Same tf tree changes some frames

edit

Hello,

I am running hector_mapping and hector_exploration_node after roslaunching my robot in gazebo and today I noticed that the tf tree changes from time to time:

I also ran roswtf and I got the following issues, which I don't know if they are indirectly relevant to the tf trees above:

Loaded plugin tf.tfwtf
No package or stack in context
================================================================================
Static checks summary:

No errors or warnings
================================================================================
Beginning tests of your ROS graph. These may take awhile...
analyzing graph...
... done analyzing graph
running graph rules...
ERROR: connection refused to [http://legged-HP-ProBook-450-G2:44318/]
... done running graph rules
running tf checks, this will take a second...
... tf checks complete

Online checks summary:

Found 2 warning(s).
Warnings are things that may be just fine, but are sometimes at fault

WARNING The following node subscriptions are unconnected:
 * /hector_mapping:
   * /syscommand
 * /gazebo:
   * /gazebo/set_model_state
   * /gazebo/set_link_state
   * /labrob/cmd_vel

WARNING These nodes have died:
 * labrob_spawn-3


Found 3 error(s).

ERROR Could not contact the following nodes:
 * /rviz_1472030068686009566

ERROR The following nodes should be connected but aren't:
 * /gazebo->/rviz_1472030068686009566 (/tf)
 * /hector_exploration_node->/hector_exploration_node (/hector_exploration_node/global_costmap/footprint)
 * /hector_mapping->/rviz_1472030068686009566 (/tf)
 * /robot_state_publisher->/rviz_1472030068686009566 (/tf_static)
 * /rviz_1472030068686009566->/hector_mapping (/initialpose)
 * /tf_broadcaster_node->/rviz_1472030068686009566 (/tf)
 * /robot_state_publisher->/rviz_1472030068686009566 (/tf)
 * /gazebo->/rviz_1472030068686009566 (/clock)

ERROR Errors connecting to the following services:
 * service [/rviz_1472030068686009566/get_loggers] appears to be malfunctioning: Unable to communicate with service [/rviz_1472030068686009566/get_loggers], address [rosrpc://legged-HP-ProBook-450-G2:59065]
 * service [/rviz_1472030068686009566/set_logger_level] appears to be malfunctioning: Unable to communicate with service [/rviz_1472030068686009566/set_logger_level], address [rosrpc://legged-HP-ProBook-450-G2:59065]

I have the following launch file for my hector_mapping node:

<?xml version="1.0"?>

<launch>
  <arg name="tf_map_scanmatch_transform_frame_name" default="scanmatcher_frame"/>
  <arg name="base_frame" default="base_link"/>
  <arg name="odom_frame" default="base_link"/>
  <arg name="pub_map_odom_transform" default="false"/>
  <arg name="scan_subscriber_queue_size" default="5"/>
  <arg name="scan_topic" default="/labrob/laser/scan"/>
  <arg name="map_size" default="2048"/>

  <node pkg="hector_mapping" type="hector_mapping" name="hector_mapping" output="screen">

    <!-- Frame names -->
    <param name="map_frame" value="map" />
    <param name="base_frame" value="$(arg base_frame)" />
    <param name="odom_frame" value="$(arg odom_frame)" />

    <!-- Tf use -->
    <param name="use_tf_scan_transformation" value="false"/>
    <param name="use_tf_pose_start_estimate" value="false"/>
    <param name="pub_map_odom_transform" value="$(arg pub_map_odom_transform)"/>

    <!-- Map size / start point -->
    <param name="map_resolution" value="0.050"/>
    <param name="map_size" value="$(arg map_size)"/>
    <param name="map_start_x" value="0.5"/>
    <param name="map_start_y" value="0.5" />
    <param name="map_multi_res_levels" value="2" />

    <!-- Map update parameters -->
    <param name="update_factor_free" value="0.4"/>
    <param name="update_factor_occupied" value="0.9" />    
    <param name="map_update_distance_thresh" value="0.01"/>
    <param name="map_update_angle_thresh" value="0.001" />
    <param name="laser_z_min_value" value = "-1.0" />
    <param name="laser_z_max_value" value = "1.0" />

    <!-- Advertising config --> 
    <param name="advertise_map_service" value="true"/>

    <param name="scan_subscriber_queue_size" value="$(arg scan_subscriber_queue_size)"/>
    <param name="scan_topic" value="$(arg scan_topic)"/>

    <!-- Debug parameters -->
    <!--
      <param name="output_timing" value="false"/>
      <param name="pub_drawings" value="true"/>
      <param name="pub_debug_output" value="true"/>
    -->
    <param name="tf_map_scanmatch_transform_frame_name" value="$(arg tf_map_scanmatch_transform_frame_name)" />
  </node>

  <!--<node pkg="tf" type="static_transform_publisher" name="map_nav_broadcaster" args="0 0 0 0 0 0 map nav 100"/>-->
</launch>

I wanted to ask what is going on and if this is an error that could lead to wrong robot's behavior during autonomous exploration ?