Updated .gazebo files

config/pan_tilt_gazebo_config.yaml

+robotNamespace: ana/pan_tilt
+

urdf/pan_tilt.gazebo

+<?xml version="1.0"?>
+<robot xmlns:xacro="http://www.ros.org/wiki/xacro">
+
+  <xacro:macro name="pan_tilt_gazebo" params="pan_joint_name tilt_joint_name sim_config">
+    <xacro:property name="properties" value="${load_yaml(sim_config)}"/>
+
+    <gazebo>
+      <plugin name="gazebo_ros_control" filename="libgazebo_ros_control.so">
+        <robotNamespace>/${properties['robotNamespace']}</robotNamespace>
+        <controlPeriod>0.01</controlPeriod>
+        <legacyModeNS>true</legacyModeNS>
+      </plugin>
+    </gazebo>
+
+    <gazebo reference="${pan_joint_name}_frame">
+      <mu1>0.2</mu1>
+      <mu2>0.2</mu2>
+      <material>Gazebo/Black</material>
+    </gazebo>
+
+    <gazebo reference="${tilt_joint_name}_frame">
+      <mu1>0.2</mu1>
+      <mu2>0.2</mu2>
+      <material>Gazebo/Green</material>
+    </gazebo>
+
+    <gazebo reference="${pan_joint_name}">
+      <implicitSpringDamper>true</implicitSpringDamper>
+    </gazebo>
+    <gazebo reference="${tilt_joint_name}">
+      <implicitSpringDamper>true</implicitSpringDamper>
+    </gazebo>
+
+  </xacro:macro>
+
+</robot>