Difference between presence sensor and motion sensor?

Devices & Integrations
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Hi - I’m new to SmartThings and noticed in their device types listings they have both a Presence Sensor and Motion Sensor. I would have thought these are the same thing. How are they different (or different enough) to make ST break them out into their own types of devices? Based on this I’ll have a better idea of which is right for my needs. Thank you!

2

Hi

I’m relatively new too, but a motion sensor is like a PIR that ‘sees’ movement so you can trigger things like lights etc.

A presence senior us designed to Indicate if someone or something is at a location. I use the iOS app to trigger when my wife and I leave and a Key fob sensor for guests. Both work an a radius from the house.

Hope this helps,

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@gupster gave you a good initial answer, but to add a bit more detail:

  1. a “motion sensor” recognizes a change in the environment around it and notifies the hub that that change has been detected.

  2. a “presence sensor” is really a misnomer – – it isn’t sensing anything at all. Instead, it simply broadcasts its own presence. The hub recognizes when the presence device crosses a specific boundary, or when it has gone out of range and is no longer checking in, and it is The SmartThings cloud that marks the device’s status as “here” or “away.” So the device itself is coming and going.

A presence sensor is normally used so that the system can know if a particular person has come or gone and then take action based on that change. Depending on the exact device used, the area that is covered can be the size of the house, or even several kilometers. The signal can usually travel through walls and windows. Since it is the device itself that is being detected by the SmartThings platform, the person has to have it with them. And each person has to have their own presence sensor device.

A motion sensor is normally used to detect that some person has entered an area, but it does not identify which specific person it was. A Motion sensor will only detect motion within a relatively small range, typically about room size, and will not detect through walls or windows. The motion sensor is doing the detecting, so it will recognize a person just walking by, they don’t have to be carrying their phone. Motion sensors are deployed based on the area they cover, not the number of people passing through. Normally the motion sensor always stays in its assigned location.

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Or a cat/dog as often at my home :slightly_smiling:

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Motion would infer presence, but presence would not necessarily infer motion. Motion does not identify what is triggering it. Presence would identify what specific device/phone triggered it. Presence is not fine or detailed enough to determine that a specific device caused the motion.

For example, you put a presence sensor on your dog. The dog is out and about the neighborhood watering flowers and sniffing fire hydrants. The dog is neither present, nor causing motion. Your dog wanders home and triggers both the presence sensor and motion sensor. All the wandering was hard work and he gets up on your bed to take a nap. He is still present, but without motion. The dog is still napping and your cat wanders through the room triggering the motion.

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So is it possible to set up your system to recognize presence per room in a house? Possibly by Rule Machine?

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Not with the usual SmartThings presence indicator methods–their detection zones are too broad. The smallest is the zigbee SmartThings branded arrival sensor, and even that is about a 50 foot radius around the hub. So way more than just one room.

This concept, locating a specific person in one specific room is called micro location. Everybody wants to do it, but the technology just isn’t quite there yet.

There are some different methods that can sort of do it, but they involve carrying a device and checking in and out as you go through rooms. And often many additional devices and a lot of custom technical work.

Kristopher Has one that probably comes closest:

You can also do something with iBeacons, which can be set to a much smaller range. There are two problems with this approach, though. First, you still have to carry a device with you (either your phone or a Beacon depending on how you’re setting it up) and because these are Bluetooth devices they are not stopped by walls. Or floors. Or ceilings. So even if you set it to say a 6 foot range, it might detect you on the opposite side of the wall as well.

I personally do have a beacon attached to my wheelchair and I set the detection range to quite small, around 6 feet, so it will pick me up just as I get to the base of the wheelchair ramp that goes to my front door. And I have one other place in the house where Detects that I have entered (and not someone else). It works well for my own purposes, but then I’m not going anywhere without the wheelchair so it’s pretty easy to have a device attached to that.

To keep from getting too far off topic, we should probably take additional discussion of microlocation to the following thread:

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I want to ask about the sensor motion, is there is anything that can recognize the identity of the person it self I mean the sensor recognize certain number of people otherwise the sensor will sent a sound sign there is someone stranger want to enter. I hope if my question is clear. I need the answer is really important for my project.