Hello, I am trying to create a moving platform that can move in roll, pitch, yaw, Z. I want to test driving a robot on such a platform. I created a SDF platform and adapted this code for controlling the movement. but the ground plane keep the platform from rolling/pitching. And if I remove the ground platform both the robot and platform fall. Is this possible ? what am I doing wrong? My ground platform is here:

    <?xml version="1.0"?>
<sdf version="1.4">
    <model name="SMP">
        <pose>0 0 2.0 0 0 0.0</pose>
      <link name="link">
        <inertial>
          <pose>0 0 0 0 0 0</pose>
          <mass>.1000</mass>

          <inertia>
            <ixx>9.99999999e+10</ixx>
            <ixy>0.0</ixy>
            <ixz>0.0</ixz>
            <iyy>9.99999999e+10</iyy>
            <iyz>0.0</iyz>
            <izz>9.99999999e+10</izz>
          </inertia>
        </inertial>
        <gavity>0</gravity>
        <collision name="collision">
          <geometry>
            <mesh>
              <uri>model://SMP/meshes/triangle.stl</uri>
              <scale>1 1 1 </scale>
          </mesh>
          </geometry>
          <surface>
              <friction>
                <ode>
                  <mu>10</mu>
                  <mu2>10</mu2>
                </ode>
              </friction>
            </surface>
        </collision>

        <visual name="visual">
          <geometry>

            <mesh>
              <uri>model://SMP/meshes/triangle.stl</uri>
              <scale>1 1 1 </scale>
          </mesh>
          </geometry>
        </visual>
      </link>
      <plugin name="plannar_mover_plugin" filename="libplannar_mover_plugin.so"/>
    </model>
</sdf>