Force/draw curve plotting program

[ChrisS]

Hey all. A week or two ago somebody asked for a method of finding the stored energy in a bow. I've been working on a program during lectures to accomplish this.  I wanted more practice programming in windows and this was a good way to get it    

It can save and open data, calculate the area under the described curve, and output graphs in png format for sharing. It can also convert all measurements from english to metric and back.

If anybody would like to give it a try:
  http://www-personal.umich.edu/~cdsnyder/drawcurve/index.html  

It should run on any windows platform. It ran fine on win2000 at home and on a 64-bit winXP machine on campus. I tested the program as extensively as time allowed me, but bugs may still exist. Let me know if you find any.

Basically, download your prefered format first. I compressed it in zip and rar format to save on bandwidth, so please use one of those if you can. Then just play around with it... it should be pretty easy to use.

Let me know what you think. Comments, annoyances, bugs, all welcome!
Chris

[ChrisS]

Oh, and I forgot to state the standard disclaimer  that the GIGO (Garbage In, Garbage Out) rule applies. Results are only as accurate as the data you enter.

[Falk]

Great! Thanks Chris!
I did all my FD-Curves with Excel up to now, but I would like to test your prog a little.
The energy feature sounds very interesting! I have just installed it and checked it does run - but nothing more ...
       

[Dano]

Pretty cool, works for me. Thanks for puuting in all the labor.

[Pete W]

Just tried it and all seems good.
 Thanks.
Pete

[ChrisS]

Good, I'm glad it runs without a problem. I wrote it mainly because I wanted an easy way to view and post F/D curves.  That way when I really like the feel of a bow, I can scribble down some F/D data and see what it looks like. Energy calculations were thrown in because it took all of 30 lines of code    

Let me know if you have any questions or problems.. I tossed the instructions page up kinda quick.

If somebody here uses metric, I'd like to hear if the units are satisfactory. I only got one response when I asked about units while I was writing the program.

This may also be a precursor to a much larger project. Next semester (my last one yay) I have what is called the "MDE", the Major Design Experience. In it we have to conceive of and complete a large scale project throughout the semester. I'm concidering a very specialized physics simulator for longbow design... might do things like energy storage distribution along the length of the limb, simulated force/draw curve, etc. I have a decent physics background and I'd like to integrate it with my love of computer science and archery    

Chris

[BenBow]

Chris here's an excel spreadsheet I've been using that you might find interesting. Avcase built this and I've been playing with it.    SuperTiller

[beleg]

Chris,
Thank you very much that was what I was looking for.
I have made a "shooting machine to try my bows. Also use it to get drwa curve. I have some problems with the scale because of the drag inside but I think I have fix it.
You progran is very good but i would like to have some print options, Im old fashion and like all on paper.
Thanks
Martin

[BenBow]

Chris I entered some test number from a bow I'm building and looks great.        
You may have already read these papers but if not they have a great deal of math info on archery related items.    Bob Kooi Archery Publications

[AZStickman]

That is Fantastic Chris!!!........ Thank You..... My Painted Pony Bow has 88 Ft/ Lbs of Energy pulling 28"@65#..... We at least Hyothetically.....   :D   I'll have to get the real #'s generated later today.......Thanks for putting this together.....       It should get into the Archives somewhere.;..... Terry

[O.L. Adcock]

Chris, it looks good! I plugged in some numbers from a Norb Mulaney test and it matched perfectly to 3 decimal points. What would be handy is a box for SE/PDF. Comparing bow "A" to bow "B"....SE/PDF and efficiency is all a person needs to see.......O.L.

[ChrisS]

Awesome! I'm glad it's useful to y'all.

