[gazebo plugin] SetForce() makes my model crash

asked 2015-10-09 07:16:06 -0500

Titozzz gravatar image

Hi there,

I'm trying to get a plugin to control wheel speed, but as soon a I apply joint::setForce() on a joint, with any value, it justs make my model crash after few iterations.

When I disable the plugin, my model seems to be stable. I can apply forces on the wheels joints inside gazebo.

But even inside gazebo, if I apply a the minimal velocity to the joints (0.001), my model starts dancing.

I don't know if both problems are related, but i thought it might help you figure out what is happening.

I think my inertia matrix are fine, when I print center of mass/inertia, it looks good.

Could it be because the link mass is under 1, which make the value in the inertia matrix very small.

Thanks,

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Comments

I believe there is a stability problem if the ratio between the masses of links connected by a joint is too large. Is the other link much heavier? @scpeters

chapulina gravatar imagechapulina ( 2015-10-09 14:13:18 -0500 )edit

One link is 10 and the other one is 0.1 ? I'm gonna try setting my wheel to 1 instead

Titozzz gravatar imageTitozzz ( 2015-10-14 03:05:45 -0500 )edit

I just changed my wheel mass from 0.1 to 1 and the model don't crash anymore. I just now have severe slip problems, but I guess the problem is not related. I'll try messing with friction parameters.

Titozzz gravatar imageTitozzz ( 2015-10-14 05:18:49 -0500 )edit

I had exactly that same problem which came for the same reason. For the slipping matter, I suggest using the ODE "damping" and "implicit_spring_damper" tags for your joints.

debz gravatar imagedebz ( 2015-11-10 17:03:03 -0500 )edit
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