Loading Controller Crashes Gazebo Server

[ros-controls]

Loading Controller Crashes Gazebo Server

[Schulze18]

Hello, it seems a problem in your gzserver launch file. Is the "gzserver" launch file working fine in your system? Just try:
ros2 launch gazebo_ros gzserver.launch.py

If not, try to reinstall gazebo11 and gazebo_ros_pkgs for ROS2.

[Thieso]

Hi @Schulze18

I am already passing it as an argument so that does sadly not solve the problem.

[MXS13]

Okay, it was my bad. The robot I wanted to control had already ros2_control tags. I added xacro conditionals to determine real HW, fake HW or Gazebo. Problem solved.

[808brick]

As an update, I have tried to recreate my launch file to better represent that in the examples, however I am running into issues launching it, as I get the following error:
ImportError: cannot import name 'GazeboRosPaths' from 'scripts' (/home/ray/Workspaces/udemy_ros2_ws/install/udemy_ros2_pkg/lib/python3.8/site-packages/scripts/__init__.py)

The launch file is as follows:

# Copyright 2020 Open Source Robotics Foundation, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import os

from ament_index_python.packages import get_package_share_directory


from launch import LaunchDescription
from launch.actions import ExecuteProcess, IncludeLaunchDescription, RegisterEventHandler
from launch.event_handlers import OnProcessExit
from launch.launch_description_sources import PythonLaunchDescriptionSource

from launch_ros.actions import Node

import xacro


def generate_launch_description():
    gazebo = IncludeLaunchDescription(
                PythonLaunchDescriptionSource([os.path.join(
                    get_package_share_directory('gazebo_ros'), 'launch'), '/gazebo.launch.py']),
             )

    # gazebo_ros2_control_demos_path = os.path.join(
    #     get_package_share_directory('gazebo_ros2_control_demos'))
    #
    # xacro_file = os.path.join(gazebo_ros2_control_demos_path,
    #                           'urdf',
    #                           'test_cart_position.xacro.urdf')
    #
    # doc = xacro.parse(open(xacro_file))
    # xacro.process_doc(doc)

    urdf_file_name = 'urdf/camera_bot.xacro'

    urdf = os.path.join(
        get_package_share_directory('ros2_sim_pkg'),
        urdf_file_name)

    params = {'robot_description': urdf}

    node_robot_state_publisher = Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        output='screen',
        parameters=[params]
    )

    spawn_entity = Node(package='gazebo_ros', executable='spawn_entity.py',
                        arguments=['-topic', 'robot_description',
                                   '-entity', 'cartpole'],
                        output='screen')

    load_joint_state_controller = ExecuteProcess(
        cmd=['ros2', 'control', 'load_start_controller', 'joint_state_controller'],
        output='screen'
    )

    load_joint_trajectory_controller = ExecuteProcess(
        cmd=['ros2', 'control', 'load_start_controller', 'joint_trajectory_controller'],
        output='screen'
    )

    return LaunchDescription([
        RegisterEventHandler(
            event_handler=OnProcessExit(
                target_action=spawn_entity,
                on_exit=[load_joint_state_controller],
            )
        ),
        RegisterEventHandler(
            event_handler=OnProcessExit(
                target_action=load_joint_state_controller,
                on_exit=[load_joint_trajectory_controller],
            )
        ),
        gazebo,
        node_robot_state_publisher,
        spawn_entity,
    ])

and the terminal output:

