add slip factor to turtlebot models

Author: aquintan4

CustomRobots/turtlebot3/models/turtlebot3_noisy_high/model.sdf

@@ -566,6 +566,8 @@
       <alpha2>0.005</alpha2>
       <alpha3>0.003</alpha3>
       <alpha4>0.003</alpha4>
+      <slip_factor>0.15</slip_factor>
+      <lateral_slip_ratio>0.25</lateral_slip_ratio>
     </plugin>
 
   </model>

CustomRobots/turtlebot3/models/turtlebot3_noisy_low/model.sdf

@@ -566,6 +566,8 @@
       <alpha2>0.0005</alpha2>
       <alpha3>0.0002</alpha3>
       <alpha4>0.0002</alpha4>
+      <slip_factor>0.05</slip_factor>
+      <lateral_slip_ratio>0.15</lateral_slip_ratio>
     </plugin>
 
   </model>

CustomRobots/turtlebot3/models/turtlebot3_noisy_med/model.sdf

@@ -566,6 +566,8 @@
       <alpha2>0.002</alpha2>
       <alpha3>0.001</alpha3>
       <alpha4>0.001</alpha4>
+      <slip_factor>0.10</slip_factor>
+      <lateral_slip_ratio>0.20</lateral_slip_ratio>
     </plugin>
 
   </model>