Floating joint in URDF?

asked 2020-04-29 04:56:25 -0500

146 ●8 ●18 ●18

updated 2020-04-29 05:53:55 -0500

Hi, I have a question regarding the floating joint type in the URDF description. I have two robot parts which are connected by a passive and non-rigid element. In kinetic, I managed to describe this "joint" with a floating joint (and publishing the tf of the two links this floating joint connects in another node). Both tf trees where successfully published by robot_state_publisher, although not connected to each other, which was ok. In melodic, I get the warning:

Converting unknown joint type of joint 'loose_joint' into a fixed joint

Apparently floating joints are no longer used? Is there any alternative?

I've though about publishing the two robot parts seperately, but URDF does not allow two seperate tf trees. Putting two different URDFs in one launch file is also not possible since robot_description only takes one file.

Any help appreciated!

EDIT: joint in urdf:

<joint name="loose_joint" type="floating">
    <parent link="joint1"/>
    <child link="joint2"/>
</joint>

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Comments

Not an answer, but there is no requirement necessarily to only have a single robot_description. Namespaces or remapping could be used to provide instances of nodes which need it access to their own specific robot_description.

What would not be possible would be to point a single node to two (or more) differentrobot_description parameters. But that is a different issue.

If you have no need for everything to be connected, it's possible to have multipe robot_state_publisher instances each with their own robot_description.