Long have I wanted a cat door that would only open for my cats, not the mean neighborhood one that eats their food. I can’t be the only one. I’ve been meaning to try to build one with a camera, rPi and Google Coral, but never got around to it. There’s the matter of the locking mechanism and more.
I have built two of these for dogs. It's really not hard,w hether you go completely from scratch or use something premade.
If you want something mostly premade,go get an autoslide.
If you want to do it completely from scratch:
1. RFID/bluetooth proximity is much easier to work with than camera + rpi + AI. For the usecase you are talking about, AI is not just overkill, but will make it actively harder to achieve your goal
2. Locking is pretty easy depending on motor mechanism - either a cheap relay'd magnetic lock, or simply a motor that can't be backdriven easily.
Motor wise, you can either use the rack and pinion style that autoslide does, or a simple linear motor if you don't want to deal with gear tracks.
Overall, i went the autoslide route and had it all set up and working in an hour or two.
That's t'he definition of (entertaining) overengineering: since every house cat should have an RFID chip already, there are doors that use that already. 4 AA batteries, "low-tech" enough, it just works
In my case I bought a pre-built solution by PetSafe that works pretty well. You scan the catś chip once and it recognizes him/her each time they try to enter. It supports up to 10 cats IIRC
You can get off the shelf doors and feeders. I use “sureflap.” The rfid pellets vary slightly based on locale and age, but probably 125 or 132khz. You can get them off of ebay if you want an easier test case. Handheld cheap scanners are about $20.
125khz reader.
The real problem is distance most of the time. Cats are curious enough about the doors that they will go right next to them. Most dogs won't.
Luckily dogs are usually pretty easy to train. My dog will tap the glass on the back door if he wants out. I'm sure I could get him to "present his chip" to a doggie door within a couple of days.
Also for your own sanity, mostly. I always wonder if mine will come back each night. Thus far he hasn’t disappointed, but I’m braced for that day.
That said, some people vehemently argue that it’s abus{e,ive} to let cats wander the neighborhood, so thank you for not trying to tell others what to do. It’s become so common that I’m braced for it every time this topic comes up.
Long ago I read about an automatic cat door that operated simply on the colour of the cat. It worked because the cat was the only red cat in the neighbourhood.
