Gazebo ros control position controller joints problem

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Hi,

I am currently working on a project using a vehicle of type EasyMile Ez10 and I have problems when it comes to control both the steering and linear joints. I am currently using Gazebo 7 with ROS Kinetic.

The urdf model in Gazebo has 8 joints and transmissions: 4 continuous (velocity controller) to move the model forward and 4 revolute (position controller) to turn each wheel (like a double Ackermann in which the back wheels mirror the front ones); The description tree of the wheels is like this one:

and this is the model:

The problem arises when I try to command the joints. If I try to spin the steer joints, the effort applied to each joint by the controller is shared between the parent (axle_joint for steering wheels) and the child (linear joints for movement), hence, the steer joint spin properly but the linear joint moves like if I applied also an effort to it. An example of that behavior can be found here:

https://drive.google.com/open?id=1RVh...

I think is a problem of contacts with the floor and the mass of the model (2000 kg) but I tried to modify the floors properties and ODE parameter with no avail.

Thanks for the help.

Edit: Ok, thanks for the suggestions. I have added new links for resources. Since I do not have enough karma I am not able to post them here direcly.

This is the urdf regarding the wheels of the model:

<robot name="wheel" xmlns:xacro="http://www.ros.org/wiki/xacro">

  <xacro:property name="M_PI" value="3.1415926535897931" />
  <!-- Wheels -->

  <xacro:macro name="cylinder_inertia" params="m r h">
    <inertia  ixx="${m*(3*r*r+h*h)/12}" ixy = "0.0" ixz = "0.0"
              iyy="${m*r*r/2}" iyz = "0.0"
              izz="${m*(3*r*r+h*h)/12}" /> 
  </xacro:macro>

  <xacro:macro name="rubber_wheel" params="prefix parent wheel_radius wheel_width wheel_mass orientation *origin">

    <!--WHEEL TIRE -->
    <link name="${prefix}_wheel">
      <visual>
        <!-- HIGH RESOLUTION WHEELS -->
        <xacro:if value="${orientation == 0}"> 
          <origin xyz="0 ${-wheel_width/2} ${-wheel_radius}" rpy="0 0 ${orientation}" />
        </xacro:if>
        <xacro:if value="${orientation == M_PI}"> 
          <origin xyz="0 ${wheel_width/2} ${-wheel_radius}" rpy="0 0 ${orientation}" />
        </xacro:if>
        <geometry>
            <mesh scale="0.061 0.061 0.061" filename="file:///$(find ares_description)/meshes/wheels/wheel.dae"/>
        </geometry>
      </visual>      
      <collision>
        <origin xyz="0 0 0" rpy="${M_PI/2} 0 0" />
        <geometry>
          <cylinder length="${wheel_width}" radius="${wheel_radius}" />
        </geometry>
      </collision>    
      <inertial>
        <mass value="${wheel_mass}" />
        <origin xyz="0 0 0" />
        <cylinder_inertia  m="${wheel_mass}" r="${wheel_radius}" h="${wheel_width}" /> <!-- macro defined at the beginning of this document -->
      </inertial>
    </link>

    <!-- Virtual link for two joints -->
    <link name="${prefix}_wheel_axle">    
      <inertial>
        <mass value="${wheel_mass}" />
        <origin xyz="0 0 0" />
        <cylinder_inertia  m="${wheel_mass}" r="${wheel_radius}" h="${wheel_width}" /> <!-- macro defined at the beginning of ...