Double Transducer: Force to Light Color

Final images

Detail photos

Final project movies

Joy's double transducer video

Narrative description

When the sensor that senses force is pressed, it changes the rotation of the motor which raises and lowers the object hanging from the pulley. A distance sensor collects the distance that the object is from the table, which changes the color of light shown on the LED ring.

Progress images

Discussion

The process of creating this double transducer was not easy, but we were able to overcome challenges a long the way through trial and error.  With the limited knowledge we had about physical computing as a whole, we were tasked to create a multi-step transducer which required understanding of both wiring and software/coding. 

Before beginning the physical building of our project, we were conflicted on how to achieve the middle conversion of distance. Originally, we were going to do a flat construction for our servo motor movement, but the ultrasonic ranger would not be able to detect the rotational motion from the servo. In response, we shifted to the pulley system and placed the distance sensor directly under the pulley object. Constructing the pulley was a matter of trial and error where we had to account for the servo motor's strength and range with a stable pulley structure. We had to implement several structural improvements such as a guardrail to keep the string in one place and supporting beams. This process could have been easier if we had measured out our building components first and accounted for the setbacks instead of responding to each new error that occurred. 

Another struggle we had was getting the force sensitive resistor to read accurate numbers and read a value of 0 when there is no pressure applied. At one point of the project, the FSR would read some kind of force and would never reach 0 because of its sensitivity, therefore affecting the irregularity of the servo motor movement. Initially we changed the mapping to reflect the range of values given by the FSR (700-1023). However, the main issue was the wiring of the force sensitive resistor on our breadboard. After talking with the professor, we realized the problem with the FSR was that one pin of the FSR should be placed into the power on the breadboard, while the other pin should be placed in the same line as a pin going to the breadboard and the resistor going to ground. This change caused the FSR to start from 0 and go all the way up to around 900, and the servo motor movement was much less irregular.

If we were to begin this process again, we would probably rethink our middle step as it was a bit complicated structurally and caused us to spend unnecessary time on it that could've been spent on making our code stronger and fix other issues with the FSR and light outputs. We also could have improved on our planning bnefore beginning our building stage, which would have made our building process much more streamlined. We would also make sure to read all the instructions so that we are able to make sure we build with the rubric in mind and not have to fix our project to fit the rubric later. Overall, our team grew much stronger in our proficiency with both software and wiring compared to the start of the project and class. 

Functional block diagram and electrical schematic

Code

/*

Double Transducer: Force to Light Color

By Hannah and Joy :)

Force is recorded using a force sensitive resistor and is mapped to a variable that corresponds to a certain degree which the servo motor moves. The servo motor determines the distance read by the HCSRO4 ultrasonic ranger. The distance is mapped to a set of eight values, which each correspond to a different color light emitted by the Neopixel LED.

outside sources used:

HCSRO4 Ultrasonic Ranger Code --> https://courses.ideate.cmu.edu/60-223/f2024/tutorials/ultrasonic-ranger

LCD Display --> https://courses.ideate.cmu.edu/60-223/f2024/reference/class-log

*/

//including the libraries needed

# include <Servo.h>

# include <NewPing.h>

# include <Adafruit_NeoPixel.h>

# include <LiquidCrystal_I2C.h>

/*

pin mapping:

   pin | role  | details

   ------------------------------

   A1     input   force sensitive resistor

   A3     output  servo motor

   4      output  neopixel LED

   7      input   button to skip middle step

   8      output  trigger for ultrasonic sensor

   9      output  echo for ultrasonic sensor

*/

//Force Sensitive Resistor analog in pin

const int FSRpin = A1;

//Servo motor analog in pin

const int SERVO = A3;

// the analog read value of the FSR

int FSRREAD;

//distance sensor pins

//ultrasonic sensor

#define TRIGGER_PIN 8

#define ECHO_PIN 9

#define MAX_DISTANCE 12 //in centimeters

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); //make a new object called sonar

//servo motor

Servo servomotor;

int ServoVal;

int servomotormove;

//light

#define NUM_PIXELS 16

#define NPPIN 4

int distance;

int LightVal;

Adafruit_NeoPixel NeoPixel(NUM_PIXELS, NPPIN, NEO_GRB + NEO_KHZ800); // new object called neopixel

//button

const int BUTTONPIN = 7;

//display

LiquidCrystal_I2C display(0x27, 16, 2); //creating object called display

unsigned long runitback = 0; //counter

unsigned long WAIT = 500; //milliseconds before refresh

void setup() {

 Serial.begin(9600);

// attachment points

pinMode(FSRpin, INPUT);

pinMode(SERVO, OUTPUT);

pinMode(BUTTONPIN, INPUT);

servomotor.attach(SERVO);

pinMode(NPPIN, OUTPUT);

//display set up

millis();

display.init();

display.backlight();

display.home();

runitback = millis() + WAIT;

