Archive for the ‘ PCOMP ’ Category

Why you should not jump the turnstile.

One the first things they tell you as a foreign graduate student in New York is that you shouldn’t jump the subway turnstiles and I’ll tell you why.

Sadly, the New York subway is my current form of transportation to the city and therefore have had lots of experience with it despite only having lived in the city a little over two months.

I first rode the New York city subway in 1994 when I first came here. Back then it was powered by tokens. They were easy, just pop them in and enter. No need to get a confiramation that you paid your fare.

When I came back in 2002, metrocards have been introduced and it took my father a bit to figure out how it worked. There wasn’t any indicator on what direction we were supposed to swipe it in until a stranger got the card the swiped it for us. Whew!

In my station, there are two ways to get to the Manhattan bound trains. One is through a regular turnstile and the other is through the more secure rotating type door that you can’t hop over.

SUBWAY
I’ve noticed that regular commuters, when faced with urgency (like the train is on the platform) will make a dash for the first vacant entrance they see.

For months I used the rotating door turnstile and not the regular turnstile though it seemed faster.
SUBWAY

People would swipe their metrocard on the sensors which are a pain for me sometimes towards the end of the month when for some reason the sensor would not recognize my card which is annoying. There are those who will swipe their card twice and they’ll get in. But usally if it hits 3 times, you can’t use the card at that entrance anymore which is a pain.

SUBWAY

With the exception of families with strollers, I’d say that most people use both entrances equally. People would go to the first available one or the easiest to access. Much like electricity, they head to the path of least resistance. Those with children would gravitate to the much easier traditional turnstyles compared to the swivel type.

Of course those without a ticket, will jump over the turnstyles unbeknownst to them of the plain clothes policeman who is known to linger in the station from time to time.

SUBWAY

More often than not, most users would not look at the indicator to pass unless they couldn’t. Those with stored value cards would occasionally look at the amount remaining on the card while others will just run by.

It’s actually interesting to watch people handle the subway metrocard shuffle. I’m more used to the RFID card type of transportation and I asked a friend to send me pictures from Singapore about their underground system.

Using whatt they call an EZlink card, they use it for a variety of items such as paying for public transportation (including taxis), toll fare, and even buying stuff from 7-11.

The method of using the card is effortless.

Just tapping the card om the sensor and off you go.

II wonder when New York will catch on to this?

Serial Part deux

There’s always something interesting when programming a microcontroller and the instructions don’t exactly tell you when to switch from one program to another. It was quite challenging at first but just read carefully between the lines, it’s all there.


This reminds me of the first word that was on the original Macintosh in 1984.

Serial conenction

Hooked up the arduino to the mac via USB and using Processing to show a visual reference to the connection which I’m manipulating via the potentiometer.

Servo and Tone

I think I’ve just made my own Theremin Machine. Or at least something to annoy the neighbors.

Stupid Pet trick

As part of every student in physical computing is to complete the stupid pet trick and mine is the “belly monitor”.

After some unusual ideas deliberated over in class, I’ve ended up with a belly monitor that monitors your eating limit. Since this varies from person to person, I’ve decided to proceed with a two inch velcro bench to attach the device.

I first thought of using a flex sensor and that didn’t work. The numbers the felx sensor was giving me is just too random for my taste and it kept falling off the female connector even when I taped it together. Soldering is not a good idea since it may melt the sensor.

I ended up using a large force sensor which I have duct taped to the velcro belt procured from Home Depot.

stupidpetrick

Now that the sensor thing has been sorted out I wanted a portable power source. I connected a 9V battery and that wasn’t giving me power or should I say consistent readings as compared to a USB connection

stupidpetrick

So I dropped that idea.

stupidpetrick

I went back to USB power and decided that a sound once you reached your limit would be funny. So I installed a tone beeper thingy or an audio transducer. This now tells you if the device is activated and will slowly increase in tone as you reach the upper limit.

IMG_2803

I decided to use a smaller breadboard since I wanted it to be as small as possible. There’s still space for a battery connection but at the moment this is what I have.

Using the code below, it gave life to my stupid pet trick.

//belly monitor
//Melissa A. dela Merced mdm532@nyu.edu

const int ledPin = 7;
const int redLED=8;
int analogValue=0;
int brightness = 0;
int flex = analogRead(A1);

void setup(){

Serial.begin(9600);
int flex = analogRead(A1);
pinMode(redLED,OUTPUT);

}

void loop(){
flex = analogRead(A1);
analogValue = analogRead(A1);
brightness = analogValue/2;
Serial.println(flex);

flex = map(flex,0, 200, 255, 0); //sensor
flex = min(flex,400);
flex = max(flex,0);

analogWrite (redLED,flex);
int frequency = map(flex, 0,255,100,1000);
tone (5, frequency,10);

}

Let’s play with electricity

electricity

This week doesn’t require any mad programming skills and just basic electrical know how.

electricity

With the help of helping hands, this allows me to both hold the points together to get a reading on the multimeter and take a picture at the same time. Of course this one beeps.

So does this one. Notice that I wired the board in such a way that both sides have power and ground.

electricity
electricity

Which of the images above has a complete circuit?

