Smart Device that Can Measure Distance

My use case is knowing if a car is present in the garage or not. My idea, if it’s possible, is to mount a device that measures distance in the rafters of the garage pointing down. If a car is present in the garage the distance between the device and the car would be x. If the car is gone, the distance between the device and the floor would be y, and setting different smart home rules based on that. Any ideas on if a device like this exists or any other ideas on how to achieve this end result? Thanks in advance!

This is called a proximity sensor. There are lots of them, some made for exactly this purpose (lining up a car in the garage).

I don’t remember seeing one that can connect out of the box with smartthings, though.

The most common way to get smartthings integration would be to add one to an Arduino and then probably use ST_anything to act on the report. But I remember a couple years ago there was somebody who set one up with a Z wave integration. I’ll see if I can find that one for you.

Meanwhile, check this out:

[RELEASE] ST_Anything - Arduino/ESP8266/ESP32

And here’s an Arduino-based project from one community member. The project report is really old, but the people in the ST anything link above could help you figure out what needs to be updated.

Smart Parking Spotter by Todd Wackford

The other alternative would be a pressure mat that would report if a car was on the mat. These are commonly used for driveway alarms and they are pretty easy to connect up to smart things. The problem, though, is getting things lined up just right, and that might be trickier.

Here’s another old project report based on the pressure mat. Again, some of this would have to be updated for the current platform but it should definitely be doable. The trick is getting the car parked on the mat each time, this method is easier for a motorcycle. Or a trashcan. :sunglasses:

Car presence for garage door openening

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I forgot, if you just want something out of the box, just throw a tracker into the glove compartment and you’ll know if the car is home or not. Unless of course this is an Airbnb situation or something like that where it’s not always the same car.

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Another option would be something that is particle-based. You could use IFTTT for the integration. But I think most people would rather use ST_anything, which would be an easy swap for those steps.

Anyway, this is the kind of sensor I was talking about in my first post,

@ogiewon could say more about doing this with ST_anything instead of photon.

Again, though, A lot of people just stick a tracker in the car if I you want to know is whether the car is home or not. You could use anything that has an IFTTT channel and get integration that way. That doesn’t require any maker skills. :sunglasses:

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Thanks @JDRoberts! All of this has been super helpful!!

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I think the smartthings arrival sensor still works with the new app, it would be the easiest if you don’t need to know the exact position of the car and you just want to know if a specific car is home or not.

If you want to know the exact position of the car in the garage, or it’s not always the same car, then you need to use one of the other options.

Not everyone is able or willing to move their devices to another hub and others have no desire, so maybe something actually helpful said instead…

The Zigbee project linked to in that post is helpful as another example of a build it yourself proximity sensor. It would have to be rewritten to work with smartthings, but so would the photon example I included above. So personally I found it interesting.


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No experience with it myself, but I think a relatively straightforward and reliable approach would be to use a device similar to this for detection:

And connect the output to a contact sensor that supports an external switch, like this:

(I’m sure there’s a cheaper source or alternative switch out there).

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2nd or a camera…

Infrared beam sensors might work but these are “break beam” Devices, where anything which interrupts the beam connection between the two pieces is reported.

Those aren’t usually used for a parking application for a couple of reasons.

First, anything which breaks the beam is reported, and you have to decide where to position it with that in mind. Most people won’t want to put the beam towards the garage door side, because then the car will trigger it both going in and going out, and will also trigger it before the car has pulled all the way in. That second part might not be an issue depending on the details of the use case, but the triggering going out is complicated.

Also, in a two car garage without Lane separators, it’s very likely that you won’t be able to distinguish between having two cars in the garage and having just one. Whether that matters or not again depends on the details of the use case.

Positioning also gets pretty tricky just in finding a path which is normally clear except when blocked by the car. This is easier to do vertically then horizontally, but vertically doesn’t typically work for a break beam because of the danger of running over the floor sensor.

Break beam sensors are very commonly used in garages right at the garage door line, where they serve as a safety feature for the garage door coming down, but they aren’t usually used as a parked car indicator.

I offered two solutions.

By my calculations, thats 2 more than you.

Thanks for the input thumbs up


Incidentally the arduino based solution I offered would work with smartthings via st_anything (by @ogiewon). That is of course, until Samsung decides to completely shag the option of using custom dth’s etc. Full disclosure.

If you don’t like smartthing either

a) leave the forum

b) stop posting negative suggestions when specifc advice was sought.

There you go, 2 suggestions for you!!

For a start, advice was (successfully) given. Link to a DIY device that can be used with smartthings to achieve the task requested.

So your reply holds no ground.

Secondly, it’s “specific”.

Finally, I’ll post as I wish. I’m not violating terms, whether you like it or not. I don’t particularly care.