mujoco_ros2_control_plugins

Plugin package for mujoco_ros2_control

README

mujoco_ros2_control_plugins

This package provides a plugin interface for extending the functionality of mujoco_ros2_control.

Overview

The mujoco_ros2_control_plugins package is designed to contain plugins that extend the capabilities of the main mujoco_ros2_control package. This separation allows for modular development and optional features without adding complexity to the core package.

[!NOTE] This interface provides flexibility for accessing information from the MuJoCo model and data. Users are responsible for handling that data correctly and avoiding changes to critical information.

Available Plugins

HeartbeatPublisherPlugin

A simple demonstration plugin that publishes a heartbeat message every second to the /mujoco_heartbeat topic.

Topic: mujoco_heartbeat (std_msgs/String) Rate: 1 Hz (every 1 second) Message Format: “MuJoCo ROS2 Control Heartbeat #N | Simulation time: Xs”

Dependencies

mujoco_vendor: Provides the MuJoCo physics simulator library
rclcpp: ROS 2 C++ client library
pluginlib: Plugin loading framework
std_msgs: Standard ROS message types

Building

This package is part of the mujoco_ros2_control workspace. Build it using:

colcon build --packages-select mujoco_ros2_control_plugins

Usage

Plugins are loaded from ROS 2 parameters under mujoco_plugins.

Each plugin must have:

A unique key (for example heart_beat_plugin)
A type field with the pluginlib class name

Use a parameters file like this:

/**:
  ros__parameters:
    mujoco_plugins:
      heart_beat_plugin:
        type: "mujoco_ros2_control_plugins/HeartbeatPublisherPlugin"
        update_rate: 1.0

Then pass that file to the mujoco_ros2_control node (for example with ParameterFile(...) in your launch file).

[!NOTE] In this repository, mujoco_ros2_control_demos/launch/01_basic_robot.launch.py already loads mujoco_ros2_control_demos/config/mujoco_ros2_control_plugins.yaml.

Example: Monitoring the Heartbeat

# Terminal 1: Launch your mujoco_ros2_control simulation
ros2 launch mujoco_ros2_control_demos 01_basic_robot.launch.py

# Terminal 2: Echo the heartbeat messages
ros2 topic echo /mujoco_heartbeat

Creating Your Own Plugin

1. Create Plugin Header

Create a header file that inherits from MuJoCoROS2ControlPluginBase:

#include "mujoco_ros2_control_plugins/mujoco_ros2_control_plugins_base.hpp"

namespace my_namespace
{

class MyCustomPlugin : public mujoco_ros2_control_plugins::MuJoCoROS2ControlPluginBase
{
public:
  bool init(rclcpp::Node::SharedPtr node, const mjModel* model, mjData* data) override;
  void update(const mjModel* model, mjData* data) override;
  void cleanup() override;

private:
  // Your member variables
};

}  // namespace my_namespace

2. Implement Plugin Methods

#include "my_custom_plugin.hpp"
#include <pluginlib/class_list_macros.hpp>

namespace my_namespace
{

bool MyCustomPlugin::init(
  rclcpp::Node::SharedPtr node,
  const mjModel* model,
  mjData* data)
{
  // Initialize your plugin
  return true;
}

void MyCustomPlugin::update(const mjModel* model, mjData* data)
{
  // Called every control loop iteration
}

void MyCustomPlugin::cleanup()
{
  // Clean up resources
}

}  // namespace my_namespace

PLUGINLIB_EXPORT_CLASS(
  my_namespace::MyCustomPlugin,
  mujoco_ros2_control_plugins::MuJoCoROS2ControlPluginBase
)

3. Create Plugin XML Descriptor

Create my_plugins.xml:

<library path="my_plugin_library">
  <class name="my_namespace/MyCustomPlugin"
         type="my_namespace::MyCustomPlugin"
         base_class_type="mujoco_ros2_control_plugins::MuJoCoROS2ControlPluginBase">
    <description>
      Description of what your plugin does.
    </description>
  </class>
</library>

4. Update CMakeLists.txt

find_package(mujoco_ros2_control_plugins REQUIRED)

add_library(my_plugin_library SHARED
  src/my_custom_plugin.cpp
)

target_link_libraries(my_plugin_library
  ${mujoco_ros2_control_plugins_TARGETS}
  # ... other dependencies
)

pluginlib_export_plugin_description_file(
  mujoco_ros2_control_plugins
  my_plugins.xml
)

Plugin Lifecycle

Initialization (init): Called once when the hardware interface is initialized
Update (update): Called every control loop iteration
Cleanup (cleanup): Called when shutting down