Launch Files and Configuration

Oct 13, 2025 by wbrum.org 101 views

Introduction

In this article, we will delve into the issue of MoveIt OMPL planning for the UR10e robot in Ros2 Humble, which results in absurd plans. The UR10e is a popular industrial robot arm that is widely used in various applications, and MoveIt is a popular motion planning library for Ros2. However, when using the OMPL (Open Motion Planning Library) planner with the UR10e in Ros2 Humble, some users have reported encountering absurd plans.

Background

MoveIt is a motion planning library that provides a set of tools for planning and executing trajectories for robots. It is widely used in the Ros2 community and is known for its ease of use and flexibility. The OMPL planner is one of the planners provided by MoveIt, and it is known for its high performance and ability to handle complex motion planning problems.

The UR10e is a 6-axis industrial robot arm that is widely used in various applications, including manufacturing, assembly, and material handling. It is known for its high precision and repeatability, making it an ideal choice for many industrial applications.

Problem Description

When using the OMPL planner with the UR10e in Ros2 Humble, some users have reported encountering absurd plans. These plans are often characterized by large joint angles, high velocities, and other unrealistic motion parameters. These plans are not only unrealistic but also potentially unsafe, as they may cause the robot to move in an unpredictable and potentially hazardous manner.

Launch Files and Configuration

To reproduce the issue, we need to use the launch files provided by the ros-humble-ur10e package. These launch files are designed to launch the MoveIt rviz plugin and the OMPL planner. To configure the launch files, we need to modify the move_group.launch.py file to use the OMPL planner.

Here is an example of how to modify the move_group.launch.py file to use the OMPL planner:

import launch
from launch.actions import DeclareLaunchArgument
from launch.substitutions import LaunchConfiguration
from launch_ros.actions import Node
from launch_ros.actions import ParameterNode
def generate_launch_description():
# Define the launch arguments
ur10e_robot_name = LaunchConfiguration('ur10e_robot_name')
planning_group_name = LaunchConfiguration('planning_group_name')
ompl_planner = LaunchConfiguration('ompl_planner')
# Define the launch nodes
move_group_node = Node(
    package=&#39;moveit_ros_move_group&#39;,
    executable=&#39;move_group&#39;,
    name=&#39;move_group&#39;,
    parameters=[
        {&#39;robot_description&#39;: &#39;robot_description&#39;},
        {&#39;move_group&#39;: {&#39;planning_group_name&#39;: planning_group_name}},
        {&#39;move_group&#39;: {&#39;ompl_planner&#39;: ompl_planner}}
    ]
)

# Define the launch parameters
parameter_node = ParameterNode(
    package=&#39;moveit_ros_move_group&#39;,
    parameters=[
        {&#39;robot_description&#39;: &#39;robot_description&#39;},
        {&#39;move_group&#39;: {&#39;planning_group_name&#39;: planning_group_name}},
        {&#39;move_group&#39;: {&#39;ompl_planner&#39;: ompl_planner}}
    ]
)

# Define the launch actions
declare_launch_argument = DeclareLaunchArgument(
    &#39;ur10e_robot_name&#39;,
    default_value=&#39;ur10e&#39;
)

declare_launch_argument = DeclareLaunchArgument(
    &#39;planning_group_name&#39;,
    default_value=&#39;ur10e_arm&#39;
)

declare_launch_argument = DeclareLaunchArgument(
    &#39;ompl_planner&#39;,
    default_value=&#39;ompl&#39;
)

# Define the launch description
launch_description = launch.LaunchDescription()

# Add the launch nodes to the launch description
launch_description.add_action(move_group_node)

# Add the launch parameters to the launch description
launch_description.add_action(parameter_node)

# Add the launch actions to the launch description
launch_description.add_action(declare_launch_argument)

return launch_description

Troubleshooting

To troubleshoot the issue, we need to check the following:

Robot Description: Make sure that the robot description is correct and up-to-date. The robot description is used by MoveIt to plan and execute trajectories.
Planning Group Name: Make sure that the planning group name is correct and matches the name of the planning group in the robot description.
OMPL Planner: Make sure that the OMPL planner is correctly configured and that the planner is able to plan and execute trajectories.
Joint Limits: Make sure that the joint limits are correctly set and that the robot is not exceeding its joint limits.
Collision Checking: Make sure that collision checking is enabled and that the robot is not colliding with itself or with other objects in the environment.

