Adding new fixed and rotating reference frames to robot URDF description

asked 2021-01-08 22:35:41 -0500

Hi there,

I would like to add new fixed and rotating reference frames to a robot description so that I can measure various kinematic variables at specific locations on the robot, expressed in those local reference frames.

For instance, the following reference frames are required:

  1. A fixed reference 'frame1' parallel to the baselink but translated at another location on the robot.

  2. An additional fixed reference 'frame2' with its origin co-located at the origin of the fixed 'frame1' but oriented with a different set of rpy angles.

  3. A rotating reference 'frame3' with its origin co-located at the origin of 'frame1' and 'frame2', such that the reference 'frame3' can rotate about the yaw and pitch axes of the 'frame2' according to the value of the angles published by a specific ROS node.

I'm hoping to use these reference frames for calculation of various kinematic variables for a given robot component and also to visualize various topics expressed in these reference frames in RVIZ.

I was wondering if these reference frames can be defined in the robot URDF description. I have tried adding them as fixed and rotating joints and the associated links, but it seem that without visual and non-zero mass properties, the joints and links do not appear in Gazebo.

I'm currently using ROS kinetic with Gazebo 7.

Please let me know if Gazebo supports adding such features to a robot and if so where can I find some relevant examples.

Thank you.

Ben

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