about singularity

[Enzo-let]

I appreciate you well. I have a question about running the lbr_demo/lbr_moveit, which is i find that the initial position of the robot is singularity, so i need to chang the initial position in the simulation. What i do is to change the lbr_movit_config with setup_assistant, but when i run the rviz.launch.py, the robot show like below. So i wanna know which files i need to change.I guess the mock.launch, and i change it like this :
`
from launch import LaunchDescription
from launch.actions import RegisterEventHandler, DeclareLaunchArgument
from launch.event_handlers import OnProcessStart
from launch.substitutions import LaunchConfiguration
from lbr_bringup.description import LBRDescriptionMixin
from lbr_bringup.ros2_control import LBRROS2ControlMixin

def generate_launch_description() -> LaunchDescription:
ld = LaunchDescription()

# Launch arguments
ld.add_action(LBRDescriptionMixin.arg_model())
ld.add_action(LBRDescriptionMixin.arg_robot_name())
ld.add_action(LBRROS2ControlMixin.arg_ctrl_cfg_pkg())
ld.add_action(LBRROS2ControlMixin.arg_ctrl_cfg())
ld.add_action(LBRROS2ControlMixin.arg_ctrl())

# Define initial positions for KUKA robot joints
ld.add_action(DeclareLaunchArgument(
    'joint_a1',
    default_value='0.0',
    description='Initial position for joint a1'
))
ld.add_action(DeclareLaunchArgument(
    'joint_a2',
    default_value='-0.7854',
    description='Initial position for joint a2'
))
ld.add_action(DeclareLaunchArgument(
    'joint_a3',
    default_value='0.0',
    description='Initial position for joint a3'
))
ld.add_action(DeclareLaunchArgument(
    'joint_a4',
    default_value='1.3962',
    description='Initial position for joint a4'
))
ld.add_action(DeclareLaunchArgument(
    'joint_a5',
    default_value='0.0',
    description='Initial position for joint a5'
))
ld.add_action(DeclareLaunchArgument(
    'joint_a6',
    default_value='0.6109',
    description='Initial position for joint a6'
))
ld.add_action(DeclareLaunchArgument(
    'joint_a7',
    default_value='0.0',
    description='Initial position for joint a7'
))

# Robot description
robot_description = LBRDescriptionMixin.param_robot_description(mode="mock")

# Robot state publisher
robot_state_publisher = LBRROS2ControlMixin.node_robot_state_publisher(
    robot_description=robot_description, use_sim_time=False
)
ld.add_action(robot_state_publisher)

# ROS 2 control node
ros2_control_node = LBRROS2ControlMixin.node_ros2_control(use_sim_time=False)
ld.add_action(ros2_control_node)

# Joint state broadcaster and controller on ROS 2 control node start
joint_state_broadcaster = LBRROS2ControlMixin.node_controller_spawner(
    controller="joint_state_broadcaster"
)
controller = LBRROS2ControlMixin.node_controller_spawner(
    controller=LaunchConfiguration("ctrl")
)

# Event handler to start joint state broadcaster and controller
controller_event_handler = RegisterEventHandler(
    OnProcessStart(
        target_action=ros2_control_node,
        on_start=[
            joint_state_broadcaster,
            controller,
        ],
    )
)
ld.add_action(controller_event_handler)


return ld

`

[mhubii]

hi @Enzo-let, this error shows due to a missing transform. Can you try to add a static transform publisher a la

from launch.substitutions import LaunchConfiguration, PathJoinSubstitution

# static transform world -> robot_name/world
ld.add_action(
    LBRDescriptionMixin.node_static_tf(
        tf=[0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
        parent="world",
        child=PathJoinSubstitution([LaunchConfiguration("robot_name"), "world"]),
    )
)

This should fix your particular issue. However, from what I can see reading through ros2_control (ros-controls/gazebo_ros2_control#100), to configure an initial position, the URDF needs to be modified, i.e. here

lbr_fri_ros2_stack/lbr_ros2_control/config/lbr_system_interface.xacro

Line 109 in cca24ae

<state_interface name="position" />

In case you wish to create a pull request to modify this behavior, may I kindly ask you to target the rolling branch? Note that in the rolling branch frame naming changed from robot_name/link_i -> robot_name_link_i