Constraints using Inventor models - axises not visible

[Oskar_Kos]

Hello everyone,

I am trying to investigate mechanism simulation in PTC Creo 4.0 using models imported from Autodesk Inventor 2017.

In the other topic I started (which unexpectedly dissapeared) I got information I should use mechanism constraints in the Creo to run mechanisms. I tried to do that, but I encoutered number of issues, if someone helps here, that would be highly appreciated:

Do I have to assembly whole model, part by part using PTC Creo constraints to study mechanisms? Is it possible to set only those constraints being meaningful for mechanism movement and left all the others as it was all set in the Inventor? I tried to do that but I found it impossible to change Inventor constraints to eg. Pin conection. I can't choose Pin conection (see attached)

 

At the same time when I tried to import Inventor parts one by one and tried to assembly them step by step I also was not able to do that. When I wanted to use Pin constraint that was possible, but I could not see the axises. Using parts created in Creo everything was all right. (see attached)

Thank you for all the support,

Oskar Kos

[MartinHanak]

Hi,

if you can replace original constraint set with new one, you have to uncheck Constraint Enabled option related to original set.

Please add data set for testing purposes, if you want someone help.

MH

[Oskar_Kos]

Hello,

Thank you for the answer.

After unchecking "Constraint Enabled" I indeed can disable particular constraint but adding new one I can not choose pin constraint and the others like one the picture below:

My goal is to import Inventor model, set the mechanism and export it via .FRA file into Keyshot software. I did it already with parts designed in Creo but in general I need to do that with much more complex model designed in Inventor. See video below:

https://youtu.be/h5TQ5JdwRHQ

Please find attached inventor model I try to do the same with. Hopefully it's gonna work that way.

Oskar Kos

[MartinHanak · Accepted solution]

Hi,

1.]

You have to create axes in 2nd and 3rd component.

2.]

You have to remove current assembly constraits related to 2nd and 3rd component and define new constraint sets. This step is necessary because components are assembled using Csys(component)-Csys(top assembly) constraint, only - this means 3rd component is not assembled relatively to 2nd component.

3.]

Creo 4.0 does not enable to combine standard and mechanism constraints. Older release have the same limitation.

4.]

Your goal - import Inventor assembly and create mechanism in Creo - is very time consuming. You have to rebuild the whole assembly using Inventor parts.

MH

[Oskar_Kos]

That is exactly what I was afraid of.

The only solution I see is to simplify a model in Inventor having all the assemblies exported as parts. I've never done it before, but may be an option.

Thank you guys for warm welcome on the forum and all the support from you.

Oskar

[psobejko]

I don't think redefining every component placement is necessary.  The sub-assemblies defined in inventor should stay "frozen" when they're imported into Creo because they should be resolved into Creo sub-assemblies.  (I don't have inventor, so I'm guessing here; but what I describe is what happens when STEP models are brought in).

Even in the nightmare case where the inventor model is a single level assembly of 1000 components, the process isn't so onerous - move the components that are meant to move as a unit into separate sub-assembly (just box-select, right-click and "Move to new sub-assembly").

You might need to go into this sub-assembly, select all the parts therein, right-click and "fix location", although at least with STEP files this step isn't necessary.

Then, once you have the model properly organized into sub-assemblies, few mechanism constraints placed between them should produce the correct motion.

BTW, you don't need to use axes to make pin joints - cylindrical surfaces work just as well.

Another tip related to slider-joints: having axes that define the relative direction of sliding motion is beneficial in that you can define this motion using a single connection;  but sometimes, it's just easier to make it work by assigning two planar connections.

[Oskar_Kos]

Psobejko, thank you for your reply.

Actually the tip to use pin constraint without using axises was very useful. I linked only moving sub-assemblies this way and it worked suprisingly easily. Thank you very much.

Now I have another issue. I want to prepare slightly more complex mechanism and export it to keyshot, as I mentioned already. Transfer to keyshot is being done by .fra file but I can export .fra file of only one analysys. I would like to have one playback consisted of two or more analysys to export via fra file some kind of sequence of movements.

Please see links below. I would like to do it in one file in keyshot:

First movement:

https://youtu.be/bYkppnk1KSg

Second one:

https://youtu.be/wKxb4CkqE5I

The another idea I have is maybe it is possible to set more advanced motor movements and by defining that prepare more complex sequences of movements. So far I foud it impossible.

Oskar Kos

[psobejko]

Hi!  I don't know about sequencing movements on keyshot side of things - and I don't know how to even create an FRA file from an analysis in Creo Mechanism, however; I think you can sequence servomotors and produce the whole movement in one single analysis.  Explore using the "motors" tab in the analysis definition:

in the above screenshot, I show one technique you can use if you want the arm to move one way and then the other: for joint 2 - I defined two servos - identical connection used, but the second one is "flipped" - and so from 9s to 18s the arm will turn to the left and then from 18s to 27s it will straighten out again...

[Oskar_Kos]

Sweet God, YOU ARE GREAT !

That is exactly what I was looking for ! Thank you very much! I did not figure out that you can set the timing for each motor in one analysis. Thank you very much once again, you saved a lot of my time.

The topic now became "off topic" a little bit but my problem has been definately solved. Thank you for your support and time. I will post the final render once it's done.

Oskar Kos

[Oskar_Kos]

Hello everyone,

I promised I'll share the final result of the project, once it's done. So if you have a while, please check the link below - that is short 'case study' briefly showing all steps of the animation design process. At the bottom you can see final result 🙂 Thank you once again for your support and enjoy the animation 🙂

http://cadilight.com/en/case-study/

[StephenW]

Very impressive animation.

[dschenken]

If you posted the evening before the change to the new forum, that post may not have been moved.

The imported files may not have axes. You may not have asked Inventor to export them or they are on a layer that is blanked and cannot be seen regardless of the axis environment visibility setting.

Since you aligned the coordinate systems in the first example, there is no way to convert that to a 'predefined' or motion connection.