custom_sim_bridge

Pluginlib-based ROS 2 bridge plugins that translate between ROS 2 services and Gazebo Harmonic transport for simulation.

For general information on pluginlib, see the official guide.

Architecture

Each bridge plugin is an rclcpp::Node subclass loaded at runtime by the generic bridge_loader executable. This avoids recompilation when adding new bridges — register a new class in plugins.xml and implement it as a shared library.

ROS 2 Service call
       │
       ▼
 AttachDetachBridge (rclcpp::Node)
       │  converts request via convert.hpp
       ▼
 Gazebo transport service call (gz-transport13)
       │  converts response via convert.hpp
       ▼
ROS 2 Service response

Bridge Plugins

AttachDetachBridge

Bridges the sim_interfaces/srv/AttachDetach ROS 2 service to the gz.custom_msgs.AttachDetachRequest/Response Gazebo service. Intended to be used alongside the DynamicDetachableJoint Gazebo plugin.

Capabilities: - Exposes a ROS 2 service that forwards attach/detach commands to Gazebo - Converts between ROS 2 and protobuf message types transparently - 5-second timeout on Gazebo service calls with proper error propagation

Parameters:

Parameter	Type	Default	Description
ros_service_name	string	""	ROS 2 service endpoint to advertise
gz_service_name	string	""	Gazebo service endpoint to forward requests to
- These are the necessary parameters to specify in order to use the AttachDetachBridge. If not specified, the param values will default to "", and ROS will crash because "" is an invalid name for a communication endpoint.

Usage:

Launch via the generic bridge_loader executable. The plugin class name is passed as a positional argument (the custom_sim_bridge:: namespace is prepended automatically). ROS parameters follow after --ros-args:

ros2 run custom_sim_bridge bridge_loader AttachDetachBridge \
  --ros-args \
  -p ros_service_name:=/standard_vtol_0/attach_detach \
  -p gz_service_name:=/model/standard_vtol/dynamic_detachable_joint/attach_detach

Or from a launch file:

Node(
    package="custom_sim_bridge",
    executable="bridge_loader",
    arguments=["AttachDetachBridge"],
    parameters=[{
        "ros_service_name": "/standard_vtol_0/attach_detach",
        "gz_service_name": "/model/standard_vtol/dynamic_detachable_joint/attach_detach",
    }],
)

Example ROS 2 service call:

ros2 service call /standard_vtol_0/attach_detach sim_interfaces/srv/AttachDetach \
  '{child_model_name: "payload", child_link_name: "payload_link", command: "attach"}'

Adding New Bridges

1. Implement a new rclcpp::Node subclass in src/.
2. Export it with PLUGINLIB_EXPORT_CLASS and register it in plugins.xml.
3. Add the source file to the custom_sim_bridge_plugins target in CMakeLists.txt.

The bridge_loader executable will be able to instantiate it without any further changes.

Building

Built as part of the colcon workspace:

colcon build --packages-select custom_sim_bridge

Depends on custom_gz_msgs for protobuf definitions and sim_interfaces for ROS 2 service types.