tello_ros gazebo errors

[AleBurzio]

I am running ros2 Dashing and I get this error whenever I try to simulate the drone in gazebo. I am able to control the actual tello drone through teleop, this problem arises only when i run the gazebo simulation. I followed every step in the readme file but there is always the possibility I might have missed something

alessandro@alessandro-K501UX:~/projects/ros_tello$ ros2 launch tello_gazebo simple_launch.py
[INFO] [launch]: All log files can be found below /home/alessandro/.ros/log/2019-12-09-18-44-13-280853-alessandro-K501UX-10266
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [gazebo-1]: process started with pid [10276]
[INFO] [inject_entity.py-2]: process started with pid [10277]
[ERROR] [inject_entity.py-2]: process has died [pid 10277, exit code 1, cmd '/home/alessandro/projects/ros_tello/install/tello_gazebo/lib/tello_gazebo/inject_entity.py /home/alessandro/projects/ros_tello/install/tello_description/share/tello_description/urdf/tello_1.urdf 0 0 1 0'].
[INFO] [robot_state_publisher-3]: process started with pid [10278]
[INFO] [joy_node-4]: process started with pid [10279]
[INFO] [tello_joy-5]: process started with pid [10280]
[ERROR] [launch]: Caught exception in launch (see debug for traceback): I/O operation on closed file
[INFO] [tello_joy-5]: sending signal 'SIGINT' to process[tello_joy-5]
[INFO] [joy_node-4]: sending signal 'SIGINT' to process[joy_node-4]
[INFO] [robot_state_publisher-3]: sending signal 'SIGINT' to process[robot_state_publisher-3]
[INFO] [gazebo-1]: sending signal 'SIGINT' to process[gazebo-1]
[robot_state_publisher-3] Initialize urdf model from file: /home/alessandro/projects/ros_tello/install/tello_description/share/tello_description/urdf/tello_1.urdf
[robot_state_publisher-3] Parsing robot urdf xml string.
[robot_state_publisher-3] The root link base_link_1 has an inertia specified in the URDF, but KDL does not support a root link with an inertia.  As a workaround, you can add an extra dummy link to your URDF.
[robot_state_publisher-3] Link camera_link_1 had 0 children
[robot_state_publisher-3] got segment base_link_1
[robot_state_publisher-3] got segment camera_link_1
[robot_state_publisher-3] Adding fixed segment from base_link_1 to camera_link_1
[gazebo-1] Gazebo multi-robot simulator, version 9.0.0
[gazebo-1] Copyright (C) 2012 Open Source Robotics Foundation.
[gazebo-1] Released under the Apache 2 License.
[gazebo-1] http://gazebosim.org
[gazebo-1]
[gazebo-1] Gazebo multi-robot simulator, version 9.0.0
[gazebo-1] Copyright (C) 2012 Open Source Robotics Foundation.
[gazebo-1] Released under the Apache 2 License.
[gazebo-1] http://gazebosim.org
[gazebo-1]
[tello_joy-5] [INFO] [rclcpp]: signal_handler(signal_value=2)
[INFO] [tello_joy-5]: process has finished cleanly [pid 10280]
[robot_state_publisher-3] [INFO] [rclcpp]: signal_handler(signal_value=2)
[INFO] [robot_state_publisher-3]: process has finished cleanly [pid 10278]
[joy_node-4] terminate called after throwing an instance of 'rclcpp::exceptions::RCLError'
[joy_node-4]   what():  Failed to create interrupt guard condition in Executor constructor: the given context is not valid, either rcl_init() was not called or rcl_shutdown() was called., at /tmp/binarydeb/ros-dashing-rcl-0.7.7/src/rcl/guard_condition.c:69
[gazebo-1] [Msg] Waiting for master.
[gazebo-1] [Msg] Connected to gazebo master @ http://127.0.0.1:11345
[gazebo-1] [Msg] Publicized address: 192.168.1.37
[ERROR] [joy_node-4]: process has died [pid 10279, exit code -6, cmd '/opt/ros/dashing/lib/joy/joy_node __ns:=/drone1'].
[INFO] [gazebo-1]: process has finished cleanly [pid 10276]
[gazebo-1]
[gazebo-1]
alessandro@alessandro-K501UX:

I will provide any further information if needed

[clydemcqueen]

Sorry, I left the "dashing" branch in a poor state. I just pushed several fixes. Please try again.

[AleBurzio]

It still did not work, but I've got a few different errors this time:

robot_state_publisher-3] Initialize urdf model from file: /home/alessandro/projects/tello_ros/install/tello_description/share/tello_description/urdf/tello_1.urdf
[robot_state_publisher-3] Parsing robot urdf xml string.
[robot_state_publisher-3] The root link base_link_1 has an inertia specified in the URDF, but KDL does not support a root link with an inertia.  As a workaround, you can add an extra dummy link to your URDF

These lines have me particularly suspicious because when i do colcon build I get an stderr message from the tello_description package

Furthermore, I had to change the names of two files in the install/tello_driver/lib/tello_driver folder: tello_joy_main -> tello_joy tello_driver_main -> tello_driver

because I was getting the following error message:

[ERROR] [launch]: Caught exception in launch (see debug for traceback): executable 'tello_joy' not found on the libexec directory '/home/alessandro/projects/tello_ros/install/tello_driver/lib/tello_driver'

and a similar one for the tello_driver executable

Lastly, I get this error again:

[INFO] [inject_entity.py-2]: process started with pid [11478]
[ERROR] [inject_entity.py-2]: process has died [pid 11478, exit code 1, cmd '/home/alessandro/projects/tello_ros/install/tello_gazebo/lib/tello_gazebo/inject_entity.py /home/alessandro/projects/tello_ros/install/tello_description/share/tello_description/urdf/tello_1.urdf 0 0 1 0'].

just like before, however this time the gazebo app opens with an empty map

[clydemcqueen]

Again, I apologize... and thank you for continuing to debug this.

Are you on the 'dashing' branch or the 'master' branch? Master includes a number of changes related to IPC that weren't fully tested. The 2 branches that should be stable are 'dashing' and 'eloquent'. I will merge eloquent into master to avoid confusion.

The stderr output from tello_description can be ignored. But it's poor practice for the build process to generate output on stderr, so I'll open an issue to fix this.

[clydemcqueen]

I just merged the eloquent branch into master, so master is now officially on Eloquent. The documentation has been updated to reflect this. Please git checkout dashing to test on Dashing.

[AleBurzio]

Ok, that seems to have solved the issue! On top of that, to solve this problem

INFO] [inject_entity.py-2]: process started with pid [11478]
[ERROR] [inject_entity.py-2]: process has died [pid 11478, exit code 1, cmd '/home/alessandro/projects/tello_ros/install/tello_gazebo/lib/tello_gazebo/inject_entity.py /home/alessandro/projects/tello_ros/install/tello_description/share/tello_description/urdf/tello_1.urdf 0 0 1 0'].

I had to change in the inject_entity.py file the python environment to python3 in the first line as it seems my system was using python 2 as the default python installation

Thank you very much!

[AleBurzio]

my bad

PS: I would like to write a small script for the drone to fly in a predefined pattern (eg takeoff, move right 10 m, move forward 10 m, then land), what should I be looking into to do something like this?