Designing dynamic folded structures?

Hello,

I'm interested in designing dynamic folded structures and robots. The fabrication process I use uses a laser cutter to make cuts in two sheets of posterboard (or composites). Then, we sandwich layer of thin plastic and adhesive between the two sheets, and everywhere where the laser cutter removed the posterboard, the plastic is exposed and forms a compliant hinge (you can see a Youtube video of the process here: https://www.youtube.com/watch?v=RLJ-FwE9KA8).

The design tools we use for this process at the moment are pretty terrible. We largely do the design manually on paper, and then map that to a flat fabrication drawing in Solidworks. The process would be a lot faster and easier if we could do 3D design in a tool that would enable us to unfold the robot or structure into a 2D fabrication plan. Ideally, the design tool that would let us do that would also allow us to visualize the kinematics of mechanisms.

Rhino + Grasshopper seems pretty promising for applications like rigid origami and folding in general, but I wonder about the ability to simulate kinematics. I've done some googling and reading of the forums, but it doesn't seem like anyone is doing anything precisely like what I've described. Can anyone recommend tutorials or existing projects that might help me get started moving in the right direction if, indeed, Grasshopper is the right tool for the job?

Thanks,

Aaron

Replies to This Discussion

Permalink Reply by Aaron Hoover on April 17, 2012 at 8:00pm

Hi Daniel,

I was finally able to get back to learning Grasshopper and trying out Kangaroo, so I attempted to open the 'Walker' file within the SimpleKangarooExamples zip. However, I'm getting a bunch of the following errors:

Plugin version: 0.8.0066

Archive file written with older version: 0.8.0004

Input parameter chunk is missing. Archive is corrupt.

Is this just a matter of an incompatible file version? Is there some other way to open the 'Walker' file? Also, can you recommend tutorials that might be helpful for me to attempt to build kinematic models with the aid of Kangaroo?

Permalink Reply by Daniel Piker on April 19, 2012 at 12:39pm

Hi Aaron,

I get the same error message on opening that file, as it was made with an earlier version, but I am still able to ignore the message and the file works.

Anyway, here it is resaved in the new version.

Generally for making kinematic models it should be as simple as taking the curves for all the struts or edges and making them springs.

This video : http://vimeo.com/20308963

shows how you can do this and move the anchor points around to make the system move.

In the walker example it moves because of changing rest lengths of the springs (like linear actuators). I guess you could also use a hinge force with a changing angle.

Attachments:

Walker2.ghx, 321 KB

Permalink Reply by Aaron Hoover on April 19, 2012 at 2:02pm

Great. Thanks for the help, Daniel. I have lots of questions, but before I open my mouth to ask them, I think I need to spend some time exploring Kangaroo in depth. At that point, if I still have questions, I'll pipe up here.