Week 18

Aplications and implications. Project development

Week assignments

1. Applications and implications

• Plan a final project masterpiece that integrates the range of units covered, answering:
  - What will it do? ✔
  - Who’s done what beforehand? ✔
  - What sources will you use? ✔
  - What will you design? ✔
  - What materials and components will be used? ✔
  - Where will come from? ✔
  - How much will they cost? ✔
  - What parts and systems will be made? ✔
  - What processes will be used? ✔
  - What questions need to be answered? ✔
  - How will it be evaluated? ✔
  Your project should incorporate 2D and 3D design, additive and subtractive fabrication processes, electronics design and production, embedded microcontroller design, interfacing, and programming, system integration and packaging. ✔
  Where possible, you should make rather than buy the parts of your project.
  Projects can be separate or joint, but need to show individual mastery of the skills, and be independently operable

2. Project development

• Prepare drafts of your final project:
  • summary slide (presentation.png, 1920x1080) ✔
  • video clip (presentation.mp4, 1080p HTML5, < ~minute, < ~25 MB) ✔
• put them in your root directory, and check that they are linked in the final presentation schedule. ✔

Slightly off topic, or maybe not.

A Special Weekend at EUBIM 2025
This repository documenting my learning journey through the Fab Academy has gradually become a kind of diary, offering me the opportunity to share in real time the tasks developed each week, recording the mistakes, successes, and experiences of our path through the program. For this reason, I cannot leave out the fantastic weekend I had the chance to enjoy at the BIM International Conference. EUBIM 2025, held in Valencia on May 21st, 22nd, 23rd, and 24th.

After 14 editions, this conference has gone far beyond being a scientific event, it has created a true family. BIM methodology is the common thread, but it is friendship, the eagerness to share, and the desire to keep learning that make this an essential event for all of us. As I mentioned in my About section, CAD, BIM, and parametric modeling have been part of my life for a long time.

On the morning of Saturday, May 24th, the EUBIM conference organizers surprised me with the EUBIM 2025 Award in recognition of a professional journey that began many years ago. The entire auditorium greeted me with warm and heartfelt appreciation that left me speechless. I would like to leave written here my sincere gratitude to all the EUBIMMERs who make up this great EUBIM family.

The memory of our dear Vicente Castell, the recent flooding that affected Valencia, and this wonderful surprise made for a deeply emotional moment. That is why I believe this memory must be part of my documentation.

Thank you, EUBIM 2025, for this recognition.

Aplications and implications

After such an emotional week, my work is slightly behind schedule. On Saturday at 23:09, I started working on the assigned tasks. As a first step, I will respond to the questions that were raised, many of them have already been addressed in the Project Development section, but I will provide a summary of all of them here.

• What will it do?
  I have always been certain that my project should serve an educational purpose. One of my main objectives is to facilitate the understanding of the internal forces that act within a structure.
  To achieve this, I designed and built a simply supported beam with two cantilevers. The beam features nine seats, each mounted over a load cell. These sensors will transmit real-time data to an LED panel that will dynamically display the bending moment diagram of the structure. The diagram will update continuously based on the occupancy of each seat.

• Who’s done what beforehand?
  I have reviewed several Fab Academy repositories related to load cells, highlighting the following projects:

• Augusto Mantilla, 2024. Smart House for Dogs.

• Shopia Döring, 2024. Test Bench for Artificial Muscles.

• Svavar Konradsson, 2023. Multichannel Data Acquisition System, which explores alternatives to the ADV HX711.

Regarding projects involving LED frames, I would like to highlight the following repositories:

• Dorian Somers, 2023. Interactive Traffic Signal for Cyclists.
• Nadieh Bremer, 2021. Interactive Puzzle with Light Effects.
• Graham Smith, 2021. Nanoleaf-style LED Panels.
• Vishnu.V.Raj, 2018. Digifab display
• Amalia Bordoloi, 2025. Educational Game for Writing Numbers and Letters, during the project review session a few weeks ago. The game uses light patterns that follow specific sequences.

I have reviewed many other projects, but these seem to be the most relevant to my proposal. Of course, I have also worked with ChatGPT to explore technical options and possibilities, and during the Input Devices and Output Devices weeks, I anticipated potential challenges related to the integration of load cells and LED panels.

