[HN Gopher] Making my own bed sensor
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Making my own bed sensor
Author : davikr
Score : 123 points
Date : 2023-12-19 12:50 UTC (10 hours ago)
(HTM) web link (www.homeautomationguy.io)
(TXT) w3m dump (www.homeautomationguy.io)
| pricechild wrote:
| https://www.revk.uk/2023/03/bed-sensor.html?m=1 has another take
| on the idea after frustration with a "smart" & expensive Withings
| solution drove him to something different.
| a_t48 wrote:
| I need one of these to stop my cat from turning on the bedroom
| lights when he's hungry. Unfortunately with HomeKit doing
| automation like this the easy way involves converting the action
| into a shortcut, which comes with execution delay.
| blorenz wrote:
| I never thought of using a water leak detector like that nor have
| ever actually used a water leak detector. I can now create my own
| pressure plate activated door or true AFK notifier. Thanks for
| the write up!
| 1-6 wrote:
| I thought the Aqara water sensor technique was brilliant. I
| wish more device makers would build IoT devices that connect
| directly to sensors.
| tapland wrote:
| Aqara zigbee devices are the first non-lights I've used and
| they have been great!
| jcrawfordor wrote:
| The Zooz ZEN16v2 or ZEN17 are also good options for connecting
| arbitrary sensors via Z-Wave, and the ZEN17 in particular is
| electrically more flexible (sink or source inputs). That said
| two water leak sensors will often be cheaper than one ZEN17
| with its two inputs. An even cheaper option are door/window
| contact sensors and desoldering the reed switch to replace it
| with whatever you want, but it's less convenient for sure. And
| to wrap it all up, Zigbee devices are often a bit cheaper than
| Z-Wave.
| robalfonso wrote:
| Fibaro makes a similar device in a smaller form factor as
| well
|
| https://www.thesmartesthouse.com/collections/fibaro/products.
| ..
| gjpolly wrote:
| Sensor shows 2 people in bed, when you're not home.
| sokoloff wrote:
| "That can't be right; it looks like there's a sinusoidal error
| signal in the sensor readings..."
| function_seven wrote:
| "Wait... something is modulating that sine! The frequency is
| rising."
| petsfed wrote:
| "I really need to tune the debouncing algorithm, these
| errors are driving me nuts"
| greenie_beans wrote:
| yeah this is creepy, i hope the writer's love life is okay.
| Larrikin wrote:
| It's not creepy.
|
| Typically one of the first types of automations you do is
| presence and motion detection, for simple things like turning
| off lights when no one is home, turning on lights when you
| enter a room.
|
| Then you find edge cases like wanting the lights to turn off
| when you're in bed, but not turn on if only one person gets
| up in the middle of the night.
|
| If you want to automate any of these things then it's
| necessary for the system to see the events.
|
| In my experience, people say it's all worthless, until they
| experience it themselves.
| distantsounds wrote:
| Yeah, super weird thing to be wrapping automation and detection
| around, I'm really unsure of the use case other than this.
| nkozyra wrote:
| Force sensor resistors can be had for $3-$8 a piece, would they
| not also do the trick? ESP32 is such a great platform, can you
| not just make an HTTP request depending on force to a Home
| Assistant API endpoint and skip the leak detector as a conduit?
| brainzap wrote:
| yup FSR, thats how I do it
| stavros wrote:
| Yes but Zigbee is great.
| michaelt wrote:
| What the leak detector gives you is a long battery life.
|
| You _can_ achieve it with DIY but if you want microamp-level
| current consumption you've got to do without a lot of the
| components that appear on dev boards
| stavros wrote:
| How does the water leak detector work? What's supposed to go onto
| those contacts?
| CiaranMcNulty wrote:
| Water
| lsaferite wrote:
| Water.
|
| It works by having water (or another conductive liquid) provide
| a path between the contacts.
| stavros wrote:
| Interesting, the terminals really look like those screw
| terminals you attach cables too.
| exhilaration wrote:
| I'm guessing they sell some kind of extension to attach to
| those terminals. For example, here's what the $12 water
| alarm in my basement looks like:
| https://www.amazon.com/Glentronics-Inc-BWD-
| HWA-00895001498-B...
| ska wrote:
| I often find reading these sort of descriptions amusing, for the
| strange mix of "hey, cool seeing someones DIY project" vs "I just
| don't understand why". I guess my personal value on hacking up
| your own stuff is just _way_ higher than that on home
| automation...
| ranting-moth wrote:
| To each his own is a good rule when it comes to hacking/geek
| projects.
|
| I've so often been asked "but why are you doing this" or
| suggested that I go and buy the stuff that I'm making.
|
| I find it very annoying. I find most people who ask so such
| questions won't "get it" even if I explain.
|
| But I do understand that most often people are trying to be
| helpful. They can't imagine going through the ordeal that I'm
| going through for something of no value to them.
