# Arduino Height Measurement System
#
## 1. Project Overview
The Arduino-based Height Measurement System uses an ultrasonic sensor to measure the distance between the sensor and a person's head.
The sensor is mounted at a fixed height, facing downward. When a person stands beneath it, the system measures the distance from the sensor to the person's head.
Python calculates the person's height using the following formula:
**Person's Height = Sensor Mounting Height − Measured Distance**
### Technologies Used
- Arduino UNO
- HC-SR04 Ultrasonic Sensor
- Arduino IDE
- Python
- Flask
- PySerial
- HTML, CSS and JavaScript
### System Architecture
```text
HC-SR04 Sensor
|
v
Arduino UNO
|
v
USB Serial Communication
|
v
Python Flask Server
|
v
Height Calculation
|
v
Web Dashboard
|
v
Display Height (cm)
```
---
## 2. Hardware Requirements
| Component | Quantity |
|---|---:|
| Arduino UNO | 1 |
| HC-SR04 Ultrasonic Sensor | 1 |
| Jumper Wires | 4 |
| USB Cable | 1 |
| Computer/Laptop | 1 |
| Fixed mounting frame | 1 |
## 3. Hardware Connections
### HC-SR04 to Arduino UNO
| HC-SR04 Pin | Arduino UNO |
|---|---|
| VCC | 5V |
| GND | GND |
| TRIG | Digital Pin 9 |
| ECHO | Digital Pin 10 |
**Sensor Installation:**
- Mount the ultrasonic sensor horizontally at a fixed height.
- The sensor must face vertically downward.
- Keep the sensor stable.
- The person should stand directly below the sensor.
- Measure the distance from the sensor's ultrasonic face to the floor.
For example:
```text
HC-SR04 SENSOR
(Fixed Position)
┌─────────────┐
│ │
└─────────────┘
|
|
| Measured Distance
|
_______
/ \
| HEAD |
| |
| PERSON |
| |
| |
| |
|_________|
----------------
FLOOR
```
**Example:**
- Sensor mounting height = 200 cm
- Distance from sensor to head = 30 cm
Person's height:
\[
H=200-30
\]
\[
\boxed{H=170\text{ cm}}
\]
*Important: The sensor mounting height must be measured accurately from the sensor's measuring face to the floor.*
---
## 4. Arduino IDE Setup
### Step 1: Install Arduino IDE
Download Arduino IDE:
https://www.arduino.cc/en/software
Install and open Arduino IDE.
### Step 2: Arduino Code
The following program measures the distance using the HC-SR04 sensor and sends the measurement to Python through serial communication.
No additional Arduino library is required.
```cpp
// HC-SR04 Configuration
#define TRIG_PIN 9
#define ECHO_PIN 10
void setup() {
// Start serial communication
Serial.begin(9600);
// Configure sensor pins
pinMode(TRIG_PIN, OUTPUT);
pinMode(ECHO_PIN, INPUT);
}
void loop() {
// Send ultrasonic trigger pulse
digitalWrite(TRIG_PIN, LOW);
delayMicroseconds(2);
digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);
// Read echo duration
long duration = pulseIn(ECHO_PIN, HIGH, 30000);
if (duration == 0) {
Serial.println("ERROR");
}
else {
// Calculate distance in centimeters
float distance = duration * 0.0343 / 2;
// Send distance to Python
Serial.println(distance);
}
delay(500);
}
```
### Step 3: Upload the Program
1. Connect Arduino UNO to your computer.
2. Select the correct board: Arduino UNO.
3. Select the correct COM port.
4. Upload the program.
5. Check the Serial Monitor at 9600 baud.
Expected output:
```text
30.20
30.10
30.25
30.15
```
These values represent the measured distance between the sensor and the person's head.
---
## 5. Python Environment Setup
### Step 1: Install Python
Download Python:
https://www.python.org/downloads/
Verify installation:
```bash
python --version
```
### Step 2: Create Project Folder
Open PowerShell or Command Prompt.
```powershell
mkdir Height_Measurement
cd Height_Measurement
```
### Step 3: Create Python Virtual Environment
```bash
python -m venv venv
```
### Step 4: Activate Virtual Environment
**Windows PowerShell:**
```powershell
.\venv\Scripts\Activate.ps1
```
If PowerShell blocks activation:
```powershell
Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
```
Then activate again:
```powershell
.\venv\Scripts\Activate.ps1
```
**Windows Command Prompt:**
```cmd
venv\Scripts\activate.bat
```
After activation, you should see:
```text
(venv) C:\...\Height_Measurement>
```
### Step 5: Install Required Libraries
```bash
pip install flask pyserial
```
Save dependencies:
```bash
pip freeze > requirements.txt
```
---
## 6. Project Structure
```text
Height_Measurement/
│
├── venv/
│
├── app.py
│
└── requirements.txt
```
The complete website, including HTML, CSS and JavaScript, will be included inside `app.py`.
---
## 7. Create the Python Application
Create a file named `app.py`.
**Important:** Set `SENSOR_HEIGHT_CM` according to the actual height of your mounted sensor.
For this example, the sensor is mounted 200 cm above the floor.
```python
from flask import Flask, jsonify, render_template_string
import serial
import threading
import time
app = Flask(__name__)
# ==================================
# CONFIGURATION
# ==================================
SERIAL_PORT = "COM3"
BAUD_RATE = 9600
# Sensor height from floor in centimeters
SENSOR_HEIGHT_CM = 200
# Measurement variables
distance = 0
person_height = 0
connection_status = "Disconnected"
last_updated = "--"
# ==================================
# ARDUINO SERIAL COMMUNICATION
# ==================================
def read_arduino():
global distance, person_height
global connection_status, last_updated
while True:
try:
print("Connecting to Arduino...")
arduino = serial.Serial(
SERIAL_PORT,
BAUD_RATE,
timeout=2
)
time.sleep(2)
connection_status = "Connected"
print("Arduino Connected!")
while True:
line = arduino.readline().decode(
"utf-8",
errors="ignore"
).strip()
if not line or line == "ERROR":
continue
try:
measured_distance = float(line)
# Validate sensor measurement
if not 2 <= measured_distance < SENSOR_HEIGHT_CM:
continue
# Calculate person's height
calculated_height = (
SENSOR_HEIGHT_CM - measured_distance
)
distance = round(measured_distance, 2)
person_height = round(
calculated_height, 2
)
last_updated = time.strftime("%H:%M:%S")
print(
f"Distance: {distance} cm | "
f"Height: {person_height} cm"
)
except ValueError:
continue
except Exception as error:
connection_status = "Disconnected"
print("Arduino Error:", error)
time.sleep(3)
# ==================================
# WEB DASHBOARD
# ==================================
HTML_PAGE = """
Height Measurement System