• What sources will you use? and What materials and components will be used?\

All materials are listed in detail in the Bill of Materials (BOM). Below is a summary of the most relevant ones:

• Materials

  • Medium-density fiberboard (MDF) for the frame that will house the LEDs
  • A wooden beam, four meters long
  • 16 mm and 20 mm thick wooden boards for seat supports and beam holders
  • PLA for 3D printed components
  • Medium-density foam for shaping the seats to be installed over the beam
  • Screws, fasteners of various sizes, and wiring for LED power supply (all detailed in the BOM)

• Tools and Machines The following tools and machines will be used for the fabrication of the final project:

  • 3D printers for the enclosures that will hold the PCBs
  • CNC milling machine
  • Robotic arm with hot wire cutter for foam cutting
  • Robotic arm with an electrospindle for wood milling
  • Laser cutter, used to cut 5 mm thick MDF panels for the LED frame
  • Soldering station and multimeter for assembling and validating the electronic systems
  • Various auxiliary carpentry workshop tools

• Electronic Components

  • 50-LED WS2812B modules arranged in a 32 x 17 pixel matrix, plus six additional LEDs for system status signaling
  • Platform-type load cells, each connected to an HX711 ADC module
  • Two Seeed Studio XIAO ESP32-C6 microcontrollers:
    • one will operate as a server reading the load cell data the other as a client controlling the LEDs based on the received values
  • Custom-designed PCBs (KiCAD) integrating the HX711 ADC, the ESP32-C6, and the LED frame
  • 5V / 12A power supply, with separate connections for each of the 11 LED modules
  • Quick-connect terminals to simplify assembly and maintenance

• Software
  The project relies heavily on parametric design and modular elements to ensure adaptability, thermal dissipation, and electrical safety throughout the system.

  • Rhinoceros + Grasshopper – parametric and geometric modeling
  • GIMP – image editing
  • KiCAD – PCB design
  • VCarve – toolpath generation for CNC
  • Ency Robot - milling with the robotic arm
  • CorelDRAW – laser cutting layouts
  • Arduino IDE + Visual Studio Code – microcontroller programming and debugging
  • Image2CPP – converts bitmap images into byte arrays compatible with the LED matrix

I have also reviewed the technical documentation on load cells and inter-microcontroller communication in the official ESP32 and HX711 documentation, as well as Adafruit’s tutorials on handling WS2812 matrices using the Neomatrix and Neopixel libraries.

• What will you design? and What parts and systems will be made?
  For my final project, I am designing both mechanical and electronic components, as well as the software that controls the entire system. Except for the electronic modules I purchased, I have attempted to fabricate all components that make up the system. The most relevant design tasks that enabled their fabrication include:

  • The structural elements that support the wooden beam and the seats, CNC milling and laser-cutting the MDF panel that houses the LED frame.
  • The geometry of the seats, modeled using parametric design tools and cut from medium-density foam using a robotic arm equipped with a hot wire.
  • The enclosures for the PCBs placed under each seat, designed to protect the electronics and facilitate easy assembly and maintenance.
  • The electronic boards (PCBs) designed in KiCAD to integrate the HX711 ADC modules with the ESP32-C6 microcontrollers and the LED matrix.
  • The arrangement of the LED matrix (32 x 17 pixels) and the configuration logic to display real-time bending moment diagrams.
  • The entire electronic system architecture, including wiring, power distribution, and communication protocols between microcontrollers.
  • The software for data acquisition, processing, and real-time LED control, developed using the Arduino IDE and Visual Studio Code.

• Where will come from? and How much will they cost?
  The materials used in the project come mostly from the FabLab inventory, which has been made available to me by Luis from A Industriosa. The MDF boards, support panels, screws, and power cables were sourced from local suppliers such as BricoSada and Cetronics. The load cells, HX711 modules, Xiao ESP32-C6 microcontrollers, and WS2812B LED modules were purchased from Aliexpress and Amazon. The cost of all materials used is detailed in the Bill of Materials (BOM).

Bill of material.

Hardware

Electronics

• What processes will be used?
  

  As I have already explained in the previous paragraphs, I will use 2D and 3D design tools to model the parts and components that make up my final project. I will employ both additive and subtractive processes, such as 3D printing, small- and large-format CNC milling, laser cutting, and hot wire cutting to fabricate all the components of the system. The beam and its supports are designed to convey simplicity, allowing students to easily identify the characteristics of the external constraints in an isostatic structure, as well as understand how the intensity and position of the loads applied to the beam influence the bending moments generated within it.

  All wiring and electronic components will be properly protected while remaining easily accessible to facilitate maintenance.

