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How Can I Build a Portable "Dead-Man's" Switch?
An anonymous reader asks: "I'm a widower caring for my very disabled child. I have family who check in on me often, but not reliably, and not every day. How can I rig up a 'dead-man's switch' that will alert family or emergency services should something happen to me, so that my child can be cared for? Her medical needs are significant enough that being alone for even an hour could be fatal for her. We do occasionally get out of the house, so a GPS type cellphone and a heart-rate monitor watch would seem to be the ticket, but how to link the two and get the desired dialing behaviour?"
There's this bluetooth enabled Alive Heart Monitor that apparently works with GPS, and with a PDA/smartphone or a server. You'd probably need to write (or hire someone to write) an application to use the data for the actual contacting other people in case of x part, but the hardware seems to exist for what you want to do.
Have you considered a medic alert bracelet for the times when you're out? Or are you in remote, non-populated areas?
If we are talking about a serious system here, you aren't going to be able to do this yourself. Just for starters, think about how complicated this would be if you decide to have a shower. You will have to deactivate the whole shooting match and then get it all back up and running again afterwards. Of course, if you slip in the shower, you're screwed. There are already solutions out there that you can sign up for. One that I have seen is a pendant you wear around your neck that has a button on it. One push, and your relatives are notified by phone. Or, fail to push the button on a regular basis and a phone call comes from the monitoring service, who can also dispatch 911, etc. Finally, at the risk of being harsh, if you truly believe you may die suddenly with no notice at any time, you seriously need to reconsider your current care arrangements. You do not strike me as qualifying to care for some with the needs you imply in your question. Please take this as honest advice, not a flame.
Are you advocating peace through censorship? Do you honestly believe that is workable?
Our species survives because most of us are decent. The day that ceases to be true this little experiment called "Man" is over. No "Loose lips sink ships" jibber-jabber is going to prevent that.
-Peter
I saw an interesting article in a Japanese newspaper, it relies upon a relatively unique cultural circumstance, but I think you'll be inspired to think of how it can be adapted. The device was invented for one guy's family, but after it got some writeups in the newspapers, the idea was so popular that it went into production, and now lots of people have them.
There are many elderly Japanese people who live alone, some are deaf and can't use the phone, etc. so it's hard to get a way to check in on them to see if they're still alive. But almost every home has a hot-pot, an insulated pot with an electric heater used to keep water near the boiling point, to make tea every day. So some clever guy put a sensor in the hot-pot, if nobody picks it up within a day, it phones a preprogrammed number to alert someone to check in on them. Yeah, these people drink a lot of tea, it was the only thing they could think of that elderly people did EVERY day.
Of course this only checks in once a day, but you could probably think of other ways to adapt this idea.
I don't think you need a dead man switch. (I work with dead man's switches all the time in industrial robotics). What you could probably get away with is a vigilance control switch. From Wikipedia:
Vigilance control, also called an alerter, is similar to a dead man's switch, the difference being that a vigilance control system requires that the operator press a button at specified regular intervals. If the operator fails to operate the vigilance control, a warning sounds, and should the driver still not operate the vigilance control the machinery will stop.
I have one of these motorola pagers that my company gave me to carry around. It may only be available in Canada, but I'm sure you can find something similar in your area.
At any rate, you can send a page to it with an email, and then you have the option to reply to the email with a canned response like "OK" or "Will call back soon", etc. I was thinking that you could write a script on a server that would kick off an email to your pager every 30 minutes and if it didn't see a response within 15 minutes, activate some kind of emergency routine like contacting a relative. The timing could be varied to your needs.
It would be easier if you had something that hung around your neck, or a wristwatch that beeped every 15 minutes and required you to push a button to silence the alarm. Not silencing the alarm would somehow trigger your emergency routine. Using a windows mobile device or a blackberry (the API is available for free) you could write a program for one of these devices to do this task and send an email if you failed to respond.
Of course, this only works during waking hours. I don't know if you hire someone to watch your child during the night while you're asleep or not.
I ran across this article. I wonder if it has gone any further than that.
Good luck with the search.
"I have never let my schooling interfere with my education." - Mark Twain
Problem is, this requires surgery so it is not a DIY project
Pussy
How about setting up a computer that requires you to punch in a code and hit the "execute" button. You could have it set on a timer... say 108 minutes.
Based on the information we're given, I think the only compassionate answer is "don't do this yourself." If a person's life depends on the reliability of this solution, trying to come up with a clever hack is just plain irresponsible. In that case, you really need to buy a tested off-the-shelf solution.