Observation+Lab-Week3

Lab

My original goal was to potentiometer and change the range of the brightness of an LED light. I soldered the potentiometer 10K and placed it in breadboard. I also wrote the code to change the brightness of the light when I turn the potentiometer.

one Arduino Nano, one potentiometer 10K, one LED light, one resistor on breadboard

screenshot of Arduino and Serial monitor

 

However, it doesn’t seem to work. I even took out the potentiometer and run the code, in the serial monitor, the number of the analog reading still changes. That confuses me. I restarted my computer and run the program again. However, it didn’t work and my potentiometer couldn’t dim the light of LED. 

loading problems when playing with potentiometer to control the brightness of the light

Therefore, I switched to use a phototransistor to control the HIGH or LOW of the led. When the reading from the phototransistor is less than 400, the led will light up. When it is higher than 400, it will be turned off. 

screenshot of codes about using phototransistor to control led light
This is the code for controlling the on and off of the led light.

 

Below are two screenshots show how the reading from phototransistor changes when my hand is covering the phototransistor.

screenshot of Arduino and Serial monitor
This is when my left hand is not covering the phototransistor.
screenshot of Arduino and Serial monitor
This is when my left hand is covering the phototransistor.

Observation

people walking towards the turnstile

Assumptions

The turnstile allows people to tab their cards to its right side corner to allow authorized people to get in.

Context

Out of security reasons, people who want to get in the NYU building at 370 Jay Street need to scan their cards in order to get in.

Process

I stayed at the entrance of our building on the first floor and observed the interactions people have when they put their NYU cards in order to get in the building. Different people react differently with the turnstile. Some of them reaches their card beforehand and press them against the card reader part. It seems like they don’t have to wait for long to enter the building. Some of them have to search through their bags to find our their card when they reach the turnstile and then tab their cards for the turnstile to let them through. 

Difficulties

Wait time for both entering and exiting through the turnstile is comparatively long. This is given that the process of entering and exiting is not as expectedly smooth. The delayed response from the turnstile makes people wait for the two doors to open when they are within 5 inches of the door. 

For entering the building, the whole transaction through the turnstile mostly takes within 5-8 seconds if people already have the card in hand when they enter. If they have to search through the card in their bags, the average time for the transaction would be around 15-30 seconds or even more. For exiting the building, the whole transaction through the turnstile takes around 3-5 seconds given the wait time for the turnstile to respond and then open the doors. 

Consideration

The turnstile could be improved by increasing its sensitivity to people when they are close to the turnstile when they exit so that the experience of going out of the building would be smoother. Moreover, if the placement of the cardreader of the turnstile would be further away from the actual two pieces of transparent doors in order to make sure the experience of walking into will be smooth rather than stopped in the middle of the action. 

Published by Yiting Liu

NYU ITP '21

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