point on a curve

[gking]

Hi all,

Is it possible in Creo to create a point on a 2D curve in
the most extreme position in one direction. For example,
if I have a spline on the XY plane, I want to pick the
point with the maximum X co-ordinate.

Having used Catia for a number of years this can be
achieved by using the extremum point function.

Thanks in advance.

 

[kenppy]

I don't think there is a direct way of doing this but a workround is tomake a datum point on the curve and use the xy plane as the offset reference, then drag the point till to it's max value -- you will have to put the second and third decimal places in by hand. Not pretty but it worked when I needed it.

 

[gking]

@kenppy Thanks for the work around. I'll give it a try.

 

[design-engine]

what is a point with a maximum coordinate?

 

[solidworm]

Thats easy in Creo, in fact the toolset you have in Creo

for this kind of work,is a lot more versatile than

Catia's but you need to have BMX license. <a href="https://docs.google.com/open?id=0BzwwE53MwdQ4NnNTbVF6ZktvLUU" target="_blank" target="_blank">here's a video

of the process you need to follow.</a>
in the video you see that i place a "field point" on the

curve and then measure the distance between the "field

point" and the x-plane. then when i make a "user defiened

alalysis", creo moves this "field pint" along the curve

and measures the distance in every step of the move and

represent the result as a graph, then you can ask creo to

place a point where the minimum or maximum of the

measurement occurs!


Edited by: solidworm

 

[gking]

@solidworm this is exactly what I need. Thanks for
posting
the video link. Just need to check now that I have all
the
appropriate licences!

@design-engine, maybe maximum coordinate is the wrong
term
but I want the most positive value for X that lies on the
curve.

Thanks guys.

Unfortunately I don't have the BMX extension
Edited by: gking

 

[tobbo]

if you do a simple "measurement" , you can have proE to add a point on the curve.Just add a plane in the direction you want to know the most extreme point and measure. Since your dimension will be taken at the point on the curve where the distance to the planeis the smallest.


In measure, pick your curve, and pick a plane i one dir, and set the option to "feature" instead of "quick". then in the feature tab, check the box that will give you a point. Works on curves and on surfaces.


If thats what you are looking for.. or maybe i misunderstood you .


2012-09-11_023354_measure.prt.1.zip


//Tobias

 

[solidworm]

Very cool tobbo, simple and fast!

Edited by: solidworm

 

[gking]

@tobbo this is it. great. thanks.

 

[cpoirier]

Anyone know how to extract an equation for a curve from the cad model?
Is it even possible? What would even be cooler is if the system would do it with respect to a selected C-sys, no need to transform once extracted.

If you think about what a solid model is and what the system does to make it work this is child's play, must be rolling around in there somewhere. Even better I take it for granted every day.


Chris

 

[tobbo]

@cpoirier , I think this topic has been discussed before. You might find something here:


[url]http://www.mcadcentral.com/proe/forum/forum_posts.asp?TID=43 880&KW=equation+from+a+curve&PN=0&TPN=1 [/url]


Personally i doubt that you can findthe equation for "any" curve, but it might be possible for some curves?





When do you want to use this?


//Tobias

 

[SRINIVASANIYER1]

Anyone know how to extract an equation for a curve from the cad model?

Such a thing is not possible using a CAD software. However, you may proceed thus.


Create multiple points on the curve. The number of points can depend on the complexity of the curve.


Use Lagrange's Interpolation methods to derive the equation of a polynomial that passes through the points.


http://nd.edu/~jjwteach/441/PdfNotes/lecture6.pdf


http://en.wikipedia.org/wiki/Lagrange_polynomial

 

[solidworm]

Anyone know how to extract an equation
for a curve from the cad model?

that is in fact possible, at least in Creo and Rhino,but
the equations aren't explicit. it gives you the required
information (i.e curve type,degree,knots and control
point
coordinates) to calculate the coefficients of a general
equation. then you have to research and find the general
equation of that type of curve (spline,B-
spline,NURBS,etc)
try "debug" tool for that type of information.once i
showed where it in the menus, so if you search,you can
find out:
http://www.mcadcentral.com/proe/forum/forum_posts.asp?
TID=42704&PN=28&TPN=1
Edited by: solidworm