Conclusion

In this article, we have discussed the issue of MoveIt OMPL planning for the UR10e robot in Ros2 Humble, which results in absurd plans. We have also provided a troubleshooting guide to help users identify and fix the issue. By following the troubleshooting guide and modifying the launch files and configuration, users should be able to reproduce the issue and fix it.

Future Work

In the future, we plan to investigate the following:

Improving the OMPL Planner: We plan to improve the OMPL planner to handle complex motion planning problems and to reduce the number of absurd plans.
Enhancing Collision Checking: We plan to enhance collision checking to detect and prevent collisions between the robot and other objects in the environment.
Providing Better Troubleshooting Tools: We plan to provide better troubleshooting tools to help users identify and fix issues with MoveIt and the OMPL planner.

References

MoveIt Documentation: MoveIt documentation provides detailed information on how to use MoveIt and the OMPL planner.
Ros2 Documentation: Ros2 documentation provides detailed information on how to use Ros2 and the MoveIt package.
UR10e Documentation: UR10e documentation provides detailed information on how to use the UR10e robot arm.

Appendix

A. Launch Files and Configuration

The launch files and configuration used in this article are available in the ros-humble-ur10e package.

B. Troubleshooting Guide

The troubleshooting guide used in this article is available in the moveit_ros_move_group package.

C. Future Work

Introduction

In our previous article, we discussed the issue of MoveIt OMPL planning for the UR10e robot in Ros2 Humble, which results in absurd plans. We also provided a troubleshooting guide to help users identify and fix the issue. In this article, we will provide a Q&A section to answer some of the most frequently asked questions related to this issue.

Q&A

Q: What is the cause of absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble?

A: The cause of absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble is not yet fully understood. However, it is believed to be related to the way the OMPL planner handles complex motion planning problems.

Q: How can I reproduce the issue?

A: To reproduce the issue, you need to use the launch files provided by the ros-humble-ur10e package. You also need to modify the move_group.launch.py file to use the OMPL planner.

Q: What are the symptoms of absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble?

A: The symptoms of absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble include:

Large joint angles
High velocities
Unrealistic motion parameters
Potential safety hazards

Q: How can I troubleshoot the issue?

A: To troubleshoot the issue, you need to check the following:

Robot description
Planning group name
OMPL planner configuration
Joint limits
Collision checking

Q: What are the potential consequences of absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble?

A: The potential consequences of absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble include:

Safety hazards
Damage to the robot or other objects in the environment
Loss of productivity
Decreased accuracy and precision

Q: How can I prevent absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble?

A: To prevent absurd plans in MoveIt OMPL planning for the UR10e robot in Ros2 Humble, you need to:

Use a different planner, such as the RRT planner
Modify the OMPL planner configuration to handle complex motion planning problems
Check the joint limits and collision checking
Use a more accurate and precise robot description

Q: What is the current status of the issue?

A: The current status of the issue is that it is still under investigation. The Ros2 community is working to identify the cause of the issue and to develop a solution.

Q: What is the expected timeline for a solution?

A: The expected timeline for a solution is not yet known. However, the Ros2 community is working to develop a solution as soon as possible.

Q: How can I get involved in the development of a solution?

A: To get involved in the development of a solution, you can:

Join the Ros2 community
Participate in the discussion forums
Contribute to the development of the MoveIt package
Report any issues or bugs you encounter

Conclusion

In this article, we have provided a Q&A section to answer some of the most frequently asked questions related to the issue of MoveIt OMPL planning for the UR10e robot in Ros2 Humble, which results in absurd plans. We hope that this article has been helpful in providing a better understanding of the issue and its potential consequences. We also hope that this article has encouraged users to get involved in the development of a solution.