# [ODE] how to count angular velocity...

Krystian Ligenza s2562 at pjwstk.edu.pl
Wed Nov 22 14:49:33 MST 2006

i forgot to add, that I'm setting my symulation to initial configuration
from motion capture data. So I need to compute by my self angular
velocity.

Krystian

> You should be able to get the angular velocity from the object using
> dBodyGetAngularVel(ID).  It returns a 3-float vector that represents an
> axis
> (the x, y, z from the vector) and a rate of rotation (the magnitude of the
> vector, or mag = sqrt(x*x + y*y + z*z)).  A magnitude of zero means no
> rotation.
>
> -----Original Message-----
> From: ode-bounces at q12.org [mailto:ode-bounces at q12.org]On Behalf Of
> Krystian Ligenza
> Sent: Wednesday, November 22, 2006 12:27 PM
> To: ode at q12.org
> Subject: [ODE] how to count angular velocity...
>
>
> Hi,
>
> is't probably very easy question, but I have gave up :(
> I have got dBody in 2 time steps. I know it's rotation matrix in both time
> step (t and t+1), and need to count body angular velocity in t+1. I have
> tried do it in this way:
>
> R(t+1) = R(t)*R(transformation), so
>
> R(transformation) = R(t)-1 * R(t+1), after this I have converted
> R(trasnformation) to euler rotation vector, and used it like this:
>
> dBodySetAngularVel(body, vEx/timeStep, vEy/timeStep, vEz/timeStep);
>
> Legend:
> R(t) -> rotation matrix in first time step
> R(t)-1 -> inverse matrix R(t)
> R(t+1) -> rotation matrix in second time step
> vEx/vEy/vEz -> euler rotation x/y/z
>
> but it don't behave good :( Can somebody help me?
>
> Thanks
> Krystian
>
>
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