improvement from my initial 60 seconds-per-coin rate.

Lessons Learned for v5

Moving Parts Fail: Mechanical flippers and funnels eventually jam. Writing functions to unjam a machine means you designed the wrong machine.

Bring Back Two Cameras: Dropping from two cameras to one saved a camera but cost me a moving part that touches every coin. That was a bad trade.

Lighting is Unforgiving: Brightness swings wildly depending on how a coin lands, either blowing out the lettering or hiding dates. For version 5, I'm moving back to simultaneous two-sided photography using museum-grade glass panels and circular polarizer filters to cut the glare.

Bringing Numi to shops and shows has been invaluable. Even during moments when I hear harsh feedback, it's immensely appreciated because my ultimate goal with Numi is to raise awareness about the usefulness, but more importantly, the upcoming impacts of AI on our community.

I'd rather ship an honest version 4 and share what broke than pretend I got it right the first time. If you have ideas, I'd love to hear from you. And if you see me at a show, come say hello! The machine will be running.

If you'd like to keep up with Numi's latest developments [as well as Dansco coin album research], come check out my Instagram page.

Justin, aka Dansco Dude

To read the earlier E-Sylum articles, see:
NUMI: AI-POWERED COIN IDENTIFICATION APP (https://www.coinbooks.org/v26/esylum_v26n47a10.html)
NUMI: HOW THE AI SAUSAGE IS MADE (https://www.coinbooks.org/v26/esylum_v26n47a11.html)
NUMI V2.0 COIN IDENTIFIER & SORTER (https://www.coinbooks.org/v27/esylum_v27n28a14.html)
NUMI V3: AUTOMATED AI COIN SORTING PROTOTYPE (https://www.coinbooks.org/v28/esylum_v28n26a15.html)
NUMI V3: AI COIN SORTING PROTOTYPE DEMO (https://www.coinbooks.org/v28/esylum_v28n29a15.html)

	NBS (coinbooks.org) Web