Bug in OAT Convert Speed Waveform to Speed Profile

[DR_redviking]

There is a bug in the SoundVib_TachProcess.lvlib:OAT Convert Speed Waveform to Speed Profile.vi that generates an erroneous speed profile output.  This scenario occurs when the function is used during continuous processing of a speed waveform for any calls after it is reset.

It seems the intent is to insert the last speed point in front of the current data in order to linearly interpolate the data.  However, the issue is the last speed point is not scaled back up from rot/sec to RPM, and this creates an artificial step effect at the beginning of the speed profile output.

Faulty VI:

Here is the faulty speed profile output.

The correction is simply to multiply the previous state data 'y' value by 60 in order to scale it back to RPM before inserting it into the data.

Corrected VI:

Corrected Output:

 

[billko]

I'm not familiar with this VI.  Is this an NI product?

[DR_redviking]

Yes it is part of the Sound and Vibration toolkit. 

[dsb@NI]

Gregopher, what version of LV and SVT are you using? I can make sure that this is fixed in 2021 and later, and I can add a test (that clearly was missing) to make sure this bug can't happen again.

[dsb@NI · Accepted solution]

Your fix has been submitted to the main line, and a new test has been added that verifies continuous result against one shot result.

[DR_redviking]

Thank you Doug!  I also submitted a bug report shortly after my original post (bug #1317940).