Looking for reliable PIR human detection sensors

  • Hi all,

    I have huge problems with PIR human detection in my smarthome.
    The sensor is mounted on the ceiling in my corridor. If I walk up stairs then the detection is very very bad. (similar to an back and forth movement)
    Some other articles also confirmed that these kind of sensors do have such problems. Sidewards movements (e.g. left to right) seems to work much better.
    Unfortunately Repositioning the sensor in this case is nearly impossible.

    I already tested different kind of sensors like:

    • HC-SR501
    • AM312
    • IKEA Molgan

    Do you have any ideas / experience with better human detection sensors?

    • Is AM612 better than AM312?
    • RCWL-0516 microwave radar sensor --> Possible false detection through walls?
    • Thermal IR Arrays like Panasonic AMG8833 or Omron D6T --> expensive

    Or do you think that it is cheaper to use an "Aeotec Multi-Sensor 6 (Zwave)".
    This sensor costs about 50-55 Euro. For example the price for an IR Array sensor starts at around 20-30 Euro.

  • the cause of the problems You have lais in how the PIR sensors works. They work by comparing heat readings in different zones of their view. The zones are 2-dimensional, so this is why they work ok, when you walk sideways and not very good when you walk towards them. Nothing You can do accept using a pir with beter resolution. Or, You can make a node with two pir sensors in different orientations.

    I used HC-SR501 and AM312. AM312 that is available as a whole module has shitty lens, but with correct lens it works as good as HC-SR501 and AM312 can work with lower voltages and has much less power consumption. So I would go for AM312 with good lens.

  • The radiowave based ones are imo better wrt. that, so why not give them a try?

    According to my experience results depend much on the environment, especially wrt. their ability to "look" through walls. If it's bricks without holes, you may get also satisfying results.

    Besides all other things a stable power sourcing seems to be essential . I use 5V, but some report also satisfying results when sourcing the IC directly with 3.3V.

    There's the option to reduce responsiveness also by adding a resistor, more details can be found here.

  • @rozpruwacz I also already thought about making a node with multiple PIR sensors in it. May you know if it is possible to connect the OUT pin of multiple PIR sensors to the same input pin on my micro controller?

    @rejoe2 Have you already made some experience or used these microwave sensors as motion sensor?
    They are not so expensive so I already ordered them. Waiting for delivery now.

  • @ehome for sure it is possible to connect them, to single pin. The circuit will depend on the pir internals. It may be as easy as just connecting the wires toghether. I will check it for am312 when i get home.

  • @rozpruwacz cool, thanks. Currently I am using the following AM312 module eBay

  • @ehome said in Looking for reliable PIR human detection sensors:

    @rejoe2 Have you already made some experience or used these microwave sensors as motion sensor?

    I use several of them on a couple of RS485 MySensors nodes and also know some others in the FHEM forum using them with ESPEasy. So as far as I know the most common problems with the RCWL's are power-related (ESP8266 is a 3.3V-device).

    As I have some problems with my RS485 setup the following is somehow preliminary (seems the 12V to 5V conversion is root cause; this also affects the RCWL's):
    The ones I use myself are in my cellar and in the garage (two rooms in the later). In the cellar, detection is indirect (PIR on same wall as entrance door): Works very well, but also detects the opening of the door from corridor towards a second cellar room - there's a small hole in the wall between these two rooms near the PIR's position... So motion is also detected when just passing the cellar.
    In the bigger garage room, it works perfectly - when there's enough power for the entire node - the converter on the pro mini seems not to supply enough power to get the RS485 chip working sufficiently in all situations. There it's placed on a side wall - no detection, when passing outside, but opening the front door is detected pretty reliable, in some cases, one has to do one step into the garage, detection angel is 80+ degrees .
    The third RCWL I only recently installed, so there's not too much enough experience to talk about, the others are up and running for months now. But at least the radio fields of both RCWL's in the neighbouring rooms in the garage seem to not influence one another I had some doubts on that point as I first tried to use 3 of the RCWL's on the cellar node to monitor the two cellar rooms and the corridor; that didn't work - as I now think due to powering issues.

    I did some experiments wrt the resistor placement, but by now, all are just without one (but I can also state: one can see a difference)

    So keep us updated once the parts you ordered are up and running!

  • @ehome as I looked at am312 datasheet I didn't find any information about its output pin. So to be on the safe side, I would connect the two sensors trough additional n-mosfet transistor. So connect output of each pir to the mosfet gate. And then sources of both mosftes connect to ground and drains of both mosfets connect togheter to the arduino input pin. You will also need a pull-up resistor (external or arduino internal).

  • I am using Panasonic EKMB1201111 - these are the best PIRs for battery nodes.
    2uA standby current.

    Expensive though.

  • @alexsh1 what about detection performance ? is it better that am312 ?

  • @rejoe2 yesterday I received my order of the RCWL' modules.
    The detection range from theses modules are much better than AM312/HC-SR501.

    But sometimes these modules also detect motion through my thick (pumice stone) walls.
    And of course this is not really practical and absolutely unwanted.

    I never thought that it will such a big challenge to get a reliable human motion detection to work...
    I think I will know try an "aeotec multisensor 6 - Zwave device".

    Maybe these devices will work more reliable? Do someone have experience with these devices?

  • If you are going to try a z-wave multisensor, you should look into getting a Fibaro FGMS-001 (https://www.fibaro.com/en/products/motion-sensor/). I tried the Aeotec and the Fibaro and the settings of the Fibaro are way richer. There are 3 settings to tune the PIR detection so that might be interesting to you. Also I never had to change batteries in 2 years.

  • @silex many thanks for your reply and share of experience.
    Batteries are not a problem for me. All my sensor nodes will be powered directly via power supply.

    I had to make the decision to buy the Fibaro or Aeotec one. The Aeotec one was the winner because the Fibaro one is missing the humidity sensor. This is an interesting value for me.

    But it's also interesting to hear that you said that the Fibaro has more settings to tweak the PIR capabilities.
    Maybe I will have to test both of them and see with which multi-sensor I can get the better human detection results.

    It's really sad that I have to give up building my own sensor nodes because of the very bad PIR results 😞

  • I understand. There is also a relatively new infrared array sensor, that has a much higher resolution than the default PIR sensors and will be able to detect temperature differences over 64 separate fields and thus human presence.

    Here is a link to a typically slightly more expensive but easy-to-prototype breakout board from Sparkfun with the Grid-Eye: https://www.sparkfun.com/products/14607

    Might be worth a shot. I am planning to use this for detecting presence without the need for the occupants to be in motion regularly (office spaces, living rooms, etc).

    Grid-eye information: https://www.mouser.de/new/panasonic/panasonic-grid-eye-infrared-array-sensors/

  • @silex I know these IR-Array sensors. But at the moment they are very expensive.
    And I think also the detection range and angle is not as good as from an PIR.

    I need a minimum range of 5-7m and tests I have seen on youtube just covered 2-3m.

    But I also see the big advantage to have human detection without active motion. With these devices it is possible to create real presence detection sensors.

  • Oh, I didn't know they perform so "bad" in real-life applications. I would love to stay informed so it would be awesome if you could post your success-story here if you got it 🙂 Very interesting topic indeed.

    Good luck!

  • @ehome
    If you need a minimum range of 5-7m have you thought of radar?

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