Welcome to My Sensory Day

E-mail Ed Ramsden

"Ubiquitous sensing" can be taken as either at face value, meaning the use of sensors everywhere, or as just another meaningless and obnoxious marketing buzzword. Whenever I hear it, I think "aren't sensors already everywhere?" Because most of them are hidden away, you might not think about how ubiquitous and pervasive sensors already are—the plain old dumb variety. During a typical day, I derive benefit from or interact with many sensors, mostly without noticing. Here is a typical day in my life of ubiquitous sensing.

Early Morning at Home
My early morning is surrounded by temperature sensors. First I get stuff out of the refrigerator to make breakfast and lunch—the refrigerator regulates temperature by a simple ON/OFF temperature sensor. After breakfast, a quick hot shower, but not too hot because of a sensor in the water heater. This time of year it can still be cold in the morning here in Oregon, so before leaving my house I look at the outside temperature reading on a wireless thermometer to see which coat I should wear (extra buzzword point for the wireless sensor!).

And on to Work
I get into my car, which, though a relatively modest Plymouth Neon, is still a rolling sensor extravaganza—a bunch of sensors with just enough engine and wheels to make it go. Traffic lights register my presence at intersections through inductive loop sensors buried in the ground. Halfway to my office the local police have a photo-radar speed trap set up, using radar or lidar speed sensors.

Ignoring the hundreds of sensors that are used in the modern factory where I work, and the sensors I design as part of the job, I will just mention the RFID transceivers that let me into the building when I present my badge. The building's environmental and energy management systems also incorporate some large number of sensors.

Going Home
On leaving work, I get back into my car and first stop at the grocery store, where a radar sensor opens the door for me. After I have gotten what I need, the do-it-yourself checkout stand rings up my total with optical sensors. On my way out I pass through anti-theft RF sensors looking for inventory-control tags that have not been removed or deactivated.

My next stop is at a gas station. While this one does not have a sensor to audibly indicate vehicle arrivals, each gas pump has at least a precision flowmeter and a sensor to prevent the attendant from overfilling the tank. Being a Luddite, I pay with cash and and an infrared sensor announces my entry into the store.

Home Again
When I get home I log onto my computer to read email, using a mouse that contains optical encoders. In the computer itself a brushless DC fan hums along, using Hall effect sensors for motor commutation. Then I turn on the TV, using an infrared sensor that responds to the remote control. At the conclusion of The Simpsons, and having had my U.S. RDA of video exposure for the day, I take out my violin to practice for a bit. Before playing I tune it up using an electronic tuner—an acoustic frequency sensor—to tell me when I have a good A440 to which I can correctly tune the rest of my violin strings. After running through a few pieces, I put the violin away and toss a music CD in the player, which uses optical sensors to read it.

A last-minute load of laundry is helped along by a water-level sensor in the washing machine and a moisture sensor in the dryer. I have low-end appliances; more sophisticated ones will contain even more sensors.

And after the laundry is done, I head off to bed. Because temperatures still get down into the 40s this time of year, the furnace will probably come on sometime during the night, thanks to yet another temperature sensor in the thermostat. Finally, the furnace has various internal sensors to ensure safe and reliable operation.

Invisible Yet Valuable
Nearly all these sensors functioned in a way almost completely invisible to me as an end user. Yet they provided clear benefits (to somebody) that justified their cost. In many cases, the sensors are surprisingly low-tech and dumb. Nonetheless, low-tech or not, sensors are already ubiquitous in my everyday life, and unless you live in a cave, they are ubiquitous in yours too. In light of the already ubiquitous and pervasive use of sensors in our lives, maybe more appropriate marketing catch phrases should be "ubiquitous-er" sensing and "pervasive-er" sensing.