Our mood sweater aims to visualize the wearer’s emotions. We created this sweater because we realized there were times when emotion is something that cannot be truly seen. For example, it can be easy to mask and hide our true emotions. In other situations, individuals may also be unable to expressively show emotion because of physical impairments such as muscle degeneration. Our sweater solves these problems by detecting emotion based off biometrics and by displaying them through color.
The sweater works based on inputs of a pulse sensor and a Galvanic Skin Response (GSR) sensor to detect different emotions. The GSR provides data about skin conductance and maps micro perspiration levels to a more active or passive emotion. The GSR works on the simple principle that the wearer’s skin completes the path of the circuit. The voltage difference across the two end of the GSR is measured and values in different ranges correspond to different states of emotion.
The Pulse Sensor, as the name implies, measures heart rate. We used example code available online, to get BPM values and infer emotional state accordingly. We used an Arduino UNO to process the data and control the LED display.
Currently, we are able to distinguish four different emotions – happiness, sadness, anger and a neutral state. Given more time, we would have liked to include temperature sensing of different parts of the body to create a heat map and widen the range of emotions the sweater can detect.
We packaged the circuitry neatly, added a switch so the user has more control over whether he wants his emotions to be on display or not and stitched the circuit on to a jacket. The sensors (GSR and Pulse) come out through the jacket’s right sleeve for the user to slip his fingers through them. The LED display sits between the shoulder and the chest and the main circuit sits in the jacket’s pocket.
// VARIABLES
// Heart Rate
int pulsePin = 0; // Pulse Sensor purple wire connected to analog pin 0
int blinkPin = 13; // pin to blink led at each beat
int fadePin = 5; // pin to do fancy classy fading blink at each beat
int fadeRate = 0; // used to fade LED on with PWM on fadePin
// GSR
int redPin = 9;
int greenPin = 10;
int bluePin = 6;
int potPin = 1;
int sensorPin = 2;
long red = 0xFF0000;
long green = 0x00FF00;
long blue = 0x000080;
long white = 0xFFFFFF;
int band = 20;
// these variables are volatile because they are used during the interrupt service routine!
volatile int BPM; // used to hold the pulse rate
volatile int Signal; // holds the incoming raw data
volatile int IBI = 600; // holds the time between beats, must be seeded!
volatile boolean Pulse = false; // true when pulse wave is high, false when it’s low
volatile boolean QS = false; // becomes true when Arduoino finds a beat.
volatile int rate[10]; // array to hold last ten IBI values
volatile unsigned long sampleCounter = 0; // used to determine pulse timing
volatile unsigned long lastBeatTime = 0; // used to find IBI
volatile int P =512; // used to find peak in pulse wave, seeded
volatile int T = 512; // used to find trough in pulse wave, seeded
volatile int thresh = 525; // used to find instant moment of heart beat, seeded
volatile int amp = 100; // used to hold amplitude of pulse waveform, seeded
volatile boolean firstBeat = true; // used to seed rate array so we startup with reasonable BPM
volatile boolean secondBeat = false; // used to seed rate array so we startup with reasonable BPM
void setup(){
pinMode(blinkPin,OUTPUT); // pin that will blink to your heartbeat!
pinMode(fadePin,OUTPUT); // pin that will fade to your heartbeat!
Serial.begin(9600); // we agree to talk fast!
interruptSetup(); // sets up to read Pulse Sensor signal every 2mS
// UN-COMMENT THE NEXT LINE IF YOU ARE POWERING The Pulse Sensor AT LOW VOLTAGE,
// AND APPLY THAT VOLTAGE TO THE A-REF PIN
// analogReference(EXTERNAL);
pinMode(potPin, INPUT); //This is to set the input resistance that comes from potentiometer A1
pinMode(sensorPin, INPUT);//This is to set the input resistance from the skin
pinMode(redPin, OUTPUT);//This is to set the output for RED Led
pinMode(greenPin, OUTPUT);//This is to set the output for green Led
pinMode(bluePin, OUTPUT);//This is to set the output for blue(or transparent) Led
}
void loop(){
Serial.println(BPM);
int gsr = analogRead(sensorPin);
int pot = analogRead(potPin);
boolean GSRhigh = (gsr > pot + band);
boolean angry = (BPM > 100);
boolean sad = ((BPM > 80) && (BPM < 100) && !GSRhigh);
boolean happy = (GSRhigh && (BPM > 80) && (BPM < 100));
if (angry)//This condition if true indicates the lie
{
Serial.println(“angry”);
Serial.print(“GSR = “);
Serial.println(gsr);
setColor(red);
}
/*
else if (gsr < pot – band)
//This condition if true indicates the need of adjusting the resistance
{
setColor(blue);
}*/
else if (sad)//This condition becomes true for other condition becomes false and is at normal resistance
{
Serial.println(“sad”);
Serial.print(“GSR = “);
Serial.println(gsr);
setColor(blue);
}
else if (happy)//This condition becomes true for other condition becomes false and is at normal resistance
{
Serial.println(“happy”);
Serial.println(gsr);
setColor(green);
}
else //This condition becomes true for other condition becomes false and is at normal resistance
{
Serial.println(“nuetral”);
Serial.print(“GSR = “);
Serial.println(gsr);
setColor(white);
}
}
void setColor(long rgb) //This functions sets the colour
{
int red = rgb >> 16;
int green = (rgb >> 8) & 0xFF;
int blue = rgb & 0xFF;
analogWrite(redPin, 255 – red);
analogWrite(greenPin, 255 – green);
analogWrite(bluePin, 255 – blue);
}
void interruptSetup(){
// Initializes Timer2 to throw an interrupt every 2mS.
