Re: Problems creating a coiled bulb filament.

MeDaveo · ‎Dec 08, 2011

Hi There,

I'm a little new to Pro-E so please bear with me on this. Thanks.

I'm currently using WF4 on 32-bit XP and need to create a bulb filament i.e. a helical coil. I've looked at some other examples of this requirement but am still a little confused as to the process right from the beginning.

I have created springs using a helical sweep as this is fairly straight forward but my math is not the best so understanding the 'Trajpar' equation etc is a bit taxing on my already wheezing brain. I've been practising and trying to understand this for over a day now. (don't tell my boss)

I came across a post quoting (Denavit-Hartenberg aproximation) ( 9 homogeneus matrix). This is new to me but the part is exactly what i'm looking to create however the example Rar file does not work on my PC. (64-bit part on my 32-bit PC perhaps) This would have been very useful to see how it was created using 'edit definition' maybe? Also the equation uses symbols i cannot find the definition off anywhere i.e.

X = c1*(c2*(c3*l3+l2)+l1)-l3*s1*s3
y = c1*l3*s3+(c2*(c3*l3+l2)+l1)*s1
z = (c3*l3+l2)*s2

Should c, l, & s just be numeric values or does it mean something more?

Apologies in advance for my limited math capability but can anyone help me with this please?

Regards,

Dave...

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BrianMartin · ‎Dec 12, 2011

Hi Dave...

The c, l, and s are numeric values... but they also mean something more. Your best bet it to go back to the trajpar solution.

For any SWEEP with a defined trajectory, trajpar varies from 0 to 1 down the length of the trajectory. This seems easy enough... and utterly useless at first glance. However, you can use this trajpar variable to create intricate patterns and variations along the trajectory. You've probably seem Vladimir Palffy's trajpar tutorial wherein he creates some crazy geometry with this variable. If not, check it out here:

http://communities.ptc.com/blogs/vpalffy/2011/02/09/user-defined-springs

If you're trying to create the coiled helical halo from the Denavit-Hartenberg discussion, you can use the matrix (which is WAY over my head), or you can use trajpar like Vladimir does.

Here, I used trajpar to create the first coil... then used that as the basis for the second coil. I was able to sketch out my last initial "M" and use that to wrap a coil around a coil... then make it hollow! Click the image for a larger size.

So Dave... what kind of shape are you after? Is it a simple coil of a coil... or something more complex? What shape is your filament?

Thanks!

-Brian

MeDaveo · ‎Dec 16, 2011

Hi Brian thanks for the info.

I managed to create the coiled coil using that (Denavit-Hartenberg aproximation) ( 9 homogeneus matrix). I noticed the equation further down the post, copy and paste and hey presto. (Thanks to Faustino Garcia)

I've created the filament as a standard 5.6 turn Coiled coil. Nothing fancy but i'm going model it into a particular bulb used at my work for analysis etc. Problem is my rig fell over at 3.5+ turns of the large coil.

New hardware on its way, hopefully soon.

I see what you mean with the trajpar but i need to try a few examples 1st i think.

I'm actually trying to create a zig zag circle now so i can sweep a tread like pattern in a tyre. Any ideas?

Regards,

Dave

John.Pryal · ‎Dec 20, 2011

Hi David,

as far as your tread like pattern is concerned, i'm not 100% sure i understand your requirements, but have you considered using Toroidal Bend? (insert, advanced, toroidal bend). I could be barking up the wrong tree here, but i saw the words tread & tyre, & i have seen a tutorial somewhere in the past using this technique to create such a thing.

Regards

John

Patriot_1776 · ‎Dec 21, 2011

"zig-Zag coil"? Huh? Do you want to sketch that out for us? I'm familiar with "coiled coils" from my short stint making miniature lamps for Mag Instrument (Maglight flashlights), so I get the concept, but I'm not sure about the zig-zag bit. And, just in looking at that matrix, I'll try it for fun, but I find trajpar works great and is far easier to underestand.

For fun, I created these "coils". Not how the Curve-01 constantly changes radius and pitch, and reverses helical rotation twice.

BrianMartin · ‎Dec 22, 2011

Hi David...

John correctly pointed out that most people use the Toroidal Bend feature to make tires. Toroidal Bend is really a very cool feature that never gets used. It's a shame that people don't think of it more often... well, unless they need a tire.

The basic idea is to make a flat extrusion (like a flat pad), cut zig-zag cuts into it, and then form it into a loop using Toroidal Bend. The feature is significant in that it can bend a model in two directions at once. You can mimic many of these same features using the new Warp feature with the Bend sub-option activated.

As John mentioned though... we need to know more about your application. For example, I think you can achieve the "tire tread" zig zag on a coil effect using Warp, Toroidal Bend, or just by using graphic trickery. Which option is best depends upon your needs. Do you NEED actual cuts in the model (for mass properties, etc)? Or... are you just concerned with making a very realistic-looking tread?

If you just need the graphic representation, you can use a Color Texture mapped on your model surface. By combining this texture with a Bump Map, you can give completely realistic depth to a surface that is totally flat. In professional productions, animators often use textures to lend color to a surface... but they also use those same textures to add depth, shadow, reflectation/refraction properties, and a host of other properties to their graphics. We're limited with Pro/E's graphics tools but we do have Bump Mapping which adds the illusion of depth to an object based on the brightness/darkness of the texture being mapped.

If this sounds useful, I can demonstrate... or if you want a demonstration of the other two techniques, I can provide that, too. Do any of these sound useful?

Thanks!

-Brian

MeDaveo · ‎Dec 23, 2011

Hey,

Again thanks gentlemen for your advice as it is greatly appreciated.

I'm just modelling some particular car features as a tutorial for myself to learn at the moment so nothing urgent. I've also been looking at mechanisms and analysis to learn more.

The tyre pattern i wanted to create would have been a real cut as i don't yet know other ways so i'll try toroidal bend etc. The Bump Map method is again something i know nothing about so a bit of reading on the menu i think.

Anyway,s just a quick reply here as i want to go home and enjoy xmas hols. Have a good holiday gentlemen

and thanks.

Marry Xmas.

BrianMartin · ‎Dec 24, 2011

Hi David...

I somehow ended up posting the reply intended for you to another thread. Your question and another users' question sort of overlapped. Take a look at the thread (link below) for examples of Toroidal Bends and the Warp Bend feature.

The link is here:

http://communities.ptc.com/message/173038#173038

Thanks!
-Brian