My smart motion sensor wasn't smart enough, so I used Python to fix it

Published Oct 21, 2026, 7:00 AM EDT Adam has a degree in Engineering and has a life-long interest in technology. He has been writing for over a decade for various print and online publications, with a focus on consumer tech. He joined How-To Geek in 2024 while working at Pocket-lint. As well as being a long-term fan of Apple products, he also has a strong interest in smart home tech, running a Home Assistant server at home to automate all his smart home devices. He believes that the ideal smart home should work with minimal interaction from the user, with automations running as if by magic rather than requiring you to push buttons on a control panel. You can find more of his work on Muck Rack. Sign in to your How-To Geek account Presence sensors can't just tell when you're in the room; some can tell where in the room you're located. The problem is that presence sensors don't always give a completely reliable location, which can break your automations. When one of my presence-based automations kept failing, I used Python to solve the problem. My office presence automation made me want to do more I wanted a way to pause the TV when someone left the room I have an Everything Presence Lite mmWave sensor in my home office. I use it to monitor my home office as a whole, turning on my lights when I'm in the room and turning them off when I'm not. I also have a zone set up around my office chair. The Everything Presence Lite is accurate enough to determine when I'm sitting in the chair, and I use this to determine how long I've been sitting still. A Home Assistant automation then nags me when I've been sitting for too long until I get up and walk around for a few minutes. The presence detection works so well that I bought another presence sensor for my living room. I wanted to be able to automatically pause my TV when someone got up to get some water or to answer the call of nature and then have the show or movie resume when they sat down again. Monitoring multiple people at a distance was more of a challenge Detected people would suddenly disappear Creating the automation was fairly similar to my office automation. I created a zone that covered the area of my sofa and armchair and set it up to pause the current media on the TV when the count of people within that zone dropped. The media then resumes when the person returns to the zone. The automation worked to an extent, but it was very unreliable. A little digging into the history of the presence sensor showed that sometimes the position of tracked targets would suddenly change, or a target would just disappear altogether. The problem was that with my office automation, I sit less than three feet from the sensor, but in the living room, the zone containing the sofa is on the opposite side of the room, so detection is happening at a much greater distance. The sensor struggles to maintain an accurate location for each target, so people can suddenly appear to jump position, or temporarily disappear completely. When a target was suddenly lost, the automation would think that someone had left the room and would pause the TV. When the position suddenly jumped for a moment, it would move the target outside the sofa zone, and the TV would also pause unnecessarily. Python gave my sensor a memory Evidence of leaving solves the disappearance problem I didn't want to give up on my TV pausing automation because I knew how well the presence-based automation in my office worked. I just needed a more reliable way to know when someone had left the sofa and then returned again. I realized that someone getting up from the sofa and leaving the room is quite different from them just suddenly disappearing into mid-air. The presence sensor should see the target move from the current location and go away from the detection zone rather than just vanishing. I decided to use some Python code running on a local server to look at a sequence of positions rather than just whether or not the target is detected in the zone. The code looks for a pattern of sustained movement out towards the room from the sofa. Several positions forming a path away from the detection zone are much more likely to indicate that someone has gotten up than the target count suddenly dropping. My presence sensor still can't handle the entire family I've had to limit it to working after the kids have gone to bed By using Python to look for clear indications of people getting up and leaving, my automation now works exactly how I wanted it to. Even if a target temporarily disappears or suddenly seems to be a foot further forward than it was a moment ago, the TV will only pause when someone gets up and leaves the sofa. It doesn't matter if detection goes temporarily weird while that person is away. The TV will only start playing again once the number of detected targets matches the original count. It took a little experimentation, and I had to force my wife to join me in getting up and sitting down again several times to ensure it worked as expected. However, by using Python, I was able to turn an automation that failed more often than it worked into one that works (almost) every time. My automation still can't handle the whole family, as the presence sensor can only track up to three targets at once. I've set it up so that it only works after the kids have gone to bed, so there are never more than two targets to track. Sometimes even the best smart home devices need a little help This isn't throwing shade at my presence sensors. They're excellent and my office chair detection is rock solid. The problem was that I was trying to use the sensor at a range where the accuracy was beginning to suffer. With a little help from a Python script that considers what happens around someone getting up, the whole setup now does everything I wanted.