O.L., yea, that should be easy to add in. I'm concidering taking out the cat-mull interpolated energy calculation. It's nearly identical to a simple linear interpolation. Plus, I believe any industry standard (unofficial or otherwise) would accept only a linear interpolated value. Removing that would take the 'step' out as well, since linear interpolation produces trapezoids without the need for further division. Primarily, I used cat-mull to produce a smooth graph curve that is probably closer to reality than jagged lines. I was also curious how close to linear interpolation it would be when appoximated with a step of 0.01 inches. Maybe I'll switch the cat-mull box out with the SE/PDF.

BenBow, I read 'em all     That's what gave me the idea. Without them I wouldn't be able to concider a larger project. I have taken enough calculus and differential equations classes to understand and follow his arguments, but I could never derive them from scratch. With this project I wanted to be sure I could pull off a decent user interface before starting a larger project.

beleg, sure thing! I believe the plot control already has a print dialog built right in. I just need to attach it to a menu item. I'd also like to save the color settings somehow... if somebody wants anything other than the default they'd have to change it every time.

Also, the plotting window wasn't written by me. It is a control already built into the wxWidgets library I used for the program. I'm not completely happy with the plot controls either.. but writing one from scratch is incredibly complicated. Creating algorithms for human-readable tick marks on an axis is *still* a topic under research by computer scientists. What seems arbitrary for a person to draw on paper can be really tough to replicate deterministically.

Chris

[ChrisS]

Wow, I'll have to get a hold of that spreadsheet. That is almost exactly what I had in mind for my final semester computer science project, except with a windows like interface in a stand-alone program. I'll have to talk to avcase and see if I can integrate some of the base equations from his spreadsheet (with credits to him of course). If I could, that would give me a head start and I could jump right into laminations of different material properties.

Thanks for the heads up Benbow

[BenBow]

Super Chris. Looking forward to seeing how your project turns out. Best of luck on it.

[ChrisS]

Ok, made a few easy changes. I switched out the cat-mull interpolated energy to a S.E./P.D.F calculation.

I also added print options to the graph for beleg. Let me know if it works. The dialogs are built into wxWidgets to be cross-platform (linux, mac, and windows) so the print preview might not be completely accurate.

I'm kicking around the idea of switching the list box into a grid control in the future. That would allow spreadsheet-style input and possibly cut and pasting. The only problem is that it makes my job a lot harder hehe. I'd have to do a whole bunch of error checking, sorting, and checking for duplicates. It would also mean that the user is responsible for organizing their data (there is no "insert row" on a grid control).

[Ray Hammond]

what did he say????????????????? Cat mull- hmmm, is that some type of warm winter drink made from feline squeezin's??????

[Falk]

Ray, Cat-Mole! Not Cat mull!
The Cat-Mole is the one with long whiskers in front of the shovle hands and slightly longer tail then the ordinary mole  :D

Chris, I just downloaded Vers.1.0 (uncompressed file) - BUT - it still says 0.9 in the info box - and as far as I see it - is pretty much identical - even the "mull-thing" is present  :confused:

[ChrisS]

Huh.. You're right. That's wierd. I just uploaded it again, sorry bout that.

And that's version 0.10 (haha). I haven't been staring at the code long enough to call it a 1.0 release  

... A cat mole eh? Well they must be good at math! Catmull-rom splines are just a specific type of cardinal spline. They are popular for doing keyframe animations, that is, given a set of points, fit a smooth line that passes through all of them. I used a template that I wrote for a graphics class to produce a smoother curve in the plot window. Just plain 'ol linear is available too of course.

[Falk]

ahhh! NOW it worked!
Very good to have a printing feature now. I really like your little tool.
On suggestion though: It would be better IMO to let it say again "stored energy" instead of only energy. Just to prevent a user will be thinking it's equivalent to his arrows kinetic energy - and soon looking out for BIG game cause of that ...

Really a very nice tool - and not overladden (?word) with unneeded stuff. Plain, simple, good - keep it that way!

Cheers,
Falk

[ChrisS]

Cool. Thanks for pointing out the label error. If you hit the units radio buttons, it will change the label to "Stored Energy" hehe. I forgot to change the initial value on program startup  :p