6.2.2使用launch组织文件节点，启动运行错误

开心

出现问题：
按display_robot.launch.py的代码清单录入，构建工作空间后运行错误，提示如下

RROR] [launch]: Caught exception in launch (see debug for traceback): Caught multiple exceptions when trying to load file of format [py]:
 - TypeError: 'module' object is not callable
 - InvalidFrontendLaunchFileError: The launch file may have a syntax error, or its format is unknown

display_robot.launch.py代码清单如下：

import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory



def generate_launch_description():
    urdf_tutorial_path = get_package_share_directory('fishbot_description')
    default_model_path = urdf_tutorial_path + '/urdf/first_robot.urdf'
    #print (str(default_model_path))
    action_declare_arg_mode_path = launch.actions.DeclareLaunchArgument(
        name='model', default_value=str(default_model_path),
        description='URDF的绝对路径')
    robot_description=launch_ros.parameter_descriptions.ParameterValue(
        launch.substitutions.Command(
            ['cat ', launch.substitutions.LaunchConfiguration('model')]),
            value_type=str)
    robot_state_publisher_node = launch_ros.actions.Node (
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description':robot_description}])
    joint_state_publisher_node = launch_ros.actions.Node(
        package='joint_state_publish',
        executable='joint_state_publisher',
    )
    rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
    )
    return launch.launch_description([
        action_declare_arg_mode_path,
        joint_state_publisher_node,
        robot_state_publisher_node,
        rviz_node
    ])

cmakelists.txt代码清单如下：

cmake_minimum_required(VERSION 3.8)
project(fishbot_description)

if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  add_compile_options(-Wall -Wextra -Wpedantic)
endif()

# find dependencies
find_package(ament_cmake REQUIRED)
# uncomment the following section in order to fill in
# further dependencies manually.
# find_package(<dependency> REQUIRED)

if(BUILD_TESTING)
  find_package(ament_lint_auto REQUIRED)
  # the following line skips the linter which checks for copyrights
  # comment the line when a copyright and license is added to all source files
  set(ament_cmake_copyright_FOUND TRUE)
  # the following line skips cpplint (only works in a git repo)
  # comment the line when this package is in a git repo and when
  # a copyright and license is added to all source files
  set(ament_cmake_cpplint_FOUND TRUE)
  ament_lint_auto_find_test_dependencies()
endif()


install(DIRECTORY launch urdf 
DESTINATION share/${PROJECT_NAME}
)

ament_package()

开心

@43996173
运行命令：

 ros2 launch fishbot_description display_robot.launch.py

print的文件的目录

/home/tingbo/chapt6/chapt6_ws/install/fishbot_description/share/fishbot_description/urdf/first_robot.urdf

开心

@43996173
运行后的完整日志：

[INFO] [launch]: All log files can be found below /home/tingbo/.ros/log/2024-04-16-15-15-20-527656-DESKTOP-NHH5E05-22235
[INFO] [launch]: Default logging verbosity is set to INFO
[ERROR] [launch]: Caught exception in launch (see debug for traceback): Caught multiple exceptions when trying to load file of format [py]:
 - TypeError: 'module' object is not callable
 - InvalidFrontendLaunchFileError: The launch file may have a syntax error, or its format is unknown