ay@ubuntu:~/Workspaces/udemy_ros2_ws$ ros2 launch ros2_sim_pkg gazebo_ros2_control_test.launch.py 
[INFO] [launch]: All log files can be found below /home/ray/.ros/log/2021-03-31-01-20-49-067692-ubuntu-26382
[INFO] [launch]: Default logging verbosity is set to INFO
Task exception was never retrieved
future: <Task finished name='Task-2' coro=<LaunchService._process_one_event() done, defined at /opt/ros/foxy/lib/python3.8/site-packages/launch/launch_service.py:271> exception=ImportError("cannot import name 'GazeboRosPaths' from 'scripts' (/home/ray/Workspaces/udemy_ros2_ws/install/udemy_ros2_pkg/lib/python3.8/site-packages/scripts/__init__.py)")>
Traceback (most recent call last):
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launch_service.py", line 273, in _process_one_event
    await self.__process_event(next_event)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launch_service.py", line 293, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  [Previous line repeated 3 more times]
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 38, in visit_all_entities_and_collect_futures
    sub_entities = entity.visit(context)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/action.py", line 108, in visit
    return self.execute(context)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/actions/include_launch_description.py", line 125, in execute
    launch_description = self.__launch_description_source.get_launch_description(context)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launch_description_source.py", line 84, in get_launch_description
    self._get_launch_description(self.__expanded_location)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launch_description_sources/python_launch_description_source.py", line 51, in _get_launch_description
    return get_launch_description_from_python_launch_file(location)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launch_description_sources/python_launch_file_utilities.py", line 62, in get_launch_description_from_python_launch_file
    launch_file_module = load_python_launch_file_as_module(python_launch_file_path)
  File "/opt/ros/foxy/lib/python3.8/site-packages/launch/launch_description_sources/python_launch_file_utilities.py", line 37, in load_python_launch_file_as_module
    loader.exec_module(mod)
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/opt/ros/foxy/share/gazebo_ros/launch/gzserver.launch.py", line 28, in <module>
    from scripts import GazeboRosPaths
ImportError: cannot import name 'GazeboRosPaths' from 'scripts' (/home/ray/Workspaces/udemy_ros2_ws/install/udemy_ros2_pkg/lib/python3.8/site-packages/scripts/__init__.py)

[Thieso]

Hi I have the same error (at least the initial one) where loading the controller manager crashes gazebo. There are also no error messages for me except the final one that the gzserver has died. Running ros2 launch gazebo_ros gzserver.launch.py works without any problems.

[Schulze18]

Hi @Thieso, I am not sure, but I think the initial problem was that the URDF has been passed as an argument to robot_state_publisher:

Node(
     package='robot_state_publisher',
     executable='robot_state_publisher',
     name='robot_state_publisher',
     output='screen',
     parameters=[{'use_sim_time': use_sim_time}],
     arguments=[urdf]), 

but it should be given as a parameter (what @808brick already did in the second post):

params = {'robot_description': urdf}
Node(
     package='robot_state_publisher',
     executable='robot_state_publisher',
     name='robot_state_publisher',
     output='screen',
      parameters=[params]

[Schulze18]

@808brick It seems that your ros2 launch file is looking only for your workspace scripts folder, did you source the ros2 distro?
source /opt/ros/foxy/setup.bash

[Thieso]

So further information on this,

I ran gazebo with gazebo --verbose -s libgazebo_ros_init.so -s libgazebo_ros_factory.so which gives me the error [Err] [Model.cc:1137] Exception occured in the Load function of plugin with name[gazebo_ros2_control] and filename[libgazebo_ros2_control.so]. This plugin will not run.

Sadly this is also not helpful for me but maybe you can see some problem there. Any hints are appreciated

My launch file is

#!/usr/bin/env python3

import os
import sys

from ament_index_python.packages import get_package_share_directory

import launch
from launch import LaunchDescription, LaunchService
from launch.actions import IncludeLaunchDescription, RegisterEventHandler, ExecuteProcess
from launch_ros.actions import Node
from launch.event_handlers import OnProcessExit
from launch.launch_description_sources import PythonLaunchDescriptionSource
import xacro


def generate_launch_description():
    # Load the URDF into a parameter
    bringup_dir = get_package_share_directory('scanbot_description')
    urdf_path = os.path.join(bringup_dir, 'scanbot_system.urdf.xacro')
    urdf = xacro.process_file(urdf_path).toxml()


    rviz_config_file = os.path.join(
        get_package_share_directory('scanbot_description'),
        'scanbot.rviz'
        )
    

    gazebo_node = launch.actions.ExecuteProcess(
        cmd=['gazebo', '--verbose', '-s', 'libgazebo_ros_init.so', '-s', 'libgazebo_ros_factory.so'],
        output='screen'
    )
    # gazebo_node = IncludeLaunchDescription(
        # PythonLaunchDescriptionSource([os.path.join(
            # get_package_share_directory('gazebo_ros'), 'launch'), '/gazebo.launch.py']),
    # )