}

void loop() {

//1. gathering input from the world

//force sensitive resistor

int FSRREAD = analogRead(FSRpin);

//button

int buttonVal = digitalRead(BUTTONPIN);

//ultrasonic sensor

int distance = sonar.ping_cm();

//2. using gathered data to make decisions

//determining motion of servomotor based on force input

 ServoVal = map(FSRREAD, 0, 900, 0, 6);

 //determining light color based on distance

 LightVal = map(distance, 0, 12, 0, 6);

//3. driving outputs

 //button is not pressed

 if (buttonVal == LOW){

   //output of the servo motor

   delay(100);

   servomotormove = ServoVal*25; //converting value to degrees

   servomotor.write(servomotormove); //making the servo motor move

   //LED component

   if (LightVal == 0){ //no force is given, pulley is all the way down

     for(int i = 0; i < NUM_PIXELS; i++){

       NeoPixel.setBrightness(15);

       NeoPixel.setPixelColor(i, NeoPixel.Color(255, 0, 0)); //red

       NeoPixel.show();

    }

   }

   if (LightVal == 1){

     for(int i = 0; i < NUM_PIXELS; i++){

       NeoPixel.setBrightness(15);

       NeoPixel.setPixelColor(i, NeoPixel.Color(255, 100, 0)); //orange

       NeoPixel.show();

     }

   }

   if (LightVal == 2){

   for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(15);

     NeoPixel.setPixelColor(i, NeoPixel.Color(255, 255, 0)); //yellow

     NeoPixel.show();

    }

   }

  if (LightVal == 3){

    for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(15);

     NeoPixel.setPixelColor(i, NeoPixel.Color(0, 255, 0)); //green

     NeoPixel.show();

     }

   }

   if (LightVal == 4){

    for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(15);

     NeoPixel.setPixelColor(i, NeoPixel.Color(0, 255, 255)); //teal

     NeoPixel.show();

     }

   }

   if (LightVal == 5){

    for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(15);

     NeoPixel.setPixelColor(i, NeoPixel.Color(0, 0, 255)); //blue

     NeoPixel.show();

     }

   }

   if (LightVal == 6){ //pulley is all the way up

     for(int i = 0; i < NUM_PIXELS; i++){

       NeoPixel.setBrightness(15);

       NeoPixel.setPixelColor(i, NeoPixel.Color(255, 0, 255)); //purple

       NeoPixel.show();

     }

   }

 }

 if (buttonVal == HIGH){

   NeoPixel.setBrightness(10);

   LightVal = ServoVal; //when button is pressed, force input immediately becomes light value input

   delay(100);

   if (LightVal == 0){

     for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(20);

     NeoPixel.setPixelColor(i, NeoPixel.Color(255, 0, 0)); //red

     NeoPixel.show();

    }

   }

   if (LightVal == 1){

     for(int i = 0; i < NUM_PIXELS; i++){

       NeoPixel.setBrightness(20);

       NeoPixel.setPixelColor(i, NeoPixel.Color(255, 100, 0)); //orange

       NeoPixel.show();

     }

   }

   if (LightVal == 2) {

     for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(20);

     NeoPixel.setPixelColor(i, NeoPixel.Color(255, 255, 0)); //yellow

     NeoPixel.show();

     }

   }

   if (LightVal == 3){

     for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(20);

     NeoPixel.setPixelColor(i, NeoPixel.Color(0, 255, 0)); //green

     NeoPixel.show();

      }

   }

   if (LightVal == 4){

     for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(20);

     NeoPixel.setPixelColor(i, NeoPixel.Color(0, 255, 255)); //teal

     NeoPixel.show();

     }

   }

   if (LightVal == 5){

     for(int i = 0; i < NUM_PIXELS; i++){

       NeoPixel.setBrightness(15);

       NeoPixel.setPixelColor(i, NeoPixel.Color(0, 0, 255)); //blue

       NeoPixel.show();

     }

   }

   if (LightVal == 6){

    for(int i = 0; i < NUM_PIXELS; i++){

     NeoPixel.setBrightness(20);

     NeoPixel.setPixelColor(i, NeoPixel.Color(255, 0, 255)); //purple

     NeoPixel.show();

     }

   }

 }

//4. displaying information

 if (millis() >= runitback){ //when the amount of milliseconds is equal to when we want it to run

   display.clear();

   display.print("I:");

   display.print(map(FSRREAD, 0, 1000, 0, 99));

   display.setCursor(0,1);

   display.setCursor(5,0);

   display.print("M-I:");

   display.print(map(servomotormove, 0, 180, 0, 99));

   display.setCursor(5,1);

   display.print("M-O:");

   display.print(distance);

   display.setCursor(12,1);

   display.print("O:");

   display.print(LightVal);

   runitback = millis() + WAIT; //increasing the value to activate the display function

 }

}