Motion Sensing

[pdubinsky]

Has anyone had any experience with using any devices for detecting human motion in a room? I can see sonar or infra-red doing it but the project needs to detect when there hasn't been motion for a period of time not just the entry into a room and I'm not familiar with sensors that could be used. Any ideas, experiences, warnings would be greatly appreciated.

TIA,
Paul

[spamiam]

Has anyone had any experience with using any devices for detecting human motion in a room? I can see sonar or infra-red doing it but the project needs to detect when there hasn't been motion for a period of time not just the entry into a room and I'm not familiar with sensors that could be used. Any ideas, experiences, warnings would be greatly appreciated.

TIA,
Paul

Well, Sonar could work, thoug I have not had terribly good luck with it.

I think that you could use an IR motion detector. Just the exact same devices tht are used for burglar alarms. They have support circuitry, and generally will bring an output high or low if motion is sensed. It will eventually turn off after no motion is detected for a specific period of time.

You might use a microcontroller to measure the time since the detector last triggered (beyond the normal detector turn-off). Maybe some detectors are user-configurable to have a longer "on" time and then the uC would not have to do timekeeping.

-Tony

[stevech]

Room occupancy sensors. Commonplace in the industrial lighting world. essentially, a better IR motion detector than in consumer products.

[pdubinsky]

Thanks for the info guys. I'd googled on infra-red but not "room occupancy sensor" (rolls right off the keyboard, doesn't it?) but never recognized what I was looking for. Eventually, I found the X10 based devices and the bare sensor from Parallax which is what I'll try to get a little smarter about the technolgy.

The application is monitoring an elderly (very) person in a multi-room apartment. She has the "I've fallen and I can't get up" pendant and service but that'll only work is she triggers it. I more interested in the software to drive the app and interpret the data.

I'll post progress about the project on the forum.

Thanks,
Paul

[stevech]

maybe a simple ball-in-tube switch. Or mercury tilt switch. If you can affix it so it doesn't false alarm unless the person is prone. If so, it could trigger a beeper or RF transmission to a call for aid device.

Oughta be pretty foolproof no matter what you come up with!