There already exists "kinetic" switches for lights etc whose switch contains some passive electronics that when actuated produces enough energy to emit a radio signal that can be read by a relay module. They're pretty handy as you can basically place the switch anywhere you want without the need for the wires to be there. The relay can live in the light fitting or somewhere else convenient.
There's probably no reason why these kinetic switches can't also be used for detecting other events like doors opening/closing etc. I feel like a radio signal is a bit more reliable and easier to detect than high frequency sound.
I also think calling these a "sensor" is a bit of a stretch. They detect events but have no knowledge of the current state of the thing they're sensing. E.g. the can detect a door opening/closing, but have no idea if the door is open or closed at a given time
Piezo harvesting switches and similar (I think there’s a flywheel design out there too) are quite expensive, not terribly reliable or consistent, and require substantial activation force. Conventional switches and batteries that can last for years in remote push buttons and sensors are extremely inexpensive in volume.
It's research, not a product. Even with that, framing it as a smart home sensor in the press release is a stretch.
1) 93.75% success rate in controlled conditions, 92.1% in a somewhat-realistic deployment scenario - too low for reliability. I wouldn't use something like that to trigger smart home automations.
2) Range hardcapped at ~1m due to how ultrasound works, you can't centralize detection. Their answer is to give everyone in the household a wearable receiver, which is eeeeeeeh idk, doesn't look consumer-friendly to me.
3) Paper suggests a mix of durable and consumable parts for the transmitter. Their numbers show that the 3d-printed PLA cantilever needs to be replaced every 900 cycles or so. Should work fine, but...
4) ...every transmitter pair needs to be tuned per-setup, every time. Not a plug&play in the consumer sense.
I can see some uses, but calling this system batteries free seems a stretch. A sensor is worth nothing if it can't be read, and to read this you need a powered microphone and computing. Some already common magnetic door systems do the same; door plate and magnet movement is enough to create a detectable current, (using no external power), then that signal is read and computed by an electronic/digital system (using power).
I'm on the side of "clever, fun, but feels useless". But to defend the project, all sensors require a powered central system. It's pretty common for Zigbee to have one repeater per room [1], which is just what is needed for this system.
[1] Because any AC-powered Zigbee device is a repeater, so just a bulb or a plug is enough
With a 1m range of detection you would need many detectors for anything larger than a ~4m3 sphere. That’s 12 detectors for a typical single bedroom (4x3x2.5m).
Obviously not, but there is larger potential than that. A microphone in a watch or phone can pick up the signal and relay the trigger to another server via for example MQTT. Then, you can have homeassistant act upon this signal.
The flow is then
Open door --> Signal triggers --> Signal caught by microphone --> Microphone device relays to server --> Server turns on smart lighting in that room.
There is a lot more that you can do, but this is just an example. The microphone to pick it up is a limitations, but the gain is:
- reduced power usage as the signal generators are not power-operated
- less waste as no empty batteries need to be discarded (if non-rechargeable batteries are used)
- improved security because the signal generators are not connected to the internet, reducing the attack surface.
Right, and they were superseded by battery-powered infrared remotes for good reasons. I would recommend revisiting those reasons before proposing this sort of technology for wireless sensors.
There's probably no reason why these kinetic switches can't also be used for detecting other events like doors opening/closing etc. I feel like a radio signal is a bit more reliable and easier to detect than high frequency sound.
I also think calling these a "sensor" is a bit of a stretch. They detect events but have no knowledge of the current state of the thing they're sensing. E.g. the can detect a door opening/closing, but have no idea if the door is open or closed at a given time
1) 93.75% success rate in controlled conditions, 92.1% in a somewhat-realistic deployment scenario - too low for reliability. I wouldn't use something like that to trigger smart home automations.
2) Range hardcapped at ~1m due to how ultrasound works, you can't centralize detection. Their answer is to give everyone in the household a wearable receiver, which is eeeeeeeh idk, doesn't look consumer-friendly to me.
3) Paper suggests a mix of durable and consumable parts for the transmitter. Their numbers show that the 3d-printed PLA cantilever needs to be replaced every 900 cycles or so. Should work fine, but...
4) ...every transmitter pair needs to be tuned per-setup, every time. Not a plug&play in the consumer sense.
[1] Because any AC-powered Zigbee device is a repeater, so just a bulb or a plug is enough
With a 1m range of detection you would need many detectors for anything larger than a ~4m3 sphere. That’s 12 detectors for a typical single bedroom (4x3x2.5m).
Also I guess this might be annoying for pets that can hear well beyond 20 kHz.
If so, will it penetrate through walls?
Could work for drywalls
The flow is then Open door --> Signal triggers --> Signal caught by microphone --> Microphone device relays to server --> Server turns on smart lighting in that room.
There is a lot more that you can do, but this is just an example. The microphone to pick it up is a limitations, but the gain is:
- reduced power usage as the signal generators are not power-operated
- less waste as no empty batteries need to be discarded (if non-rechargeable batteries are used)
- improved security because the signal generators are not connected to the internet, reducing the attack surface.