The Blog of Ian Mercer.

Home Automation Block Diagram

3/8/2010, 8:32 AM

Here is a block diagram of my home automation system showing the various software and hardware interfaces. Click it to view the full image.

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

Home Automation Sensors

2/21/2021

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

Collinearity test for sensor data compression

7/15/2021, 3:47 PM

One way to reduce the volume of sensor data is to remove redundant points. In a system with timestamped data recorded on an irregular interval we can achieve this by removing co-linear points.

Ian Mercer

Event blocks

4/23/2020, 8:42 PM

Home automation systems need to respond to events in the real world. Sometimes it's an analog value, sometimes it's binary, rarely is it clean and not susceptible to problems. Let's discuss some of the ways to convert these inputs into actions.

Ian Mercer

Logistic function - convert values to probabilities

3/22/2020, 9:48 PM

Another super useful function for handling sensor data and converting to probabilities is the logistic function 1/(1+e^-x). Using this you can easily map values onto a 0.0-1.0 probability range.

Ian Mercer

ATAN curve for probabilities

2/28/2020, 4:53 PM

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

Probabilistic Home Automation

2/14/2018, 1:14 AM

A probabilistic approach to home automation models the probability that each room is occupied and how many people are in that room.

Ian Mercer

Multiple hypothesis tracking

2/11/2018, 9:00 PM

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

Ian Mercer

A state machine for lighting control

2/11/2018, 4:58 AM

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