Hi, I want to build a tracking device for wandering dementia patients and need help on the right sensor to use.
The scenario is the person walks outside the front door and I'd like to sound an alarm inside the house.
I am thinking of embedding something small inside a shoe's soles and attach sensors near the door that can detect the location of the shoe. Ideally I wouldn't need batteries on the device inside the shoe.
I'm also open to other ideas or direction.
This is a questions asked quite recently. Search for it. Maybe some helper remember and can point out that topic.
It is not easy.....
michaelvo:
Hi, I want to build a tracking device for wandering dementia patients and need help on the right sensor to use.The scenario is the person walks outside the front door and I'd like to sound an alarm inside the house.
I am thinking of embedding something small inside a shoe's soles and attach sensors near the door that can detect the location of the shoe. Ideally I wouldn't need batteries on the device inside the shoe.
I'm also open to other ideas or direction.
The old time commercial devices only let the doors open for staff and others carrying the associated transponder. Has been that way for decades. Go visit such a facility.
Paul
There are a least 2 major difficulties.
I just read the thread Arduino Forum.
GPS sounds like it will work though I was looking for something simpler and if possible with as little electronic parts.
I've considered a scale that would detect weight and alert. Kind of like how the fitbit aria scale can recognize multiple people on one scale.
Or a type of magnet in the shoe that activates a sensor.
| The old time commercial devices only let the doors open for staff and others carrying the associated transponder. Has been that way for decades. Go visit such a facility.
I'll read up on these devices
Good luck in experimenting and hopefully having fun. I'm out.
GPS is gud but its kind of a redundant here, means task is not that difficult and you are selecting expensive way. I think you should go with RF or Bluetooth, you can use NRF24L01 RF module.
One RF in the door.
Second RF in the shoe.
When the shoe comes close to the door, it will staart sending RF data and you can switch on the buzzer.
oliviasmithh900:
GPS is gud but its kind of a redundant here, means task is not that difficult and you are selecting expensive way. I think you should go with RF or Bluetooth, you can use NRF24L01 RF module.One RF in the door.
Second RF in the shoe.When the shoe comes close to the door, it will staart sending RF data and you can switch on the buzzer.
Agreed RF is looking like the most promising approach, bought one to try it out.
And, what if the guest is barefoot?
If you want something completely passive requiring nothing on the guest, then consider using a camera on a Raspberry Pi and face recognition software
michaelvo:
GPS sounds like it will work
Imagine;
GPS is running indoors, has no fix, because GPSs dont work well indoors.
GPS goes out the front door, anywhere between 30 seconds and a couple of minutes later the GPS gets a fix and the device sends an alert.
Is the possible long delay for the alert acceptable ?
And remember GPSs do use a large amount of battery power.
It seems all you really need is an alarm when passing through a doorway. Look at anti-theft tags as used in shops, have the patient wear it as bracelet or ankle strap.
SteveMann:
And, what if the guest is barefoot?If you want something completely passive requiring nothing on the guest, then consider using a camera on a Raspberry Pi and face recognition software
Currently the person always wears sandals.
Cameras would be a fun project though too complex at the moment. I'll definitely use facial recognition for a future project.
I would go in the opposite direction. Staff and visitors carry RFID tags. Residents do not. RFID tag slows a quiet departure, non tagged departures set off the alarm.
OP- The biggest problem you are going to have is that the low-cost RFID readers that most of us have used only has a range of a couple of centimeters. If you want to detect a wristband tag from a meter or so, bump your project budget by two orders of magnitude.
Why RFID tags? You probably don't care who is walking through that door, just want to know authorised or not.
Indeed something like a break beam sensor (detect someone is walking through) plus carrying a simple anti-theft tag (authorised with; not authorised without - or the other way around) can get the job done. Those tags must be really cheap considering they are disposable: for many years I've encountered clothes with such tags sewn in.
Another option is of course keeping the doors locked, give everyone an RFID card that they swipe to open the door.
Neither option requires batteries on the tag.
wvmarle:
...Those tags must be really cheap considering they are disposable: for many years I've encountered clothes with such tags sewn in.
The tags are dirt cheap. Pennies each in the quantity that the department stores buy them. It's the readers that cost many thousands of dollars each.
I tested out the RC522 RFID sensors. Those didn't have enough range and had to be in contact with the reader.
I found sensor PN5180 that's supposed to have about 6 inch range and the price increases to about 20$.
However, this approach isn't feasible for my use case. Installing readers everywhere isn't going to be a reliable solution. I think I'll try vision detection or bluetooth technology next up.
Did you look into the anti-theft gates that I suggested before? That should make for a pretty good gatekeeping solution.
Those gates, by the way, can easily be hidden in a door frame. Shops just prefer to have them very visible as deterrent.
michaelvo:
I am thinking of embedding something small inside a shoe's soles and attach sensors near the door that can detect the location of the shoe. Ideally I wouldn't need batteries on the device inside the shoe.
Under door mat loop 500 turns (or more) + op amp
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