Wednesday, November 25, 2015

Elderly Monitoring: Revisiting with Brutal Simplicity

Short backstory:

I've been running over a year now with the current Elderly Monitor system in my house. Mother-in-law has dementia and the current system lets us know her general movements throughout her living space (e.g. how long has she been up this morning? How many trips to the bathroom?)  and whether or not she has opened the front door (e.g. is she going for a walk? Has she made her escape?).
The current system consists of X10 wireless monitors for the door (open/close) and living spaces (motion detection).  This is fed to a small Linux computer I've coded with tracking logic, the ability to speak "Front Door is Open", and the ability to communicate (event message and status query) using XMPP to a cloud server (Digital Ocean) and to our smart phones (running Xabber XMPP clients).
It has been a success but with the lessons learned  I've found the most critical aspect of this setup is the ability to simply detect that the front door has opened and then notify us via a speaker in our bedroom.  All of this flows from X10 to Linux computer to soundcard (the Cloud is not involved here).  Still, this seems overly complex. Can it be simplified yet still be expanded to deal with "enhancements" in the future?

Let's review some of the short comings of the current solution:

  1. X10 Wireless - This has been "mostly" reliable and inexpensive. Still, I do have an RF noisy house and what if the neighbor starts using X10 RF?  (Not likely, but for a rock solid solution, this is a weakness).  Also X10 pretty much means that I have to have a full blown PC (with X10 CM19a transceiver) unless I decide to seriously hack the protocol and build my own RF receiver.
  2. The PC - Why do I need a full blown PC just to do the basic "Door is Open"?  
  3. The Cloud - Sure, I've got it, but if I want to distribute the "Door is Open" beyond the bedroom speakers, I have to connect via the Cloud (currently) and subscribe to XMPP messages (essentially what I do with the smartphone).  I need to make some of this stuff local.
  4. Batteries. Batteries. Batteries - Damn. Did the X10 sensor batteries die? When did I change them last? Ugh.
  5. There is no indication of whether or not she has just opened the door or left the house. I can code this logic, but since I want to address the above short comings first, this will have to wait.
What is the simplest thing I can possibly do?  Especially if I want to add logic like #5?
I am revisiting this problem and addressing it with brutal simplicity. 

Two things are going to get ripped out:
  1. The PC. No more computer. A microcontroller should be able to do this.
  2. No more X10. I'm going "wired". No more batteries either. I want to "set and forget" this thing. I'll deal with a little wiring. All of the current sensors are less than 20 feet apart: Door, hallway, bedroom, bathroom.
Stay tuned.  More details to follow as I hash out my brutal "simplest thing that could possibly work" design.


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