twisting rope ladder

Trying to make a twisting rope ladder model. With the steps on a curve that goes through the centre of the steps...

Step width = line distance between one step end to the next;

like in the picture... However, those side lines are not constant length.

(colour indicating difference from original length)

A real proper dynamic model would maybe start with steps flat to xy plane in order to set up the model for kangaroo with springs and some twisting force on the top step. (?)

As the next step / rung in the ladder twists ... it necessarily comes closer to the first step / rung . . . now I can model this for 2 steps using hoopsnake and some other methods... but can't then extent along the curve for ~8 - 10 plus steps very dynamically / parametrically

any suggestions welcome.

a couple of lame attempts attached in one file.

Attachments:

induced strain double helix on curve.jpg, 131 KB
ladder twist 7 fixed line lengths.3dm, 30 KB
ladder twist 7 fixed line lengths.gh, 21 KB

Replies to This Discussion

Permalink Reply by roderick read on September 8, 2014 at 3:23pm

It's probably something like setting up a series of hoopsnakes running small functions and

smarter working of a data table so that each loop is only doing a small job...

rotate plane with rung on curve...

move plane on curve...

measure rung to rung length

store state of new rung and relation to curve....

start again with latest as input...

repeat until ~8 rungs are twisted onto line at proper length for twisted amount

NOTE: as they twist onto the curve... the rungs and lines create a double helix... only 1 of the lines can be the right length (fully tight) assuming you use perp frames on the line to set the rungs... I was going to just get one right ... then indicate the slackness or strain degree in the other.

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