Using motion detection to turn lights on and off or turn off with Alexa?

[JDRoberts]

Latency is most commonly an issue of the brand/model of sensor and, just as importantly, the placement of the sensor.

You may already know this, but most of the motion sensors that work with SmartThings are PIR, passive infrared sensors. They measure very small changes in heat the passes across the lens of the sensor.

Many people will think of the motion sensor like a camera and place it so that a person walks straight on towards it. But this can actually result in the sensor not triggering. The best placement is to position the sensor so that the person walks sideways across the detection field. See the community FAQ for details (the topic title is a clickable link)

FAQ: Where to locate motion sensor for fastest response?

[image] I have a downstairs hallway that’s perhaps 12 feet long, with a doorway to a spiral staircase at one end (where the picture is taken from) and a door into the garage on the other end. As you can see in the picture, there’s a jog in the hallway. Not seen here are another doorway about 4 feet to the right of the one by the staircase, a bedroom door to the left at a 45-degree angle (you can just make out a bit of the trim on the corner of the wall, near the top), and a laundry room doorway on the right as you go through the jog. The hallway is dark and I want to automatically turn on the lights when I come off the stairway or enter from the garage. I have an Ecolink motion sensor and I’ve tried placing it in each of the four locations marked with circles. (The two near the top are …

Also, some sensors have parameters that allow you to adjust the “sensitivity“ which will reduce latency. But it will also reduce battery life, so that’s a trade off you have to consider.

Finally, the official smart light feature can run locally, without requiring a cloud trip to turn the light on, but only when certain device type handlers are used. So that’s another possible factor.