anymal_b_simple_description: Add missing inertia, fix for simulator

robots/anymal_b_simple_description/robots/anymal.urdf

 <?xml version="1.0" ?>
 <!-- =================================================================================== -->
-<!-- |    This document was autogenerated by xacro from anymal.urdf.xacro              | -->
-<!-- |    EDITING THIS FILE BY HAND IS NOT RECOMMENDED                                 | -->
+<!-- |    This URDF was edited to fix inertias.                                        | -->
 <!-- =================================================================================== -->
 <!-- This file contains the description of the ANYmal B robot. -->
-<robot name="anymal" xmlns:xacro="http://www.ros.org/wiki/xacro">
+<robot name="anymal" 
+  xmlns:xacro="http://www.ros.org/wiki/xacro">
   <material name="black">
     <color rgba="0.0 0.0 0.0 1.0"/>
   </material>
@@ -100,21 +100,26 @@
         <box size="0.531 0.02 0.07"/>
       </geometry>
     </collision>
+    <inertial>
+      <origin rpy="0 0 0" xyz="-0.001960558279 -0.001413217745 0.050207125344"/>
+      <mass value="16.793507758"/>
+      <inertia ixx="0.217391101503" ixy="-0.00132873239126" ixz="-0.00228200226173" iyy="0.639432546734" iyz="-0.00138078263145" izz="0.62414077654"/>
+    </inertial>
   </link>
   <!-- Fixed joint to add dummy inertia link -->
-  <joint name="base_to_base_inertia" type="fixed">
+  <!-- <joint name="base_to_base_inertia" type="fixed">
     <parent link="base"/>
     <child link="base_inertia"/>
     <origin rpy="0 0 0" xyz="0 0 0"/>
-  </joint>
+  </joint> -->
   <!-- Dummy inertia link, because KDL cannot have inertia on the base link -->
-  <link name="base_inertia">
+  <!-- <link name="base_inertia">
     <inertial>
       <origin rpy="0 0 0" xyz="-0.001960558279 -0.001413217745 0.050207125344"/>
       <mass value="16.793507758"/>
       <inertia ixx="0.217391101503" ixy="-0.00132873239126" ixz="-0.00228200226173" iyy="0.639432546734" iyz="-0.00138078263145" izz="0.62414077654"/>
     </inertial>
-  </link>
+  </link> -->
   <!-- Xacro:Properties -->
   <!-- [kg * m^2] -->
   <!-- [A] -->
@@ -278,6 +283,18 @@
         <sphere radius="0.031"/>
       </geometry>
     </collision>
+    <inertial>
+      <mass value="0.001"/>
+      <inertia ixx="4.90e-07" ixy="0.0" ixz="0.0" iyy="4.90e-07" iyz="0.0" izz="4.90e-07"/>
+      <!-- for a sphere: 2/5 m * r**2 -->
+    </inertial>
+    <!-- Bullet specific parameters -->
+    <contact>
+      <lateral_friction value="1.0"/>
+      <stiffness value="300000"/>
+      <damping value="15000"/>
+      <!--<restitution value="0.5"/>-->
+    </contact>
   </link>
   <!-- Gazebo customization -->
   <gazebo reference="LF_FOOT">
@@ -449,6 +466,18 @@
         <sphere radius="0.031"/>
       </geometry>
     </collision>
+    <inertial>
+      <mass value="0.001"/>
+      <inertia ixx="4.90e-07" ixy="0.0" ixz="0.0" iyy="4.90e-07" iyz="0.0" izz="4.90e-07"/>
+      <!-- for a sphere: 2/5 m * r**2 -->
+    </inertial>
+    <!-- Bullet specific parameters -->
+    <contact>
+      <lateral_friction value="1.0"/>
+      <stiffness value="300000"/>
+      <damping value="15000"/>
+      <!--<restitution value="0.5"/>-->
+    </contact>
   </link>
   <!-- Gazebo customization -->
   <gazebo reference="RF_FOOT">
@@ -620,6 +649,18 @@
         <sphere radius="0.031"/>
       </geometry>
     </collision>
+    <inertial>
+      <mass value="0.001"/>
+      <inertia ixx="4.90e-07" ixy="0.0" ixz="0.0" iyy="4.90e-07" iyz="0.0" izz="4.90e-07"/>
+      <!-- for a sphere: 2/5 m * r**2 -->
+    </inertial>
+    <!-- Bullet specific parameters -->
+    <contact>
+      <lateral_friction value="1.0"/>
+      <stiffness value="300000"/>
+      <damping value="15000"/>
+      <!--<restitution value="0.5"/>-->
+    </contact>
   </link>
   <!-- Gazebo customization -->
   <gazebo reference="LH_FOOT">
@@ -791,6 +832,18 @@
         <sphere radius="0.031"/>
       </geometry>
     </collision>
+    <inertial>
+      <mass value="0.001"/>
+      <inertia ixx="4.90e-07" ixy="0.0" ixz="0.0" iyy="4.90e-07" iyz="0.0" izz="4.90e-07"/>
+      <!-- for a sphere: 2/5 m * r**2 -->
+    </inertial>
+    <!-- Bullet specific parameters -->
+    <contact>
+      <lateral_friction value="1.0"/>
+      <stiffness value="300000"/>
+      <damping value="15000"/>
+      <!--<restitution value="0.5"/>-->
+    </contact>
   </link>
   <!-- Gazebo customization -->
   <gazebo reference="RH_FOOT">