Urdf problem with Gazebo

Hi,
I tried to build a three-wheeled forklift from scratch. I generated stl with a cad and file.dae with blender. I assigned the colors to the right wheel via Blender itself. I was able to view in Rviz as the image shows. But if I try to spawn the urdf in Gazebo I don’t see anything, but the system returns:


I have attached the urdf file.
Any help is appreciated
Thanks
Salvatore

<?xml version="1.0"?>
<!-- * * * Link Definitions * * * -->
<link name="base_link">

    <inertial>
        <origin xyz="0.34 0.009 0.57" rpy="0 0 0"/>            
        <mass value="198.0" />
        <inertia ixx="1" ixy="0.0" ixz="0.0" iyy="1" iyz="0.0" izz="1"/>
    </inertial>

    <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/ME10C_tpx4350.dae"/>
        </geometry>
    </collision>  

    <visual>
        <origin rpy="0 0 0" xyz="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/ME10C_tpx4350.dae"/>
        </geometry>
        <material name="red"/>
    </visual>

</link>

<gazebo reference="base_link">
    <kp>100000.0</kp>
    <kd>100000.0</kd>
    <mu1>10.0</mu1>
    <mu2>10.0</mu2>
    <material>Gazebo/Red</material>
</gazebo>

<link name="Motor_Gear_link">
    <inertial>
        <origin xyz="0 0 0" rpy="0 0 0"/> <!-- posizione CoM rispetto SdR1 -->           
        <mass value="80" />
        <inertia ixx="0.05" ixy="0.0" ixz="0.0" iyy="0.05" iyz="0.0" izz="0.05"/>
    </inertial>

    <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
             <cylinder length="0.100" radius="0.100"/>
        </geometry>
    </collision>  

    <visual>
        <origin rpy="0.0 0 0" xyz="0 0 0"/>
        <geometry>
            <cylinder length="0.100" radius="0.100"/>
        </geometry>
        <material name="grey"/>
    </visual>

</link>

<gazebo reference="Motor_Gear_link">
    <kp>100000.0</kp>
    <kd>100000.0</kd>
    <mu1>10.0</mu1>
    <mu2>10.0</mu2>
    <material>Gazebo/Grey</material>
</gazebo>

 <joint name="yaw_joint" type="revolute">
    <parent link="base_link"/>
    <child link="Motor_Gear_link"/>
    <origin xyz="0 0 0.5" rpy="0 0 0"/> <!-- posizione SdR1 del Motor_Gear_link -->
    <limit lower="-0.2" upper="0.2" effort="0.1" velocity="0.005"/>
    <axis xyz="0 0 1"/>
</joint>

<link name="wrc_link">
    <inertial>
        <origin xyz="0 0.009 0.150" rpy="0 0 0"/>            
        <mass value="30" />
        <inertia ixx="0.01" ixy="0.0" ixz="0.0" iyy="0.01" iyz="0.0" izz="0.01"/>
    </inertial>

    <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/wrc.dae"/>
        </geometry>
    </collision>  

    <visual>
        <origin rpy="0.0 0 0" xyz="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/wrc.dae"/>
        </geometry>
        <material name="grey"/>
    </visual>

</link>

<gazebo reference="wrc_link">
    <kp>100000.0</kp>
    <kd>100000.0</kd>
    <mu1>10.0</mu1>
    <mu2>10.0</mu2>
    <material>Gazebo/Grey</material>
</gazebo>

<joint name="wrc_joint" type="revolute">
    <parent link="Motor_Gear_link"/>
    <child link="wrc_link"/>
    <origin xyz="0 0 -0.35" rpy="0 0 0"/>
    <limit lower="-0.2" upper="0.2" effort="0.1" velocity="0.005"/>
    <axis xyz="1 0 0"/>
</joint>

<link name="wfl_link">
    <inertial>
        <origin xyz="0 0.0 0" rpy="0 0 0"/>            
        <mass value="30" />
        <inertia ixx="0.01" ixy="0.0" ixz="0.0" iyy="0.01" iyz="0.0" izz="0.01"/>
    </inertial>

    <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/wfl.dae"/>
        </geometry>
    </collision>  

    <visual>
        <origin rpy="0.0 0 0" xyz="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/wfl.dae"/>
        </geometry>
        <material name="grey"/>
    </visual>

</link>

<gazebo reference="wfl_link">
    <kp>100000.0</kp>
    <kd>100000.0</kd>
    <mu1>10.0</mu1>
    <mu2>10.0</mu2>
    <material>Gazebo/Grey</material>
</gazebo>

<joint name="wfl_joint" type="revolute">
    <parent link="base_link"/>
    <child link="wfl_link"/>
    <origin xyz="0.38 -0.95 0.15" rpy="0 0 0"/>
    <limit lower="-0.2" upper="0.2" effort="0.1" velocity="0.005"/>
    <axis xyz="1 0 0"/>
</joint>

 <link name="wfr_link">
    <inertial>
        <origin xyz="0 0.0 0" rpy="0 0 0"/>            
        <mass value="30" />
        <inertia ixx="0.01" ixy="0.0" ixz="0.0" iyy="0.01" iyz="0.0" izz="0.01"/>
    </inertial>

    <collision>
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/wfr.dae"/>
        </geometry>
    </collision>  

    <visual>
        <origin rpy="0.0 0 0" xyz="0 0 0"/>
        <geometry>
            <mesh filename="package://ME10C_tpx4350_description/models/ME10C_tpx4350/meshes/wfr.dae"/>
        </geometry>
        <material name="grey"/>
    </visual>

</link>

<gazebo reference="wfl_link">
    <kp>100000.0</kp>
    <kd>100000.0</kd>
    <mu1>10.0</mu1>
    <mu2>10.0</mu2>
    <material>Gazebo/Grey</material>
</gazebo>

<joint name="wfr_joint" type="revolute">
    <parent link="base_link"/>
    <child link="wfr_link"/>
    <origin xyz="-0.38 -0.95 0.15" rpy="0 0 0"/>
    <limit lower="-0.2" upper="0.2" effort="0.1" velocity="0.005"/>
    <axis xyz="1 0 0"/>
</joint>

Hi,

I answere you to the same issue here: ANSWER