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Topic: Automatic door opener in fence for Automower (Read 1 time) previous topic - next topic


Hello all! Thank you for taking the time to open and read this. I'm not "new" to arduino exactly, but I have not done many hardware projects involving arduino (other Hardware yes.)

Before I start typing all this, I will let you know that I found a similar thread on these forums dealing with almost the exact same issue, but it never seemed to be resolved and it appears that the OP never finished his project, so I'm starting my own thread in the hope of getting a bit more guidance, and eventually to post a completed project.

Here's what I'm working on and I'm hoping some of you will be able to help guide me in the right direction, or at least help me manage my expectations.

I have a Husqvarna Auto Mower 315X running between my back and front yards, with the charging dock in the back yard, and a fence between the two. In order for it go between the front and back yards, I had to cut a hole in the fence, run the "guide wire" through the center of the hole, and the boundary wire around the inside edges of the hole, which allows it to pass through it freely.

I have 3 dogs, all three of which can easily pass through said hole, and have discovered how easy it is to do so, which is bad because we live on the corner of two somewhat busy streets. They are normally inside dogs, but we let them out back to play, pee, etc somewhat frequently. Right now, we have a 1 foot by 3 foot board that covers the hole in the fence when we want to make sure they don't leave the back yard.

What I need:
1: A system that opens the door when the mower is about to reach the door, but not open when a dog walks by, and closes as soon as it has cleared the door.
2: A system that stops closing the door if something is under it.
3: A system that deters the dogs from coming near it if it is open.

The option I originally considered was RFID. However doing a bit of research, I found that this would not be feasible, as RFID typically has very, very limited range, and anything that is longer range is very expensive.

Doing some additional research, I had the idea that perhaps I could modify an existing technology on the market, which is electronic dog doors that have some sort of transmitter that is worn on the animal's collar. I came across this product, which is very similar to what I want to achieve, but is pretty expensive and might not produce the results I want after I hack into it and modify it, resulting in a $300 pile of plastic and wiring.

Basically what I'm thinking of is using an ultrasonic transceiver system that sends a signal from the mower, and a microphone on both sides of the door picks up on the signal, opens the door, then uses either a "light curtain" or photoelectric sensor and reflector to detect if something (mower, animal, etc.) is present so it will not close on the animal or mower. While I realize that my dogs are reasonably smart, I would rather them escape than be crushed and killed by a door closing on them.

As far as deterrents go, I was thinking either a brief blow of a dog whistle or some kind of water spray towards the entrance. Ideally, the deterrents would only activate if there was a dog present, but that would add another level of sophistication that I am not currently prepared to implement, perhaps in the future after I get the basics done, but for now I just need it to open and close to keep the dogs in, and the mower through.

My questions are this:
Since the mower would have an ultrasonic transmitter on it (probably housed under the cover) and the dogs are outside when it is mowing, I need it to be above their hearing range. From what I've found, most of the transmitters are 40kHz, which would be painful or at least irritating to them. Dogs don't hear above about 63kHz, so I'm thinking in the 65-75 range would do the trick. Does anyone know where to find something like this that would be small and relatively inexpensive?

Is there a better way to activate the door from 2-4 feet away? If the mower bumps into anything, it will stop, turn slightly, and try to continue in the new direction (much like the bump navigation roombas), and would likely never make it into the front yard, so solutions that require it to hit a button or bump the door won't work. Is there some sort of magnetic sensor that would do the trick? I am not opposed to having a small "detection plate" or similar near the door, but it would have to sit level with the ground or buried.

And finally, is this even possible or do I need to stick with my low-tech board in front of the hole method, which leaves something to be desired as the mower needs to mow constantly to keep the grass cut.

Thank you in advance again. I appreciate any input I can get.


Also, I should note I plan on using an Arduino uno or Mega for this project.


The art of getting good answers lies in asking good questions.


Animal control methods for this usually use a double door method.

In your case a small tunnel for the mower size plus a bit. Then two doors. The mower enters the first and it closes then the second opens and vice versa for mower return.  With a bit of experiment using a wooden tunnel and it should work.

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