Case study 2023

Smart Cat Feeding Systems & Collar

A connected cat-care product line for a client: a wet-food feeder family anchored by a compressor-based sub-zero hopper for week-long safe storage, plus a wearable smart collar with activity tracking and location-context beacons. Prototyped through bench and on-cat testing.

A client engaged Groundplane to design a connected cat-care product line: a family of feeders and a wearable smart collar. The feeders would address the central problem with automated wet-food serving: wet food spoils fast. The collar would track activity, location-context, and biometrics in a form factor a cat would actually wear. The program ran through initial prototype builds, bench testing, and on-cat data collection.

Concept render of the wet-food feeder in a kitchen: a round white serving dish beside the white hopper unit, with a tabby cat looking at a portion of wet food. — Fig. 1Wet-food feeder, concept render. The compressor-cycle hopper holds food below freezing; a single portion warms to serving temperature on the way out.

The feeders

Three feeder concepts, with one standout. The standout was a wet-food feeder that solved the spoilage problem at its root. Most automated wet-food feeders use a Peltier element to drop food temperature by 10 to 20 degrees, which buys hours, not days, of safe storage. This design used a small compressor-based refrigeration cycle to hold food below freezing in the hopper, then warm a single portion before serving. Holding it below freezing was designed to keep food for up to a week. Two adjacent products ran alongside: a smart dry-food feeder paired with a connected water fountain, and a more experimental wet-food dispenser that mixed dry kibble with water at serve.

Wet-food feeder with compressor-based sub-zero hopper and per-portion warmup at serve
Designed for up to a week of wet-food storage
Smart dry-food feeder paired with a connected water fountain
Experimental wet-food dispenser that mixed dry kibble with water at serve

Smart cat collar render with PCB visible. — Fig. 2Collar render with the 14 by 30 mm PCB inside.

The collar

The collar lived on a 14 by 30 mm board, sized so a cat would actually wear it. An nRF52-series SoC sat at the center for low battery draw. A 9-axis sensor (accelerometer, gyroscope, magnetometer) read motion and orientation to classify activity throughout the day. Tracking beacons placed near common stations (food, water, litter) gave the activity classifier the context it needed to label what the cat was actually doing. A microphone captured audio for later interpretation. A buzzer and LED helped owners locate a cat that had wandered off. Heart rate, SpO2, and skin-temperature sensors were on the board for biometric tracking, though early on-cat trials did not yet produce clinically useful signal.

14 by 30 mm board, sized to be worn by a cat
nRF52-series SoC for low-power operation
9-axis sensor (accelerometer, gyroscope, magnetometer) for activity classification
Tracking beacons at common stations (food, water, litter) for activity context
Onboard microphone for cat audio capture
Heart rate, SpO2, and skin-temperature sensors for biometric tracking (early data quality limited)
Buzzer and LED to help locate the cat

Hard parts

Refrigeration in a feeder. A Peltier in a feeder is easy and cheap and bad. The right answer for week-long wet-food storage was a small compressor cycle, which carries its own design problems in a consumer device: noise, vibration, condensation management, and the mechanical and thermal partition between a sub-zero hopper and a warm serving zone two inches away. Designing that boundary, and the portion-extraction mechanism that bridges it, was the most mechanically interesting work in the program.

A cat using the prototype feeder. — Fig. 3Prototype validation: the early feeder, in use.

Form factor on a cat. A 14 by 30 mm board is not a lot of real estate for a SoC, radios, a 9-axis sensor, biometric optics, a microphone, a buzzer and LED, plus battery and charge circuit. Every component had to earn its square millimeter. The constraint that pushed back hardest was recharge cadence: a small battery means frequent recharges, which fights the entire premise of a wearable a cat keeps on. The collar layout was driven by that two-sided balance from the first board revision.

Biometrics on a moving cat. Heart rate and SpO2 sensing through fur, with the cat moving, was the part of the collar that did not work yet in initial prototypes. Motion artifacts, fur contact, and skin-coupling all stack up against optical sensors. The collar shipped data collection for the paths that did work (activity, location-context, audio) while the biometric path stayed in research.

At a glance

Wet-food feeder: Compressor-based sub-zero hopper with per-portion warmup; up to a week of safe storage
Dry-food feeder: Smart feeder paired with a connected water fountain
Experimental feeder: Wet-food dispenser mixing dry kibble with water at serve
Collar SoC: nRF52 series
Collar size: 14 by 30 mm board
Collar sensors: 9-axis IMU plus magnetometer; microphone; heart rate; SpO2; skin temperature
Collar I/O: Buzzer, LED
Location context: Tracking beacons at food, water, and litter stations
Status: Initial prototypes built and bench-tested

Outcome

The feeders moved through mechanical and refrigeration design. The collar was prototyped through on-cat data collection. The sub-zero hopper architecture from the feeder and the small-form-factor sensor-fusion layout from the collar are patterns Groundplane carries forward into future wearable and perishable-food-storage work.

A cat sitting at a workstation in front of PCB design software. — Fig. 4At the bench. Cat-product design has its own opinionated QA.