Robotics StackExchange | Archived questions

Xacro - Strangest behaviour with inertia

Good day to everyone,

I was designing a robot with xacro and started seing the strangest behaviours from the "" component. I have a component, which is rotated 90 degrees in the roll axis. The inertia was also rotated (as the visual and collision), but, analysing in gazebo, I see that the inertia ends up not being rotated, as shown in the following image: https://ibb.co/fk30Q2C (I have to put links to the images since I can't upload them directly).

I thought this behaviour to be very weird and so I tried with a different inertia, this time not the one taken from the CAD but considering that the inertia from the object was represented by a cuboid. So, I used the following inertia (which is very close to the one given by the CAD tool for the object):

<inertia ixx="8.5474390625e-4" ixy="0" ixz="0" iyy="8.5474390625e-4" iyz="0" izz="1.7094878125e-3" />

This time, gazebo couldn't even display the inertia, as shown here: https://ibb.co/yXBgPTf

Finally, with a try and error approach, i changed the izz moment of inertia to 1.5e-3, resulting in:

<inertia ixx="8.5474390625e-4" ixy="0" ixz="0" iyy="8.5474390625e-4" iyz="0" izz="1.5e-3" />

This time, i got the inertia to be displayed correctly: https://ibb.co/hYVRWRk .

Everything seems correct to me in all the cases so, what may be causing this issue?

Thanks

PS: I also ended up posting in gazebo forum, since the topics I read here, when there was a problem in the simulation with gazebo, moderators changed closed the topic as asked the user to post in gazebo. Here is the link: https://answers.gazebosim.org/question/26819/error-with-display-of-inertia/ (is waiting for moderation)

Asked by noobita on 2021-04-16 06:21:10 UTC

Comments

Answers