Final Project

Final project presentation

SLIDE

Final project video

Final project

What does it do?

The project is a self-assembling wooden bridge equipped with a structural health monitoring (SHM) system. It will measure loads at critical joints using load cells, detect vibrations with accelerometer and display structural health status through LED lights. The LEDs will change color depending on the bridge’s condition, helping to visually communicate structural integrity in real time.

Who has done what beforehand?

Previous research has explored SHM systems in full-scale bridges using professional-grade sensors and complex data acquisition systems. Projects in academia and industry have used load cells and accelerometers to monitor stress and vibrations, while deployable structures have been developed in robotics and emergency engineering. However, few have integrated all these elements—self-assembly, low-cost sensing, environmental monitoring, and real-time visual feedback—in a small-scale timber prototype. This project fills that gap by combining these concepts with open-source tools and modular construction techniques.

What did you design?

The structure will consist of an arch that is assembled by many little blocks, I have to design the blocks and the joints between them. Also the supports need to be designed with specific consideraions to properly traspase the tension to the floor.

I have to design a part that direction the vertical load to the cell load to bending.

On the electronic topic I have to design the pcb’s. This means using kicad design the components, tracks the pcb will have.

Finally I need to design the system integration. Which consist of 3d printed boxes to rpotect electronics.

What materials and components were used?

• Timber beams and dowels for the bridge structure
• Load cells (e.g., 50 kg strain gauge type)
• ADXL345 accelerometers
• Humidity and temperature sensor (e.g., DHT22 or SHT31)
• Xiao ESP32C3 microcontroller
• Custom PCB
• LEDs and resistors
• Wires, headers, and mounting hardware
• 3D-printed or CNC-fabricated parts

Where did they come from?

Most materials came from the Fab Lab inventory. MDF and specific tools were sourced locally (BricoSada, Cetronics), and the electronic components were purchased from Aliexpress and Amazon.

How much did it cost?

What parts and systems were made?

Bridge modules with embedded joints A sensor mounting system A custom PCB for data handling Firmware for sensor reading and LED control A user interface through visual LED cues Possibly a web interface for sensor monitoring

What processes were used?

Woodworking (cutting, drilling, assembly) - CNC and lasser cutting 3D printing Soldering and PCB assembly Microcontroller programming (Arduino/C++) Data collection and basic signal processing Structural testing (static and dynamic loads)

What questions were answered?

How accurate and reliable are the sensors in this configuration? Can the modular joints handle the necessary loads without failure? What thresholds define safe vs. critical conditions in the bridge? How responsive and clear is the LED-based feedback? How scalable is the design for future applications?

What worked? What didn’t?

The structure and it mechanism wrok very well, on the electronics the led lights responed very well to the loads. Although, what I haven’t test yet is the accuracy, because sometime the lights don’t trun on in the colour they should. The accelerometer couln’t behave in how it was expected although it worked.

How was it evaluated?

The functionality and stability of the self-assembling structure The successful integration and accuracy of the sensor system The clarity and responsiveness of the visual feedback (LEDs) Testing under different loading conditions and environmental changes The completeness of documentation and reproducibility of the system

What are its implications?

This arch provides a tangible educational tool for teaching structural concepts. It demonstrates effective integration of mechanics, electronics, and programming within a Fab Lab, and it is replicable for pedagogical use in architecture and engineering.

Licensing

I have decided to license my project under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) license. This means that:

Others may view and share my work, but they may not use it commercially, modify it, or distribute derivative works based on it.

This license fits my current needs because this project is preliminary to a doctoral thesis, and I do not want it to be reproduced or altered until the thesis is completed and published.

I understand that by making the project public under this license, there is still a risk that someone could copy it without authorization, although they cannot legally modify or use it commercially.

For more information about this license, I have consulted the following link: https://creativecommons.org/licenses/by-nc-nd/4.0/

Why CC BY-NC-ND 4.0? I chose the CC BY-NC-ND 4.0 license because it aligns with my goal of protecting the originality and integrity of my work during its development stage. It ensures proper attribution while restricting commercial use and modifications, preserving the project’s current status as a non-commercial and unaltered academic resource.

My Final project summary

• Initial idea

• Project development

  • Week 3
    Geomtry design
  • Week 9
    I tested the led lights, first aproximation to input electornics.
  • Week 10
    With the cnc machine I did the structure.
  • Week 17
    PCB Design and production.
  • Weeks 18
    Mounting the strcutre, I used a milling machine to do the holes for lateral rigidity and use the laser machien for supports.
  • Week 20
    System integration, test and presentation.

Acknowledgement

I would like to sincerely thank the research project ED431F 2024/17 funded by the Xunta de Galicia and led by Principal Investigator Pablo Guindos, as well as the excellence program BERCE (Code 00958), also under the direction of Pablo Guindos Bretones at the University of A Coruña, for their financial support. Their contribution made it possible for me to join the Fab Academy 2025.