Pressure Sensor Seat - Smart Occupancy Detection 🪑📊

🏆 Bachelor's Thesis (TFG) awarded with Distinction (Matrícula de Honor - 9.6/10). Universidad CUNEF - Engineering School.

📄 Full Documentation

You can read the full academic dissertation here: 👉 Download Project Memory (PDF)

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This project is a smart occupancy detection system for seats using piezoresistive pressure sensors (MD30-60) and an ESP32 microcontroller. It is designed for real-time monitoring and wireless data transmission to the cloud using Google Sheets.

Features

• Reads analog pressure values from 4 sensors.
• Sends timestamped data to a Google Sheets document via WiFi.
• Uses Google Cloud service account for secure authentication.
• Code written in C++ using the Arduino framework.

System Architecture

The ESP32 reads data from 4 piezoresistive sensors connected as voltage dividers. The values are processed and sent every few seconds to a Google Sheets spreadsheet via the ESP_Google_Sheet_Client library.

Hardware Components

• ESP32-S3 DevKitC-1
• 4 × MD30-60 piezoresistive pressure sensors
• 4 × 10kΩ resistors (for voltage divider)
• Dupont cables, breadboard, USB-C cable

Software Setup

1. Libraries Needed (Install via Library Manager):

   • WiFi.h
   • ESP_Google_Sheet_Client
   • GS_SDHelper
   • FirebaseJson

2. Google Cloud Setup:

   • Create a Google Cloud project.
   • Generate service account credentials.
   • Share the target Google Sheet with the service account email.
   • Store credentials in a separate secrets.h file.

3. secrets.h Structure:

   #define WIFI_SSID "YourWiFiSSID"
   #define WIFI_PASSWORD "YourWiFiPassword"
   #define PROJECT_ID "your-google-project-id"
   #define CLIENT_EMAIL "your-service-account-email"
   const char PRIVATE_KEY[] PROGMEM = R"EOF(
   -----BEGIN PRIVATE KEY-----
   YourPrivateKeyHere
   -----END PRIVATE KEY-----
   )EOF";
   

Data Format

The Google Sheet stores data with the following structure:

| Timestamp (Unix) | Sensor 1 | Sensor 2 | Sensor 3 | Sensor 4 |