NX Motion Simulation: Joint Limits 1

[schmied]

Hi!

After having gathered a host of valuable information from these forums, I have now joined eng-tips.com, because I can't seem to find an answer to a problem I am having in NX (6) Motion Simulation.

I have added limits to a slider joint, but when I solve my mechanism (using RecurDyn), it runs right past the limit. What am I missing (or what other information do I need to provide for anyone to be able to tell me what I am missing)?

Thanks, and greetings from Germany,
Karsten

 

[schmied]

Don't mean to be rude by bumping my first thread on this forum, but my mechanism's shooting past the set limits is driving me nuts.

I've defined a slider joint to have a lower limit of 0 and an upper limit of 500mm. If I add a constant scalar force to the mechanism (and give it enough time), the moving link goes past the limit and continues straight on into sweet oblivion. Expected behaviour would be that no matter what force is applied, the link stops at 500mm. The Documentation simply states: "Select check box and enter values," which doesn't seem to cut it (for me).

Please, anyone?
Karsten

 

[jmarkus]

I figured I'd piggy-back off this thread because I'm looking for the answer as well. I noticed in the documentation that limits only apply to the articulation motion driver. So how do I limit something using other (e.g. velocity) motion drivers?

I tried to set up 3D contact between solids so the link in question would stop up against the other (fixed) link, but it just passes right through.

Any and all help is appreciated.

Thanks,
Jeff

 

[schmied]

It's been a while... ;-)

You are right: limits only apply to the articulation driver, and for everything else, 3D Contacts are the way to go. It's a little tricky getting them to work and if you have complicated geometry, Motion may or may not go postal on you. The trick is (IIRC) to tweak the penetration depth and reaction force just right for your Links to neither pass through each other nor be unnaturally pushed away.

Can't tell you more about it, it's a long while since I played with 3D Contacts in NX Motion, sorry. But hang in there, I'm sure you'll get it to work.

Karsten