小鱼

@43996173 这是一个语法错误。你可以运行

ros2 launch fishbot_description display_robot.launch.py --debug

查看详细的日志信息。

开心

@小鱼在 6.2.2使用launch组织文件节点，启动运行错误中说：

ros2 launch fishbot_description display_robot.launch.py --debug
运行此，还不行：

tingbo@DESKTOP-NHH5E05:~/chapt6/chapt6_ws$ ros2 launch fishbot_description display_robot.launch.py --debug
[DEBUG] [launch.launch_context]: emitting event synchronously: 'launch.events.IncludeLaunchDescription'
[INFO] [launch]: All log files can be found below /home/tingbo/.ros/log/2024-04-16-20-04-15-269096-DESKTOP-NHH5E05-141776
[INFO] [launch]: Default logging verbosity is set to DEBUG
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7f8a8a67d420>'
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7f8a8a67d420>' ✓ '<launch.event_handlers.on_include_launch_description.OnIncludeLaunchDescription object at 0x7f8a89a2ca00>'
[DEBUG] [launch]: An exception was raised in an async action/event
[DEBUG] [launch]: Traceback (most recent call last):
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_description_sources/any_launch_file_utilities.py", line 54, in get_launch_description_from_any_launch_file
    return loader(launch_file_path)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_description_sources/python_launch_file_utilities.py", line 68, in get_launch_description_from_python_launch_file
    return getattr(launch_file_module, 'generate_launch_description')()
  File "/home/tingbo/chapt6/chapt6_ws/install/fishbot_description/share/fishbot_description/launch/display_robot.launch.py", line 30, in generate_launch_description
    return launch.launch_description([
TypeError: 'module' object is not callable

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 336, in run_async
    raise completed_tasks_exceptions[0]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 230, in _process_one_event
    await self.__process_event(next_event)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 250, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
  File "/opt/ros/humble/lib/python3.10/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/humble/lib/python3.10/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/humble/lib/python3.10/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/humble/lib/python3.10/site-packages/launch/action.py", line 108, in visit
    return self.execute(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/actions/include_launch_description.py", line 148, in execute
    launch_description = self.__launch_description_source.get_launch_description(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_description_source.py", line 84, in get_launch_description
    self._get_launch_description(self.__expanded_location)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_description_sources/any_launch_description_source.py", line 53, in _get_launch_description
    return get_launch_description_from_any_launch_file(location)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_description_sources/any_launch_file_utilities.py", line 57, in get_launch_description_from_any_launch_file
    raise InvalidLaunchFileError(extension, likely_errors=exceptions)
launch.invalid_launch_file_error.InvalidLaunchFileError: Caught multiple exceptions when trying to load file of format [py]:
 - TypeError: 'module' object is not callable
 - InvalidFrontendLaunchFileError: The launch file may have a syntax error, or its format is unknown

小鱼

@43996173 试试这个：

import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory


def generate_launch_description():
    # 获取默认路径
    urdf_tutorial_path = get_package_share_directory('fishbot_description')
    default_model_path = urdf_tutorial_path + '/urdf/first_robot.urdf'
    default_rviz_config_path = urdf_tutorial_path + '/config/rviz/display_model.rviz'
    # 为 Launch 声明参数
    action_declare_arg_mode_path = launch.actions.DeclareLaunchArgument(
        name='model', default_value=str(default_model_path),
        description='URDF 的绝对路径')
    # 获取文件内容生成新的参数
    robot_description = launch_ros.parameter_descriptions.ParameterValue(
        launch.substitutions.Command(
            ['xacro ', launch.substitutions.LaunchConfiguration('model')]),
        value_type=str)
    # 状态发布节点
    robot_state_publisher_node = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description': robot_description}]
    )
    # 关节状态发布节点
    joint_state_publisher_node = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
    )
    # RViz 节点
    rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        arguments=['-d', default_rviz_config_path]
    )
    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        joint_state_publisher_node,
        robot_state_publisher_node,
        rviz_node
    ])

