Aliexpress has load cells that go up to the hundreds of KGS. One of those, an esp32/pico and some wiring and you should be good to go?
This. I bought a few myself, but didn't have time to put them together with ESP32/program them with ESPHome
Couldn't find the exact one I ordered a few months ago, but this type of pressure sensor aliexpress link is apparently a common bed occupancy sensor type used when building medical beds for hospitals and care homes so staff can be alerted when a patient gets out of bed. I'm not sure the specific model I linked is quite right specs-wise, but the idea is that it goes on a slat or other surface between the matress and the frame that doesn't necessarily get the full weight of the occupant, but still gets enough to measure on the sensor.
I have an Aqara FP-2 doing just this thing. It works pretty well after setting up zones. Those get pulled into Home Assistant and then you can tie those to automations to control lamps or what have you.
I also used a mmWave sensor in the past for this, one from a youtuber. Worked well enough for my case, but it had some interruptions during the night.
I don’t have one myself, but several of the guys on YouTube use them. See “The Home Automation Guy” or “Smart Home Solver“. I can’t remember the brand they use.
I'm a bit late to the conversation here, but I bought four of these car seat occupancy sensors - https://www.ebay.co.uk/itm/316523892197 - and installed them between the mattresses, one at butt level and the other at shoulder level on both sides of the bed - and connected them to an ESP32 on ESPHome. Works a treat. They're sensitive enough to momentarily disengage if someone rolls over or shuffles about if you need that, otherwise a generous bounce detection allowance smooths it out.
I've never done anything like this, but would it be possible to place such a sensor between the mattress and the frame instead? That would result in a fraction of the load due to the distribution of the weight. The challenge would be to set the threshold right.
@bus_factor Some of the #mmWave (Radar) Presence sensors may be able to detect bed presence through the mattress, mounted under frame. I have not tried this yet but I’ve been planning to. The Aqara FP-1 or Aqara FP-2 are candidates, but maybe too pricey for an experiment. The Apollo MTR-1 is far less expensive and excellent for short range. It is also small and with a sturdy enclosure you could easily place it between and mattress. These sensors can pick up very small motions, even the human heartbeat (sometimes through walls). I use both Aqara (easier set up) and Apollo MTR-1 for room and zone presence detection, with #HomeAssistant for integrated automation.
Use car occupancy sensors and an esp board. That's what I did. I stuck them to corregated cardboard and put one under each side. Aim for the butt area as that seems to apply the most pressure. I would order 4. 2 for each side because you can put them in parallel to divide the resistance and make them easier to trigger.
Buy them on AliExpress or eBay.
How about mm radar?
I grabbed a couple of Ali last month to use for lighting sensors for the hall and toilet, not set up yet
https://community.home-assistant.io/t/fsr-the-best-bed-occupancy-sensor/365795
This is the best write-up I've seen - essentially a force sensitive resistor on the bed slats and an ESP32 will get you the results you're after.
I’ve got parts on order for this very project, should arrive this week.
I previously tried using one of those large pressure mats but it didn’t work under the mattress.
I can't believe I'm even engaging this post, but... what's the use-case? Gotta say, this sounds extra creepy.
Turn on the lights in the bedroom based on presence sensor, but only if the bed occupancy sensor detects no one is in bed.
Turn off the lights when 2 people in bed. Turn the lights on really low when only 1 person gets up. Track time you went to bed / time in bed as a low-budget sleep tracker not tied to a big data broker, like a smart watch would be....
@just_another_person Turning on or off nightlights. Changing iOS focus (e.g., sleeping). Activating outside security monitoring… all kinds of interesting use cases.
Can one change iOS focus modes from home assistant?
@spitfire I said that but the fact is I don’t really know. But I’d like to know. I know #HA #HomeAssistant can launch apps and select channels on #AppleTV so I think it should be possible on iOS. Using webhooks maybe.
Some of us like to automate our homes with our home automation systems instead of finding new ways to remote control them.
Just because you go to a dark place in your imagination doesn't mean everyone else does.
Gotta make sure the dogs aren't jumping on the bed while the humans are gone. What else could you possibly use this for? 🤷🏻♂️
Taking care of an elderly person whose a fall risk? There are lots of valid reasons.
Presence sensors do fall detection and human presence to a great degree. No need for a BED sensor and measuring occupancy.
And how is a presence sensor in a bedroom less creepy? Its measuring the same thing as you say.
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