What you say is true in a fixed one-g environment. You can derive a crude
measurement of angular rotation in any fixed, uni-directional acceleration
environment in the manner that you suggest. But as I understand the
proposed application, the accelerometer(s)/instruments are to be mounted in
a dynamic environment. The accelerometers mentioned are designed to measure
linear acceleration. That is what the manufacturer designed them to do.
They are NOT designed to measure rotation or rotational rates. That is
generally a domain reserved for gyroscopes and related insruments or
systems.

As an exercise, consider how you would perform your suggested computation in
an orbiting spacecraft(i.e., zero g).

Max Lynn

"Meindert Sprang" wrote in message
...
"maxlynn" wrote in message
news:VpLKb.102178$pY.42460@fed1read04...
Well, it IS pretty close to correct. An accelerometer measures exactly
what
its name implies - acceleration. And 99% of the time the name implies
linear acceleration. So if you integrate that once, you have velocity.
But
nowhere in this process do you get pitch, roll, azimuth, or any other
angular measurement.

??????
If I mount an ADXL with one axis vertical and the other horzontal, I
measure
a constant gravitational acceleration on the vert. axis and 0 on the hor.
axis. If I now rotate the sensor, I get a nice sine/cosine relation
between
the signals on both axes. So there's my angular measurement!

Meindert