`controller_manager` hangs when parsing URDF.

[ralphieraccoon]

Describe the bug

When launching the following controller_manager hangs after "Received Robot Description From Topic". The spawners then time out with no other error messages:

[INFO] [launch]: All log files can be found below /home/ralphieraccoon/.ros/log/2026-01-08-13-23-35-866565-ralphieraccoon-MS-7885-83428
[INFO] [launch]: Default logging verbosity is set to INFO
Using load_yaml() directly is deprecated. Use xacro.load_yaml() instead.
[INFO] [webots-1]: process started with pid [83444]
[INFO] [ros2_supervisor.py-2]: process started with pid [83445]
[INFO] [robot_state_publisher-3]: process started with pid [83446]
[INFO] [webots_controller_linear_track_robot-4]: process started with pid [83447]
[robot_state_publisher-3] [INFO] [1767878616.293899225] [linear_track.robot_state_publisher]: Robot initialized
[webots_controller_linear_track_robot-4] The specified robot (at /tmp/webots/ralphieraccoon/1234/ipc/linear_track_robot/extern) is not in the list of robots with <extern> controllers, retrying for another 50 seconds...
[ros2_supervisor.py-2] The specified robot (at /tmp/webots/ralphieraccoon/1234/ipc/Ros2Supervisor/extern) is not in the list of robots with <extern> controllers, retrying for another 50 seconds...
[webots_controller_linear_track_robot-4] The Webots simulation world is not yet ready, pending until loading is done...
[ros2_supervisor.py-2] The Webots simulation world is not yet ready, pending until loading is done...
[webots_controller_linear_track_robot-4] [INFO] [1767878624.087931163] [linear_track.controller_manager]: Using ROS clock for triggering controller manager cycles.
[webots_controller_linear_track_robot-4] [INFO] [1767878624.090457688] [linear_track.controller_manager]: Subscribing to '/linear_track/robot_description' topic for robot description.
[webots_controller_linear_track_robot-4] [WARN] [1767878624.093248259] [linear_track.linear_track_robot]: Desired controller update period (33ms / 30Hz) is different from the Webots timestep (32ms). Please adjust the `update_rate` parameter in the `controller_manager` or the `basicTimeStep` parameter in the Webots `WorldInfo` node.
[webots_controller_linear_track_robot-4] [INFO] [1767878624.093443451] [linear_track.linear_track_robot]: Controller successfully connected to robot in Webots simulation.
[INFO] [spawner-5]: process started with pid [83641]
[INFO] [spawner-6]: process started with pid [83642]
[webots_controller_linear_track_robot-4] [INFO] [1767878624.101047013] [linear_track.controller_manager]: Received robot description from topic.
[spawner-5] [INFO] [1767878624.589487594] [linear_track.spawner_linear_track_controller]: waiting for service /linear_track/controller_manager/list_controllers to become available...
[spawner-6] [WARN] [1767878644.520688388] [ros2_control_controller_spawner_joint_state_broadcaster]: Attempt 1 failed. Retrying in 3 seconds...
[spawner-6] [WARN] [1767878667.535908499] [ros2_control_controller_spawner_joint_state_broadcaster]: Attempt 2 failed. Retrying in 3 seconds...
[spawner-6] [WARN] [1767878690.556986460] [ros2_control_controller_spawner_joint_state_broadcaster]: Attempt 3 failed. Retrying in 3 seconds...
[spawner-6] [WARN] [1767878713.566505340] [ros2_control_controller_spawner_joint_state_broadcaster]: Attempt 4 failed. Retrying in 3 seconds...
[spawner-6] [WARN] [1767878736.580213880] [ros2_control_controller_spawner_joint_state_broadcaster]: Attempt 5 failed. Retrying in 3 seconds...
[spawner-6] [ERROR] [1767878739.582078034] [ros2_control_controller_spawner_joint_state_broadcaster]: Failed to acquire lock after multiple attempts.
[ERROR] [spawner-6]: process has died [pid 83642, exit code 1, cmd '/opt/ros/jazzy/lib/controller_manager/spawner joint_state_broadcaster --controller-manager-timeout 1000 --ros-args -r __ns:=/linear_track --params-file /tmp/launch_params__jjaonmy'].

