hello im in chapter 4 and i try to run this command:
ros2 launch my_moveit2_config my_planning_execution.launch.py launch_rviz:=true
but every time i got this error:
InvalidLaunchFileError(extension, likely_errors=exceptions)
launch.invalid_launch_file_error.InvalidLaunchFileError: Caught exception when trying to load file of format [py]: Unexpected type for parameter value None
help?
Hello @Scotvers ,
From the error message it looks like you have some kind of errror in the my_planning_execution.launch.py launch file. But without seeing the contents of that file is hard to tell what the error is. Could you share it here? Before that, make sure that the contents of the file are as indicated in the notebook.
Best,
import os
import yaml
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.conditions import IfCondition
from launch.substitutions import Command, FindExecutable, LaunchConfiguration, PathJoinSubstitution
from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageShare
def load_yaml(package_name, file_path):
package_path = get_package_share_directory(package_name)
absolute_file_path = os.path.join(package_path, file_path)
try:
with open(absolute_file_path) as file:
return yaml.safe_load(file)
except OSError: # parent of IOError, OSError *and* WindowsError where available
return None
def get_package_file(package, file_path):
"""Get the location of a file installed in an ament package"""
package_path = get_package_share_directory(package)
absolute_file_path = os.path.join(package_path, file_path)
return absolute_file_path
def load_file(file_path):
"""Load the contents of a file into a string"""
try:
with open(file_path, 'r') as file:
return file.read()
except EnvironmentError: # parent of IOError, OSError *and* WindowsError where available
return None
def generate_launch_description():
declared_arguments = []
# UR specific arguments
declared_arguments.append(
DeclareLaunchArgument(
"safety_limits",
default_value="true",
description="Enables the safety limits controller if true.",
)
)
declared_arguments.append(
DeclareLaunchArgument(
"safety_pos_margin",
default_value="0.15",
description="The margin to lower and upper limits in the safety controller.",
)
)
declared_arguments.append(
DeclareLaunchArgument(
"safety_k_position",
default_value="20",
description="k-position factor in the safety controller.",
)
)
# General arguments
declared_arguments.append(
DeclareLaunchArgument(
"description_package",
default_value="ur_e_description",
description="Description package with robot URDF/XACRO files. Usually the argument \
is not set, it enables use of a custom description.",
)
)
declared_arguments.append(
DeclareLaunchArgument(
"description_file",
default_value="ur3e_robot.urdf.xacro",
description="URDF/XACRO description file with the robot.",
)
)
declared_arguments.append(
DeclareLaunchArgument(
"moveit_config_package",
default_value="my_moveit2_config",
description="MoveIt config package with robot SRDF/XACRO files. Usually the argument \
is not set, it enables use of a custom moveit config.",
)
)
declared_arguments.append(
DeclareLaunchArgument(
"moveit_config_file",
default_value="ur3e.srdf",
description="MoveIt SRDF/XACRO description file with the robot.",
)
)
declared_arguments.append(
DeclareLaunchArgument(
"prefix",
default_value='""',
description="Prefix of the joint names, useful for \
multi-robot setup. If changed than also joint names in the controllers' configuration \
have to be updated.",
)
)
declared_arguments.append(
DeclareLaunchArgument("launch_rviz", default_value="true", description="Launch RViz?")
)
# Initialize Arguments
safety_limits = LaunchConfiguration("safety_limits")
safety_pos_margin = LaunchConfiguration("safety_pos_margin")
safety_k_position = LaunchConfiguration("safety_k_position")
# General arguments
description_package = LaunchConfiguration("description_package")
description_file = LaunchConfiguration("description_file")
moveit_config_package = LaunchConfiguration("moveit_config_package")
moveit_config_file = LaunchConfiguration("moveit_config_file")
prefix = LaunchConfiguration("prefix")
launch_rviz = LaunchConfiguration("launch_rviz")
robot_description_content = Command(
[
PathJoinSubstitution([FindExecutable(name="xacro")]),
" ",
PathJoinSubstitution([FindPackageShare(description_package), "urdf", description_file]),
