fixed friction issue

scout_description/launch/scout_v2_stock.launch

@@ -4,7 +4,6 @@
     <arg name="urdf_extras" default="$(find scout_description)/urdf/empty.urdf"/>
 
     <param name="robot_description" command="$(find xacro)/xacro '$(find scout_description)/urdf/scout_v2.xacro'
-        --inorder 
         robot_namespace:=$(arg robot_namespace) 
         urdf_extras:=$(arg urdf_extras)" />
 </launch>

scout_description/urdf/scout_v2.gazebo

@@ -1,5 +1,12 @@
 <?xml version="1.0"?>
-<robot xmlns:xacro="http://ros.org/wiki/xacro" >
+
+Reference:
+[1] https://answers.ros.org/question/246914/four-wheeled-skid-steering-in-gazebo-and-ros-using-gazebo-ros-control/
+[2] https://answers.ros.org/question/10119/gazebo-controller-for-skid-steering/
+[3] https://answers.ros.org/question/9640/rotation-error-in-gazebo-simulation/
+[4] https://www.youtube.com/watch?v=fuRAv6PDwdw
+
+<robot xmlns:xacro="http://ros.org/wiki/xacro">
     <xacro:include filename="$(find scout_description)/urdf/scout_wheel.gazebo" />
 
     <!-- Additional definitions for simulation -->
@@ -20,6 +27,17 @@
         </plugin>
     </gazebo>
 
+    <!-- kp spring constant, kd damping constant -->
+    <gazebo>
+        <mu1 value="1.0"/>
+        <mu2 value="0.9"/>
+        <kp value="10000000.0" />
+        <kd value="1.0" />
+        <fdir1 value="1 0 0"/>
+        <minDepth value="0.001" />
+        <maxContacts value="64"/>
+    </gazebo>
+
     <!-- <gazebo>
         <plugin name="skid_steer_drive_controller" filename="libgazebo_ros_skid_steer_drive.so">
             <updateRate>100.0</updateRate>

scout_description/urdf/scout_v2.xacro

@@ -32,6 +32,14 @@
         <child link="base_link" />
     </joint>
 
+    <!-- For testing, hang the robot up in the air -->
+    <!-- <link name="world" />
+    <joint name="world_to_base_link=" type="fixed">
+        <origin xyz="0 0 0.5" rpy="0 0 0" />
+        <parent link="world"/>
+        <child link="base_link"/>
+    </joint> -->
+
     <!-- Base link -->
     <link name="base_link">
         <visual>
@@ -87,14 +95,6 @@
         <origin xyz="${-wheelbase/2} ${-track/2} ${wheel_vertical_offset}" rpy="3.14 0 0" />
     </xacro:scout_wheel_type2>
 
-    <!-- For testing, hang the robot up in the air -->
-    <!-- <link name="world" />
-    <joint name="world_to_base_link=" type="fixed">
-        <origin xyz="0 0 0.5" rpy="0 0 0" />
-        <parent link="world"/>
-        <child link="base_link"/>
-    </joint> -->
-
     <!-- Additional definitions -->
     <xacro:include filename="$(arg urdf_extras)" />
 

scout_description/urdf/scout_wheel.gazebo

@@ -28,17 +28,6 @@ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSI
 <robot xmlns:xacro="http://ros.org/wiki/xacro" name="scout_wheel">
 
     <xacro:macro name="scout_wheel_transmission" params="wheel_prefix">
-        <!-- kp spring constant, kd damping constant -->
-        <gazebo reference="${wheel_prefix}_wheel_link">
-            <mu1 value="1.0"/>
-            <mu2 value="0.9"/>
-            <kp value="10000000.0" />
-            <kd value="1.0" />
-            <fdir1 value="1 0 0"/> 
-            <minDepth value="0.001" />
-            <maxContacts value="64"/>
-        </gazebo> 
-
         <transmission name="${wheel_prefix}_wheel_trans" type="SimpleTransmission">
             <type>transmission_interface/SimpleTransmission</type>
             <actuator name="${wheel_prefix}_wheel_motor">