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Easiest way for closed kinematic chain? [closed]

asked 2022-08-09 07:01:09 -0500

NotARobot gravatar image


I have a model containing a closed kinematic chain, which is not supported by ROS URDF file standard. Therefore I could write the description also in SDF which allows closed kinematic chains, however, I am not certain if I could use something like XACRO to parametrize the SDF similar to an URDF.

Alternatively, is it possible to use the <gazebo> tag in the context of the URDF for the definition of the joints which close the kinematic chain?


  • I have a closed kinematic chain within a robot configuration.
  • Is it possible to parametrize the SDF which allows for the closed kinematic chain?
  • Is it possible the achieve the closed kinematic chain with the use of the
    <gazebo> tag within the URDF?
  • Is there a fast, straight forward way to get a parametrizable robot description for closed kinematic chains?
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Closed for the following reason the question is answered, right answer was accepted by shonigmann
close date 2022-08-10 10:44:54.578342

1 Answer

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answered 2022-08-09 12:34:37 -0500

shonigmann gravatar image
  • Yes, you could use xacro to parse a parameterized SDF file directly if you want, either using extensions of the base xacro tool (e.g. or with a little copy paste (or scripting) of the generated output
  • Yes, you can use Xacro with <gazebo>tags to create closed kinematic chains that would function in gazebo when the generated URDF gets converted to SDF. This might be a useful example:
  • Fast and straightforward is a bit arbitrary... depends a bit on your needs and what you're starting with. I'd recommend using the "standard" xacro->urdf->sdf pipeline so your description file remains compatible with other tools like RViz without requiring duplicate definitions. Adding the gazebo tags isn't too cumbersome.
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Thank you very much! As you, I prefer the approach with <gazebo> tags, so I have only one file to maintain.

NotARobot gravatar image NotARobot  ( 2022-08-10 05:58:43 -0500 )edit

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Asked: 2022-08-09 07:01:09 -0500

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Last updated: Aug 09 '22