Motion detectors to determine direction and presence, I'd like other thoughts

In an effort to speed up some of my motion triggered automations, I’ve started changing out some of my motion sensors. I currently have an in ceiling motion sensor inside every room entry door. I’ve placed them to minimize triggering things when I’m just close to the door and not going in the room. Now that I have a few to play with I’m wondering if I put some additional sensors in hallways etc can I get automations to know which what to do based on the sensors that are triggered. Sort of like the shows that have lights turning on and off as they go down a hallway. I’m thinking of the webcore trigger that says something like if this happens within X time of this than do this. Anyone using this and does this sound reliable? or other ideas?

It all depends on what you’re trying to accomplish and what you mean by “reliable.”

I am a wheelchair user and I depend on automation to create a pathway of lights ahead of me as I move through several rooms. For example, I have a “bedtime” routine that turns on a couple of lights in each room from the family room to my bedroom. But I don’t care exactly when the lights go off behind me as I pass through, in fact I usually turn them all off myself with a different scene after I’m in bed.

Other people are looking for some cool waterfall type effect as they go downstairs where, say, two steps at a time light up and the steps behind them keep turning off.

The first kind of use case is pretty easy. You just trigger the lights ahead as desired. If you want to try and figure out what direction the person is moving in, That’s possible, but can get trickier. The protocols that work with smartthings that are typically used for sensors, that is Zigbee and Z wave, are both mesh protocols where messages can bounce around the mesh for a little bit before they get to the hub and there is no forced sequencing. So you can write the code to say “if sensor A detects before sensor B” using webcore, but you can’t guarantee That the hub will actually receive the message from sensor a before it receives a message from sensor B, particularly if they are physically close together.

You may also need a very sensitive sensor, like the Fibaro multi sensor, but then you use up the battery a lot quicker.

So a lot of it is just trial and error to see what actually works on your set up.

And of course if what you are going for is some fancy aesthetic effect, the timing becomes even trickier.

There have been previous discussion threads about directional detection, usually as part of occupancy counting, and the most reliable way to do this is with a double infrared beam that gets broken similar to garage door collision detectors. You can find discussion of that option in the following thread:

In room detection of Occupancy

But the truth is smartthings is mostly a cloud-based system, and the cloud component introduces a lot of unpredictable latency that make these type of timing projects just tricky to pull off. You can try it, but it’s not something that smartthings is really well-suited to.

On the other hand, if you’re just looking for something practical to turn on lights ahead of where you are as you are moving towards them, and you don’t worry about exactly when they turn off again, then smartthings can work very well for that. :sunglasses: