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How to close a four bar link?

Hello friends, I am working in a robot simulation with ROS+Gazebo and I have a question concerning URDF and SDF.

In order to simulate the operation of all joints of the robot, I need a package called ROS control, which is not compatible with SDF. However, my robot model requires a four-bar mechanism, which is not supported by URDF. I am kind of blocked.

I want to try two solutions in order to keep using ROS control and closing the four-bar mechanism:
-Start from URDF, convert it to SDF for later adding manually the fourth joint for the four-bar mechanism. I would be risking to lose all ros control tags defined in the URDF in the process.

Or a more general one,

-Load the model of the robot in gazebo using URDF. I understand during the spawning process the URDF is automatically converted to SDF. Then I would like to add programatically the fourth joint of the four-bar mechanism using a gazebo plug in.

So, my question is, how can I modify a model programatically? Name, parent, child, pose etc.

Thank you in advance

Asked by nexus8 on 2020-11-24 15:52:21 UTC

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Answers

you could manually write the SDF and include the ros_control tags. Manually keeping a urdf and sdf in sync is not that bad, because once you write it you rarely go back and edit it.

Asked by Peter Mitrano on 2020-11-25 13:55:42 UTC

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