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Accelerometer-based heart beat detection
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<!DOCTYPE html> | |
<html> | |
<head> | |
<meta charset="UTF-8"> | |
<title>Accelerometer Data</title> | |
<script src="https://d3js.org/d3.v7.min.js"></script> | |
<style> | |
body { | |
display: flex; | |
flex-direction: column; | |
align-items: center; | |
justify-content: center; | |
height: 100vh; | |
margin: 0; | |
background-color: #f0f0f0; | |
} | |
.heart { | |
width: 200px; | |
height: 200px; | |
position: relative; | |
animation: none; /* Initially no animation */ | |
} | |
.heart:before, | |
.heart:after { | |
content: ''; | |
position: absolute; | |
top: 0; | |
width: 100px; | |
height: 160px; | |
background-color: red; | |
border-radius: 100px 100px 0 0; | |
} | |
.heart:before { | |
left: 100px; | |
transform: rotate(-45deg); | |
transform-origin: 0 100%; | |
} | |
.heart:after { | |
left: 0; | |
transform: rotate(45deg); | |
transform-origin: 100% 100%; | |
} | |
@keyframes heartbeat { | |
0%, 100% { | |
transform: scale(1); | |
filter: blur(0px) drop-shadow(0 0 0.1rem crimson); | |
} | |
10% { | |
transform: scale(0.95); | |
filter: blur(0.1px) drop-shadow(0 0 0.2rem crimson); | |
} | |
40% { | |
transform: scale(1.3); | |
filter: blur(0.3px) drop-shadow(0 0 0.4rem crimson); | |
} | |
80% { | |
transform: scale(0.95); | |
filter: blur(0.1px) drop-shadow(0 0 0.1rem crimson); | |
} | |
} | |
.animate-heartbeat { | |
animation: heartbeat .4s ease-out; | |
} | |
button { | |
margin-top: 20px; | |
padding: 10px 20px; | |
font-size: 32px; | |
cursor: pointer; | |
} | |
#chart-container { | |
width: 500px; | |
height: 200px; | |
border: 1px solid #ccc; | |
} | |
</style> | |
</head> | |
<body> | |
<div id="chart-container"></div> | |
<div id="accelerometerData"> | |
<p>Acceleration X: <span id="accelerationX"></span></p> | |
<p>Acceleration Y: <span id="accelerationY"></span></p> | |
<p>Acceleration Z: <span id="accelerationZ"></span></p> | |
</div> | |
<div class="heart" id="heart"></div> | |
<button onclick="heartbeat()">Trigger Heartbeat</button> | |
<div> | |
<h3>Statistics</h3> | |
<div id="statistics"></div> | |
</div> | |
<div id="lastTenData"> | |
<h3>Last 10 Accelerometer Measurements:</h3> | |
<ul id="lastTenList"></ul> | |
</div> | |
<button id="permissionButton">Request Accelerometer Permission</button> | |
<button id="saveDataButton">Save Data as CSV</button> | |
<script> | |
let permissionButton = document.getElementById('permissionButton'); | |
let saveDataButton = document.getElementById('saveDataButton'); | |
let accelerometerValues = []; | |
let measurementCount = 0; | |
let lastFiredDate = Date.now(); | |
let plotValues = Array.from({ length: 500 }, () => 0.0 );; | |
// Create SVG element | |
const svg = d3.select("#chart-container") | |
.append("svg") | |
.attr("width", 500) | |
.attr("height", 200); | |
// Create scales | |
const scaleX = d3.scaleLinear() | |
.range([0, 500]); | |
const scaleY = d3.scaleLinear() | |
.range([200, 0]); | |
// Create line function | |
const line = d3.line() | |
.x((_, i) => i * (500 / plotValues.length)) | |
.y(d => scaleY(d)) | |
.curve(d3.curveMonotoneX); | |
// Add path for the line | |
const path = svg.append("path") | |
.attr("class", "line") | |
.style("fill", "none") | |
.style("stroke", "black") | |
.style("stroke-width", 2); | |
// Function to update chart | |
function updateChart() { | |
plotValues = plotValues.slice(-500); | |
vals = plotValues; | |
// Update scales domain | |
scaleX.domain([0, vals.length - 1]); | |
scaleY.domain([d3.min(vals), d3.max(vals)]); | |
// Update line path | |
path.attr("d", line(vals)); | |
// Update points color | |
svg.selectAll("circle").remove(); | |
svg.selectAll("circle") | |
.data(vals) | |
.enter().append("circle") | |
.attr("cx", (_, i) => i * (500 / vals.length)) | |
.attr("cy", d => scaleY(d)) | |
.attr("r", d => d > 2.25 ? 3 : 0) | |
.attr("fill", d => d > 2.25 ? "red" : "black"); | |
} | |
permissionButton.addEventListener('click', async () => { | |
try { | |
await requestDeviceMotionPermission(); | |