But fun question, does electricity pass through our bodies? Yes, but we still provide enough resistance that the 5V from the Arduino will not shock us nor complete the circuit.

electricity

And just like that with a resistor and all, we have another lit LED.

electricity

Interesting that the LED uses approximately 1.72 V out of 5V.

electricity

The amount of electricity passing through the resistor is approximately 3.31 V. Add that up it’s almost 5V. At least we know where all the power is going.

electricity

electricity

Let’s add a switch and see if it affects the power flow.

electricity

Well apparently all it does is just cut off the power completely.

electricity

Notice that the gree light is not as bright as the red one. Different color LEDs have different power requirements.

electricity

electricity

Notice the difference between the power usage of the green and the red LED and the amount that passes through the resistor.

electricity

Now when we add another LED, they don’t light up as brightly as before.

electricity

The resistor is now only getting 0.14 V.

electricity

But if we re-arrange the LED’s that they’re all being powered by a single line instead of a series of leads. It’s a whole lot brighter.

electricity

The resistor is using up 3.38V. while the LED’s are at 1.65 V.

electricity

Under pressure

Named after that song from Queen, now I have to program the arduino to recognize an analog input. Meaning, it’s not just as simply flipping a switch. This requires and entirely different mindset.

pcomp

Using a knobthingy commonly known as a “potentiometer”, it allows the light to switch on once you turn it past a certain point. Notice that the potentiometer does not use a resistor and is an exception to the rule.

Now I wanted to control the intensity of the LED using a light sensor. So I ended up with this. It still needs a bit of tweaking on the range the sensor recognizes but it more or less captures the desired result.

I’m still working on two LEDs and two pressure sensors.

pcomp

Wind machine

There used to be a cable channel back home that was called the “Aquarium channel” which was basically a camera pointed at a very large aquarium and played classical music the whole day. Sometimes, there would be dead fish floating and other times it was being cleaned or something. Eventually they took it out and replaced it with something more profitable.

I thought it was a great break in the channel programming where people could just stare at the aquarium and just relax but saddened that as with any television entity, you couldn’t really interact with it.

I propose a visual array of bamboo trees with the sound of wind just rustling through and moving each tree individually.

 

Thank you softypapa for the great video.

Instead of using a camera to capture motion to sway the trees, I was thinking of using various microphones strategically positioned around the display to sense where the wind is coming from and move the image accordingly.

Or I can put an array of flex sensors inserted into actual bamboos located in a remote location to and via IP addressing to send the signals back to the display to move the bamboo trees visualization.

device

What are the sensors in my neighborhood?

This weekend while taking the subway I noticed a number of physical sensors that I didn’t notice before.

sensors

This particular button is not common in New York well at least I haven’t seen much of it in Manhattan. But pressing this button will tell the traffic signal light that there is a pedestrian who wants to cross and the light will change shortly afterward. But then again, it could be a placebo effect, giving the user the illusion that the light will change soon but in reality, it’ll change when the program tells it to change.

sensors

Here’s a light that doesn’t have a sensor but in my opinion needs one. I see three different sensors that could work here. One is light sensor, which would tell the streetlight to turn off once it detects a particular amount of light (supposedly sunlight) to detrmine it’s on and off. Another is solar panels so it’s not too bad that the light is on all the time since the light is powered by solar energy. Then the third sensor would be the exisiting sensor which is based on time. Much like water sprinkers, these are set on a timer where the on and off is determined by a timer on the switch.

sensors

The Metrocard machine is a plethora of sensors. There are the input buttons on the touchscreen. There’s the numeric keypad for credit card and debit card holders to enter their information. The coin and bill sensors that determine US legal tender is being inserted into the machine. The braile pads that help the blind in getting their passes. And then of course the Metrocard slot where the machine either accepts or dispenses the card and reads how much is left on the card.

sensors

Of course what’s a Metrocard without the sensor that you use it on. Other cities such as Singapore, Tokyo, Hong Kong and London use RFID cards instead of the magnetic strip that the NYC transit system uses. I first used the Metrocard in 2002. I was used to the tokens all this time that it took a while to figure out which direction the magnetic swipe had to be for it to work.

sensors

I’m not sure if it can be seen here but I suspect the subway is outiftted with all sorts of sensors. Most of it detecting the position of the trains. This particular sensor at the station, I guess that sensor tells all the other trains along the line that there is a train present at this station and informs the other stations down the line with the announcement ” There is a Manhattan bound train one station station away.”

I saw this at church today. This emergency light has an electrical sensor. In the event of a power outage, these lights turn on.

Sensors

These exterior lights can be switched to detect motion in the event someone walks in front of the range of the sensor. This is great at night so you don’t have the light on all the time.

ttmmoma

At the MOMA there is this device. Though not part of the installation but still has the “do not touch” warning next to it, I could guess that thsese are motion sensors that detects the presence of someone in front of the display. This is only present on displays that use a monitor and will then play the video once there’s a person in front of the display.

ttmmoma

ttmmoma

The displays are each identified with QR codes which directly links the viewer to a website with more information about the artwork. Of course in order to read this, your smartphone should have a QR reader.

Barcodes on everything is no different. These help stores and companies track inventory as well as make purchases accurate and efficient at the checkout counter.

If I see anything more before Wednesday, I’ll update this post.

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