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Schreeching Axis

Mary West
Intellectual 400 points

Hi -

I'm evaluating InstaSPIN control to replace existing motor control in our products.  I have one axis that screeches when I do a long move in one direction and is quiet when I move it in the opposite direction.  The videos are attached.

I've changed bandwidth and all bandwidths settings when it successfully runs exhibit the noise.  I've played with acceleration and jerk and still get noisy moves in the one direction.  If I lower the velocity significantly, the noise goes away.  I get the noise with both ST and S-curve profiles.

This motor uses an off-axis linear encoder.  The actual number of encoder counts per motor revolution is fractional (6502.4 counts).  The qep is set up with (4*1626 -1) counts which is 6503.  Could this be the source of the noise in one direction?

The position error on the noisy move looks good compared to our current motor control, but the screeching is a problem.

Thanks-

Mary

Click here to play this videoClick here to play this video

  • 0
    Intellectual 400 points
    Update -

    I reinstalled my original board with the original controller to see if the axis would screech when moving backward. It would not even move before erroring out. So - InstaSPIN came out miles ahead. It moved the axis the full distance and did a good job keeping the position error low. It turned out that a car that was holding the unit onto a set of rails had become misaligned. Once this was remedied, the axis could move again. On Tuesday, I will reinstall the InstaSPIN board and I bet that the noise goes away.... Stay tuned.

    Thanks-
    Mary
  • 0 in reply to Mary West
    Guru 12800 points

    Mary,

    I'm glad that you were able to get the problem (hopefully) resolved!