RFID pet feeder

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.  

Features:
- 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.

Little Cat Toos demonstrates cat feeder from champenoise on Vimeo.
The video shows the first version with the ID-20 as the reader.

Step 1 Materials

- A working CD player tray mechanism+motor from an old cd-rom player
- Sharp GP2D120 Proximity sensor
- 125KHz RFID reader (e.g. ID-innovations ID-20, SEEED studio RDM630, Parallax)
- 1.25" diameter 125KHz RFID tag (or as large as can be worn comfortably on the animal's collar. Tag size influences read range. Bigger is better in most cases)
- Arduino Duemilanove
- 1 adafruit motorshield
- 3 Pushbuttons
- 1 Toggle Switch
- 5  100-220Ω Resistors
- 4  10kΩ Resistors
- 1 Red LED
- 1 Green LED
- The material for the enclosure (such as cardboard, wood or plastic)

Comments

[solaralternatives]

For a single cat, wouldn't a magnet/switch combo be a much more elegant and inexpensive solution, eliminating the arduino circuit? (all other cats/animals in the home simply wouldn't have the magnet, so voila, no access!)

[landmanr]

Great idea, although magnets don't typically have a lot of range. One could train the cat to do it exactly right, but the magnet would not always be hanging straight down so perhaps with several magnets around the collar.

[solaralternatives]

I was thinking neodynium.. and a coil detector

[landmanr]

That would be pretty neat

[solaralternatives]

Instead of arduino, the magnet induces an electric pulse in the coil, which opens the door concealing the food. When the cat leaves, another pulse of electrical current is induced, which closes the door. Thus all you need is a very simple flip-flop IC circuit, even ancient TTL circuits would work.

[dexerit]

This is what I'd like to do but with implanted RFID tags...:
http://www.czamd4.com/pages/video.html

[tlshea]

Hello,
I realize this is the instructables.com site and the idea is to do it myself, but I am a desperate woman in need of something like this now (before my cats make me crazier). Is there anything commercial that performs this?
I do salute your inventiveness and everyone's successful modifications.
Thank you for any insight.

[gcresse]

I just ordered this ID Bowl from https://www.idbowl.com/ and it seems to be exactly what a person needs to keep one cat from eating the other cat's food. It hasn't arrived yet, but hopefully it works as well as on the video.

[landmanr]

That's pretty neat! The only downside I see from that design is that it utilizes infrared, so the tag will have a little battery which I could run out of power.

[gcresse]

Yeah, I also ordered an extra battery. We'll see how happy I am with it after I've used it for a while.

[bobbi0126]

Hi gcresse. Did you have success with the id bowl? I'm looking at buying three sets and I haven't found any other reviews.

[bunner_bob]

We have an ID bowl and have been disappointed so far. The bowl is fairly noisy when it opens and closes, so our regular cats are a bit scared of it (while the fat one just comes running whenever he hears it). The IR tags seem to be prone to failing when they get wet (though they seem to resume working when they dry out), which means when the cat drinks out of a bowl it can kill the tags. The triggering is somewhat inconsistent, depending on what angle the cat approaches at. And, it tried to close on one cat's head, I think because they were eating from an angle. The first one we got had a tendency to "bounce" a few times when manually switched off (it opens when switched off). The replacement was a lot noisier and kind of stuck mid-opening, releasing with a "clack" (again, cats didn't appreciate). Waiting on replacement #2 now. This is the "first infrared pet feeder" - I'm thinking maybe when the design evolves to the third or fourth (and build quality improves) we'll get the one that actually works. And I think RFID is probably a better way to go.

[bobbi0126]

Thanks for the feedback Bob! I'll keep searching for a solution to the #1 dog on a diet, #2 blind dog eating cats food, and poor cat searching for left-overs since the dogs eat everything . ;)

[landmanr]

Hmm, not that I know. There is a host of electronic pet doors available, so if you have a larger space to put the food in you could use such a door to control access. Just an idea.
http://www.solopetdoors.com/home.htm
http://www.petsafe.net/Products/Doors.aspx
http://www.petdoors.com/electronic-pet-doors.html

[lesizz]

The implanted tag idea IS doable, as there is a commercial product on the market that does just that -- it senses the vet-implanted rfid transponder. Check it out. I'm sure that you or someone else will come up with an upgrade to make this project implanted-tag friendly.
http://www.moorepet.com/SureFlap-Cat-Door-s/475.htm

[lesizz]

Replying to my own comment:
I just want to add important notes regarding safety:
Cat collars are dangerous, as cats have been known to be strangled when the collar catches on something. Fortunately there are snap-away collars available that will un-snap if the cat gets caught on something. Available in pet stores.

Another safety note: DO NOT depend on this or any other mechanical device to feed your catters when you're away for an extended period of time. Mechanical/electrical devices can and do fail, leaving the cat with nothing to eat.

Really cool project. I have some expired drives and will soon use one to build this project.

[dexerit]

Very nice job man!

Do you think the RFID implanted in the dog/cat 's neck will work?

[yoyology]

Great idea, great Instructable. Almost makes me want to get a cat. Almost.

