[ODE] brush simulation - next steps..

Patrick Enoch Hendrix_ at gmx.net
Thu May 17 06:24:54 MST 2007


> Okay, I assigned a velocity to the head of the bristle instead of a
> force. Now it keeps it's track, BUT
> the collision of the bristles with the box on the ground cause a
> force on the head, that it starts spinning
> on it's way.

Hmm, maybe start over with ball-joints instead of universal joints.

Or did you follow the fixed-joint solution? You need to specify  
different ERPs for the different rotation axes. Also, the axes need  
to (dynamically) be aligned with the head. The translation ERP should  
be very high.

I really wonder why the "heavy" head is so much affected by the  
bristles? What weights do you use exactly for each body in the system?

> @Patrick: in your movie with the example brush, the bristles behaved
> like filaments hanging on the
> head. How did you fix it in a way, that there is no force on the
> bristles at all?

Only gravity acts on them. And later collision with the cube. They  
only weight  0.0348 grams each, while the head is 1e20 g.

> Another thing about your example: You adjusted the gravity to -9.81
> downwards. Why don't the bristles
> fall down?

Each bristle is made of 5 capsules which are connected by  
ball.joints. 5 capsules - 5 joints including that one with the head.


> My two example-brushes (in horizontal and vertical direction) look
> like something like jellyfish now,
> but I'm feeling pretty near the point I want to get to.
> Thanks very much for the help already,
> Tobias
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