How to add a custom tool to a UR3e - ROS2

edit

Thanks for your Answer!!

Do you suggest to make these changes here: /opt/ros/humble/share/ur_description/urdf? Because in the UR Description they explain under the headline Creating your own description including this description this:

It is recommended to create a separate ROS package containing this particular description. Inside this description you could also store your robot-specific kinematics parameters file.

But i didn't know what files i need to copy to my workspace. I tried to copy the whole repo but this didn't work.

If i got i right, the script could look like this. Or did i misunderstand something there?

<!-- ROS-Industrial 'flange' frame - attachment point for EEF models -->
<link name="${prefix}flange" />   #i added a `/`. Maybe a typo in your example
        <visual>
            <origin xyz="0 0 0" rpy="0 0 0"/>
            <geometry>
                <cylinder length="0.3" radius="0.03"/>
            </geometry>
        </visual>
        <collision>
            <origin xyz="0 0 0" rpy="0 0 0"/>
            <geometry>
                <cylinder length="0.3" radius="0.03"/>
            </geometry>
        </collision>
    </link>
<joint name="${prefix}wrist_3-flange" type="fixed">
  <parent link="${prefix}wrist_3_link" />
  <child link="${prefix}flange" />
  <origin xyz="0 0 0" rpy="0 ${-pi/2.0} ${-pi/2.0}" />
</joint>

<!-- ROS-Industrial 'tool0' frame - all-zeros tool frame -->

I tried to change it here: /opt/ros/humble/share/ur_description/urdf but i dont have permissions to do that.

It seems that you installed ur_description via apt (as binary). To be able to make changes to the URDF you need to build the package from source, do the following:

1. Create a workspace
2. Clone the repo to your workspace
3. Change the URDF to your needs
4. Build your workspace

Hope that helps, if you get stuck feel free to reach out.

Yes I installed the binary.

Anyway I have a bad feeling about changing something in the UR Driver Package. I would rather create my own package and change something in there.

As I understand the UR Description Repo this must be possible, right?

But i don't know what files I need from there. Also I dont know if i need to make any more changes than the one you mentioned above to get it running in my own package.

Thanks for updating your answer with some other solutions. I will try it to get it working quick.

But if i want to use it more often i think a change in the URDF would be the best way. Do you think this is only possible, if i make changes in the ur_description package? Or is there also a way to do it in my own workspace?

I've posted a comment under #q408953, which is a similar question.

Anyway I have a bad feeling about changing something in the UR Driver Package. I would rather create my own package and change something in there.

@LucB: your hesitation about editing / copying files is completely correct. With xacro:macros, it should not be needed. Compose things. Don't edit them.

Also: do not edit tool0 nor flange. That's not what they're for. An attachment point is exactly that: a point to attach new things to, not to edit it to add new things. Create new links and attach those using fixedjoints (but not in the same file, create a new file in a new package, see my comment under #q408953).

This sounds good.

Do i just need the ur_macro.xacro file in my workspace or do i need anything else from the ur_description package?

And how can i override/add the loaded description which i launch with

 ros2 launch ur_robot_driver ur_control.launch.py ur_type:=ur3e robot_ip:=192.168.56.101 launch_rviz:=false initial_joint_controller:=joint_trajectory_controller

ros2 launch ur_moveit_config ur_moveit.launch.py ur_type:=ur3e launch_rviz:=true