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# [Which] is the average resolution and accuracy of accelerometer sensor ?

edited February 1

Accuracy/Precision and Resolution are two extremely relevant parameters when doing a measurement and, consequently, to achieve a complete and objective understanding during the analysis of the measured values.

Resolution - "...smallest change (of the physical unit) that can be measured..."
Accuracy - defines "... how close a reported measurement is to the true value being measured..."

Definitions taken from

Relatively to the resolution of Accelerometer (ACC) sensor, taking into consideration that the range of values collected by ACC sensor are between -3 g and +3 g:
For a 8-bit acquisition the achievable resolution will be approximately:

$resolution=\frac{3 g - (-3 g)}{2^8} \approx 0.02344 g$

For a 16-bit acquisition the achievable resolution will be approximately:
$resolution=\frac{3 g - (-3 g)}{2^{16}} \approx 0.00009 g$

In terms of accuracy a brief test can be executed in order to estimate this parameter but a small note should be taken into consideration, because the transfer function of accelerometer sensor requires two constants resulting from a calibration procedure, which you should follow to achieve the maximum accuracy (as described here ).

For determining the accuracy we need a known reference value.

In our case, this reference value was the gravitational acceleration, so we conducted a set of 10 seconds acquisitions collecting gravitational acceleration from the 3-axes of ACC sensor.

The average difference between the real (1 g) and the acquired sample values are:
* $\pm 0.054 g$ (ACC X - 16 bits)
* $\pm 0.037 g$ (ACC Y - 16 bits)
* $\pm 0.022 g$ (ACC Z - 16 bits)

We can always replicate the same logic to other sensors, with slightly adjustments !

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