Gmapping Launch File

edit

At the moment we are trying to increasingly use launch files (for obvious resons).

With Gmapping in the Gazebo simulator I am somehow stuck. The mapping works fine, when I start it via rosrun as follows:

$ rosparam set use_sim_time true
$ rosrun gmapping slam_gmapping scan:=youbot/scan_front _base_frame:=youbot/base_link _odom_frame:=youbot/odom

We then tried to do the same thing in a launch file, which resulted in something like this:

<launch>
  <param name="use_sim_time" value="true" />
  <node pkg="gmapping" type="slam_gmapping" name="gmapping_thing" output="screen" >
    <remap from="scan" to="youbot/scan_front" />
    <remap from="base_link" to="youbot/base_link" />
    <remap from="odom" to="youbot/odom" />
  </node>
</launch>

which results in debug messages like:

Node: /gmapping_thing
Time: 01:01:51.823000000 (1970-01-01)
Severity: Debug
Published Topics: /gmapping_thing/entropy, /map, /map_metadata, /rosout, /tf

MessageFilter [target=odom ]: Added message in frame youbot/base_laser_front_link at time 111.818, count now 5

Location:
/opt/ros/indigo/include/tf/message_filter.h:MessageFilter<M>::add:280

and:

Node: /gmapping_thing
Time: 01:01:51.823000000 (1970-01-01)
Severity: Debug
Published Topics: /gmapping_thing/entropy, /map, /map_metadata, /rosout, /tf

MessageFilter [target=odom ]: Removed oldest message because buffer is full, count now 5 (frame_id=youbot/base_laser_front_link, stamp=111.806000)

Location:
/opt/ros/indigo/include/tf/message_filter.h:MessageFilter<M>::add:264

One thing I already find strange here is the date, which seems to be low unix time stamps? The actual date of the machine is:

$ date
Fri Sep 25 13:22:50 CEST 2015

After further searching we found that the remap-tag might not be the best approach here, as the parameters can be set directly, which lead to the following launch file (it yields the same result when using _odom_frame and _base_link respectively):

<launch>
  <param name="use_sim_time" value="true" />
  <node pkg="gmapping" type="slam_gmapping" name="gmapping_thing" output="screen" >
    <param name="scan" value="youbot/scan_front" />
    <param name="odom_frame" value="youbot/odom" />
    <param name="base_frame" value="youbot/base_link" />
  </node>
</launch>

This leads to dropping of /clock messages

Node: /gmapping_thing
Time: 01:16:09.648000000 (1970-01-01)
Severity: Debug
Published Topics: /gmapping_thing/entropy, /map, /map_metadata, /rosout, /tf

Incoming queue full for topic "/clock".  Discarding oldest message (current queue size [0])

Location:
/tmp/buildd/ros-indigo-roscpp-1.11.13-0trusty-20150522-1157/src/libros/subscription_queue.cpp:SubscriptionQueue::push:67

We are kinda stuck here, so if anyone could provide some input, we would be glad.