Turtlebot-Gazebo-Demo: Gazebo sends wrong timestamps.

edit

Hi all,

I get some warnings when I start the turtlebot gazebo amcl demo. Here is the warning:

Warning: TF_OLD_DATA ignoring data from the past for frame odom at time 1 according to authority /amcl
Possible reasons are listed at http://wiki.ros.org/tf/Errors%20explained
     at line 260 in /tmp/binarydeb/ros-kinetic-tf2-0.5.13/src/buffer_core.cpp

Here is what I use:

• Ubuntu 16.04 LTS 64bit
• ROS Kinetic
• roslaunch turtlebot_gazebo turtlebot_world.launch
• roslaunch turtlebot_gazebo amcl_demo.launch

By debugging the problem with roswtf, rqt_tf_tree_view, rostopic echo, etc. , I now know that AMCL is publishing the following tf message sometimes:

---
transforms:
  -
    header:
      seq: 0
      stamp:
        secs: 1
        nsecs:         0
      frame_id: map
    child_frame_id: odom
    transform:
      translation:
        x: 0.0877543308947
        y: -0.113482781495
        z: 0.0
      rotation:
        x: -0.0
        y: -0.0
        z: 0.276478026871
        w: 0.961020239463

The rosparam use_sim_time is set to true. I am not so sure why this happens, or whether there is a bug in the amcl_demo.launch configuration, or even in amcl? Any help is welcome. :)

EDIT:

I further debugged it and traced the wrong time stamp back to gazebo. The gazebo_ros_openni_kinect plugin sends these timestamps. But I don't know why this is happening.

Greetings, Stephan