diff --git a/launch/demo/demo_turtlebot_mapping.launch b/launch/demo/demo_turtlebot_mapping.launch
index ccd0458b..26fd5f80 100644
--- a/launch/demo/demo_turtlebot_mapping.launch
+++ b/launch/demo/demo_turtlebot_mapping.launch
@@ -85,7 +85,8 @@
 	  <param name="Rtabmap/TimeThr"              type="string" value="700"/>
 	  <param name="Mem/RehearsalSimilarity"      type="string" value="0.30"/>
 	  <param name="Optimizer/Slam2D"             type="string" value="true"/>
-	  <param name="Reg/Force3DoF"                type="string" value="true"/>   
+	  <param name="Reg/Force3DoF"                type="string" value="true"/>
+	  <param name="GridGlobal/MinSize"           type="string" value="20"/>
 	  
 	  <!-- localization mode -->
 	  <param     if="$(arg localization)" name="Mem/IncrementalMemory" type="string" value="false"/>