• What questions need to be answered? Key questions to successfully complete the final project

  • How will reliable weight data be obtained from the nine load cells?
    I need to validate the stability of the readings and the communication between the HX711 modules and the ESP32-C6 microcontrollers. This was addressed during the Input Devices week, where I implemented an automatic tare procedure and defined the measurement scale. The tare is executed automatically every time the system is powered on, and the scaling factor is stored in the MCU’s internal memory.

  • How will the two microcontrollers synchronize and communicate in real time?
    A robust WiFi connection and efficient data exchange are essential to accurately represent the bending moment diagram. During the Networking and Communications week, I configured the connection parameters using two load cells. The code was already designed to scale up to nine seats, so there should be no issue accessing all sensor data. It is important to ensure that the external antenna is properly connected on both microcontrollers.

  • What mechanical tolerances are acceptable for the seats and supports?
    As users will physically interact with the structure, the seats and frame must be safe, ergonomic, and structurally sound. The seats will allow for tolerances compatible with the expected structural deformations. As a safety measure, each seat support will include an additional backup beneath the central bearing point. Moreover, the code could include a warning system to detect excessive loads on the structure.

  • How will the power requirements for the entire LED matrix and electronics be managed?
    The system includes 550 WS2812B LEDs, requiring careful power supply analysis and thermal management. Over the past few weeks, I tested the power consumption of the LED modules, and the selected power supply is sufficient to meet the anticipated demand.

  • How will the electronic components under the seats be protected and mounted?
    All enclosures housing the load cells and PCBs are accessible for maintenance and designed to be impact-resistant to ensure adequate protection during use.

  • What plan will ensure timely fabrication of all components?
    I have scheduled the use of the laser cutter, 3D printer, and CNC machines. At this stage, the LED frame is nearly complete. The casing prototypes are finalized, and the nine enclosures with their covers are being 3D printed. I still need to finalize the design of the LED panel control area, which I plan to complete over the next week. This week, I have had a serious problem due to the malfuntion of the power supply of the CNC machine. I have ordered a new one, but in the meantime, I am using the robotic arm for milling.

  • How will the project be documented and presented to clearly convey its educational purpose?
    Since the project is intended as an educational tool for teaching structural behavior in early years of technical degrees, I have prioritized clarity and intuitive visualization. Once the bench is operational, at some point in the future I plan to program a set of basic structural scenarios to be displayed cyclically when no loads are detected. These scenarios will simulate:

    • A single load applied to the left cantilever end
    • A single load applied at the center of the main span
    • A single load applied to the right cantilever end
    • Lads applied to all seats in the central span
    • A combination of the three previous scenarios
    • Loads applied to all seats along the entire beam

These next two weeks, I must complete the physical assembly of the beam and LED frame, and check that the system as a whole functions correctly.

• How will it be evaluated? I believe the success of my final project should be evaluated based on the following criteria:

  • Functionality:
    the system must correctly read the weight from each of the nine load cells and represent in real time the corresponding bending moment diagram on the LED matrix, based on the position of users on the bench.

  • Robustness and reliability:
    the readings must be stable and accurate, even when several users sit down or move simultaneously. The system should respond according to the delay established in the programmed code.

  • Design and fabrication quality:
    all structural and electronic components must be correctly designed, fabricated, and integrated using digital fabrication tools. All connections must be robust and properly executed.

  • Educational value:
    this is a key aspect of the project. The system must clearly demonstrate structural principles to architecture and engineering students. The visualization should help users understand how loads influence the internal bending moments of a beam.

  • Documentation and reproducibility:
    the design, code, and fabrication processes must be thoroughly documented to allow others to understand, replicate, or improve the system.

  • Integration of knowledge acquired during Fab Academy:
    the project should reflect skills and knowledge gained throughout the program, including electronics design and production, embedded programming, device networking, input and output devices, mechanical design, and effective use of digital fabrication tools.

Project development

slide test

video test

Final thoughts

This week has been essential to put all matters related to the final project on the table. I have learned how to organize the different tasks and have also been able to solve unexpected issues, such as the failure of our CNC machine’s power supply. Thanks to my understanding of the robotic arm and the availability of an electrospindle capable of cutting wood of a certain thickness, I was able to fabricate the supports for the beam. Perhaps I should have manufactured the larger parts during the week specifically dedicated to large-scale fabrication, but I am very satisfied with the high table we now have at the Fab Lab. Moreover, students from the school are using it continuously.

This week I also took an important step forward in learning how to use DaVinci Resolve, with the help of Miguel Bujía, the audiovisual coordinator of the center. This will allow me to prepare the final video presentation, which I have to deliver on June 10. There is still work to do, but I believe I am on the right track to finish this cycle successfully.