iansebryk:
my project requires the measurement of vertical change of position with reference to a datum line. can this be done with an ADXL345 accelerometer? maximum vertical displacement would be about 50m. is it possible to do this? and to what degree of precision? +/- 2mm? or +/- 2cm?

i have already read this post, but his project is quite dissimilar. i am only concerned with measuring vertical distance travelled and whether or not it has returned to it's zero-state.

thanks all. :)

No,
**x=X0+V0T+1/2aT^2**

given this equation, how many variables are constants in your application. I see 3 variables,
**T** time
**V0** initial Velocity
**a** acceleration.

this simple quadratic can only be solved if **V0** and **a** are constants.

Each reading of the accelerometer gives you an instantaneous acceleration reading. The interval between readings becomes a delta Time value.

If you wanted to use an accelerometer to get a ruff reading on displacement you would need to construct an integrating OpAmp circuit. This OpAmp circuit would do the Series Summation for you. You could measure the OpAmp output an get a ruff approximation.

You need to use a IMU.

Chuck.