    spawn_entity_node = Node(package='gazebo_ros', executable='spawn_entity.py',
            arguments=['-entity', 'scanbot', '-topic', 'robot_description'],
            output='screen')

    joint_state_publisher_node = Node(
            name='joint_state_publisher',
            package='joint_state_publisher',
            executable='joint_state_publisher',
            output='screen'
    )
    robot_state_publisher_node = Node(
            name='robot_state_publisher',
            package='robot_state_publisher',
            executable='robot_state_publisher',
            parameters=[{'robot_description': urdf}],
            output='screen'
    )
    rviz_node = Node(
            package='rviz2',
            name='rviz2',
            executable='rviz2',
            output='screen',
            arguments=['-d', rviz_config_file],
    )

    return LaunchDescription([
        joint_state_publisher_node,
        rviz_node,
        gazebo_node,
        robot_state_publisher_node,
        spawn_entity_node,
    ])


def main(argv=sys.argv[1:]):
    """Run lifecycle nodes via launch."""
    ld = generate_launch_description()
    ls = LaunchService(argv=argv)
    ls.include_launch_description(ld)
    return ls.run()


if __name__ == '__main__':
    main()

[808brick]

I apologize for being inactive on this thread, was a busy week.

@Schulze18 my terminals are automatically sourced to ROS Foxy via .bashrc (so the line source /opt/ros/foxy/setup.bash is at the end of the .bashrc file, which is how my ROS commands are able to run) then I go into the workspace, source it and try to launch.

I am not on the system in question right now, but I will try to do more experimenting this weekend with the comments you have given and report back. Thanks for all the feedback and help.

[newcanopies]

hi @Schulze18

is it even possible to launch Gazebo with both plugins as suggested above #67 (comment)
gazebo --verbose -s libgazebo_ros_init.so -s libgazebo_ros_factory.so

[MXS13]

Hi @Schulze18, hi @808brick
Was this issue resolved? I still have the issue on Foxy Branch with Gazebo-11 and would like to know if there's a workaround.

Somehow it seems to function out of the box when looking at eg. https://www.youtube.com/watch?v=xBhYHOSxMOk.

My controller config:

`
controller_manager:
ros__parameters:
update_rate: 100 # Hz

joint_trajectory_controller_spj:
  type: joint_trajectory_controller/JointTrajectoryController
joint_state_broadcaster_spj:
  type: joint_state_broadcaster/JointStateBroadcaster

joint_trajectory_controller_slj:
  type: joint_trajectory_controller/JointTrajectoryController
joint_state_broadcaster_slj:
  type: joint_state_broadcaster/JointStateBroadcaster

joint_trajectory_controller_ej:
  type: joint_trajectory_controller/JointTrajectoryController
joint_state_broadcaster_ej:
  type: joint_state_broadcaster/JointStateBroadcaster

joint_trajectory_controller_w1j:
  type: joint_trajectory_controller/JointTrajectoryController
joint_state_broadcaster_w1j:
  type: joint_state_broadcaster/JointStateBroadcaster

joint_trajectory_controller_w2j:
  type: joint_trajectory_controller/JointTrajectoryController
joint_state_broadcaster_w2j:
  type: joint_state_broadcaster/JointStateBroadcaster

joint_trajectory_controller_w3j:
  type: joint_trajectory_controller/JointTrajectoryController
joint_state_broadcaster_w3j:
  type: joint_state_broadcaster/JointStateBroadcaster

joint_trajectory_controller_spj:
ros__parameters:
joints:
- shoulder_pan_joint
interface_name: position
command_interfaces:
- position
state_interfaces:
- position
- velocity

joint_trajectory_controller_slj:
ros__parameters:
joints:
- shoulder_lift_joint
interface_name: position
command_interfaces:
- position
state_interfaces:
- position
- velocity

joint_trajectory_controller_ej:
ros__parameters:
joints:
- elbow_joint
interface_name: position
command_interfaces:
- position
state_interfaces:
- position
- velocity

joint_trajectory_controller_w1j:
ros__parameters:
joints:
- wrist_1_joint
interface_name: position
command_interfaces:
- position
state_interfaces:
- position
- velocity

joint_trajectory_controller_w2j:
ros__parameters:
joints:
- wrist_2_joint
interface_name: position
command_interfaces:
- position
state_interfaces:
- position
- velocity

joint_trajectory_controller_w3j:
ros__parameters:
joints:
- wrist_3_joint
interface_name: position
command_interfaces:
- position
state_interfaces:
- position
- velocity
`