Note that webots_ros2 creates the controller_manager itself using WebotsController().

Minimal launch file:

import os
import launch
import xacro

from launch.substitutions import LaunchConfiguration
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, OpaqueFunction
from launch.conditions import IfCondition
from launch.actions import ExecuteProcess
from launch_ros.actions import Node

from webots_ros2_driver.webots_launcher import WebotsLauncher
from webots_ros2_driver.webots_controller import WebotsController
from webots_ros2_driver.wait_for_controller_connection import WaitForControllerConnection

def generate_launch_description():

 chassis_stage = DeclareLaunchArgument("chassis_stage", default_value="1")
  
  linear_track_robot_description_path = "linear_track_robot.urdf.xacro",
  linear_track_ros2_control_params = "linear_track_ros2_control.yml"

  use_sim_time = LaunchConfiguration("use_sim_time", default=True)

  tf_node_1 = Node(
          package="tf2_ros",
          executable="static_transform_publisher",
          name="static_transform_publisher",
          output="log",
          arguments=["0.0", "0.0", "0.0", "0.0", "0.0", "0.0", "world", "chassis_link"],
      )

   tf_node_2 = Node(
        package="tf2_ros",
        executable="static_transform_publisher",
        name="static_transform_publisher",
        output="log",
        arguments=[
            "-1.515",
            "0.5245",
            "0.0067",
            "0.0",
            "0.0",
            "0.0",
            "world",
            "track_link",
        ],
    )

   tf_node_3 = Node(
        package="tf2_ros",
        executable="static_transform_publisher",
        name="static_transform_publisher",
        output="log",
        arguments=[
            "0.0",
            "0.0",
            "0.175",
            str((np.pi) / 4),
            "0.0",
            "0.0",
            "carriage_link",
            "base_link",
        ],
    )

  def chassis_function(context):
  
          with open(
              os.path.join(package_dir, "sim/webots/worlds", "combined_assembly.wbt"), "r"
          ) as readfile, open(
              os.path.join(package_dir, "sim/webots/worlds", "combined_assembly_p.wbt"),
              "w",
          ) as writefile:
              text = readfile.read()
              writefile.write(
                  text.replace(
                      "<chassis_stage>",
                      LaunchConfiguration("chassis_stage").perform(context),
                  )
              )

    webots = WebotsLauncher(
        world=os.path.join(package_dir, "sim/webots/worlds", "combined_assembly_p.wbt"),
        ros2_supervisor=True,
    )

# Linear Track ROS control spawners
    controller_manager_timeout = ["--controller-manager-timeout", "1000"]
    controller_manager_prefix = "python.exe" if os.name == "nt" else ""
    linear_track_position_controller_spawner = Node(
        package="controller_manager",
        executable="spawner",
        output="screen",
        namespace="linear_track",
        prefix=controller_manager_prefix,
        arguments=[
            "linear_track_controller",
            # "-c",
            # "bedcontroller/controller_manager",
            "--param-file",
            linear_track_ros2_control_params,
        ]
        + controller_manager_timeout,  # + ['--inactive'],
        parameters=[
            {"use_sim_time": use_sim_time},
        ],
    )
    linear_track_joint_state_broadcaster_spawner = Node(
        package="controller_manager",
        executable="spawner",
        output="screen",
        namespace="linear_track",
        prefix=controller_manager_prefix,
        arguments=[
            "joint_state_broadcaster",
            # "-c",
            # "lineartrackcontroller/controller_manager",
        ]
        + controller_manager_timeout,
        parameters=[
            {"use_sim_time": use_sim_time},
        ],
    )

    linear_track_state_publisher = Node(
        namespace="linear_track",
        package="robot_state_publisher",
        executable="robot_state_publisher",
        output="screen",
        parameters=[
            {
                "robot_description": xacro.process_file(
                    linear_track_robot_description_path, mappings={"sim": "true"}
                ).toxml()
            }
        ],
        # arguments=["--ros-args", "--log-level", "DEBUG"],
    )

