How To Add Custom Planner In Moveit2

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Introduction

Moveit2 is a powerful motion planning library for ROS2, providing a wide range of motion planners to choose from. However, sometimes the built-in planners may not meet the specific requirements of a project, and a custom planner is needed. In this article, we will guide you through the process of adding a custom planner in Moveit2.

Environment Setup

Before we dive into the process of adding a custom planner, let's make sure our environment is set up correctly.

  • Operating System: Ubuntu 22.04
  • ROS2 Distribution: Humble
  • Moveit2: Installed from source

Step 1: Choose a Planner

The first step in adding a custom planner is to choose the planner you want to use. There are many motion planners available, each with its strengths and weaknesses. Some popular planners include:

  • OMPL (Open Motion Planning Library): A widely used and highly customizable planner.
  • STL (Simple Trajectory Library): A simple and efficient planner for simple motion planning tasks.
  • CHOMP (CHomp Motion Planner): A planner designed for complex motion planning tasks.

For this example, we will use OMPL as our custom planner.

Step 2: Install OMPL

To use OMPL as our custom planner, we need to install it first. We can do this by running the following command:

sudo apt-get install libompl-dev

Step 3: Create a Custom Planner Package

Next, we need to create a custom planner package that will contain our custom planner. We can do this by running the following command:

ros2 pkg create custom_planner

This will create a new package called custom_planner in the current directory.

Step 4: Add the Custom Planner to the Package

Now that we have created our custom planner package, we need to add the custom planner to the package. We can do this by creating a new file called ompl_planner.cpp in the src directory of the package:

// src/ompl_planner.cpp

#include <ompl/tools/planners/rrtstar.h>
#include <moveit/planning_scene_interface/planning_scene_interface.h>
#include <moveit/move_group_interface/move_group_interface.h>


class OMPLPlanner : public moveit::planning_interface::MotionPlanRequest 
public
OMPLPlanner(const planning_scene::PlanningSceneConstPtr& planning_scene,
const moveit::core::RobotStateConstPtr& start_state,
const moveit::core::RobotStateConstPtr& goal_state)
: planning_scene_(planning_scene), start_state_(start_state), goal_state_(goal_state) {


bool solve(moveit::core::MotionPlanResponse& motion_plan) override {
// Create an OMPL planner
ompl::geometric::RRTstar<ompl::se2n::StateSpace> planner;


// Set the planning scene and start and goal states
planner.setProblemDefinition(planning_scene_-&gt;getPlanningScene());
planner.setStartAndGoalStates(start_state_-&gt;getRobotState(), goal_state_-&gt;getRobotState());

// Plan the motion
if (planner.solve(0.1)) {
  // Get the planned motion
  motion_plan.trajectory_ = planner.getSolution();

  // Return true to indicate that the motion plan was found
  return true;
}

// Return false to indicate that the motion plan was not found
return false;



}


private:
planning_scene::PlanningSceneConstPtr planning_scene_;
moveit::core::RobotStateConstPtr start_state_;
moveit::core::RobotStateConstPtr goal_state_;
};


// Register the custom planner
moveit::planning_interface::PlanningInterface::registerPlanner("ompl_planner", OMPLPlanner);

This code creates a custom planner called OMPLPlanner that uses OMPL to plan the motion.

Step 5: Build the Package

Now that we have created our custom planner package and added the custom planner to the package, we need to build the package. We can do this by running the following command:

colcon build

Step 6: Add the Custom Planner to the Moveit2 Configuration

Finally, we need to add the custom planner to the Moveit2 configuration. We can do this by creating a new file called moveit_config.yaml in the config directory of the package:

# config/moveit_config.yaml

planning:
planners:
- name: ompl_planner
plugin: custom_planner::OMPLPlanner

This code adds the custom planner to the Moveit2 configuration.

