Just looking at your data, something is clearly wrong. I'm assuming that the trace marked "Displ" and lasting about 25 seconds is a displacement trace. It is unclear what the trace "Velocity", with a time scale about 10000 times larger, represents -- is this a calculated trace (and how is it calculated?) or a recorded trace (and how does it compare to the presumed-recorded Displacement trace?).
Looking at the displacement, a Velocity trace should look like a noisy square wave, with a value of about 0.7 units/second for 10 seconds and -0.7 units/second for 10 seconds, then 0. Instead, it looks to be uniformly 0 (except for some additional noise bursts).
An integral of velocity would just give you back displacement (if done correctly). The simplest way to integrate is simply to take a running sum (recall that you can approximate the integral of [f(x) dt] by sum [f(x) * delta-t] = delta-t * sum[f(x)]. I have no idea what you did, but the integral trace you show looks suspiciously like a very weakly low-pass filtered version of the "velocity" trace.
Explain the origins of the Displacement and Velocity traces. Explain what the missing VIs in your Block Diagram are supposed to do.
Bob Schor
