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375 Views 3 Replies Latest reply: May 24, 2013 1:24 AM by JWayman RSS
JWayman Silver 135 posts since
Oct 7, 2010
Currently Being Moderated

May 23, 2013 2:24 AM

Motion Skeletons

I am trying to use a Motion Skeleton to drive a pantograph mechanism.

I create my Motion Skeleton, create my Design Skeleton, create my (7) Body Skeletons, then try to put some limits on my axes.

Whenever I flex my Motion Skeleton, it seems hell-bent on folding up so that several of my Body Skeletons lie on top of each other. This is clearly not the case in the Design Skeleton. Once it has made up its mind to do this, there seems to be no way to get the offending Bodies to clamber off each other and resume a separate existence. It seems to me that the system has settled on what I believe to be an impossible configuration. Even if I am wrong, it is a highly unlikely configuration, and certainly not one that resembles the Design Skeleton sketch.

Now, call me an incurable optimist, but I am sure there must be an easy way to revert the Motion Skeleton to the configuration shown in the Design Skeleton. So far, I have been reduced to the age-old Pro/E recovery procedure of :

Delete the offending items and re-do them.

This is becoming tedious.

 

What clever twists am I missing?

 

Is there a 'Revert to Design Sketch' button staring me in the face?

Please say 'Yes.'

 

 

WF4, M220

 

Cheers,

 

 

John

  • TomD.inPDX Platinum 4,454 posts since
    May 25, 2012
    Currently Being Moderated
    May 23, 2013 8:27 AM (in response to JWayman)
    Re: Motion Skeletons

    Yes and no... not specifically a button but you can recover the previous mechanism "default state" if that is what you are looking for.

     

    The idea behind this is that you had run a Mechanism Analysis and saved it.  It can do anything, or nothing; you just need an analysis saved.  From there you would Play the analysis.  Slide the Play slider all the way to zero and exit.  This is the position of the start of the analysis that you ran earlier.

     

    Not elegant if you are not looking for motion, but it is the only way I have found to -reliably- reset the linked structure.

     

    Again, I am not sure this is fully applicable to your needs, but it is an observation I've made playing with mechanisms. 

     

    Of course, limits in your constraints are the other way to avoid illogical conditions but they are not the be-all and end-all solution.

  • vzak PTCEmployee 119 posts since
    Jul 12, 2008
    Currently Being Moderated
    May 23, 2013 2:18 PM (in response to JWayman)
    Re: Motion Skeletons

    JWayman

     

    Motion Skeleton is a regular mechanism in all meanings, same way mechanism can "collapse" so MS can.

    Easiest way to restore initial state of affairs is to create a snapshot right after you create your Body Skeletons.

     

    Then whenever your mechanism (of any type) collapses to an undesired position due to high # of DOFs you can restore initial position by one button hit.

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