create a static mount in gz with urdf

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Hey there,

I would like to create a static mount for a plate: So that the plate can rotate and is not hitting the ground plate.

The bar in the picture should just hold the plate at its center position.

How to set the inertias of the bar?

I tried like this: but when I start the simulation the bar is moving like crazy and shaking etc.....

<link name="bar_mount" >
<inertial>
   <origin rpy="${0} 0 0" xyz="0.0 0.0 0.5"/>
   <mass value="10" />
   <inertia ixx="${0}" ixy="0" ixz="0" iyy="${0}" iyz="0" izz="${0.8333333333333334}" />
</inertial>
<collision>
   <origin rpy="0 0 0" xyz="0.0 0 0" />
   <geometry>
       <mesh filename="package://plate_aruco_description/meshes/collision/bar.stl" scale="2 2 1" />
   </geometry>
</collision>
  <visual name="plate">
    <origin rpy="0 0 0" xyz="0 0 0" />
    <geometry>
      <mesh filename="package://plate_aruco_description/meshes/collision/bar.stl" scale="2 2 1"/>
    </geometry>
  </visual>
</link>