When we started this project, we thought we would have to place sensors everywhere, on every wall, behind every wall plate and peeking out of every corner. We hate things that sound so random and that suggest such inconsistencies, not to mention so many wiring runs. That, in turn, was a driving reason to reconsider. While some sensors might well have to stand alone, others could benefit from being in clusters.
We were inspired to rethink that approach when we learned about the Panasonic Grid-EYE, a component that can take 64 analog temperature readings (in an 8 x 8 grid). That led us to design a CAP (Ceiling Awareness Pod) that would go near the center of each ceiling to read the area's temperature m and, as it turns out, a lot more.
Everything fits or connects into a standard 2-gang electrical box that gets mounted in the ceiling; all you see from inside the room is a nearly blank cover plate.
Inside, there's a Raspberry Pi (in the role of node controller), the Grid-EYE, sensors for ambient light, relative humidity, temperature and barometric air pressure, a small amplified speaker (an actuator), an optical range sensor and an infrared remote control pulse emitter (an actuator). A small cable (telephone wire) connects a sensor pod in the attic space just above to take readings there of ambient light, barometric air pressure, relative humidity and temperature. Those same 4 sensor types similarly connect to inside the ventilation duct registers. A different cable connects to the motor that controls the ventilation register flow-through (an actuator).
The wall switches in the room are not connected to power wiring; these, too, are sensors that connect to the CAP, which can then interpret different lengths or patterns of taps to mean different things. A magnetic reed switch in the door frame is another sensor that connects to the CAP, as is an inductive current sensor in one of the wall plugs, which is there to identify whether a TV plugged in there is on or off.
We'll elsewhere get into the ways this collected data is useful. We are making arrangements now that, if successful, will make the CAP a commercially available product (from one or more third parties) around the time of the debut media event for the house project.
Overall, the CAP is one of 3 items in a row on the ceiling, on one side of a ceiling fan and with a smoke detector at a similar position on the other side of the ceiling fan. That ceiling fan creates a need for one more sensor: an optical range reader to signal if a ceiling fan blade is blocking the view of the Grid-EYE; if it is, the DALI control system is alerted to send a brief burst of power to nudge that fan blade out of the way.
A CAP would be overkill in a bathroom, and we would rather not have warm-body tracking activities inside the bathroom or lavatory spaces, but neither should they be sensor-free.
Hacking (meaning, without the manufacturer's approval and risking a violation of warranty terms, modifying or adding to or connecting to or reading values from the internal electronics of manufactured products) lets us take advantage of clever product features that we'd like to use for our own purposes. The Broan motion-detecting bathroom fan is a great example of something we plan to hack.
It combines a motion sensor and a timer. When you enter a lavatory space, it automatically turns the fan on and keeps the fan on until the timer times out. It is unlikely for anyone to continue to need to services of the fan for any longer period without moving the small bit required for the motion sensor to restart the timeout, and this also keeps the fan running for that period once they're done with their use of the facilities.
We can (through a relay or optoisolator) use the fan's status as one indicator of that room being occupied; the system is also aware (because of its warm-body tracking of adjacent spaces) of when anyone moves toward or away from the entrance to that space.
Lavatory and bathroom nodes will connect to hacked ventilation fans (as sensors), to switches on the wall, to a magnetic reed switch in the door frame and to ambient light, temperature, relative humidity and barometric air pressure sensors. They may also connect to water leak sensors under sink drain traps and to optical range readers in their holders that can tell when it's time to bring in another roll of toilet paper.
We have reason to believe that we can adapt small, inexpensive radar modules to a special purpose: knowing whether or not somebody is in one side of a bed or the other and if there is somebody there, whether that person is awake or asleep.
If you go to bed and doze off with the TV still on, and if automation knows you've dozed off, it's easy enough to send instructions to turn off the TV set; in fact, that's why we added the infrared emitter (actuator) to the CAP design.
Adjusting the lights is a little trickier because the automation has to figure out if there's still somebody coming to bed later who isn't yet there. This provides a good example of a small benefit of being cybernetic, because the relational database will know whether that second bed position is routinely occupied.
In fact, it takes an ability to remember in order to recognize whether someone is awake or asleep, since there is no threshold heart rate for that; it requires watching for a change in heart rate and the degree to which it slows down or speeds up as you fall asleep or awaken again.
These sensors would be installed underneath the floor (atop the crawl space) just beneath each of 2 sleeping positions in each of 3 beds. We may also try to place them under comfy chairs or sofas in the living room.
Our project house has one very large (more than 28 feet deep) garage space with three single-width doors, meaning three parking spaces. Each parking space supports a line of 5 ultrasonic rangefinders (sensors) pointing down from the ceiling. Starting at the door:
Each reading takes 40 ms or less, so activating each in turn allows 25 readings per second, 5 per sensor, and prevents mutual interference. There is enough raw information here to derive the status of the garage door, the status of the garage space, the presence or absence of something in that space and the direction of travel of both the garage door and the vehicle.
We're not done. A single-beam Lidar (like a radar but using the time of flight of laser light) at the back of each garage space provides a second source for some of the same information, plus some extras. It can report:
But we are still short of some significant information that yet one more sensor can provide.
We want to be able to recognize cars we know, cars that may belong in a garage space. And we also want to know whether their engines are running. Bluetooth 4.1 LE includes a Beacon service. We can equip each car with a beacon transmitter, hidden up and under the dash, that operates only when the engine has power. A beacon receiver can report every beacon it sees and, since each beacon is uniquely identified, identify which car is there. When a beacon presence disappears within minutes after appearing, it's an indication that the car has been turned off, and that is a signal that a moment later, if the garage door has not been closed, it should be.
