i know that adxl345 measures both static and translational acceleration
but the measured value is
translation + static
translation - static
Hi - the output you get from an accelerometer just depends on one thing: the resultant force on the sensing element, which of course is proportional to the acceleration along the sensing axis of that element. I think what you're getting at is where the reading is coming from being in motion (as in a brake tester) or being fixed in place (as in a tilt sensor).
Basically, the accelerometer doesn't care. Remember, what you're getting is the resultant force on it.
So if you have readings x, y, z for a level, static sensor, and you accelerate it purely in the x direction, you'll now get readings of x+ δx, y, z where δx is from your linear acceleration along the x-axis.
If you then pitch the device forward about the y-axis (ie in the XZ plane) as it's moving, you'll now get x + δx + Δx, y, z + δz where Δx and δz are from the gravitational pull and depend upon the angle φ that you've pitched the device by.
If you now stop the device moving, but keep its spatial orientation the same (ie you leave it pitched forward at angle φ) then you'll now have readings of x + Δx, y, z + δz, since the only resultant forces are due to gravity and you've now ended up with a tilt sensor.
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