} catch (error) { | |
console.error('Error requesting permission:', error); | |
} | |
}); | |
saveDataButton.addEventListener('click', () => { | |
downloadCSV(); | |
}); | |
async function requestDeviceMotionPermission() { | |
if (typeof DeviceMotionEvent.requestPermission === 'function') { | |
let permission = await DeviceMotionEvent.requestPermission(); | |
if (permission === 'granted') { | |
startAccelerometer(); | |
} else { | |
console.error('Permission denied'); | |
} | |
} else { | |
console.error('DeviceMotionEvent.requestPermission is not supported'); | |
} | |
} | |
function startAccelerometer() { | |
window.addEventListener("devicemotion", handleMotionEvent, true); | |
} | |
function handleMotionEvent(event) { | |
var acceleration = event.acceleration; | |
if (acceleration) { | |
let timestamp = performance.now(); | |
let data = { | |
x: acceleration.x.toFixed(4), | |
y: acceleration.y.toFixed(4), | |
z: acceleration.z.toFixed(4), | |
t: timestamp, | |
t_utc: Date.now() | |
}; | |
accelerometerValues.push(data); | |
measurementCount++; | |
if (measurementCount % 3 == 0) { | |
updateDisplay(acceleration); | |
updateChart(); | |
displayLastTenValues(); | |
displayStatistics(); | |
} | |
} | |
} | |
function updateDisplay(acceleration) { | |
document.getElementById("accelerationX").innerText = acceleration.x.toFixed(2); | |
document.getElementById("accelerationY").innerText = acceleration.y.toFixed(2); | |
document.getElementById("accelerationZ").innerText = acceleration.z.toFixed(2); | |
} | |
function displayStatistics() { | |
let div = document.getElementById("statistics"); | |
div.innerHTML = ''; | |
const rvals = accelerometerValues.slice(-300).map((m) => Math.sqrt(m.x*m.x + m.y*m.y + m.z*m.z)); | |
const rmean = rvals.reduce((acc,curr)=>acc+curr,0)/rvals.length; | |
const rstd = Math.sqrt(rvals.reduce((acc, val) => acc + (val - rmean) ** 2, 0) / rvals.length); | |
const zscore = (rvals[rvals.length-1] - rmean)/rstd; | |
plotValues.push(zscore); | |
if ((zscore > 2.25) && (Date.now() - lastFiredDate > 200)) { | |
div.innerHTML = `<b>${rmean.toFixed(4)} ${rstd.toFixed(4)} ==> PEAK!</b>`; | |
heartbeat(); | |
lastFiredDate = Date.now() | |
} else { | |
div.innerHTML = `<b>${rmean.toFixed(4)} ${rstd.toFixed(4)}</b>`; | |
} | |
console.log("HERE"); | |
} | |
function displayLastTenValues() { | |
let lastTenList = document.getElementById("lastTenList"); | |
lastTenList.innerHTML = ''; | |
const startIndex = Math.max(0, accelerometerValues.length - 10); | |
const lastTen = accelerometerValues.slice(startIndex); | |
lastTen.forEach((data, index) => { | |
let timeDiff = index > 0 ? (data.t - lastTen[index - 1].t).toFixed(2) : '-'; | |
let listItem = document.createElement('li'); | |
listItem.innerText = `#${startIndex + index + 1}: ${data.x}, ${data.y}, ${data.z}, t=${data.t.toFixed(2)}, tdelta: ${timeDiff}`; | |
lastTenList.appendChild(listItem); | |
}); | |
} | |
function downloadCSV() { | |
const now = new Date(); | |
const utcTimestamp = now.toISOString().replace(/[:T-]/g, '_').split('.')[0]; | |
const filename = `accelerometer_data_${utcTimestamp}.csv`; | |
const csvContent = "data:text/csv;charset=utf-8," + | |
"x,y,z,t,t_utc\n" + // Header row | |
accelerometerValues.map(item => Object.values(item).join(',')).join('\n'); | |
const encodedUri = encodeURI(csvContent); | |
const link = document.createElement("a"); | |
link.setAttribute("href", encodedUri); | |
link.setAttribute("download", filename); | |
document.body.appendChild(link); | |
link.click(); | |
} | |
function heartbeat() { | |
const heart = document.getElementById('heart'); | |
heart.classList.remove('animate-heartbeat'); | |
void heart.offsetWidth; // Trigger reflow to restart the animation | |
heart.classList.add('animate-heartbeat'); | |
heart.addEventListener('animationend', () => { | |
heart.classList.remove('animate-heartbeat'); | |
}, { once: true }); | |
} | |
</script> | |
</body> | |
</html> |
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90% written by ChatGPT. All I did was tweak + offline analysis to figure out that zscore works remarkably well.