spheres and dmu kinematics

[marcofa]

I reconnect to the previous post not solvedhttp://www.cad3d.it/forum1/showthread.php?t=8583 where I encountered problems simulating a mechanism in the presence of spherical joints.
now I have the same problem with spherical joints like those represented in the attached photo, where biella and crank must have spherical freedom.
There are degrees of freedom beyond which commands cannot be applied.
the biella crank with blue motor moves a pendulum.
Could someone explain to me how to do it?
Mar

 

[marcofa]

Come on, guys, can somebody give me some smoke? Nobody understands simulation? I don't believe it.
in a German forum I found only the information that the spherical joint must be accompanied by another joint (rotation, planar, etc) to be able to work, but without giving explanations on how to do it.
Mar

 

[marcofa]

Can someone simulate this mechanism?
in the annex there is also a video of how it should move with only one command.
Mar

 

[ferrezio]

Hello Marco

no I can help you immediately because I have the pc ko, but in memory, I seem to remember that in dmu there is the spherical alley, and in the environment product you can simulate the spherical coupling I assign a bond of coincidence point.

I'll let you know when I can check.

Hi.

 

[www.cad-3d.net]

Hello, Marco.

I think I understand the ark.

I write in "key" and not privately because it could be useful to others too.

if you grasp in the subtle part the "bilanciere" with the two spheres at the ends and move it this you can move with more than one degree of freedom and this is index of the fact that the structure is not "isostatic" (I say so to make me understand with less words) even if the total of the gdl would seem to give value 1 giving the guarantee of being able to govern the mechanism with only one command.

In fact, as I suggested in the previous message, the structure is with a "intrinsic" lability and this makes go in "panne" the mathematics of the solver. This also explains why by inserting the other joint instead of one of the two sphericals the mechanism can move.

Greeting! ! !


of the noble

 

[marcofa]

I attach the model with the changes (addition of universal joint) and perfectly working.
the intermediate biella with the two spherical joints maintains the freedom of rotation along its axis, but this does not affect the operation or compels to a further command.
Thank you, sir.
Mar