issue on occupancy detection

hello,

I am an engineering. I am doing my final project on "Intelligent Energy Saving System" in which I am using the Dual-Tech Motion Detection ( consisting of PIr and an ultrasonic sensor).

However, I am having concern when there is no motion despite the room is occupied. That is, the PIR motion sensor is not triggered if the person remains stagnant ; only the Ultrasonic Motion Sensor gives a "high" output.

This is preventing the project to be reliable. It will be much appreciable if you could suggest me any alternative to this problem. I rely on your consideration and hope to hear from you the earliest possible.

Great detail.
Good luck with your career in engineering management

There are true occupancy sensors. They work on thermal detection.

Google is useless here.
Occupancy and motion is all mixed up.
Be prepaired to dig deep (into Google and your wallet).
Leo..

Hi,
I think you need to review your logic.
If there is no one in the room, then PIR will be OFF and ULTRASONIC will be OFF

As you have proven OCCUPANCY will be a mix of the two sensors.

If there is someone in the room PIR will be ON, AND , ULTRASONIC will be ON.
If there is someone in the room PIR will be OFF, AND , ULTRASONIC will be ON. (your combination.)
If there is someone in the room PIR will be ON, AND , ULTRASONIC will be OFF.

The only thing you can positively detect is when the room is EMPTY, I think you are trying to detect OCCUPANCY.
So just reverse your logic.

I hope you are using more than one PIR as one may not fully cover a room.

Tom.... :slight_smile:

If there is someone in the room PIR will be ON,

Umm, no. Standard PIR sensors detect warm, moving objects only. There are much more expensive options, like thermal imaging sensors, that can detect warm objects that are not moving.

I use a flow-through CO2 detector to tell if my tutoring room is occupied, plus it gives an estimate of how many are present.

Hi,

ChrisTenone:
I use a flow-through CO2 detector to tell if my tutoring room is occupied, plus it gives an estimate of how many are present.

Or still alive? Sorry Chris couldn't resist.
Tom... :slight_smile:

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How fast does this need to respond?

Why not just put a delay in the code that requires NO detection of any kind for X time? Unless they are sleeping or passed out geed sensors will see movement at some point.

I have never seen a commercial system that controls the lights work correctly so I think the chances of getting a home made system to work are slim.

Grumpy_Mike:
I have never seen a commercial system that controls the lights work correctly so I think the chances of getting a home made system to work are slim.

Exactly. PIR controlled lights in toilets/bathrooms can be a a nuisance for people who tend to sit for a long time taking the opportunity to read through part of their newspaper.

Incidentally, with Google, some interesting things come up:

6v6gt:
PIR controlled lights in toilets/bathrooms can be a a nuisance for people who tend to sit for a long time...

At a previous doctor's office, the sensor was just inside the outer door and the timer was set to about four minutes. After being left in pitch black a dozen times I punched the sensor badly breaking it. After that it was stuck on. Satisfaction.

TomGeorge:
Hi,Or still alive? Sorry Chris couldn't resist.
Tom... :slight_smile:

My students talk about a "zombie apocalypse" all the time, so I can imagine a scenario where that would come in handy. I suspect though, that there is a certain amount of 'post-mortem outgassing' that would take place, due to bacterial action and other effects. This would make it appear, at least to the instruments, that recently deceased bodies were continuing to respire.