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 | 1 | initial version |
With regards the question on CG location, the <inertial> tags defines the mass properties of the robot. More details of the description can be found through urdf page.
| | 2 | No.2 Revision |
With regards the question on CG location, the <inertial> tags defines define the mass properties of the robot. More details of the description can be found through urdf page.
| | 3 | No.3 Revision |
With regards the question on CG location, the <inertial> tags define the mass properties of the robot. More details of the description can be found through urdf page.
Gazebo does automatic "mass-lumping" between links connected by fixed joints. Therefore, looking at the expanded link tree generated by running
rosrun urdf_parser urdf_to_graphiz nxt.urdf
For efficiency sake, all of the child links rigidly connected to parent link via fixed joints are lumped into the top parent in the tree. You can also run
rosrun gazebo urdf2model -f nxt.urdf -o nxt.model
and see that the first <body:empty name="base_link"> in nxt.model contains a mass that was the aggregate of all its children as well as multiple <geom> and <visual> from it's fix attached children links.
Hope that makes sense.
That said, does your model still oscillate when you spawn it? I turned off the controllers and things appear stable.
| | 4 | No.4 Revision |
Update:
It appears you have found a bug! The model is is stable for me if I comment out the single line
<canonicalBody>base_link</canonicalBody>
as you can see in this video, but the model does break if that line is left in the urdf.
While I find out why this is happening, you can comment out the <canonicalBody> tag and things should be a little bit better.
Thanks!
With regards the question on CG location, the <inertial> tags define the mass properties of the robot. More details of the description can be found through urdf page.
Gazebo does automatic "mass-lumping" between links connected by fixed joints. Therefore, looking at the expanded link tree generated by running
rosrun urdf_parser urdf_to_graphiz nxt.urdf
For efficiency sake, all of the child links rigidly connected to parent link via fixed joints are lumped into the top parent in the tree. You can also run
rosrun gazebo urdf2model -f nxt.urdf -o nxt.model
and see that the first <body:empty name="base_link"> in nxt.model contains a mass that was the aggregate of all its children as well as multiple <geom> and <visual> from it's fix attached children links.
Hope that makes sense.
That said, does your model still oscillate when you spawn it? I turned off the controllers and things appear stable.
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