Oribotics - the art/science of robotic origami

New 5bot crease pattern

August 7, 2005 on 11:23 pm | In Uncategorized |

Well, the past 2 weeks have been quite productive (so I have been busy working not blogging!). This time has produced some breakthroughs, which are quite significant for this residency. The first is a new crease pattern for the 5bot (5 bot is so called because its extremelly short and easy to type and it also describes the number of petals, and the degree of rotational symmetry).

The development of the new crease pattern evolved from experiment 1 to 4:

With the final choice being #4 due to its aesthetic appeal, and foldability; it looks good and works well.

The key difference is that the closed form has a raised pentagonal pyramid in the centre. This pyramid actually reduced the angle that the petals fold, therefore using less force. The model is not rigid, there is curvature in the model, which occurs mostly in the outer petals. Not being rigid does require increased force at the turning point (the point which creates the most tension in the model).

The advantage of the raised pyramid is 2 fold (^_^).

The second breakthrough came after an extensive study of the new crease pattern. Late at night I had a creative drive, I couldnt sleep from too many ideas and thoughts. And while in this state I saw a vision of the working mechanism. I immediately woke up and sketched down the rough ideas. The day after I went to Tokyu hands and bought all the materials I needed and on return built a protoype crease pattern and mechanism to test the idea. While I have yet to build a fully working model - I am in the middle of working on a 3D model which can be built on return to Australia.

SEE THIS VIDEO OF MECHANISM WORKING BY HAND 2.2 MB

If you can excuse the quality of the video, you can get an idea of the quality and simplicity of the movement created by this mechanism. It’s beautiful, and it also means the design of the flower like, as the extended arms which ‘pulled on the petals are no longer required, instead, a mechanism with strings and pulleys actuate the levers (see the 3D image below) and are repositioned by tensioned springs. It could also be done with motors, but the simplicity of a single motor contracting 5 strings (or wires) is far easier to control. Also I intuit that the springs will create a nice tension for the strings to pull against, meaning the motion will be extremely smooth. I’m looking forward to coming back home and making these new ones.

Here is an image of the 3D model at the moment

Here is a QUICKTIME VR model [925K]