topic Re: Any way to create a "driven constraint" that behaves like a driven dimension? in Inventor Forum

Any way to create a "driven constraint" that behaves like a driven dimension?

LSKELLY — Fri, 01 Oct 2021 20:31:13 GMT

Please don't confuse my question with the "drive constraint" function.

I wonder if anybody knows how (or knows a workaround) to create a "driven constraint". In part sketches, you can set dimensions as driven, after which they behave more like a measuring tape than a constraining device. I think it would be very useful if assembly constraints could be set in the same way that they do not fix objects in place but rather provide a "readout" in a parameter.

I have looked around the internet/forums and found nothing. However, it makes no sense to me that such a feature does not exist as I think it would be very useful for a number of applications and I can't imagine that programming this functionality would be too much more complicated than including regular constraints in the software.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

JDMather — Fri, 01 Oct 2021 20:34:49 GMT

@LSKELLY wrote:

I wonder if anybody knows how (or knows a workaround) to create a "driven constraint".

This is pretty easy to do.

Can you Attach your assembly here?

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

LSKELLY — Fri, 01 Oct 2021 21:22:25 GMT

@JDMather

Thanks for the quick reply. I have attached my working files in a RAR file.

In the main assembly Tipper Skip 01 Assembly.iam, I have created the dimensions "Translation" (d3) and "Tipping Angle" (d8).

If I manually alter d8 (between 0° and 35°), the formula in d3 moves the skip to simulate a rolling motion. The problem is, I cannot loosen d8 so that I can simulate the rolling motion by dragging the skip with my mouse pointer.

It would be nice if I could suppress d8 and have the d8 parameter still keep track of its value as I drag it around. That way the formula in d3 could still calculate the appropriate translation accordingly.

I hope this illustrates what I mean.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

JDMather — Sat, 02 Oct 2021 11:07:43 GMT

@LSKELLY wrote:

@JDMather

Thanks for the quick reply. I have attached my working files in a RAR file.

I don’t own a license to a rar extractor on my clean Inventor machine.

I only own a license of Windows 10 for zipping/extracting *.zip files on my clean Inventor machine. I have no interest in installing other software.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

SBix26 — Sat, 02 Oct 2021 13:23:02 GMT

Here you go, @JDMather . Inventor 2021 files.

Sam B
Inventor Pro 2022.1.1 | Windows 10 Home 21H1
LinkedIn

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

LSKELLY — Sat, 02 Oct 2021 13:28:44 GMT

@JDMather

I have attached a Zip File instead.

Same description applies.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

JDMather — Sun, 03 Oct 2021 15:44:26 GMT

@LSKELLY wrote:

However, it makes no sense to me that such a feature does not exist...

@LSKELLY

Are you familiar with the Environments>Dynamic Simulation in Inventor Professional?

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

JDMather — Sun, 03 Oct 2021 16:25:46 GMT

I have changed the problem description a bit.

We can also add Traces to keep track of the distances between points while moving.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

BDCollett — Mon, 04 Oct 2021 03:44:48 GMT

JD's solution gives you the best real world results. I think I could also do something to simulate this with iLogic driving your constraints outside the simulation environment. I can't look at the files right now however.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

LSKELLY — Mon, 04 Oct 2021 05:10:29 GMT

Thanks @JDMather

I had no idea about dynamic simulation. Good to know that you can allow gravity to play out like that. I can think of a million places I could use this.

Although I did not intend for the skip to drag along the base. A later screenshot of the model shows the locating teeth.

Although your answer will be useful to me I really want to drag it around and play with it in the normal Inventor environment as one would with a cylinder-powered lever system, for example.

It occurred to me that a constraint-like feature whose purpose is not to constrain but rather to measure would be very useful to achieve this. Perhaps I could add a post for suggestions for AutoDesk in this regard.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

BDCollett — Mon, 04 Oct 2021 09:51:16 GMT

@LSKELLY wrote:
Thanks @JDMather

I had no idea about dynamic simulation. Good to know that you can allow gravity to play out like that. I can think of a million places I could use this.

Although I did not intend for the skip to drag along the base. A later screenshot of the model shows the locating teeth.

Although your answer will be useful to me I really want to drag it around and play with it in the normal Inventor environment as one would with a cylinder-powered lever system, for example.

It occurred to me that a constraint-like feature whose purpose is not to constrain but rather to measure would be very useful to achieve this. Perhaps I could add a post for suggestions for AutoDesk in this regard.

That does sound great in theory. Probably not so simple in reality.

In the past when I have built something like this and I need to see the motion I will drive the dimensions in the background with iLogic and forms. Then you can drag a slider and have it move as you expect. You can simulate some very complex motion with 2d blocks and have that control an assembly.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

JDMather — Mon, 04 Oct 2021 11:20:22 GMT

@LSKELLY wrote:

Although I did not intend for the skip to drag along the base. A later screenshot of the model shows the locating teeth….

….as one would with a cylinder-powered lever system, for example.

Can you Attach the new assembly here?

I do not see the “cylinder-powered” mechanism in your image?

Approximately where will it be located?

All of this can be done with Sketch Blocks before even modeling solid bodies.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

admaiora — Mon, 04 Oct 2021 11:27:37 GMT

No sure of the final objective.

Can something like this work?

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

LSKELLY — Mon, 04 Oct 2021 17:23:51 GMT

@admaiora

That looks about right!

Was that done in the context of a dynamic simulation or in the context of a normal assembly?

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

LSKELLY — Mon, 04 Oct 2021 17:28:59 GMT

Thanks for the suggestions @BDCollett .

I will give the prospect of using iLogic a bit of thought. I never thought of using a slider in conjunction with iLogic.

Was just hoping to make it roll in a regular assembly though, the way you might drag a lever mechanism around in a regular assembly with the angle constraints suppressed.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

swalton — Mon, 04 Oct 2021 17:43:37 GMT

Would a 3d annotation in the assembly give you an useful dimension readout?

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

admaiora — Mon, 04 Oct 2021 17:45:59 GMT

@LSKELLY

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

JDMather — Mon, 04 Oct 2021 18:22:17 GMT

Is this where you are heading?

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

BDCollett — Tue, 05 Oct 2021 00:15:05 GMT

@JDMather wrote:
Is this where you are heading?

This is what I was suggesting. From here you can drive any kind of output information you might want. Nice work JD.

Re: Any way to create a "driven constraint" that behaves like a driven dimension?

LSKELLY — Tue, 05 Oct 2021 17:40:23 GMT

Sorry @JDMather.

The cylinder-and-linkage mechanism I mentioned was just an example. I was saying I would like to drag the rolling skip freely in a normal assembly, in the same way that one might drag a cylinder and linkage assembly. An unintentional red-herring.

To further illustrate my goal, it seems it is possible to achieve exactly the desired result in a sketch, but not in an assembly. I have attached a part containing a sketch. the sketch is missing one constraint which is left free to be able to drag it (best results by dragging the point at the center of the arc, I found). Give it a whirl.

Why is it possible to mathematically create rolling motion in a sketch? Because sketches allow you to create driven dimensions. What I am looking for is an assembly constraint equivalent to a driven dimension. To the best of my knowledge, no such entity exists for assembly constraints.

Also, I am asking not only for the application of the tipper skip example. The tipper skip example is only one place where this type of "driven constraint" might be useful. Theoretically, one could use such a type of constraint to make all kinds of mathematically complex motions.