RFID Cat Food Dispenser Prevents Overfeeding

Life is good when you only own a single pet, because you can dedicate all of your attention to them and feed them in whatever way they prefer. But adding a second pet into the mix complicates things, especially feeding. If one pet is a voracious eater and doesn't have boundaries, then they're likely to gobble up all the chow that you set out for the second pet. The thicc boi gets chonkier and the skinny boi loses even more weight. To solve this problem, Ben Krejci built an RFID cat feeder.

Krejci has two cats. One is a slow eater named Luna and the other, Fermi, is food-insecure, which means she will eat whatever food she can get to—usually Luna's noms. This cat feeder prevents that, because it uses RFID to recognize Luna and only opens up when she is ready to take a few bites. When she walks away, the feeder closes a lid so that Fermi can't sneak in and start chowing down on Luna's food. This ensures that Luna gets as much food as she needs and keeps Fermi from overeating and gaining too much weight. Win/win!

RFID is an obvious way to identify a cat, especially since many cats already have RFID implants for tracking. The problem is that RFID has a very short range. RFID pet implants in particular, which usually operate at 125 kHz or 134.2kHz, require almost physical contact with the scanner to register. It would be very difficult to train a cat to rub the back of their shoulders against an RFID scanner, so Krejci had to take a chance on an overpowered RFID reader module from AliExpress. Because RFID tags pull their transmission power from the reader, this increases the working range. It may be dangerous, but Krejci figured it was worth the (likely minimal) risk.

The cat feeder's design is simple and attractive. Krejci modeled it in Autodesk Fusion 360 and then 3D-printed the parts on a Prusa MINI+. It has a small compartment to contain the food, a motorized lid for that compartment, a custom antenna for the RFID reader, and an infrared beam sensor. Krejci designed the antenna structure so that Luna would naturally duck beneath it to get to her food, putting it near the RFID implant between her shoulder blades.

An Adafruit ItsyBitsy M4 controls the cat feeder's operation. It monitors the RFID reader to determine when Luna is in position, and the infrared beam sensor to make sure the lid doesn't close on her noggin. A small stepper motor actuates the lid through a simple geared mechanism, which is quite clever considering that this was Krejci's first foray into Fusion 360. It keeps the operation quiet so that the lid opening doesn't frighten Luna.

From what we can see, this RFID cat feeder works really well. We have no doubt that it will inspire many other cat owners. If you want to duplicate the project, Krejci was kind enough to upload all of the necessary files.