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Electronic tether to tether my father's rollator to him Answered

My father lives independently but has poor mobility and dementia.  He frequently walks away from his rollator and then gets trapped when he realises he has left it elsewhere in his home.  A physical tether would be impractical and might actually increase his risk of falling.  I think he would benefit from an electronic tether that would sound an alarm whenever he moved more than, say, three feet from the rollator.

There does not appear to be a commercially-available product to meet such a need.

Giving him a passive RFID tag to wear and attaching a light-weight alarm to the rollator that polls the tag every few seconds might generate a workable solution, but I don't have sufficient experience with RFID to generate a solution in a reasonable time-scale.  I would probably favour CMOS timers and logic over a microcontroller for similar reasons.

Does anyone have a project that could be adapted, or expertise that could be applied, to this task?


Also http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html holds promise :)
And thats a really low power...

Thanks! Your thinking and research are really helpful. :)

No Problem! :)
I love to tackle such tasks if i find them interesting and challenging

See http://electroschematics.com/496/74f13-mini-bug-transmitter/ for a nice one.
Add a simple oscillator instead of the mic and you roll on! :)

I little lowpower RF-emiter (maybe >1mW for lower than a few yards) on his chair with a sizeable battery (maybe D-cells) for months of power.

He carrys a simple "negative reciever" which sounds off if the signal fails to reach it.
I would go with something like:
- Antenna picks up the RF
- band-pass-filter (Passive) filters for the given frequency
- OpAmp1 amplifies it
- Bridge-rectifier rectifies it
- A RC (with maybe added parasitic resistance) acts as measure-device
- OpAmp2 measures the voltage on the Capacitor. If it drops too low (the Cap wasnt charged for a few seconds by the pulsating voltage of the amplified signal) it simply triggers the beeper.

The last part also could be done with an inverting schmittrigger...

My 2 cents.

Thanks, Orgrimm! Such an approach would be cheap and easily adaptable. It also meets his need to be tethered to alternative rollators on each floor of his house!

Indeed. If the different rollators are emiting on the same frequency, it would become more of a "thee are NO MORE rollators around"-solution than the "the ONE rollator is left behind".
Every rollator in range can satisfy the reciever.

There are those child-walkaway alarm proximity alarm units but reviews on them show inconsistent alarms and annoying false triggers. Maybe just have a backup rollator walker or canes positioned throughout the house? Maybe fix on some high visibility flags that pop up on the rollator that must be pressed down when gripped on the handles in use to serve a visual reminder "Don't forget me".Good luck.

Thanks, caitlinsdad! Yes, an electronic solution needs to be reliable. The keyword is dementia, so my father's house is already cluttered and there is limited space for backup devices. Also, when my mother was at a similar stage a few years back, the backup devices tended to end up congregated in one place. My father needs to be able to let go of the thing to attend to business at his destination, but by the time he moves on he can easily have forgotten that he needs to keep the rollator with him.

I think this may have commercial potential if anyone can produce a good solution.

Yes, I have even tested one or two, and they are very flakey