And my xacro:

`

<xacro:macro name="gazebo_control" params="
prefix
shoulder_pan_lower_limit
shoulder_pan_upper_limit
shoulder_lift_lower_limit
shoulder_lift_upper_limit
elbow_joint_lower_limit
elbow_joint_upper_limit
wrist_1_lower_limit
wrist_1_upper_limit
wrist_2_lower_limit
wrist_2_upper_limit
wrist_3_lower_limit
wrist_3_upper_limit
">

    <!-- ROS 2 Control -->
    <ros2_control name="GazeboSystem" type="system">
        <hardware>
            <plugin>gazebo_ros2_control/GazeboSystem</plugin>
        </hardware>

        <joint name="${prefix}shoulder_pan_joint">
            <command_interface name="position_spj">
                <param name="min">${shoulder_pan_lower_limit}</param>
                <param name="man">${shoulder_pan_upper_limit}</param>
            </command_interface>
            <state_interface name="position"/>
            <state_interface name="velocity"/>
            <state_interface name="effort"/>
        </joint>
        <joint name="${prefix}shoulder_lift_joint">
            <command_interface name="position_slj">
                <param name="min">${shoulder_lift_lower_limit}</param>
                <param name="man">${shoulder_lift_upper_limit}</param>
            </command_interface>
            <state_interface name="position"/>
            <state_interface name="velocity"/>
            <state_interface name="effort"/>
        </joint>
        <joint name="${prefix}elbow_joint">
            <command_interface name="position_ej">
                <param name="min">${elbow_joint_lower_limit}</param>
                <param name="man">${elbow_joint_upper_limit}</param>
            </command_interface>
            <state_interface name="position"/>
            <state_interface name="velocity"/>
            <state_interface name="effort"/>
        </joint>
        <joint name="${prefix}wrist_1_joint">
            <command_interface name="position_w1j">
                <param name="min">${wrist_1_lower_limit}</param>
                <param name="man">${wrist_1_upper_limit}</param>
            </command_interface>
            <state_interface name="position"/>
            <state_interface name="velocity"/>
            <state_interface name="effort"/>
        </joint>
        <joint name="${prefix}wrist_2_joint">
            <command_interface name="position_w2j">
                <param name="min">${wrist_2_lower_limit}</param>
                <param name="man">${wrist_2_upper_limit}</param>
            </command_interface>
            <state_interface name="position"/>
            <state_interface name="velocity"/>
            <state_interface name="effort"/>
        </joint>
        <joint name="${prefix}wrist_3_joint">
            <command_interface name="position_w3j">
                <param name="min">${wrist_3_lower_limit}</param>
                <param name="man">${wrist_3_upper_limit}</param>
            </command_interface>
            <state_interface name="position"/>
            <state_interface name="velocity"/>
            <state_interface name="effort"/>
        </joint>

    </ros2_control>

    <gazebo>
        <!-- <plugin name="gazebo_ros2_control" filename="/root/ros2_ws/install/gazebo_ros2_control/lib/libgazebo_ros2_control.so" > -->
        <plugin name="gazebo_ros2_control" filename="libgazebo_ros2_control.so" >
            <parameters>$(find modprof_bringup)/config/ur_joint_controller_angle.yaml</parameters> -->
           <!--  <parameters>$(find modprof_bringup)/config/tst.yaml</parameters> -->
        </plugin>
    </gazebo>
</xacro:macro>

`

[bmagyar]

Please don't expect many things to be fixed in Foxy. We'd appreciate if you could give us feedback about what's on rolling ATM as it will be the baseline for the Humble release, thanks!

…

On Wed, 11 May 2022, 10:58 MXS13, ***@***.***> wrote: Okay, it was my bad. The robot I wanted to control had already ros2_control tags. I added xacro conditionals to determine real HW, fake HW or Gazebo. Problem solved. — Reply to this email directly, view it on GitHub <#67 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA24PYPICHK2KKLNPKR3SZ3VJOADFANCNFSM42ELBKMQ> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>