Pet-Selective Food Dispenser

One of Tomasdiazwahl’s two cats needs medicated food. The problem is that the other cat would sometimes eat this food, meaning there was no way to tell how much nourishment the medication-dependent kitty was actually eating. Sometimes he would trick tomasdiazwahl into feeding him twice, and at other times, it would seem, he went hungry.

His solution was to make an automatic cat feeder that only opens for the correct cat. Initial ideas included reading a collar-mounted NFC tag, but this proved to be unworkable, as the tag needs to be a few millimeters away for activation. Instead he settled on weighing the cat for verification.

A 3D-printed dispenser was designed and implemented, which opens a lid with a gear and servo setup. This is placed on a platform with four load cells for measurement. When the proper kitty puts its whole weight on the platform it recognizes its presence, and opens the 3D-printed food door automatically for consumption.

Weight measurement-wise, the device is set up based on the Arduino Bathroom scale found here. The four load cells are read with the help of an HX711 amplifier/breakout, and an Adafruit Pro Trinket provides overall computing power for the device.

Calibration was performed with the help of an Arduino Uno, allowing it to accurately weigh the hungry cat. With the maximum activation weight set a little higher than the pet in question, it’s able to open and close the lid as needed, keeping the proper cat fed… and its humans less confused.