Cameras, weight trays, or RFID: how a smart cooler knows what was taken

A smart cooler works out what a shopper took in one of three ways: cameras, weight-sensing trays, or an RFID tag on every item. Most coolers covered here (Haha, Vendera, Micromart, 365, Grabot, ReyVend) use cameras. Weight trays are on Cantaloupe’s Smart Store (Cantaloupe⁸) and Nayax’s Nova S (Nayax²¹). Byte uses RFID (Byte⁹).

Camera and weight-tray vendors claim 99% accuracy or better. Their own support pages describe where each method goes wrong.

Cameras

Cameras record the shopper’s session and software compares the shelves before and after. Haha, Vendera, Micromart, 365, SandStar, Wittern, Grabot, and ReyVend all work this way. The number of cameras runs from two on a Grabot (GeniusVend¹⁸) to nine on 365’s Stockwell (365¹⁶).

What the vendors say about the limits:

• Small items. 365 says an item needs to be more than 4 inches tall or wide to stay visible in a hand. Its examples of unsupported products are a 5-hour Energy shot, a single-dose Tylenol, and a pack of Extra gum (365²).
• Look-alikes. 365 tells operators to keep similar-looking items off the same shelf, stock one item per lane, and not mix flavors in a lane (365³).
• Fresh food. 365 says fresh food without distinguishable packaging is not supported at any size (365²).
• New products. 365’s system needs about 100 sales of an item before training on it is complete (365¹).
• Blocked cameras. Micromart says blocking all three of its cameras at once is hard and that “in many cases” it can still detect the item (Micromart⁵).

A person often finishes the job

When the software is not confident, someone looks at the video.

• 365 sends low-confidence transactions to a manual reviewer and says about 3% of transactions need manual input. Flagged sales are emailed to the operator and can be lost if not acted on (365⁴).
• Micromart forwards suspicious transactions to a human reviewer (Micromart⁵). Operators cannot view the video but can request it after a theft.
• Haha creates an “abnormal order” that the operator reviews in the app and charges manually, within 24 hours (Haha⁶).

That review is why charges are not instant. 365 says receipts typically arrive in 5 to 10 minutes (365¹). Micromart says its itemized text receipt arrives within a few hours (Micromart⁵). Wittern, which sells the competing Spectra, claims its own coolers settle in one to three seconds (Vending.com¹⁴).

Weight trays

Each tray sits on a load cell. When the weight drops, the system matches the change to the known weight of the product assigned to that tray. Cantaloupe says its trays detect 15 grams (Cantaloupe⁸).

The constraints follow from that:

• One product per tray. Cantaloupe’s dividers are not adjustable. An 18-tray Smart Store 600 holds at most 18 products, fewer if you drop a shelf for 20oz bottles or give a fast seller two trays (Cantaloupe⁸).
• Wrong-shelf putbacks. A shopper who returns an item to a different tray registers as an invalid putback and the sale is flagged. Cantaloupe uses the cameras, where enabled, to tell that apart from a bad reading (Cantaloupe⁷).
• Ghost weights. Cantaloupe’s troubleshooting document describes an unstable or misaligned shelf registering false weight when the door shakes the cabinet. In its example the customer was charged for an extra product and had to be refunded. The fix is recalibration (Cantaloupe⁷).
• Uneven products. Cantaloupe recommends raising the weight allowance to 15% to 20% for handmade items (Cantaloupe⁷).

A 2020 academic study of autonomous checkout found that products of similar weight on one sensing plate are hard to tell apart, and that swapping in an object of similar weight defeats weight-only detection. Combining weight, cameras, and shelf layout, it reached up to 92.6% item identification on a 33-product test shelf (Frontiers in Built Environment¹³).

RFID

Every item carries a tag, and the cabinet reads which tags are present when the door closes. Any product can go on any shelf.

• Tag cost. Byte charges $0.15 a tag, ordered in hundreds and deducted from your monthly payout (Byte⁹). FoodSpot’s stickers were listed at $1,039 for 5,000, or $0.21 each (WebstaurantStore¹¹).
• Tagging. Someone applies a sticker to every unit before it goes in. Byte has four tag types: regular, a flag tag for drinks, microwave-safe, and a flag tag for metal (Byte⁹).
• Liquids and metal. Liquids absorb the radio signal and metal reflects it, which is why cans and bottles need special tags (atlasRFIDstore¹²).
• Missed reads. Byte says mischarges average about 0.4% of transaction volume. They happen when a tag is not seen at door close and the customer is charged for an item still in the fridge. It names tagging, merchandising, and nearby kiosks as causes (Byte¹⁰).

How the three compare