[ODE] Center of Mass of Mesh

yyd_iris@yahoo.com yyd_iris at yahoo.com
Mon Jun 25 17:06:00 MST 2007


In ODE, center of mass must coincide with geom
reference points. I have read some posts about setting
center of mass of geoms. Basically there are two ways
to do it: 1. use geom-translate and 2. geom offset. 

I have some questions about the case of TriMesh geom.
1. Is there default defintion of TriMesh reference
point? I have mesh models of some manufacture parts.
Their reference points are just somewhere in the
middle of the models. I also have the dynamics data:
center of mass and the inertia at the center of mass. 

The next two questions are general to all geoms. 

2. In my understanding, dMassSetParameters is equal to
dMassTranslate plus setMassRoate, if I do the right
computation, right? 

3. If I apply a torque to a hinge joint with two gemos
(one end is fixed), I should be able to get an
acceleration of q_dotdot = torque/inertia. But in my
experiments, I need to apply a much bigger torque to
get the accelerations. Is there any parameters I
should pay attention to? 



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