This shouldn't be too difficult. Wait until it is dinner time, put food in the feeder and encourage the animal to point his nose where it is likely to...
If you have two cats and one of them is on a diet but the other needs free food, you can build a feeder with RFID capability that only opens for the cat that needs free access. The free-food cat wears a collar with an RFID tag.
- An old CD-rom player is used as a sliding door
- Timer-controlled open duration
- Proximity sensor (Sharp GP2D120) prevents door from closing while the cat is eating
- Sensors detect whether the door is fully opened/closed.
- Automatic/manual mode switch (on manual it opens with a pushbutton)
- Arduino controlled
On the downside:
- Mine was made out of cardboard so it is easily broken into by smart/strong animals. One could use a stronger material and add a servo that slides a bar into the door to lock it into place.
- It doesn't hold a lot of food.
The first version (shown in the video) used an ID-20 (ID Innovations), which worked, but the range was limited. The cat's tag sometimes hangs on the side, so it did not always activate the reader even when he was in the exact same place every time. Not that big a deal because the cat usually just tried from different angles, but my latest version (shown in the photograph) uses a SEEED studio RDM630 RF-reader with a self-made circular antenna. This antenna is large enough that the cat can poke his head through, which works 100% of the time. The antenna is described in step 7.