    linear_track_ros_control_spawners = [
        linear_track_position_controller_spawner,
        linear_track_joint_state_broadcaster_spawner,
    ]

    linear_track_robot_driver = WebotsController(
        robot_name="linear_track_robot",
        namespace="linear_track",
        parameters=[
            {
                "robot_description": linear_track_robot_description_path,
                "xacro_mappings": ["sim:=true"],
                "use_sim_time": use_sim_time,
                "set_robot_state_publisher": False,
            },
            linear_track_ros2_control_params,
        ],
        respawn=True,
    )

    linear_track_waiting_nodes = WaitForControllerConnection(
        target_driver=linear_track_robot_driver,
        nodes_to_start=linear_track_ros_control_spawners,
    )
  
return LaunchDescription(
        [
            chassis_stage,
            launch.actions.OpaqueFunction(function=chassis_function),
            webots,
            webots._supervisor,
            linear_track_state_publisher,
            linear_track_robot_driver,
            linear_track_waiting_nodes,
         ]
)

The URDF file linear_track_robot.urdf.xacro:

<?xml version="1.0" ?>
<robot xmlns:xacro="http://www.ros.org/wiki/xacro" name="linear_track_robot">
<xacro:arg name="sim" default="false" />

    <webots>
        <plugin type="webots_ros2_control::Ros2Control" />
    </webots>

    <ros2_control name="linear_track_robot_control" type="system">
        <hardware>
            <xacro:if value="$(arg sim)">
                <plugin>webots_ros2_control::Ros2ControlSystem</plugin>
            </xacro:if>
            <xacro:unless value="$(arg sim)">
                <plugin>ampi_project_hardware/LinearTrackHardwareInterface</plugin>
            </xacro:unless>
        </hardware>

        <joint name="linear_track_motor">
            <command_interface name="position"/>
            <state_interface name="position"/>
            <state_interface name="velocity"/>
            <state_interface name="effort"/>
        </joint>
    </ros2_control>

    <link name="track_link"/>
    <link name="carriage_link"/>

    <joint name="linear_track_motor" type="prismatic">
        <origin xyz="0.400866 0 0" rpy="0 0 0" />
        <axis xyz="-1 0 0" />
        <parent link="track_link"/>
        <child link="carriage_link"/>
        <limit effort="10" lower="0" upper="1" velocity="0.1"/>
    </joint>

</robot>

The ros2_control YAML linear_track_ros2_control.yml:

/linear_track/controller_manager:
  ros__parameters:
    update_rate: 30

    joint_state_broadcaster:
      type: joint_state_broadcaster/JointStateBroadcaster

/linear_track/linear_track_controller:
  ros__parameters:
    type: position_controllers/JointGroupPositionController
    joints:
      - linear_track_motor

The file webots.tar.gz can be used for a minimal implementation of the webots simulation.

Expected behavior
URDF should be parsed and "hardware" activated.

Environment (please complete the following information):

• OS: Ubuntu 24.04
• Version: Jazzy
• ros2_control: Binary
• Custom branch of webots_ros2 which can be found here.

[christophfroehlich]

Why are you using a custom branch of webots_ros2?
The URDF seems to be fine, but I never used webots and can't help here.

[ralphieraccoon]

Why are you using a custom branch of webots_ros2? The URDF seems to be fine, but I never used webots and can't help here.

It's got some extra functionality that I need and the pull request hasn't gone through yet, there is no difference to the code that interacts with ros2_control. That package hasn't been updated in six months and this setup was working before Christmas, so whatever has gone wrong it's not because of webots_ros2 and I have confirmed that the URDF being sent to the controller_manager has not been altered or mangled. The log suggests that something is going wrong with controller_manager and not Webots, hence why I'm posting the issue here and not there (plus the current inactivity).

[christophfroehlich]

can you test this with upstream binaries? then this would be easier to reproduce for us

[ralphieraccoon]

can you test this with upstream binaries? then this would be easier to reproduce for us

Sure, no problem, output is identical.