Joachim Franek wrote: > And I am not sure what was measured. From this motion > profile (0.1 to 0.2 s time to reach max. velocity) > I do not expect frequency components in the > 800 to 1200 Hz range. > Right, I think this is a bunch of noise from the servo drive, motor, encoder, etc. > Another point is that the spectrum does not look alike sinc. > But I may be totally wrong. > > My experience using a MMA7260 > http://www.freescale.com/files/sensors/doc/data_sheet/MMA7260QT.pdf > is that you have some spectral components > without a move. Switching off the drives > makes sometimes a remarkable difference. > > Conclusion: not all vibrations are movement induced. > Absolutely! Some things like jerk can trigger resonances in the machine and show up in the measured velocity, but there are all sorts of mechanical events in a real machine. There are motor cogging, belt teeth, ball nut balls rolling against the screw and nut, and the linear slide itself. The sum of all this is a very complex spectrum.
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