Stephen Evans
Guest
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 Posted:
Tue Sep 28, 2004 2:08 pm Post subject:
Pro/MECHANISM Servo Motors |
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We're trying to conceptualise a new machine, and it would be great if we
could animate it in a very controlled way.
I've looked into Pro/MECHANISM and followed the tutorials, but come up with
a really big snag. If you define a servo to be table driven (i.e. indexing
from position to position), the analysis will always interpolate as a
spline, even if linear interpolation is selected.
The graph showing the servo's position will be linear, but the resulting
motion of the driven part will be a spline. This results in all sorts of
inaccuracies, and from what I've read on the PTC website (including a
horrible workaround) the dynamic analysis has to be done this way. My
rotating part overshoots the required position, comes back and then starts
again, never stopping.
If the same servo is created in the animation module it works as expected
but there appears to be less options and controls in the this module.
Has anyone gotten round this problem?
To be clear I want to rotate a part, pause, rotate again, pause, with no
smoothing and overshooting of the motion.
Stephen.
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meld_b
Guest
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| Posted:
Wed Sep 29, 2004 10:17 am Post subject:
Re: Pro/MECHANISM Servo Motors |
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Ah...Well I'm speaking from a Mechanica perspective... but I believe
that bringing in position vs. time tables always ends up a bit jerky. If
you work out what the acceleration is and put that in your table you can
then get smooth velocities and positions.
Everyone (including me) should write an enhancement request!
-meld
Stephen Evans wrote:
| Quote: | We're trying to conceptualise a new machine, and it would be great if we
could animate it in a very controlled way.
I've looked into Pro/MECHANISM and followed the tutorials, but come up with
a really big snag. If you define a servo to be table driven (i.e. indexing
from position to position), the analysis will always interpolate as a
spline, even if linear interpolation is selected.
The graph showing the servo's position will be linear, but the resulting
motion of the driven part will be a spline. This results in all sorts of
inaccuracies, and from what I've read on the PTC website (including a
horrible workaround) the dynamic analysis has to be done this way. My
rotating part overshoots the required position, comes back and then starts
again, never stopping.
If the same servo is created in the animation module it works as expected
but there appears to be less options and controls in the this module.
Has anyone gotten round this problem?
To be clear I want to rotate a part, pause, rotate again, pause, with no
smoothing and overshooting of the motion.
Stephen.
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