gazebo_models/submarine_sinking/model.sdf.erb

<?xml version='1.0'?>
<sdf version='1.5'>
  <%
    body_density = 1500
    body_radius = 0.3
    body_length = 2.6
    body_volume = body_length*Math::PI*body_radius**2
    spacer_radius = 0.0933402
    spacer_length = 0.127211

    mass = body_density*(body_volume)

    body_ixx = mass/12.0 * (3*body_radius**2  + body_length**2 )
    body_iyy = mass/12.0 * (3*body_radius**2  + body_length**2 )
    body_izz = mass/2.0 * body_radius**2
   
    blade_dx = 0.5
    blade_dy = 0.154178
    blade_dz = 0.05455
    blade_volume = blade_dx * blade_dy * blade_dz
    blade_mass = blade_volume * body_density

    total_blade_mass = 4*blade_mass

    blade_ixx = total_blade_mass/12.0 * (blade_dx**2 + blade_dz**2)
    blade_iyy = total_blade_mass/12.0 * (blade_dz**2 + blade_dx**2)
    blade_izz = total_blade_mass/12.0 * (blade_dx**2 + blade_dx**2)

    blade_angle = 45 * Math::PI/180

    fluid_density = 999.1026

    material_block =
          '<material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/Black</name>
            </script>
          </material>'
   %>
  <model name='submarine_sinking'>
    <pose>0 0 <%= blade_dx + 1.0 %> <%= Math::PI/2%> 0 0</pose>
    <link name='body'>
      <pose>0 0 -1.07935 0 0 0</pose>
      <inertial>
        <mass><%= mass %></mass>
        <inertia>
          <ixx><%= body_ixx %></ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy><%= body_iyy %></iyy>
          <iyz>0</iyz>
          <izz><%= body_izz %></izz>
        </inertia>
      </inertial>

      <% body_geometry =
            '<geometry>
              <cylinder>
                <radius>'+ body_radius.to_s + '</radius>
                <length>'+ body_length.to_s + '</length>
              </cylinder>
            </geometry>'
       %>

      <visual name='body_visual'>
        <%= body_geometry%>
        <%= material_block%>
      </visual>
      <collision name='body_collision'>
        <%= body_geometry%>
      </collision>
      <% spacer_geometry_pose =
            '<pose>0 0 ' + (0.299196 + 1.07935).to_s + ' 0 0 0</pose>
            <geometry>
              <cylinder>
                <radius>'+ spacer_radius.to_s + '</radius>
                <length>'+ spacer_length.to_s + '</length>
              </cylinder>
            </geometry>'
       %>
      <visual name='spacer_visual'>
        <%= spacer_geometry_pose%>
        <%= material_block%>
      </visual>
    </link>

    <link name='propeller'>
      <pose>0 0 0.3455 3.14159 0 0</pose>
      <inertial>
        <mass><%= total_blade_mass %></mass>
        <inertia>
          <ixx><%= blade_ixx %></ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy><%= blade_iyy %></iyy>
          <iyz>0</iyz>
          <izz><%= blade_izz %></izz>
        </inertia>
      </inertial>

    <% for i in 1..4
       x = (i%2)*(spacer_radius + blade_dx/2)*(if i > 2 then -1 else 1 end)
       y = ((i+1)%2)*(spacer_radius + blade_dx/2)*(if i > 2 then -1 else 1 end)
       roll = blade_angle*(if i > 2 then -1 else 1 end)
       yaw = ((i+1)%2)*Math::PI/2

       geometry_pose =
         '<pose>' + x.to_s + ' ' + y.to_s + ' 0 ' + roll.to_s + ' 0 ' + yaw.to_s + '</pose>
          <geometry>
            <box>
              <size>' + blade_dx.to_s + ' ' + blade_dy.to_s + ' ' + blade_dz.to_s + '</size>
            </box>
          </geometry>'
       %>
      <visual name=<%= 'blade' + i.to_s + '_visual'%>>
        <%= geometry_pose %>
        <%= material_block%>
      </visual>
      <collision name=<%= 'blade' + i.to_s + '_collision'%>>
        <%= geometry_pose %>
      </collision>
    <% end %>
    </link>