开心

@小鱼
还是不行：

tingbo@DESKTOP-NHH5E05:~/chapt6/chapt6_ws$ ros2 launch fishbot_description display_robot.launch.py --debug
[DEBUG] [launch.launch_context]: emitting event synchronously: 'launch.events.IncludeLaunchDescription'
[INFO] [launch]: All log files can be found below /home/tingbo/.ros/log/2024-04-16-20-38-13-594595-DESKTOP-NHH5E05-156593
[INFO] [launch]: Default logging verbosity is set to DEBUG
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7fad2aec5420>'
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7fad2aec5420>' ✓ '<launch.event_handlers.on_include_launch_description.OnIncludeLaunchDescription object at 0x7fad2a270a00>'
[DEBUG] [launch]: An exception was raised in an async action/event
[DEBUG] [launch]: Traceback (most recent call last):
  File "/opt/ros/humble/lib/python3.10/site-packages/ament_index_python/packages.py", line 58, in get_package_prefix
    content, package_prefix = get_resource('packages', package_name)
  File "/opt/ros/humble/lib/python3.10/site-packages/ament_index_python/resources.py", line 86, in get_resource
    raise LookupError(
LookupError: Could not find the resource 'joint_state_publish' of type 'packages'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 336, in run_async
    raise completed_tasks_exceptions[0]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 230, in _process_one_event
    await self.__process_event(next_event)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 250, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
  File "/opt/ros/humble/lib/python3.10/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/humble/lib/python3.10/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/humble/lib/python3.10/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 1 more time]
  File "/opt/ros/humble/lib/python3.10/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/humble/lib/python3.10/site-packages/launch/action.py", line 108, in visit
    return self.execute(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/actions/node.py", line 509, in execute
    ret = super().execute(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/actions/execute_local.py", line 619, in execute
    self.prepare(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/actions/execute_local.py", line 594, in prepare
    self.__process_description.prepare(context, self)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/descriptions/executable.py", line 175, in prepare
    cmd = [perform_substitutions(context, x) for x in self.__cmd]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/descriptions/executable.py", line 175, in <listcomp>
    cmd = [perform_substitutions(context, x) for x in self.__cmd]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/perform_substitutions_impl.py", line 26, in perform_substitutions
    return ''.join([context.perform_substitution(sub) for sub in subs])
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/perform_substitutions_impl.py", line 26, in <listcomp>
    return ''.join([context.perform_substitution(sub) for sub in subs])
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_context.py", line 240, in perform_substitution
    return substitution.perform(self)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/substitutions/executable_in_package.py", line 76, in perform
    package_prefix = super().perform(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/substitutions/find_package.py", line 79, in perform
    result = self.find(package)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/substitutions/find_package.py", line 96, in find
    return get_package_prefix(package_name)
  File "/opt/ros/humble/lib/python3.10/site-packages/ament_index_python/packages.py", line 60, in get_package_prefix
    raise PackageNotFoundError(
ament_index_python.packages.PackageNotFoundError: "package 'joint_state_publish' not found, searching: ['/home/tingbo/chapt6/chapt6_ws/install/fishbot_description', '/opt/ros/humble']"

[ERROR] [launch]: Caught exception in launch (see debug for traceback): "package 'joint_state_publish' not found, searching: ['/home/tingbo/chapt6/chapt6_ws/install/fishbot_description', '/opt/ros/humble']"
[DEBUG] [launch.launch_context]: emitting event: 'launch.events.Shutdown'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7fad2a270f70>'
[DEBUG] [launch]: processing event: '<launch.events.shutdown.Shutdown object at 0x7fad2a270f70>' ✓ '<launch.event_handlers.on_shutdown.OnShutdown object at 0x7fad2a272c50>'

小鱼

@43996173 在 6.2.2使用launch组织文件节点，启动运行错误中说：

package='joint_state_publish',

这里应该是 publisher

@43996173 在 6.2.2使用launch组织文件节点，启动运行错误中说：

return launch.launch_description([

这里应该是 LaunchDescription

开心

@小鱼
好了，谢谢

x

@小鱼 /您好，我也遇到了同样的问题，我的launch文件是：
from launch import LaunchDescription
from launch.substitutions import EnvironmentVariable
import launch.actions
import launch_ros.actions

def generate_launch_description():
use_sim_time = launch.substitutions.LaunchConfiguration('use_sim_time', default='true')
return LaunchDescription([
launch_ros.actions.Node(
package='slam_gmapping', node_executable='slam_gmapping', output='screen', parameters=[{'use_sim_time':use_sim_time}]),
])
请您帮我检查是否存在致命错误