Pressure Sensors for Home Automation
I haven't found many uses for these yet, potentially detecting clogged filters through an increase in differential pressure.
The Blog of Ian Mercer.
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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
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.
Ian Mercer
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.
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
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.
Ian Mercer
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.
Ian Mercer
Filtering techniques
Filtering raw data is essential for a reliable home automation system. Here are some of the many ways you can filter sensor data.
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
Gas sensors
Gas sensors come in many different flavors including CO2, VOC and particulate sensors.
Ian Mercer
Humidity Sensors (DHT11, DHT22, AM2320)
Humidity sensors are great for controlling extractor fans in bathrooms and other damp spaces.
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
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
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
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
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
Temperature sensors for home automation
Temperature sensors I've experimented with for home automation.
Ian Mercer
Event blocks
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
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
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
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
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.
Ian Mercer
Multiple hypothesis tracking
A statistical approach to understanding which rooms are occupied in a smart house
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
The Grideye 8x8 camera sensor
Experiments with an 8x8 IR camera for privacy-preserving people detection using cameras.
Ian Mercer
CCTV Cameras as Home Automation Sensors
CCTV cameras are an option for detecting people but within the home there are privacy concerns that need to be addressed.
Ian Mercer