topic Re: Is it possible to update/change the COG for different model states in Inventor Forum

Is it possible to update/change the COG for different model states

jwmontgomeryGZ7Z8 — Thu, 12 Dec 2024 17:00:25 GMT

Hello all, I'm an intermediate Inventor user. I just started with a new organization and I need to take an existing model and do a study that requires showing the COG in 3 different model states. In each model state items are suppressed/shown as needed.

These are existing models that are being used by others in other projects, so I want to avoid doing Save-As to make 3 different iam files to show the proper COG.

Is there a way to show the updated COG per model state within the same file? When I change model states the COG is stagnant and does not change even after updating the iproperties.

Thanks in advance.

Re: Is it possible to update/change the COG for different model states

kacper.suchomski — Thu, 12 Dec 2024 17:28:41 GMT

The center of gravity updates automatically when you power it up again. If you click the COG commands twice, you will get the updated version.

Re: Is it possible to update/change the COG for different model states

jwmontgomeryGZ7Z8 — Thu, 12 Dec 2024 19:00:38 GMT

Thank you. Unfortunately, I'm trying to update the COG as I change model states (configurations). So, if I decrease the overall size of a structure then the COG should move significantly. It is not. I've tried recreating the different model states but that has led to other problems.

Re: Is it possible to update/change the COG for different model states

andrewiv — Thu, 12 Dec 2024 19:17:05 GMT

The COG will only move if you do an update to the mass properties. There are different ways to do this update but you can't just suppress a part and have the COG move instantly. You could write an iLogic rule to update mass and add it to the model state activated event trigger to make it update whenever you change model state or suppress a component. I think this would satisfy your request.

Re: Is it possible to update/change the COG for different model states

pcrawley — Thu, 12 Dec 2024 20:37:25 GMT

You can 'force' the mass properties to update by a single line of iLogic:

mass = iProperties.Mass

Save this in a rule (or an external rule if you want to use it on any assembly).

Go to Manage > Event Triggers and drop your rule under "Model State Activated".

Now any Model State activation (or change) causes the rule to run - update the mass - and the CofG indicator updates immediately.

Re: Is it possible to update/change the COG for different model states

jwmontgomeryGZ7Z8 — Fri, 13 Dec 2024 15:12:23 GMT

This may work. I will let you know if this works for me.

Re: Is it possible to update/change the COG for different model states

jwmontgomeryGZ7Z8 — Fri, 13 Dec 2024 15:14:53 GMT

If it was an issue of having to go into iProperties and updating then I would completely be fine with that. However, when I do that, the COG is still (painfully) obviously incorrect for the given model state. It's as if the items are not suppressed but only the visibility is turned off. Please note that this is an assembly that has utilized frame generator. I don't know if that might have anything to do with the problem.

Re: Is it possible to update/change the COG for different model states

jwmontgomeryGZ7Z8 — Mon, 16 Dec 2024 20:50:16 GMT

Thank you for the solution. The rule is great and works well. However, it doesn't solve the problem. I'm afraid that as soon as I can return to this item it will have to be remodeled.

Re: Is it possible to update/change the COG for different model states

pcrawley — Mon, 16 Dec 2024 20:56:32 GMT

I don't understand what you are asking.

"I'm afraid that as soon as I can return to this item it will have to be remodeled." - What "item" are you returning to?

Re: Is it possible to update/change the COG for different model states

kacper.suchomski — Wed, 25 Dec 2024 18:38:53 GMT

I tested Peter's rule and everything works fine.
Can you describe your problem?

Re: Is it possible to update/change the COG for different model states

jwmontgomeryGZ7Z8 — Tue, 31 Dec 2024 16:31:22 GMT

Yes sir.

Scenerio: So, let's say you have a skid that gets bolted together. This skid gets lifted all bolted together and also gets lifted as 2 separate weldments. These 2 weldments are not equal. So, there are three lifting arrangements (configurations) to be made with 3 different COG (1 COG per lifting arrangement).

The model: The model was built as 1 assembly. It's not how I would have done it, but that is the situation. The different configurations are within the same assembly. Each configuration has a model state. So, 1 model state per lifting arrangement. I believe it was created like this because it was faster at the time. They used frame generator.

The problem: As I activate different model states the COG does not update to a realistic position. It does not update even after you manually update or run the iLogic. I've been advised "DO NOT REMODEL."

Trouble shooting: I've tried recreating the model states with my manager supervising me as a second pair of eyes, but that did not fix the issue. In other software, I know you can suppress items and the COG updates accordingly. I called up old colleagues that still use Inventor and had them test it on different networks, licenses, etc. and they all faced the same problem I have. Their solutions were to use promote/demote to create subassemblies. (This is more how I would have organized the files.) However, frame generator doesn't allow me to separate the skeleton like that.

The only fix I see is remodeling as 2 separate weldment assemblies and then putting those together as 1 main assembly. Thankfully this is background noise for me since I'm working on other projects.

Re: Is it possible to update/change the COG for different model states

kacper.suchomski — Tue, 31 Dec 2024 16:45:01 GMT

Try this:

' Iteracja przez komponenty zespołu Dim comp As ComponentOccurrence For Each comp In ThisApplication.ActiveDocument.ComponentDefinition.Occurrences ' Odczytanie masy komponentu, co automatycznie wymusza jej aktualizację Dim compMass As Double = comp.MassProperties.Mass Next ' Aktualizacja masy i środka ciężkości zespołu Dim assemblyMass As Double = ThisApplication.ActiveDocument.ComponentDefinition.MassProperties.Mass Dim assemblyCenterOfMass As Point = ThisApplication.ActiveDocument.ComponentDefinition.MassProperties.CenterOfMass

Also, remember to set the modem state activation as the trigger.

Re: Is it possible to update/change the COG for different model states

jeanchile — Tue, 31 Dec 2024 18:45:42 GMT

I know exactly what you are talking about, and we have encountered the "exact same" issue (meaning different scenario, but really the same thing). Where do you want this COG represented? Is this just for your internal design use? Do you also want the lifting lugs to change positions based on the new COG?

We have to do this for a lot of our Critical Lift Plans and we've never encounterd a good solution. There are work-arounds though, depending upon who in your chain eventually needs to see this "updating" COG. Post more if you can and I'll try to help (e.g. if it's just a rigging drawing, it could be simple).

Re: Is it possible to update/change the COG for different model states

jwmontgomeryGZ7Z8 — Tue, 31 Dec 2024 21:55:02 GMT

Excellent! Finally someone on the same page. So yeah, they are basically for rigging drawings. We don't need the lugs/padeyes to change or tilt. We are planning for some slight out of plane lifts onvthe lightest lift. Also, compared to places I've worked in the past thus would not be a critical lift. This is less than 10t. I unfortunately cannot share any geometry on here and I can get a very good approximate COG, but eas just wondering if i was doing something wrong. Thank uou so much.