Namazu: Low-cost tunable shaking table for vibration experiments under generic signals

This repository contains supplementary material to the publication "2024 Grashorn, Bittner, Banse et al. - Namazu: Low-cost tunable shaking table for vibration experiments under generic signals" published in Experimental Techniques. The repository contains software, coded examples, firmware, and CAD files usable for vibrational experiments in the context of dynamic analysis of structures and stochastic dynamics in general.

Updates 17.06.2024

Namazu architecture (Software & Hardware)

Figure 1: Flowchart and design concept of the Namazu framework, from signal generation via the software over the control system to plate motion, as in our paper.

Preparations

When this readme was written the following OS, platforms, and software were used:

• Windows 10.0.19041.4355 (professional)
• Microsoft Visual Studio Code 1.90.0 (VSC)
• MATLAB version 2023a
• Python version 3.12.3
• PlatformIO with Core 6.1.15 and Home 3.4.4

It is necessary to upload the firmware to a compatible ESP32 device. If this readme is not enough, you can find more information here: "Namazu documentation". Please note that there are a multitude of ESP32 variants, so far we tested NodeMCU ESP32 WROOM32 and Firebeetle ESP32 modules. Please also note that we cannot test every variant and we are currently not recommending using ESP32-S2 or -C3 variants, since this could require code adaptations.

Flashing of ESP32

Connect the ESP32 via a USB cable with your computer and identify the USB port by e.g. the device manager or PlatformIO.

In Windows you should located something like this: "Port: COM3; Description: Silicon Labs CP210x USB to UART Bridge (COM3); Hardware: USB VID:PID=10C4:EA60 SER=0001 LOCATION=1-6" The port COM3 could have a different number on your machine, depending on the USB socket you used. In Linux the port is displayed differently (e.g. /dev/ttyUSB0), but the description should remain the same.

Start VSC, locate and navigate to the Firmware folder (\Firmware\), start PlatformIO (in VSC), make sure the ESP32 has been located as described above. To verify that everything is installed okay and no libraries are missing, press build. As indicated by 1. in Figure 2 below. Alternatively you can also use the buttons that are normally in the VSC UI located in the top-right corner, here see 4. Figure 2.

Figure 2: PlatformIO.

A successful build should reveal this:

Figure 3: Build.

Then upload by pressing the upload button (inicated by 2. in Figure 2 above) in PlatformIO. VSC will build again and then upload, the COM port should be identified automatically.

A successful upload should display this:

Figure 4: Upload.

The connecting pins of your ESP32 to the driver (in our case we used a DM430) are given in the window as in 3. in Figure 2.

We advise you to not change or touch the firmware software in \Firmware\, unless you know what you are doing.

Safety Precautions

Remember, if you built Namazu, you are dealing with machinery.

Disclaimer: The authors assume no responsibility or liability for any use of the software and provided ideas. By using this software, you acknowledge that you are solely responsible for any consequences that may arise. It is your responsibility to ensure you fully understand the operation and potential risks associated with the software and any machinery or systems it controls.

Safety Warning: Always ensure you have a reliable power switch or safety mechanism to completely disconnect the machinery from the power grid in case of an emergency. Thoroughly assess the risks and plan your actions carefully. Double-check all connections and settings before proceeding. Safety should always be your top priority.

Start with a main file

We provided coded examples and implementations for MATLAB and Python. Once you have your hardware ready and safety precautions were taken, we suggest to start with simple examples.

MATLAB

For MATLAB, go to \MATLAB\MainCreateSimulation.m. Here check line 179.

Make sure the correct com port is stated. If ran successfully a fixed harmonic with amplitude 1 and frequency 1 is started.

%% find shaking table controller on the correct COM port, COM port needs to be identified manually

dev = serialport("COM3",921600);

Python

For Python, go to \Python\main_FixedHarmonic.py. There check line 47.

Make sure the correct com port is stated. If ran successfully a fixed harmonic with amplitude 1 and frequency 1 is started.

# Set the COM port and baud rate according to your ESP32 configuration
com_port = 'COM3'  # Change this to your COM port on Windows, e.g., 'COM3'
baud_rate = 921600  # Change this to match your ESP32 configuration

# Open the serial connection
ser = serial.Serial(com_port, baud_rate, timeout=1)

Cite

For technical paper:

Grashorn J., Bittner, M., Banse, M. et al. (2024). Namazu: Low-cost tunable shaking table for vibration experiments under generic signals https://doi.org/10.1007/s40799-024-00727-8

BibTex:

@article{NamazuEXTE2024,
    author = {Grashorn J., Bittner, M., Banse, M., Chang, X., Beer, M., Fau, A.},
    title = {Namazu: Low-cost tunable shaking table for vibration experiments under generic signals},
    year = {2024},
    publisher = {Springer Nature},
    journal = {Experimental Techniques},
    doi = {10.1007/s40799-024-00727-8},
}

For the repository:

https://github.com/NamazuST/Namazu

doi: https://zenodo.org/doi/10.5281/zenodo.10533795

BibTex:

@misc{NamazuRepo2024,
    author = {Grashorn J., Bittner, M., Banse, M.},
    title = {Namazu},
    year = {2024},
    publisher = {GitHub},
    journal = {GitHub repository},
    doi = {10.5281/zenodo.10533795},
}

Showcase

Figure 5: Experimental campaign with a Namazu realization, a 3D printed specimen and love

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