Assembly Limit Constraint Range of Movement
There are two ways to accomplish what you are after:
- Constraint Limits - If you click the double arrow on the constraint box you will get the limits input. This is exactly what you referred to.
2. Contact Set + Contact Solver - The contact set/solver way is a little more true to life (albeit occasionally janky and heavy on processing). The contact solver makes Inventor function as if the bodies were truly solid. To use it you have to add parts to the contact set (right click on them and then check contact set) and then activate the contact solver (located under Inspect). The solver is a simple toggle on/off. When active, the parts will not penetrate each other. If their contact is complex, the solver can be quite slow. You'll find this to be a good tool for sanity checks, but not for constant usage.
Hello @fred.hillhouse I see that you are visiting as a new member to the Inventor Forum.
Welcome to the Autodesk Community!
Be careful when using limits as you can fudge your design and things look right but don't line up.
Would recommend designing to exacting specification and then add tolerance for manufacture.
Defining Positions and Relationships with Constraints and Joints
Assembly - Constrain and Place Parts with limited movement
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Kelly Young
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@fred.hillhouse thanks for supplying more information. If you don't want it to snap back, in the Constraint Limits, uncheck Use Offest as Resting Position. It will be free to move to the Min/Max Limits.
It sounds like you are trying to setup constraints where if/then actions are happening. Ex: If the door is open, then the top can raise.
In the design stage this is a bit of overkill as you can perceive where they will collide with simple constraints but making the assembly intuitive for collision like this is not really necessary.
Where they will become more valuable is with Inventor Studio making animations showing how it is operated. You can drive the constraints to a certain distance over time.
For example:
- 1-5sec door opens. Animate Joint/Motion/Angle Contraint from 0-90°
- 5-10sec front roof opens. Animate Constraint from 0-45°
- 10-15sec rear roof opens. Animate Constraint from 0-45°
- 15-20sec support arms lock front and rear roof. Animate.
Not really sure if that makes sense. If you want to provide your parts (you can delete detail features to a create a simple part if necessary) we can show good methods for constraints and animations.
Hope that helps!
Please select the Accept as Solution button if a post solves your issue or answers your question.
Kelly Young
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Hi @fred.hillhouse,
Years back when I taught Inventor to professionals, I often used popsicle stick models as the hands-on exercise files. I found that it was much easier for users to visualize the picks and clicks and understand the concepts of the constraint, when working with something simple and familiar.
So with that in mind here is a simple model based off of the 10 second glimpse I took of the image at the link you provided... meaning that I know its not accurate to what you need, but it demonstrates the use of simple components used to set up a proof of concept.
If mythbusters has taught us anything, it's to start with small scale models to prove out our ideas... and that we learn a lot from proving our assumptions wrong.
See the attached 2017 files and maybe try building your basic mechanism with these stick models to see if constraint limits will work for you, and if so which ones. and how they need to be set up.
In the example I've attached I actually use 2 constraints with limits, one Flush constraint on work planes, and one Angle constraint. Using them together has some advantages, in that you can say I want to limit the angle to a max of X, and I want to limit the travel of the flush constraint to max of Y. You simply set the minimum angle to be less than what the flush constraint allows, and vice-versa.
Typically when doing this kind of thing you have to create one, set the limits, get it how you want it, then suppress it. Then create the other, work out the limits for it, ensuring that they will not conflict with the other, and then once it's set up you can un-suppress the other.
If your needs are for switching between constraints sets, meaning suppressing constraint_B when constraint_A reaches a value of X, then I think a tiny bit of iLogic will be the way to go. If you get to that point with a simple stick model data set, post back and I'm sure someone will be able to help.
I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com
Hi @fred.hillhouse,
Ahh, those files help. I think the flexible sub assemblies were getting in the way. See the attached 2017 files for how I think you want to set this up.
edit: btw your simple proof of concept models were perfect!
I watched this to get a better idea of the desired motion:
I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com
@fred.hillhouse thanks for attaching the parts, much easier to see what you're trying to accomplish.
Made a somewhat longer screencast but wanted to show how to take parts with relationships and easily Derive reference between them.
Where the setup pays off is at the end where you can change any of the dimensions and the parts update without losing geometry or constraints.
Wanted to show you a few different ways to draw and edit the Derive Properties to really show how they work. Have to turn on Sketch Visibility in order to link the sketch to the derived part.
If you use Joint Constraint you don't have to have any other flush/mate constraints. As a general rule, always Ground and Root your most stationary/base component.
If there are not any motion constraints you can just Ground and Root Component for all parts and they will just immediately drop into place like initially shown when the parts were first brought in.
Good start, hope this helps!
Please select the Accept as Solution button if a post solves your issue or answers your question.
Kelly Young
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@fred.hillhouse no audio, I should probably start. Unfortunately the only way to slow it down is for me to slow down.
Kelly Young
* Ideas * Help * AKN * Updates * Pack & Go * Reset Utility * Repair Install * Customization * iLogic Examples * Autodesk University *
