I’ve been thinking for quite a long time for a DIY solution to automatically feed our two cats. Firstly because i find really annoying to hear them asking for food all day long. And also, we need a solution for leaving them alone during short holidays. I’ve finally achieve something working well for this purpose.
To begin, I started to look at existing commercial solution. At prices ranging from 50 to 100$, two types of systems exists:
In the first category, we have horizontal round box with up to 8 compartments filled in advance. The cover on top of the box turn from few degrees and make the food available. I find this design very smart. Their is only low mechanical stress on the moving parts and it must probably be quite robust (as long as the cats don’t try to break into it). Yet, the capacity is not very large. If we want to distribute food twice a day, the autonomy is limited to 4 days at max, which is too short for me.
Vertical devices, are also available. They have a much greater capacity for a price generaly higher than horizontal one. After a little digging, it seems that in this type of device, the distribution is done through a worm screw. My main concern over the model in picture: can’t the dog easily crash it on the ground by shaking it a little? The detailled desassembly and study of such device can be found here : Automatic pet feeder
My realisation is inspired from this blog “the creative family“.with a large wood/plexiglass reservoir to hold a large quantity of pellets.
I adopted for a DIY linear actuators to pull pellets outside of the box.
I had microwave oven motors in stock, so I tried to use it to power the dispenser. I quickly realized that this solution wouldn’t probably be very robust. The microwave oven motors is not powerful enough to crush the pellets when they append to get blocked in the mechanism. In case of deadlock, these motors can in theory reverse their direction of rotation, but this happens in such a horrible sound of gears that it wouldn’t probably have last very long.
So I replaced the motor in microwave by a generously size servomotor developing a torque around 20kg/cm. To control the servo, I used an arduino.When it’s time distribution, the arduino controls the servo push and pull the distributor board and then waits until the next meal time. The electronics could not be simpler. It is a shame to see the computation power available in the arduino performing such simple task. Maybe some day i will add a bunch of blinking leds to the design … ;o)
The resulting system can be loaded with 4kg of pellets, which gives an autonomy of nearly two weeks.