topic Re: parametric inputs for clothoid loop in Inventor Forum

parametric inputs for clothoid loop

kevcarro — Wed, 16 Oct 2019 14:32:43 GMT

I am trying to make a clothoid loop curve for a roller coaster model except I cant seem to find the proper !MATHMATICAL! inputs to make it happen in the equation curve tool

Re: parametric inputs for clothoid loop

TheCADWhisperer — Wed, 16 Oct 2019 18:15:58 GMT

What version of Inventor are you using?

Can you use a 3D intersection rather than equation curve?

Re: parametric inputs for clothoid loop

kevcarro — Mon, 04 Nov 2019 16:08:13 GMT

Version 2020

A 3d intersection isnt as clean

I think the issue I had before was that I wasnt entering the function in the form of an integral but I dont know how to submit it as such

Re: parametric inputs for clothoid loop

johnsonshiue — Mon, 04 Nov 2019 22:16:44 GMT

Hi! Please share your attempt here. There should be a workflow in Inventor to do that.

Many thanks!

Re: parametric inputs for clothoid loop

kevcarro — Tue, 05 Nov 2019 13:32:42 GMT

Yeah there is..... its called telling me how to input an integral in the equation curve tool.

Re: parametric inputs for clothoid loop

TheCADWhisperer — Tue, 05 Nov 2019 13:44:48 GMT

@kevcarro wrote:
A 3d intersection isnt as clean

What is your manufacturing/assembly tolerance for the finished design?

Re: parametric inputs for clothoid loop

kevcarro — Tue, 05 Nov 2019 21:56:15 GMT

Here is the unclean version now how about you guys just tell me how do I properly go about implementing the fresnel integrals into the equation curve tool since apparently it wont let me just copy/paste the ∫ symbol into it

Re: parametric inputs for clothoid loop

johnsonshiue — Tue, 05 Nov 2019 23:08:16 GMT

Hi! Could you zip up the file and attach it here?

Many thanks!

Re: parametric inputs for clothoid loop

kevcarro — Wed, 06 Nov 2019 00:32:57 GMT

Hi! could you tell me why you arent divulging the cleaner faster method of just using the equation tool?

Many thanks!

Re: parametric inputs for clothoid loop

johnsonshiue — Thu, 07 Nov 2019 00:31:01 GMT

Hi! I believe there are equations available to tackle this curve. Google it and you may find some suitable equations. In 3D Equation Curve, make sure you set coordinate system to Cylindrical. It will make life much easier. I don't think using the spline is the right approach in your case.

Many thanks!

Re: parametric inputs for clothoid loop

kevcarro — Thu, 07 Nov 2019 02:27:15 GMT

OMG YOU'RE NOT EVEN PAYING ATTENTION TO MY LAST POSTS

I ALREADY TOLD AND SHOWED YOU THE EQUATION THAT I NEED TO USE BUT THE EQUATION IS IN INTEGRAL FORM AND THE EQUATION CURVE TOOL WONT SEEM TO LET ME USE THE ∫ SYMBOL

HOW DO I INPUT INTEGRALS GAWD **** IT!!!!!!!

Re: parametric inputs for clothoid loop

karthur1 — Thu, 07 Nov 2019 20:27:59 GMT

You can't enter an Integral as an equation in Inventor. Integrals are not used to plot functions. You can enter the clothoid function in Inventor. There are a few different ways to approach this, but the easiest I found is to use a 3D equation curve. For the x-coordinate, it will be a function of Cos (t) and the y-Coord will be a function of sin (t). I am not sure of some of the constants you are working with, but this is what I came up with for a sample curve.

The function that I used for this is:

Re: parametric inputs for clothoid loop

kevcarro — Thu, 07 Nov 2019 20:51:28 GMT

Thank you for getting the closest answer but is there one to make a perfect clothoid?

https://www.physicsclassroom.com/Class/circles/u6l2b2.gif

Re: parametric inputs for clothoid loop

karthur1 — Thu, 07 Nov 2019 21:14:17 GMT

"Perfect" would be left for interpretation. Here is a webpage that will plot a parametric equation. With this you can quickly see the shape and tell if it is where you want it to be. You can always scale it and get it where it needs to be in Inventor.

Re: parametric inputs for clothoid loop

kevcarro — Fri, 08 Nov 2019 10:15:27 GMT

Seriously how are you a software engineer when it seems quite apparent that you fail at reading comprehension?