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I am building a digital spirit level using an inertial measurement unit (IMU), and I want to calibrate the device so that it shows the angle correctly. Does anybody here have experience with this kind of calibration? How can I be sure that the reference surface that I use to calibrate the IMU is completely flat? I thought maybe there could be a physics trick to build a calibration jig or something along those lines.

Any suggestions are welcome.

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  • $\begingroup$ do you mean "flat" or "level" or both? $\endgroup$
    – Dale
    Commented Feb 13, 2023 at 15:25
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    $\begingroup$ @Dale now that I have read more about the definitions of "flat" and level" I want to calibrate the sensor so that it is level (The definition I found was "'Level' means at the same height or perpendicular to the direction of Earth's gravity"). I am using the acceleration in xyz directions to calculate the angle, so I guess what I am asking is how can I calibrate my sensor so that when the physical sensor is level and thus perpendicular with earth's gravity, my sensor will show 0.0 degrees of rotation about any axis. $\endgroup$
    – eidetech
    Commented Feb 14, 2023 at 16:24

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This method works for calibrating old fashioned bubble levels, but you can use it with your device as well.

You need a flat stable surface, which can be precisely adjusted. It has to be roughly level when you begin. Put your level on the surface and make a reading. Now turn your level by 180° (left to right) and make another reading. The readings will most probably differ. Now adjust the surface a little in any direction. Repeat the two measurements. If the difference is larger than before, you made the surface more steep when adjusting. If the difference is smaller this time, you made the surface less steep. Now adjust the surface so that it is less steep and repeat the two measurements. Keep measuring and adjusting until the readings are precisely the same whether the device is straight or rotated by 180°. This will indicate that the surface is perfectly level. You will then be able to calibrate your device so that it indicates 0.

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  • $\begingroup$ That sounds perfect! So simple, yet so genious. Thanks a lot! $\endgroup$
    – eidetech
    Commented Feb 19, 2023 at 10:53

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