Inventor Assembly Constaints Functioning Improperly

[rrichardson]

Hello,

I currently have a file which contains 1/2 of a profiled conveyor belt assembly.  I import two instances of this part and attempt to constain them together to give a compelted belt. 

After only placing 2 constaints to "glue" the two pieces together I am unable to move the resulting part.  Even tho I only have 1 Mate & 1 Flush constaint and no grounded items, I cannot move the completed "glued" part.

This isnt the only instance that I have been encountering problems with Inventors constaint system when working in an assembly.  I have also had parts which should have a degree of freedom remaining but are unable to move, yet when I suppress ALL constaints associated with the ungrounded item, I still cannot move the item.

Please let me know if I need to submit any additional information to diagnose this issue.

Thanks

Edit - I have changed my selection filter between "Part Priority" and "Component Priority" to no avail.

[dan_inv09]

First, let's try restarting.

Second, what are your system specs and Inventor version (also Service Packs/etc.)?

The assembly is nothing but two instances of of the same part? Just how complex is the part?

Do you have Updates Deferred? Have you tried clicking Update?

I've had ungrounded parts that wouldn't move but not for quite a while and usually when I had something like a long pipe assembly where everything was daisy-chained together, only constrained to the parts it was touching. But in addition to the parts acting as if they were grounded, there was a general lag as well.

[rrichardson]

Hello Dan,

Thank you for the response!

I updated to SP2 and restarted my machine, but this did not solve the issue.

I was able to debug the problem myself and thought I would share the solution.

It is actually a 2MB assembly file with approx 75 part files (including 20 subassemblies).  It is a profiled conveyor system which interfaces with a drop bucket system.

The problem appeared to be a number of "sick constraints" that were unrelated to the parts in question.  Basically I had sets of brackets with 3 constraints applied to them, 1 Mate (face to face) and 2 Mate (Axis to Axis) which aligned a bracket and 2 mounting holes to a plate.  The second Axis to Axis alignment was considered to be "sick" even tho the spacing between all features was equivelent (the bracket holes were derived from the plate via top down modeling in the Assembly environment).  These "sick constraints" appeared to be causing a problem, after I suppressed these the other items would move correctly according to the constraints attached to them i.e. I can not suppress constraints on other items to allow them to move.

I hope this helps anyone else encountering this issue and maybe it is something that Autodesk can look into....I am unsure why a constraint unassociated with the parts in question lock the parts into place.

[johnsonshiue]

Hi! Purely based on your description and similar examples I had seen before, I bet the part you are trying to move is adaptive to other parts. An adaptive part is not allowed to be dragged, because draggging constraint solving is a mutually effective process (driver and slave). In this case, the adaptive part is driven by another part, so it cannot "drive" other parts.

I believe if you turn off the adaptivity on the part (right-click -> uncheck adaptive), the part will become draggable.

Thanks!

[rrichardson]

John,

Thank you for following up with me, the feedback is very helpful!

I believed this to be the case as well, before posting I removed all adaptive links and references from all parts.  This did not resolve my issue.  I would be more than happy to provide a copy of the assembly before the sick constraints were suppressed if you would find this helpful.  I am using Inventor 2014 SP2 on a Windows 7 SP1 64 bit machine

[dan_inv09]

I think the problem is that when you try to move anything it wants to check all the constraints in case things need to move together.

Not being able to move a part is preferable to locking up or crashing - but some sort of error message would be nice.

Even better would be if it could point directly to the problem constraints. Maybe the error dialog could include a button to temporarily ignore any sick constraints, or to suppress them (I'd want them flagged differently than constraints that may have been suppressed for other reasons - although maybe I could just get in the habit of renaming suppressed constraints to indicate why they are suppressed and why I might need to unsuppress them at some point.)

[johnsonshiue]

Hi! You can zip up the files and post it here or send it to me directly (johnson.shiue@autodesk.com). I would like to take a look at the files.

Many thanks!

[rrichardson]

Hello,

This is my first time sending an entire project so please bear with me.  I have bundled all the part files & assemblies together into one directory.

The assembly in question is Full.Conveyor.Rev3.iam

This file contains the complete system with the "sick constraints", I was attempting to move "Pulley.Bracket.Flipped:1" but was unable to move it after I suppressed all of the constraints.  After I diagnosed the "sick constraints" I can suppress the Pulley.Bracket.Flipped:1 constraints and it will move freely.

Please let me know if anything is unclear or if you require any additional information or files.

Thanks