Conclusion

In this article, we have shown you how to add a custom planner in Moveit2. We have covered the following steps:

  • Step 1: Choose a planner
  • Step 2: Install the planner
  • Step 3: Create a custom planner package
  • Step 4: Add the custom planner to the package
  • Step 5: Build the package
  • Step 6: Add the custom planner to the Moveit2 configuration

By following these steps, you can add a custom planner in Moveit2 and use it to plan complex motion tasks.

Troubleshooting

If you encounter any issues while following these steps, here are some common troubleshooting tips:

  • Make sure you have installed the planner correctly: Check that you have installed the planner correctly by running the following command: ros2 pkg list
  • Make sure you have created the custom planner package correctly: Check that you have created the custom planner package correctly by running the following command: ros2 pkg list
  • Make sure you have added the custom planner to the package correctly: Check that you have added the custom planner to the package correctly by running the following command: ros2 pkg list
  • Make sure you have built the package correctly: Check that you have built the package correctly by running the following command: colcon build
  • Make sure you have added the custom planner to the Moveit2 configuration correctly: Check that you have added the custom planner to the Moveit2 configuration correctly by running the following command: ros2 run moveit2 moveit_config

Q: What is the purpose of adding a custom planner in Moveit2?

A: The purpose of adding a custom planner in Moveit2 is to provide a more specialized and efficient motion planning solution for specific tasks or applications. By adding a custom planner, you can tailor the motion planning process to meet the unique requirements of your project.

Q: What are the benefits of using a custom planner in Moveit2?

A: The benefits of using a custom planner in Moveit2 include:

  • Improved motion planning efficiency: Custom planners can be optimized for specific tasks or applications, resulting in faster and more efficient motion planning.
  • Increased motion planning accuracy: Custom planners can be designed to take into account specific constraints or requirements, resulting in more accurate motion planning.
  • Enhanced flexibility: Custom planners can be modified or extended to meet the changing needs of your project.

Q: How do I choose the right custom planner for my project?

A: To choose the right custom planner for your project, consider the following factors:

  • Task requirements: Consider the specific requirements of your project, such as the type of motion, the environment, and the constraints.
  • Planner capabilities: Consider the capabilities of the custom planner, such as its ability to handle complex motion planning tasks or its efficiency.
  • Development time and resources: Consider the time and resources required to develop and integrate the custom planner.

Q: What are some common custom planners used in Moveit2?

A: Some common custom planners used in Moveit2 include:

  • OMPL (Open Motion Planning Library): A widely used and highly customizable planner.
  • STL (Simple Trajectory Library): A simple and efficient planner for simple motion planning tasks.
  • CHOMP (CHomp Motion Planner): A planner designed for complex motion planning tasks.

Q: How do I integrate a custom planner into Moveit2?

A: To integrate a custom planner into Moveit2, follow these steps:

  1. Create a custom planner package: Create a new package for your custom planner.
  2. Add the custom planner to the package: Add the custom planner to the package.
  3. Build the package: Build the package.
  4. Add the custom planner to the Moveit2 configuration: Add the custom planner to the Moveit2 configuration.

Q: What are some common issues that can arise when adding a custom planner in Moveit2?

A: Some common issues that can arise when adding a custom planner in Moveit2 include:

  • Installation issues: Issues with installing the custom planner or its dependencies.
  • Integration issues: Issues with integrating the custom planner into Moveit2.
  • Performance issues: Issues with the performance of the custom planner.

Q: How do I troubleshoot issues with a custom planner in Moveit2?

A: To troubleshoot issues with a custom planner in Moveit2, follow these steps:

  1. Check the installation: Check that the custom planner and its dependencies are installed correctly.
  2. Check the integration: Check that the custom planner is integrated correctly into Moveit2.
  3. Check the performance: Check the performance of the custom planner and optimize it if necessary.

By following these steps and troubleshooting tips, you should be able to successfully add a custom planner in Moveit2 and use it to plan complex motion tasks.