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nmayorov / allan-variance

Simple allan variance in Python
MIT License
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Units of imu sensor errors #4

Closed swapnilsayansaha closed 6 months ago

swapnilsayansaha commented 2 years ago

If I feed accelerometer data in m/s^2 unit and dt in seconds, what is the unit of flicker and walk?

Same question for gyroscope data with unit in deg/s.

nmayorov commented 6 months ago

Sorry I've missed your question. This is indeed a somewhat tricky to figure out.

The easiest way is to consider AVAR dependency. An effect with parameter p has theoretical dependency AVAR ~ p**2 / tau**k, where k varies from 2 to -2 for the parameters 'quantization', 'white', 'flicker', 'walk', 'ramp' respectively. And AVAR values for a unit U has units U**2.

Then for units of p we have P = U * tau**(0.5 * k).

For accelerometers in m/s/s: m/s, m/s**1.5, m/s**2, m/s**2.5, m/s**3. For gyros in deg/s: deg, deg/s**0.5, deg/s, deg/s**1.5, deg/s**2.

I will add a note into the docstring.