Hi,
Here is a light prototype I have just tested today.
It needs :
- A 3D printed anemometer : https://www.thingiverse.com/thing:2527455
- Just insert a magnet at the bottom of the anemometer axis
- code a small B4A App to read the magnetometer
Then, when rotating the you should see a tiny fluctuation of the magnetic field.
- Perform a FFT (again thank you @klaus )
- extract the main pick and you get the frequency of rotation of the magnets
Then fix the device on your eBike and run it at various speeds while the app is in calibration mode.
You will get a serie of dots (freq, speed). Add all this into excel sheet, perform a polynomial regression and get the curve parameters
And that's it you have a calibrated WindMeter
Here is a light prototype I have just tested today.
It needs :
- A 3D printed anemometer : https://www.thingiverse.com/thing:2527455
- Just insert a magnet at the bottom of the anemometer axis
- code a small B4A App to read the magnetometer
Then, when rotating the you should see a tiny fluctuation of the magnetic field.
- Perform a FFT (again thank you @klaus )
- extract the main pick and you get the frequency of rotation of the magnets
Then fix the device on your eBike and run it at various speeds while the app is in calibration mode.
You will get a serie of dots (freq, speed). Add all this into excel sheet, perform a polynomial regression and get the curve parameters
And that's it you have a calibrated WindMeter
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