TCCR2A = 0x02; // DISABLE PWM ON DIGITAL PINS 3 AND 11, AND GO INTO CTC MODE
TCCR2B = 0x06; // DON’T FORCE COMPARE, 256 PRESCALER
OCR2A = 0X7C; // SET THE TOP OF THE COUNT TO 124 FOR 500Hz SAMPLE RATE
TIMSK2 = 0x02; // ENABLE INTERRUPT ON MATCH BETWEEN TIMER2 AND OCR2A
sei(); // MAKE SURE GLOBAL INTERRUPTS ARE ENABLED
}
// THIS IS THE TIMER 2 INTERRUPT SERVICE ROUTINE.
// Timer 2 makes sure that we take a reading every 2 miliseconds
ISR(TIMER2_COMPA_vect){ // triggered when Timer2 counts to 124
cli(); // disable interrupts while we do this
Signal = analogRead(pulsePin); // read the Pulse Sensor
sampleCounter += 2; // keep track of the time in mS with this variable
int N = sampleCounter – lastBeatTime; // monitor the time since the last beat to avoid noise
// find the peak and trough of the pulse wave
if(Signal < thresh && N > (IBI/5)*3){ // avoid dichrotic noise by waiting 3/5 of last IBI
if (Signal < T){ // T is the trough
T = Signal; // keep track of lowest point in pulse wave
}
}
if(Signal > thresh && Signal > P){ // thresh condition helps avoid noise
P = Signal; // P is the peak
} // keep track of highest point in pulse wave
// NOW IT’S TIME TO LOOK FOR THE HEART BEAT
// signal surges up in value every time there is a pulse
if (N > 250){ // avoid high frequency noise
if ( (Signal > thresh) && (Pulse == false) && (N > (IBI/5)*3) ){
Pulse = true; // set the Pulse flag when we think there is a pulse
digitalWrite(blinkPin,HIGH); // turn on pin 13 LED
IBI = sampleCounter – lastBeatTime; // measure time between beats in mS
lastBeatTime = sampleCounter; // keep track of time for next pulse
if(secondBeat){ // if this is the second beat, if secondBeat == TRUE
secondBeat = false; // clear secondBeat flag
for(int i=0; i<=9; i++){ // seed the running total to get a realisitic BPM at startup
rate[i] = IBI;
}
}
if(firstBeat){ // if it’s the first time we found a beat, if firstBeat == TRUE
firstBeat = false; // clear firstBeat flag
secondBeat = true; // set the second beat flag
sei(); // enable interrupts again
return; // IBI value is unreliable so discard it
}
// keep a running total of the last 10 IBI values
word runningTotal = 0; // clear the runningTotal variable
for(int i=0; i<=8; i++){ // shift data in the rate array
rate[i] = rate[i+1]; // and drop the oldest IBI value
runningTotal += rate[i]; // add up the 9 oldest IBI values
}
rate[9] = IBI; // add the latest IBI to the rate array
runningTotal += rate[9]; // add the latest IBI to runningTotal
runningTotal /= 10; // average the last 10 IBI values
BPM = 60000/runningTotal; // how many beats can fit into a minute? that’s BPM!
QS = true; // set Quantified Self flag
// QS FLAG IS NOT CLEARED INSIDE THIS ISR
}
}
if (Signal < thresh && Pulse == true){ // when the values are going down, the beat is over
digitalWrite(blinkPin,LOW); // turn off pin 13 LED
Pulse = false; // reset the Pulse flag so we can do it again
amp = P – T; // get amplitude of the pulse wave
thresh = amp/2 + T; // set thresh at 50% of the amplitude
P = thresh; // reset these for next time
T = thresh;
}
if (N > 2500){ // if 2.5 seconds go by without a beat
thresh = 512; // set thresh default
P = 512; // set P default
T = 512; // set T default
lastBeatTime = sampleCounter; // bring the lastBeatTime up to date
firstBeat = true; // set these to avoid noise
secondBeat = false; // when we get the heartbeat back
}
sei(); // enable interrupts when youre done!
}// end isr