    <joint name='spinning_joint' type='revolute'>
      <parent>body</parent>
      <child>propeller</child>
      <axis>
        <xyz>0 0 1</xyz>
        <use_parent_model_frame>1</use_parent_model_frame>
        <limit>
          <lower>-1e+12</lower>
          <upper>1e+12</upper>
          <effort>-1</effort>
          <velocity>-1</velocity>
        </limit>
      </axis>
    </joint>

    <allow_auto_disable>1</allow_auto_disable>

    <% lift_drag_properties =
      "<air_density>" + fluid_density.to_s + "</air_density>\n" +
      "      <cla>" + (1.75/1.396).to_s + "</cla>\n" +
      "      <cla_stall>" + (-0.25/0.1745).to_s + "</cla_stall>\n" +
      "      <cda>0</cda>\n" +
      "      <cda_stall>" + (2/1.396).to_s + "</cda_stall>\n" +
      "      <alpha_stall>" + 1.396.to_s + "</alpha_stall>\n" +
      "      <a0>0</a0>\n"
     %>

    <!-- Commented out because it behaves poorly -->
    <!-- 
    <plugin name="submarine_propeller_1" filename="libLiftDragPlugin.so">
      <%= lift_drag_properties%>
      <area><%= blade_dx*blade_dy*2 + blade_dx*blade_dz*2 + blade_dy*blade_dz*2 %></area>
      <upward>0 <%= -Math.cos(blade_angle) %> <%= -Math.sin(blade_angle) %></upward>
      <forward>0 <%= -Math.sin(blade_angle) %> <%= Math.cos(blade_angle) %></forward>
      <link_name>propeller</link_name>
      <cp><%= blade_dx*0.7 %> 0 0</cp>
    </plugin>

    <plugin name="submarine_propeller_2" filename="libLiftDragPlugin.so">
      <%= lift_drag_properties%>
      <area><%= blade_dx*blade_dy*2 + blade_dx*blade_dz*2 + blade_dy*blade_dz*2 %></area>
      <upward><%= -Math.sin(blade_angle) %> 0 <%= -Math.cos(blade_angle) %></upward>
      <forward><%= -Math.cos(blade_angle) %> 0 <%= Math.sin(blade_angle) %></forward>
      <link_name>propeller</link_name>
      <cp>0 <%= -blade_dx*0.7 %> 0</cp>
    </plugin>

    <plugin name="submarine_propeller_3" filename="libLiftDragPlugin.so">
      <%= lift_drag_properties%>
      <area><%= blade_dx*blade_dy*2 + blade_dx*blade_dz*2 + blade_dy*blade_dz*2 %></area>
      <upward>0 <%= Math.sin(blade_angle) %> <%= -Math.cos(blade_angle) %></upward>
      <forward>0 <%= -Math.cos(blade_angle) %> <%= -Math.sin(blade_angle) %></forward>
      <link_name>propeller</link_name>
      <cp><%= -blade_dx*0.7 %> 0 0</cp>
    </plugin>

    <plugin name="submarine_propeller_4" filename="libLiftDragPlugin.so">
      <%= lift_drag_properties%>
      <area><%= blade_dx*blade_dy*2 + blade_dx*blade_dz*2 + blade_dy*blade_dz*2 %></area>
      <upward><%= Math.cos(blade_angle) %> 0 <%= -Math.sin(blade_angle) %></upward>
      <forward><%= Math.sin(blade_angle) %> 0 <%= Math.cos(blade_angle) %></forward>
      <link_name>propeller</link_name>
      <cp>0 <%= blade_dx*0.7 %> 0</cp>
    </plugin>
    -->

    <plugin name="buoyancy" filename="libBuoyancyPlugin.so">
      <fluid_density><%= fluid_density%></fluid_density>
    </plugin>

  </model>
</sdf>