Very heavy platforms in Gazebo

edit

I tested your solution. The simulation is stable, but a portion of the wheels penetrates the ground. I don't know whether this can influence the behavior of the platform (increasing friction for example). Anyway, I post the urdf of the platform and the world file with the updates suggested by you. Just a note: I changed the kp and kd of the ground plane model in the world file, and the cfm and erp of the wheel joint (is this correct?).

Platform (it is based on the PR2 base):

<?xml version="1.0"?>
<robot xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
   xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
   xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
   xmlns:xacro="http://ros.org/wiki/xacro">

<include filename="$(find prototype_description)/urdf/base.gazebo.xacro" />
<include filename="$(find prototype_description)/urdf/base.transmission.xacro" />


<property name="M_PI" value="3.1415926535897931" />

<property name="caster_offset_x" value="1.5" />
<property name="caster_offset_y" value="0.5" />
<property name="caster_offset_z" value="0.0282" />

<property name="caster_wheel_offset_y" value="0.049" />
<property name="wheel_length" value="0.085" /> 
<property name="wheel_radius" value="0.205" /> 
<property name="base_mass" value="5000.0" /> 

<!-- simplified box collision geometry for base -->
<property name="base_size_x" value="4.0" />
<property name="base_size_y" value="2.0" />
<property name="base_size_z" value="0.2" />
<property name="base_collision_size_z" value="0.04" />

<!--                                                      -->
<!--           wheel                                      -->
<!--                                                      -->
<xacro:macro name="experimental_wheel_v0" params="suffix parent reflect"> <!-- The idea is to remove reflect from here -->

<joint name="${parent}_${suffix}_wheel_joint" type="continuous">
  <axis xyz="0 1 0" />
  <limit effort="500" velocity="100"/>
  <safety_controller  k_velocity="10" />
  <dynamics damping="0.0" friction="0.0" />
  <origin xyz="0 0 0" rpy="0 0 0" /> 
  <parent link="${parent}_rotation_link"/>
  <child link="${parent}_${suffix}_wheel_link"/>
  <cfm>0.00000017</cfm> 
  <erp>0.17</erp>    
</joint>
<link name="${parent}_${suffix}_wheel_link">
  <inertial>
    <mass value="10.44036" /> <!-- original value = 0.44036 -->
    <origin xyz="0 0 0" />
    <inertia  ixx="0.012411765597" ixy="-0.000711733678" ixz="0.00050272983"
              iyy="0.015218160428" iyz="-0.000004273467" izz="0.011763977943" />
  </inertial>
  <visual>
    <origin xyz="0 0 0" rpy="${M_PI/2} 0 0" /> <!-- original rpy="0 0 0"-->
    <geometry>
  <cylinder radius="${wheel_radius}" length="${wheel_length}" /> 
    </geometry>

    <material name="Wheel_${suffix}" />
  </visual>
  <collision>
    <origin xyz="0 0 0" rpy="${M_PI/2} 0 0" /> <!-- rotation because cyl. geom primitive has symmetry axis in +x direction -->
    <geometry>
      <cylinder radius="${wheel_radius}" length="${wheel_length}" />
    </geometry>
  </collision>
</link>

<!-- extensions -->
<xacro:experimental_wheel_gazebo_v0 parent="${parent}" suffix="${suffix}" />
<xacro:prototype_wheel_transmission_v0 parent="${parent}" suffix="${suffix}" reflect="${reflect}" /> 

</xacro:macro>

<!-- Macro for caster hub only -->
<xacro:macro name="experimental_caster_hub_v0" params="suffix parent *origin ref_position" >
  <joint name="${suffix}_rotation_joint" type="continuous">
    <axis xyz="0 0 1" />
    <limit effort="1000" velocity="1000"/>
    <safety_controller  k_velocity="10" />
    <calibration rising="${ref_position}" />
    <dynamics damping="0.0" friction="0.0" />
    <insert_block name="origin" />
    <parent link="${parent}"/>
    <child link="${suffix}_rotation_link" />
  </joint>
  <link name="${suffix}_rotation_link">

  <inertial>
    <mass value="53.473082"/>
    <origin xyz="0 0 0.07" />
    <inertia  ixx="0.012411765597" ixy="-0.000711733678" ixz="0.00050272983"
              iyy="0.015218160428" iyz="-0.000004273467" izz="0.011763977943 ...