Grasshopper

algorithmic modeling for Rhino

Hello Daniel,

I notice that some years ago many people are following a very interesting topic about pulley-simulation. So far I know this component is not released in kangaroo yet.

http://www.grasshopper3d.com/forum/topics/pulley

 

I have tried using physics rule (with some kangaroo force-components, e.g. collideMesh...etc.) and geometrically approach to solve it. But it doesn't work appropriate.

 

There are some problems to be bear in mind, e.g. the mechanical properties of  rove and friction over the pulley, namely how to transmit a tension force around one or more pulleys...etc.

It seems a pretty tough problem! do you have any elegant hint to solve this interesting mechanisms?

 

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Replies to This Discussion

Hi Frank,

I actually did some work on this recently.

Attached is a definition containing a scripted custom goal which preserves the total length of 2 segments.

This can be used to simulate an idealized pulley where the cable turns at a point.

The next step (which I've not tried yet, but think should be possible) is to extend this to work not just with 2 segments, but over a polyline of many segments.

Alternatively, if you do actually want to model the radius of the pulley, there might be an alternative approach involving collisions that I'll post in a moment.

Attachments:

Hi Daniel,

 

thx a lot for example and sorry that I took so long time to reply coz I have been trying this how can I use it trickily for 3-segment pulley mechanisms, namely I try to combine 2 Pulley-Goals...unfortunately it doesn't work coz it is difficult to keep the total length...

So I was wondering that you mention about that a polyline of many segments can roll over pulleys and a alternative approach to model a pulley with radius which works with Collision...

 

It would be nice if you could help a step forward ;-)

Hi Daniel,

This component running very well in Rhino 64bit, but recently I have to use it in Rhino 32bit. It seems a problem to manage assembly in rhino 32 bit. I was wondering if the costum goal can only be used in Rhino 64bit?

Hi Jon,

It should work in both 32 and 64bit. I know there are sometimes issues with custom goals and the COFF loading option though. Have you tried switching this (from GrasshopperDeveloperSettings on the Rhino command line)?

yes it works now, thx lot for hint!

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