[insuranceman1]

I'd bring a cat into my home just so I could show off this carazy device to my friends.

[captain Jack]

indeed.
i wonder if this would work for a turtle?

[hsjade1]

I want to build this but new to RF. Was wondering do u have an image of all parts used

[fuzzydale]

This can be used to control entry on a Cat or Dog Door"

NOTE: There may be some changes and improvements coming.
However this circuit does work and you can build it as shown.


The PCB Shown below is Available from me, or make it yourself.
It Measures 2.75" by 1.1"

This circuit uses one tuned coil for on the door and just a single wire loop
on the animals collar.

When the two coils come close together, it produces a signal that can cause
a an LED to light and also trips a solenoid to unlock the door so it can open.
Since all these doors are somewhat different, I leave The Solenoid and Mechanical
Parts of this design for you to figure out.

The Main Advantage of this unit is it does Not Require any Battery on the
animal, as is the case with most store bought devices for this purpose.

--------------------------------------------------------------------------------

The Single turn coil can be joined with plugs so it can be removed easly.
But if the plug comes apart or has a poor connection, the door won't open.
So Better yet, make it Just Barely big enough to slip over the animals head,
and Solder it to make a solid loop, than tape it to the animals collar.
And the Larger the diameter of this coil, the Greater the Sensivity will be.

Also Important, the Cat or Dog door and the surroundings "Can't contain any
large pieces of metal".
(This circuit is also a Metal Detector and This detector see's the Single Loop
of wire as a solid piece of metal.)

Additionally, the coil on the door needs to be mounted in such a way that the coil
on the animal can actually get almost inside the coil on the door.
Possibly a Round or Rectangular Extension, outward from the door will be
needed to accomplish this.

Either way, the coil on the door will probably need to be mounted a few
inches from the door.

Ideally the coil on the door will have an inductance of about 150 uH.
My Inductance calculator can determine this for a Round Coil.

http://www3.telus.net/chemelec/Projects/Cat-Dog/Cat-Dog.htm

[tinker234]

boy my cats would love this yours looks like my cat lunna

[musick7]

Hey thats pretty Slick!

Trying to find a Clever way to do this with Two Cats. One Fat the other always Hungry

[SolomonsJim]

I'm in the same predicament. I'm thinking about modifying this somewhat so that it is capable of responding to two different RFIDs: i.e. when my skinny cat who rarely gets to eat his own food come to the station, the gate will open right away, but when his older, much fatter sister pushes him aside it will read her RFID tag and slam the gate shut. Hmm...I'll have to think about this.

[landmanr]

You can totally do that. You need to modify the code a little bit. Get two tags, figure out what the code for each one of them is (by holding them in front of the reader and monitor serial output), then put each code in an array, and when rfid() gets a tag you check the values against the stored codes. Make rfid() return a 1 if it's tag A, a 2 if it's tag B (and 0 if there is nothing). If it is tag B, you close the door.

I haven't tried it, but I suppose you would have to add something like this to rfid():

int tag1[5] = {2E, 0, CA, EB, 81};
int tag2[5] = {2E, 0, CA, EB, 80};

result=0;count1=0;count2=0;
for (i=0; i<5; i++) {
if (code[i] != tag1[i])
count1+=1;
}
if(count1==5)
result=1;
if(count2==5)
result=2;


And then anytime you're in a timer loop that the door is kept open, check the reader once in a while and if the result==2, you say MoveDoor(CLOSE);

[landmanr]

I have put this feature in a new Instructable, an RFID cat door. The final code for that has the modified function rfid(). It returns a 1 for tag1, a 2 for tag2 and a 0 if neither. Don't try the code I suggested previously, it won't work.

http://www.instructables.com/id/RFID-cat-door/

[jensah]

Could you please attach it as a text file, since this is totally unreadable :(

[landmanr]

You can now download the code directly from here:
http://www.writtensound.com/arduino/cat_feeder.htm
hopefully that helps

[doby162]

yet another ingenious tech marvel to make our lives easier. I always say: it's better to spend a week building a robot to do something trivial than to spend 5 minutes doing something trivial. i need to write an instructable on that floor sweeping robot i made. totaly awesome cat feeder! my dog would destroy it if it were weak and outsmart it if it were strong but then most animals aren’t as bent on destruction as she is.

[kill-a-watt]

totally awesome. The only shortfall I see is if the cat on a diet had a habit of guarding food. When I had two cats we needed two litter boxes, two water dishes, and two free-choice dispensers. When the ex took one of them away I now have one lonely cat that lost about 4 pounds (now that I can keep him on a proper diet)

[MrPhelps]

Nice. Would it work with sub-cutaneous identification implants ? AFAIK all pets have these now. A possible improvement would be to add a light when you fill the bowl, that way the animal can know when there is food, and it might improve training. For example press a button to turn on the light, and turn it off when the door is first open afterwards.

[landmanr]

An implanted tag would work in principle, provided tag and reader would be at the same frequency. The read range might become an issue though, since smaller tags yield a weaker signal.