| ska wrote:
| Oh I would never ask someone why; let a thousand flowers
| bloom.
|
| I just find I get tickled by the ratio of my interest in how
| someone solved their problem to (my) lack of interest in the
| product in this particular genre at least.
|
| "To each their own" is a good principle :)
|
| I guess a different way of looking at it is this, I'm
| laughing at myself realizing that I would happily spend hours
| helping _you_ figure out a hardware /software problem in your
| home automation setup, but I wouldn't spend minutes
| automating my own home. probably. maybe the right itch hasn't
| presented itself.
| userbinator wrote:
| For me, most of the amusement was that my mind went in a _very_
| different direction upon seeing both "leak sensor" and "bed
| sensor" being mentioned.
|
| Count me in the "I just don't understand why" group too --- I
| work with enough software in my day job that I really don't
| want more of it in my life beyond that.
| MarkusWandel wrote:
| Kinky jokes aside, this sort of thing can give a pretty good
| overview of how much you slept and how well. I use a
| piezoelectric sensor plate from an "Angel Care" baby monitor.
| Takes only a handful of passives to safely interface to an
| Arduino analog pin (safety: The transient from the thing getting
| jolted not burning out the input pin).
|
| The result, graphed (at 1 minute per sample bin - don't get kinky
| ideas) gives a very good overview of awake/tossing and
| turning/really asleep. Which to a lousy sleeper like me can
| actually be reassuring - yes, I did get some sleep in all this.
| minimalist wrote:
| Andreas Spiess' recent video [0] covered some milimetre-wave
| radar chips whose application includes presence detection at a
| distance (including if the bed is occupied).
|
| Does anyone know of any bed automatable bed heating/cooling
| solution (DIY or otherwise) that can work offline of with Home
| Assistant? I had my eyes on E*ght Sleep but it looks like a lot
| of the functionality is behind a subscription wall [1] and the
| device is very chatty [2] and I haven't been able to find any API
| reverse engineering / firmware mods.
|
| [0]: https://www.youtube.com/watch?v=s-GzUTyIH9c
|
| [1]:
| https://old.reddit.com/r/EightSleep/comments/1248wgz/buyer_b...
|
| [2]:
| https://old.reddit.com/r/EightSleep/comments/185cgm4/pod_3_t...
| alxlu wrote:
| there's bedjet. i find that it doesnt work well with adjustable
| beds though because when you raise the leg part up, the bedjet
| hose thing tends to slip off.
|
| https://github.com/pjt0620/Home-Assistant-Bedjet/
| lm741 wrote:
| I suspect the sleep.me chilipad systems (ooler/dock pro)
| would work pretty well with adjustable beds since they just
| run a pair of insulated water hoses to a capillary tube
| network in a mattress pad. Further, if the hose routing
| didn't work for you out of the box with those you could DIY
| something else pretty easily since they use off the shelf
| connectors (https://www.cpcworldwide.com/General-
| Purpose/Products/Multil...)
| lm741 wrote:
| On the bed heating/cooling front, you might try the Ooler
| series from sleep.me
|
| The older generation Oolers use bluetooth and there are a fair
| number of integrations including an [MQTT
| bridge](https://github.com/turmoni/ooler-mqtt-bridge) and a
| [HomeAssistant
| integration](https://github.com/PostLogical/ooler).
|
| I'm less familiar with their latest generation which uses WiFi,
| though there [seems to be an
| API](https://docs.developer.sleep.me/api/ ) available for it
| now.
| filterfiber wrote:
| Does anyone know if mmWave could differentiate between my cat
| and I?
| itishappy wrote:
| In theory, but probably not in practice. The fancy non-metal-
| detector airport security scanners use mmWave to detect
| object through clothing, so the light itself capable of
| producing high-resolution images. However, cheap home
| automation sensors are probably not imaging, so you're
| probably going to be stuck with a single depth measurement.
| ulf-77723 wrote:
| Great project! Until now I do not have anything connected to my
| bed, I can't sleep with something attached to my wrist, so no
| sleep data. Tracking the sleep would be really great, but the
| current solutions seem not right to me.
|
| I would welcome a system, which may be used as a pod sensor, like
| the mentioned EightSleep or Withings, both not visible. But I
| want to set when something is radioing around my bed. Just like
| on my smartphone, where the flight mode is activated, I would
| like to set the device so that the data is only synchronized via
| WLAN or Bluetooth when I am no longer lying in bed.
| lawn wrote:
| > I can't sleep with something attached to my wrist, so no
| sleep data.
|
| Another option would be Whoop that you can add to your
| underwear.
|
| Expensive I know, but it works very well.
