Weight Alchemist

Project Overview

Daily weight measurement is often skipped or forgotten due to its inconvenience, which becomes a barrier to consistent health monitoring.This project introduces a smart weight measurement system that automatically records your weight just by sitting on the toilet seat.

Built-in sensors capture your body weight and send the data directly to the cloud, making it easily viewable through a web interface on smartphones or PCs.By eliminating the effort of manual measurement, this system promotes a more sustainable and effortless approach to health management.

🔧 Components Used

M5Stack

Microcontroller for measurement and communication

Load Cells (x4)

Sensors for detecting weight

HX711

High-precision ADC for load cells

Toilet Seat + Hand Tools

Base for installation and mechanical modification

AWS (RDS, etc.)

Cloud database for storing and retrieving measurement data

Web App (HTML/CSS/JavaScript)

Frontend interface to display and manage the data

🛠 Development Process

1. Modifying the Toilet Seat

• Four load cells were mounted under the toilet seat in a 4-point configuration.
• Sensor positions and heights were carefully adjusted to ensure balanced load distribution.

2. Circuit Design & Assembly

• Each load cell was connected to an HX711 module, which was then connected to the M5Stack.
• Special care was taken with wiring length and insulation to minimize electrical noise.

3. Software Development (M5Stack)

• Programmed using Arduino IDE, the M5Stack reads the weight data and performs averaging/filtering.
• The data is then transmitted to AWS via Wi-Fi using HTTP requests.

4. Web Interface

• A simple yet effective web app was created to visualize the weight history.
• Users can view their data on smartphones or PCs with graphical representation and date-based filtering.

5. Prototyping & Iteration

• Prototype #1: Exposed issues with sensor alignment and measurement accuracy.
• Prototype #2: Improved with better sensor positioning and structural support, resulting in more stable and accurate readings.

🧪 Prototype Overview

Prototype #1

Prototype #2

M5stack screen layout

WEB screen layout

🏁 Summary

• Innovative integration of a toilet seat and a weight scale to eliminate the need for manual measurement.
• End-to-end system built: sensor data acquisition, cloud integration, and web-based display.
• Clear explanation of the process, challenges, and improvements, accompanied by visual documentation.
• Effortless weight logging encourages habit formation for health management.　Potential applications include elderly care and medical monitoring in the future