Using Geogebra to design robots

[mathking]

OK, I am not exactly sure where to put this thread. It is not quite CAD, and doesn't seem to fit anywhere else, so here goes...

I did a search and couldn't find any references to Geogebra (http://www.google.com/url?sa=t&source=web&cd=1&ved=0CBgQFjAA&url=http%3A%2F%2Fwww.geogebra.org%2F&rct=j&q=Geogebra&ei=qqczTe6mLMH3gAe3l4zJCw&usg=AFQjCNFL_N5-ca6XEdQ1v4r_Uw_2modi1A&sig2=bOmh-MWCcq15xKrLVNdkdA&cad=rja) on CD. It is really hard to describe Geogebra in a sentence. It is part Mathematica, part graphing calculator and not really the same as either of those.

If you click here (http://homepage.mac.com/mathking/Robotics/RobotGeogebraModels/RobotDesign2011B.html) it will take you to a model I threw together in a couple of minutes to look at the geometry of a double articulate arm. (One of Geogebra's nicer features is the ability to export dynamic web pages of it's models. Many content management systems, such as a Moodle, also have Geogebra plug-ins.) There are sliders to adjust the angles and lengths of the parts of the arm. This is just one example of how to use Geogebra. It's a really cool program, with a large development community. In any event, since I haven't seen any references here, I thought I would throw this up for the ChiefDelphi community.

[bakejame]

I really like this program, but I would like a little more flexibility in the location of some of the pivot points and members. Otherwise, I think it would be a valuable tool in design.

[Trying to Help]

Thank you for posting this design and the use of Geogebra. I'll be forwarding this off to our other mentors to have them take a look also.

Trying to Help

[whackedwatchdog]

This tool looks like it will be very useful to a team with limited CAD experience, or who wants to quickly and accurately model distances (if not necessarily entire parts). Definitely looking into this program for the future!

[mathking]

I really like this program, but I would like a little more flexibility in the location of some of the pivot points and members. Otherwise, I think it would be a valuable tool in design.

If you use the Geogebra program (as opposed to a Geogebra file exported as a dynamic web page) you can do a lot more with it.

One of the interesting things we have also done is to create some simple dynamic vector models to demonstrate what will be (approximately) required to move the arm in different configurations. As you move the model, and the position of the arm changes, the vectors grow or shrink.

[Mark_K]

Thanks for that great tip. We are using it to model a possible arm along the lines of this thread:
http://www.chiefdelphi.com/forums/showthread.php?threadid=90284

Here is our model.
http://concordrobotics.com/arm/
I made it so you can play with the position on the robot (for cg calculations), different sprocket ratios between the shoulder and elbow and different starting angles.

Mark

[tdramble]

Here is the GeoGebra model of our double articulated arm. The Shoulder and Elbow Motor sliders represent spinning the drive motor. Both joints are controlled by the motors at the base of the main 2 inch support bar, blue colored points, the lower blue point is the drive shaft of the shoulder joints motor. The points spinning around are to show a visualization of how fast they spin, so the sprockets they are chained to will have spinning points as well, but their rate of spin will vary depending on sprocket teeth and subsequent reduction.

http://coffman.dublin.k12.oh.us/teachers/Teacherpages/dramble/Arm_2.html

[mathking]

Here is the more complete model (http://badrobots.com/wp-content/uploads/2011/03/Arm_2.html) of our arm in Geogebra. This one adds the ability with sprocket ratios and count rotations so we can help with automated control of the arm.