Ryobi provided 3 of their garage door openers (yes, these are actuators) to our project. They are expandable like no others, and they also provided several of those add-ons: a battery that can keep the unit working during power failures, lasers that can indicate where to stop, an inflater with a hose reel and more.
Unlike the garage door openers of our youth, we can't simply connect 2 wires to activate these openers (we can find a way to hack them, but we will not document it); the reason is a fear that the inrush of air when the door opens might trigger ignition of combustible vapors in the garage. We are adding sensors for combustible and flammable vapors, to monitor carbon monoxide levels, to monitor oxygen levels and more; also the garage includes 3 CAP locations.
The garage also has an industrial-scale brushless (so no sparks) high-volume exhaust fan (an actuator) that we can turn on to vent flammable gases out of the garage without introducing fresh air.
Our project house is well up a hillside, meaning the driveway is over 400 feet long, so it will tend to take at least 10 seconds for even an aggressive driver to travel to the house from the street. By embedding sensors in what appear to be stone lamp posts, we can give both automation and occupants a head start.
Dual IR beam break pairs (half a pair shown in the picture) operating at different pulse frequencies and offset fore and aft of the lamp posts can not only alert us to the presence of a vehicle in the driveway but also tell us whether it's making an entry or an exit.
Adding another Bluetooth Beacon sensor (like we use in the garage) lets us identify whether a detected car is a known car; this helps our automation know what to do with garage doors and, as you will later see, other elements. .
We can bury a dual Inductive coil in the driveway when the concrete is poured as an additional way to detect the presence and direction of a vehicle.
Adjacent to one lamp post and right at the street, our mailbox includes cameras and proximity sensors
We're hopeful that artificial intelligence can also play a role. It should be possible to recognize some limited catalog of logos or emblems on incoming vehicles (DHL, UPS, FedEx, police, landscaper, pizza guy, etc.) .It should also be possible to perform optical character recognition on captured license plate images to compare to a list of known and unknown plates, and in any case, as an aid to investigators in the event of trouble.
Do you think of a light switch as a sensor? Ours is nothing but a sensor, meaning there are several ways to rethink light switches. The Eaton decorator switch at the right is a momentary switch, meaning its contacts remain closed only for as long as you push on the rocker. It may look fancy but electrically, it might as well be a doorbell button.
We have enough automation sensors (for ambient light levels, for detecting where people are or are not present and where they are heading and more) that we could fully automate lighting everywhere to make lighting control by the occupants entirely unnecessary (as Cisco recently accomplished at a new data center), but that would be a mistake. People never want to feel like they have no control and a house without a light switch could create that toehold for resentment.
But this simple-looking switch can offer more than you might guess at first glance.
Obviously, to meet user expectations, just a tap will turn the lights from on to off or off to on, immediately (more or less; it might take a quarter of a second). Press on it for more than a second and it will work like a dimmer making the lights brighter or less bright, always beginning in the direction opposite the direction of its last usage..
Can you say, “A thou - sand - one”? Press and hold it during “A thou” (longer than a quarter second, roughly a half second), then tap twice after “sand” and “one” to temporarily put it into a command mode. The room speaker will sound a single tone. In the next 3 seconds, tap it once to tell the automation to now consider the room occupied, twice to consider it vacant or maybe 3 times to indicate the presence of an intruder or some other appropriate peril to get the house to respond by silently placing a prerecorded voice call to 911. You could also, of course, substitute a recorded gag to play over the local speaker; maybe, “This house will self-destruct” or “Pathogen released - begin quarantine.
So, most of the time, the light switch seems to just work as a light switch, but any time you need it to, it can become an automation interface.
Is a smoke alarm a sensor? Several current models offer ways to communicate with various current-generation home control protocols, but they never quite make it easy. Phooey on that. In some residential, many multi-family, some commercial and many industrial environments, the companies behind many of the smoke alarm brands familiar to you also offer AC wire-in smoke (or smoke and CO combination) alarms that interconnect with each other so that a fire detected at any one location can also trigger alerts at dozens of others. An interconnectable system can also include a small accessory that's significant to us: an SPDT (single-pole, double-throw) electromechanical relay. An Arduino can easily take advantage of either its normally open or normally closed dry contact to alert our automation.
A wind sensor outdoors can allow us to pause irrigation (lawn and garden sprinkling) systems when the spray would just get blown away; it also lets us turn off outdoor-exposed ceiling fans when a nice breeze renders their contribution unnecessary. Soil moisture sensing can help husband watering times, as can weather information.
We hope to implement a self-contained weather station with a wireless link to our controllers; we are also planning access to macro weather data through APIs to various professional online weather resources that offer micro-forecasts, some with precision down to two decimal places in latitude and longitude (essentially, a single address). This can also let us tailor irrigation scheduling based on expected rainfall, heat and other factors.
Surveillance cameras ringing the house monitor significant pixel shifts within otherwise still images to alert the system to motion anywhere around the house.
And the septic system can send a notification in the critical event of high levels, indicating a need for fast field intervention.
No matter how we try to set up our classifications, a few outliers always remain. For example, our sensor in the range hood over the kitchen cook top that directly controls when its vent fans turn on and off.
And we should probably mention a disconnected sensor, the camera in the drone that has several jobs to do. During construction, for example, we are using it to help document the build.
Once the house is up, we will use it to patrol the gutters, its video able to minimize the number of trips up the ladder we ever need to take to clear them. And in the event of a major storm, we will similarly use it to patrol just inside the property line to spot such signs of damage as fallen trees or standing water.
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