" ",
"safety_limits:=",
safety_limits,
" ",
"safety_pos_margin:=",
safety_pos_margin,
" ",
"safety_k_position:=",
safety_k_position,
" ",
"name:=",
# Also, ur_type parameter could be used, but then the planning group names in YAML
# configs has to be updated!
"ur",
" ",
"prefix:=",
prefix,
" ",
]
)
robot_description = {"robot_description": robot_description_content}
# MoveIt Configuration
srdf_file = get_package_file('my_moveit2_config', 'config/ur3e.srdf')
robot_description_semantic_file = load_file(srdf_file)
robot_description_semantic = {"robot_description_semantic": robot_description_semantic_file}
kinematics_yaml = load_yaml("my_moveit2_config", "config/kinematics.yaml")
robot_description_kinematics = {"robot_description_kinematics": kinematics_yaml}
# Planning Configuration
ompl_planning_pipeline_config = {
"move_group": {
"planning_plugin": "ompl_interface/OMPLPlanner",
"request_adapters": """default_planner_request_adapters/AddTimeOptimalParameterization default_planner_request_adapters/FixWorkspaceBounds default_planner_request_adapters/FixStartStateBounds default_planner_request_adapters/FixStartStateCollision default_planner_request_adapters/FixStartStatePathConstraints""",
"start_state_max_bounds_error": 0.1,
}
}
ompl_planning_yaml = load_yaml("my_moveit2_config", "config/ompl_planning.yaml")
ompl_planning_pipeline_config["move_group"].update(ompl_planning_yaml)
# Trajectory Execution Configuration
controllers_yaml = load_yaml("my_moveit2_config", "config/controllers.yaml")
moveit_controllers = {
"moveit_simple_controller_manager": controllers_yaml,
"moveit_controller_manager": "moveit_simple_controller_manager/MoveItSimpleControllerManager",
}
trajectory_execution = {
"moveit_manage_controllers": False,
"trajectory_execution.allowed_execution_duration_scaling": 1.2,
"trajectory_execution.allowed_goal_duration_margin": 0.5,
"trajectory_execution.allowed_start_tolerance": 0.1,
}
planning_scene_monitor_parameters = {
"publish_planning_scene": True,
"publish_geometry_updates": True,
"publish_state_updates": True,
"publish_transforms_updates": True,
"planning_scene_monitor_options": {
"name": "planning_scene_monitor",
"robot_description": "robot_description",
"joint_state_topic": "/joint_states",
"attached_collision_object_topic": "/move_group/planning_scene_monitor",
"publish_planning_scene_topic": "/move_group/publish_planning_scene",
"monitored_planning_scene_topic": "/move_group/monitored_planning_scene",
"wait_for_initial_state_timeout": 10.0,
},
}
# Start the actual move_group node/action server
move_group_node = Node(
package="moveit_ros_move_group",
executable="move_group",
output="screen",
parameters=[
{'use_sim_time': True},
robot_description,
robot_description_semantic,
robot_description_kinematics,
ompl_planning_pipeline_config,
trajectory_execution,
moveit_controllers,
planning_scene_monitor_parameters,
],
)
# rviz with moveit configuration
rviz_config_file = PathJoinSubstitution(
[FindPackageShare(moveit_config_package), "rviz", "view_robot.rviz"]
)
rviz_node = Node(
package="rviz2",
condition=IfCondition(launch_rviz),
executable="rviz2",
name="rviz2_moveit",
output="log",
arguments=["-d", rviz_config_file],
parameters=[
robot_description,
robot_description_semantic,
ompl_planning_pipeline_config,
robot_description_kinematics,
],
)
nodes_to_start = [
move_group_node,
rviz_node,
]
return LaunchDescription(declared_arguments + nodes_to_start)