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Physical Computing Week 1: Sensor Observation

This weekend I took a walk around my block and catalogued any sensors I spotted/interacted with.

Before heading out, I took out the trash and therefore interacted with our building's elevator. It's all push buttons. They don't sense you per-say, but when you push the button there is a light in the center that confirms that button has been pressed and it knows where to drop you off (in my case the basement). I also never noticed but there are braille and embossed numbers next to each button. The panel itself if metallic, which is easy to spot in a wood-paneled elevator. I also interact with the close door button quite frequently (a bad habit I guess), as I'm not sure it really does anything in our particular elevator. The door closes at the same time rate and at the same time, as soon as the external wood door is shut.

In the trash room in our basement there is a motion sensor that controls the light in the room and turns on when movement is detected. There's no feedback to confirm that it's on and working, but there's a button below that which you can press to manually turn the light on or off, which has a green light on it. The sensor is working properly if the light turns on when motion is detected. Honestly it's pretty inconspicuous as it looks pretty similar to the power outlet next to it, but it is positioned right inside the entry way of the room.

On the way back up to the landing floor from the basement I noticed a security camera and mirror in our elevator. There were no visible indicators to show that it's on and it's unclear exactly what it's sensing. The camera doesn't move automatically from what I can tell, it's in a fixed position so that it can see the mirror on the other side of the elevator. It's not hidden, and is easy to spot. I'm wondering if there's an array of LEDs surrounding the camera lens. It also looks like there are a few smaller sensors packed into the main body of the camera surrounding the lens. Maybe a light sensor, maybe a motion sensor?

Above is another camera in our lobby. This one has the mural painted over the white housing, which allows it to blend a bit more into the space. This camera has a tinted dome over the lens so there's really no way to see what's going on in there.

We took a walk to our local park, their bathrooms have air hand dryers. I actually looked it up because I was curious, but this model uses Infrared motion sensors to detect your hands beneath the exhaust port. The issue with this device us that the sticker that tells you where to place your hands has worn off, so you may not know how these are supposed to work if you haven't used one before. But the design of the exhaust port gives you visible indication of where the air would come out of. Also the lack of any other visible vents on the machine may also be a helpful indicator of where you hands don't need to go. I also read that this unit shuts off after 35 seconds of continuous operation -

even if your hands are still being detected.

For fun, here's the wiring diagram of this particular hand dryer. I'm assuming the B, G, and W colors represent the wire colors and I'm maybe that square block with 3 prongs on the control assembly is a transistor, I have no idea.

There are cameras on nearly every street corner and on every shop awning. Most of the corner cameras look like this one and are really obvious to spot. There are some really impressive police cameras all over the main drag in my neighborhood. It's basically a large metal pole covered in cameras with the NYPD logo on them, which I should have snagged a picture of.

Here are our crosswalk buttons. The buttons embossed arrows on the button itself on top of the arrow on the sign that's pointing in the same direction above the button. The button is about 2 inches in diameter and has a red light just above it that turns on when the button has been pressed. The button also appears to make a beeping noise when it's time to cross the street. This bright yellow housing draws your attention when trying to locate the button, and can be seen from quite a long distance away. This particular button was a bit sticky to press. The button doesn't depress very far but I felt like it was a bit harder to push than it should have been and I felt that there was some friction partially-obstructing the depression of the button. Not sure what that was about, but after trying several other crosswalks, it seems like this button is an anomaly.

Lastly there's the automatic door at our local drugstore, which appears to have a sensor above the door on the outside frame. Maybe it's another infrared sensor to detect motion? There is no footpad on the entrance or exit side, just these black bars. I've never had an issue with these doors, They open a bit slowly so I always have to wait for them to open but they are snappier than some of the other automatic doors I've used in our neighborhood. They're also quite loud so it's easy to know when they're opening and closing. You can also hear them open and close from the other side of the store, but there is not audible alarm or chime to signal the comings and goings of patrons.


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