| roywashere wrote:
| I use a Google Nest Hub for two weeks now. It has sleep
| tracking via IR cameras. It promises this is all on-device. I
| think it is reasonably accurate. Google said it is going to
| charge 8 euros per month for it starting January 1st. I'll stop
| using it then
| LCoder wrote:
| I spent years in a previous job developing acute care pressure
| pads like these utilizing pressure-sensitive conductive ink. The
| simple open/closed circuit pads shown here work well above the
| mattress but (depending on your mattress weight and bed frame
| structure) can provide false positives when placed below. We had
| fun stories with our first home testers where many people (me
| included) planted our elbows and lifted when we turned during the
| night. This movement was enough of a weight lift over the pad to
| cause the first iteration of our sensors to trigger. The ability
| to adjust your bed's unoccupied zero point using an analog
| measurement, deciding how much weight should be added (or
| removed) to determine a state change, and over how much time the
| movement occurred makes a big difference in reliability.
|
| Near the end of my grandmother's life, she was living with my
| parents and a fall risk. I did this same ESPHome implementation
| to HomeAssistant to provide us with alerts when she got up on her
| own in the middle of the night, and it helped my mother sleep
| much better.
|
| Side note: those other two wires the author says they "have NFI
| what they do" are most likely wired into the pad as a permanently
| connected loop. Most monitoring equipment will look for a closed
| circuit on those wires to detect that a sensor pad is connected
| correctly and the sensor wire hasn't been broken (ripped, torn,
| cut, etc).
| mattmaroon wrote:
| Damn, why did I never think to use a leak sensor? I've been
| goofing around with building some unusual devices and messing
| with relays and io pins and arduino and completely missed this
| obvious solution.
|
| It's literally a device designed to do exactly what I sometimes
| need (start an action if a circuit closes) and I just never
| thought about it even though I know how leak sensors work and
| that there are ones available. Duh!
|
| Stuff like that is why I love HN. Thanks to the author if you're
| reading.
| shellfishgene wrote:
| Door/window sensors also work and are even smaller than the
| leak ones. Just replace the reed switch with whatever.
| timemct wrote:
| Some d/w sensors will even have dry contacts specifically
| meant for wiring in whatever open/close type thing you'd like
| to use, like a pressure pad.
| robalfonso wrote:
| I've done this as well, but I moved to 500kg load cells on the
| bed legs for reliability.
|
| 2 Load cells one on each back leg of the bed. Upside too is I've
| been able to discern things like, sitting on the edge of the bed
| to put on shoes etc based on the weights.
|
| Esphome, load cell, and hx711 chip for the load cell comes out to
| about $40-$50 each leg.
| paradox460 wrote:
| Many years ago, I bought a bed/sleep sensor made by Withings. It
| worked fantastically, for about a year. Decent sleep measures,
| circadian aware alarm, all that.
|
| Then it just stopped working. Contacting support thought it might
| be the pad, and they sent me a replacement. That worked for a
| while longer, until it didn't. At that point, Withings had been
| sold to Nokia, and wasn't interested in maintaining their system
| anymore.
|
| I miss it. I'm sure that this system won't be able to do all the
| measurements the Withings one did, but thats OK. I've got a watch
| for that. Def. going to have to try this soon!
| neilv wrote:
| I see the photo of the sensor atop some springy bed slats, but
| don't see mention of how the sensor setup distinguishes the
| weight of of mattress above springy bed slats from when a person
| is atop.
| chetumal wrote:
| I have a similar setup with the same kind of sensor. It just
| doesnt register the matress at all. My guess is that the
| matress weight is evenly distributed so it doesnt actually put
| that much pressure on the sensor.
| logtempo wrote:
| matress are around 40, maybe 50kg/m3.
|
| water is 1kg/dm3, and acording to this website
| (https://www.aqua-calc.com/page/density-
| table/substance/human...) human is arround 1000kg/m3 which
| make sense.
|
| So, yes matress is light compared to human, I guess it does
| nothing to the sensor pad.
| pants2 wrote:
| I've always thought a Thermal Imaging camera mounted above the
| bed would be the best sleep tracking system. It could even be
| hooked up to a feedback loop where if it detects your body
| temperature rising it can increase your fan speed, things like
| that. It would be a fun computer vision project.
| mft_ wrote:
| An averaged heat-map would also help solve the pirennial
| relationship question of who encroaches on whose side of the
| bed the most :)
| taneq wrote:
| I think you'd find that the actual physical locations of the
| bed's occupants are less relevant than you might think to
| these accusations, ;)
| throwaway81523 wrote:
| Obligatory:
|
| https://biggaybunny.tumblr.com/post/166787080920/tech-enthus...
| chpatrick wrote:
| I think it makes a big difference if your home is running on
| open source stuff or not.
|
| I wouldn't be comfortable with Google or Amazon running my
| house but if it's stuff I flashed myself from github it's a lot
| better.
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(page generated 2023-12-19 23:00 UTC)