The Blog of Ian Mercer.

Probabilistic Home Automation

My recent addtion of multiple hypothesis tracking enables my home automation system to not only say how many people it thinks are home and which rooms are occupied but also to assign a probability to each of those numbers. That changes the way it will work as I replace boolean values with probability comparisons to see if it is, say 95% certain before it acts on a value. It also enableds exciting new scenarios that I'll explore here.

More intelligent lighting control

In the past my home automation relied mostly on time-outs to decide when a room was no longer occupied. After a period of no activity on any of the sensors in the room (motion, strain-gauge, TV volume control, light switches, or telephones) it would start dimming the lights in that room and would turn off any audio playing. There were a couple of more complicated scenarios where it attempted to use logic to reason that someone was still in a room if that room could be closed off. And while my house does have a lot of sensors this approach really wasn't that much smarter than a cheap PIR motion light switch.

The light state machine makes it seem smarter because it will leave a light on or off when a user wants to override this relatively dumb behavior and the gradual, imperceptible dim feature makes it a lot more forgiving (or rather 'forgiven' when it makes a mistake).

Now, however with a probabilistic model of the home based on 'target tracking' it can turn lights off much sooner as it can be almost certain that the one person in that room just moved to a neighboring room. This will allow it to save even more energy over my baseline from years ago before any home automation was installed.

Related Stories

Home Automation

I've been working on home automation for over 15 years and I'm close to achieving my goal which is a house that understands where everyone is at all times, can predict where you are going next and can control lighting, heating and other systems without you having to do or say anything. That's a true "smart home".

Ian Mercer
Ian Mercer

Home Automation Sensors

An overview of the many sensors I've experimented with for home automation including my favorite under-floor strain gauge, through all the usual PIR, beam and contact sensors to some more esoteric devices like an 8x8 thermal camera.

Ian Mercer
Ian Mercer

Bluetooth Sensing for Home Automation

Bluetooth sensing for home automation is a great proxy for people counting as it can detect and locate each cellphone in the house. iBeacons attached to tools, cars and pets can provide a 'find my anything' feature too.

Ian Mercer
Ian Mercer

Light sensors for Home Automation

Having at least one light sensor is critical for any home automation system that controls lightng. Lights need to be turned on when it's dark not at specific times of day, especially here in Seattle when it can be dark and cloudy at any time of day.

Ian Mercer
Ian Mercer

Microwave Doppler Sensors (RCWL-0516)

Microwave doppler sensors can be found in some alarm sensors but there are also available very cheaply as a separate component. They offer exceptional range but suffer from false triggers requiring a probailistic approach to people sensing.

Ian Mercer
Ian Mercer

Optical-beam sensors

Optical-beam sensors are reliable and can cover a long-distance such as across a garage or aisle-way. When they include multiple-beams they have good false-trigger rejection.

Ian Mercer
Ian Mercer

PIR Sensors for Home Automation

PIR sensors are cheap and easy to use but they suffer from slow response times and low repeat rates.

Ian Mercer
Ian Mercer

Strain-gauges

Strain-gauges are my top-rated sensor for home automation because they are invisible, reliable and can be tuned to detect people and ignore pets.

Ian Mercer
Ian Mercer

ATAN curve for probabilities

In a home automation system we often want to convert a measurement into a probability. The ATAN curve is one of my favorite curves for this as it's easy to map overything onto a 0.0-1.0 range.

Ian Mercer
Ian Mercer

Bluetooth

One of my inventions recently won a $20k global competition for applications that could help in a pandemic. It uses Bluetooth to count people.

Ian Mercer
Ian Mercer

Multiple hypothesis tracking

A statistical approach to understanding which rooms are occupied in a smart house

Ian Mercer
Ian Mercer

A state machine for lighting control

An if-this-then-that style rules machine is insufficient for lighting control. This state machine accomplishes 90% of the correct behavior for a light that is controlled automatically and manually in a home automation system.

Ian Mercer
Ian Mercer

Home Automation States

Understanding the many different 'states' a house can have is critical to creating great home automation

Ian Mercer
Ian Mercer

Graphing gigabytes of home automation data with tableau

Some interesting charts from the gigabytes of data my home automation system produces

Ian Mercer
Ian Mercer

iBeacons for Home Automation

My investigations into using iBeacons for home automation

Ian Mercer
Ian Mercer

iBeacon meetup in Seattle - January 2015

My notes on the iBeacon meetup in Seattle held in January 2015

Ian Mercer
Ian Mercer

Home Automation Systems as a Graph

Using nodes and links to represent a home and all the devices in it

Ian Mercer
Ian Mercer

N-Gram Analysis of Sensor Events in Home Automation

Using n-gram analysis to spot patterns in sensor activations

Ian Mercer
Ian Mercer

Xamarin Forms Application For Home Automation

Building a Xamarin Forms application to control my home automation system

Ian Mercer
Ian Mercer

The Internet of Hubs (and things)

Maybe it should be called the Internet of Hubs instead

Ian Mercer
Ian Mercer

Showing home status with just a single RGB LED

Multicolored LEDs can convey a lot of information in a small space

Ian Mercer
Ian Mercer

A wireless sensor network using Moteino boards

The diminutive Arduino boards include a powerful transmitter/receiver

Ian Mercer
Ian Mercer

The home as a user interface

Ian Mercer
Ian Mercer

A RESTful API for sensor data

POSTing data to a home automation system from Arduino devices

Ian Mercer
Ian Mercer

The Internet of Boilers

An experiment to measure every aspect of an HVAC / boiler system

Ian Mercer
Ian Mercer

VariableWithHistory - making persistence invisible, making history visible

A novel approach to adding history to variables in a programming language

Ian Mercer
Ian Mercer

A Quantified House - My Talk to the Seattle Quantified Self Meetup

My talk to the Seattle Quantified Self meetup

Ian Mercer
Ian Mercer

Integrating an Android phone into my home automation system

Some new features for my home automation using an Android phone

Ian Mercer
Ian Mercer

The Internet of Dogs

Connecting our dog into the home automation

Ian Mercer
Ian Mercer

GreenGoose Review

A review of the now defunct GreenGoose sensor system

Ian Mercer
Ian Mercer

Home power meters revisited

Ian Mercer
Ian Mercer

Home Automation Calendar Integration

Ian Mercer
Ian Mercer

Smart home energy savings - update for 2010

Ian Mercer
Ian Mercer

A smart power strip

Ian Mercer
Ian Mercer

What does a Smart House do at Halloween?

My favorite home automation features for Halloween

Ian Mercer
Ian Mercer

Home Automation Top Features

Ian Mercer
Ian Mercer

Weather Forecasting for Home Automation

Ian Mercer
Ian Mercer

How can I tell if my house is smart?

Ian Mercer
Ian Mercer

Home Automation Block Diagram

Ian Mercer
Ian Mercer

World's Smartest House Demonstration

Ian Mercer
Ian Mercer

Future proof your home with a new conduit system?

Running conduit can be expensive but maybe you don't need one to every room

Ian Mercer
Ian Mercer

New Home Automation Server

Ian Mercer
Ian Mercer

World's Smartest House

Over 15 years of experimentation with home automation

Ian Mercer
Ian Mercer

World's Smartest House Videos

A collection of videos about my smart home efforts

Ian Mercer
Ian Mercer

Pressure Sensors for Home Automation

Pressure sensors can detect HVAC system operation and could potentially detect clogged filters.

Ian Mercer
Ian Mercer