Using a servo to control a hinged doggie door

Overall goal: Implement access control for my dog by motorizing a small, hinged doggie door. An earlier post on reddit steered me towards an Arduino Uno + servo setup.

My system uses a touchpad as the inside trigger and an RFID tag reader as the outside trigger. When triggered by either sensor, the servo should fully open the doggie door for a period of time, then close it again. Code, sensors, and servo work as expected.

I'm a newbie at the mechanical stuff, so I'm seeking guidance for translating the rotational servo movement into a force that can operate this door. Pics for context:

Inside view with the door in resting (closed) position. Hinge is on the right, and that lock in the picture (left side) won't be used once my project is finished.

Movement of the door. Door swings horizontally 95° to 100° in each direction, though I only want it to open outward, as shown below.

Outside view. Hinge is on the left; door moves horizontally.

The pupper in question. She loves broccoli.

The plastic (plexiglass?) door is 185mm x 185mm x 5mm (7.25" x 7.25" x 0.20"), including the hinged portion on the right side. The hinged portion is ~19mm (0.75") wide, spanning the full height of the door.
I have a Hitec HS-311 servo, which should provide sufficient torque for this job.

Guessing I'll need to attach a controlling plate of sorts near the hinge on the plastic door, then connect that to something translating that motion to the servo's rotation (ball link + pushrod?). Found a few online videos that look perfect, but I'm not really knowledgeable enough to know if that particular design is good or bad for this scenario.

The best solution will be minimally intrusive into the overall opening so my dog has plenty of room to go in/out without hitting the mechanism that moves the door. How should I approach this?

It’s a dog, teach it to push the door open.....

Use a servo and arduino to actuate the lock.

Suppose you just need a linearl actuator with a L bracket and hinge pins, but then you need to add system in place to make sure door doesn’t close on the pup.

Slumpert:
It’s a dog, teach it to push the door open.....

Found a cat in my dining room a few weeks ago. We do not own a cat.

Use a servo and arduino to actuate the lock.

The lock in picture #1 will not be used. Consider it out of scope.

Suppose you just need a linearl actuator with a L bracket and hinge pins, but then you need to add system in place to make sure door doesn’t close on the pup.

I'd like to use the servo to control the door, if possible. Think an L bracket + swivel attachment + push rod would work?

Might be able to take a piece of light gauge tin like from a large can of tomatoes.

Cut it into a 80 degree arc about 1 inch wide, fold the one end “up about 1 inch,space of your door thickness, then down one inch”. so it can “slip” on top of the door itself.

On the other end just a hole to slip your pushrod into. For best angles with a rotation servo you should have the servo bottom towards wall and mount pushrod under the horn so that it’s as close to the wall as possible.

Slumpert:
For best angles with a rotation servo you should have the servo bottom towards wall and mount pushrod under the horn so that it’s as close to the wall as possible.

My plan was to mount it so the servo's rotation is parallel with the floor. Screws on the side of the servo would point towards the floor.

Mounting the servo with its base towards the wall (screws going towards the wall) generates vertical rotation, which would need to be converted 90° to open the door. Prefer avoiding complexity whenever possible.

You should definately add a servo saver by the way. Adding a bit of “give” to anything that closes is good.

Hello,

Door swings horizontally 95° to 100° in each direction, though I only want it to open outward, as shown below.

if you didnt know the rotation and position of your servo, you can do calibration code for servo.

like this, use Serial.available

while (Serial.available() > 0)
    {
        mycommand += char(Serial.read());
        delay();
    }

The pupper in question. She loves broccoli.

She looks preety :slight_smile:

Rotate the door 90 so gravity shuts it , and have a magnet at the bottom to hold it shut .
Then just use your servo to lock the door.
When unlocked the dog should be able to push against the door to open it.
Look at pet flaps you can buy for inspiration.

brystmar:
Found a cat in my dining room a few weeks ago. We do not own a cat.
The lock in picture #1 will not be used. Consider it out of scope.
I'd like to use the servo to control the door, if possible. Think an L bracket + swivel attachment + push rod would work?

Can you share the design

grcshekar71:
Can you share the design

Unfortunately, I never completed this project because the risk of failure (raccoons in the house -- this actually happened awhile back) outweighed the potential benefits.

Would love to revisit this project again someday when I have more time to devote.

"Found a cat in my dining room a few weeks ago. We do not own a cat."
NOBODY owns a cat, they have staff.

Hammy posted the answer, that is the way that commercial flaps are done. Even a daft Labrador can be taught to push it open. All you need is a way of sensing said daft Labrador and releasing a catch at the bottom. My cat flap has a sensor coil outside and reads the microchip number.
The magnet at the bottom stops it blowing around in a breeze and rattling.