[gazebo plugin] SetForce() makes my model crash

asked 2015-10-09 07:16:06 -0600

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,

edit retag flag offensive close merge delete

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 -0600 )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 -0600 )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 -0600 )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 -0600 )edit