Topic: iot
Time Series Data Compression
This new technique to compress the time series data collected by my home automation system seems to be working really well.
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".
Bluetooth Tracking Project
My year long Bluetooth project that won the $20,000 HCI and Microsoft competition during lockdown has continued to grow and now reliably tracks how many people are in the house and outside and can locate any device down to room level.
Digital Twins are never identical
Digital Twin are an online representation of a real world object, a copy of its properties in the digital world and a way to send updated and commands to it. In effect I've been making them for years but now they have a trendy name.
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.
Collinearity test for sensor data compression
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.
3d Printed ESP32 Brick
ESP32 provides a great platform for sensors around the house but by the time you've added a USB power brick, cable and enclosure it's quite messy. I wanted a device that I could just plug in with no exposed wires and no mounting needed so I designed one in OpenSCAD.
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.
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.
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.
PIR Sensors for Home Automation
PIR sensors are cheap and easy to use but they suffer from slow response times and low repeat rates.
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.
Logistic function - convert values to probabilities
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.
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.
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.
Probabilistic Home Automation
A probabilistic approach to home automation models the probability that each room is occupied and how many people are in that room.
Multiple hypothesis tracking
A statistical approach to understanding which rooms are occupied in a smart house
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.
Pressure Sensors for Home Automation
Pressure sensors can detect HVAC system operation and could potentially detect clogged filters.