ROS2 Interface for Universal Robot CoBots Control with ur_rtde (C++, Python)

ROS2 interfaces based on ur_rtde for communication with Universal Robot collaborative manipulators. The software was developed within RIMLab, the robotic laboratory of the University of Parma.

This project is currently under development, with ongoing updates and enhancements planned for the future. If you have any thoughts or feedback about the software, feel free to contact us at [email protected].

Use this software with caution. The robot may collide with objects or people if not properly monitored. Always ensure a safe environment during operation. The developers are not responsible for any damages or injuries caused by improper use.

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Capabilities of ur_ros_rtde

• Reception of various data including joint positions, force, torque, etc.
• Configuration of internal robot parameters such as payload.
• UR control box digital pin reading and writing.
• Execution of MovePath, MoveJ, and MoveL commands.
• Execution of MoveL commands until contact is detected.
• Execution of MoveL commands until force or torque exceeds predefined thresholds.
• Sending and executing trajectories in the joint state space (e.g., trajectories planned with MoveIt!).
• Control of Schmalz GCPi vacuum gripper and OnRobot Soft Gripper (SG).
• Possibility of using ROS2 interfaces in simulated environments, even in the absence of physical hardware (e.g., trajectory evaluation).
• Possibility of using ROS2 interfaces along with MoveIt! configuration packages.
• Visualization of the 3D robot in RViz.
• Extension of robot commands through ROS2 plugins.

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Contents of ur_ros_rtde

• ur_ros_rtde: the core of our software, ROS2 nodes which provides messages on topics, services and actions.
• ur_ros_rtde_msgs: messages, services and actions definitions.
• ur_ros_rtde_simple_clients: utility header files for services and actions.
• ur_ros_rtde_gripper_commands: example of plugins that extend the robot commands enabling the control of real grippers.
• simple_ur10e_description: example of description package containing meshes, xacro and urdf files. The package is a simplified version of this repository, but specific for UR10e.
• simple_ur10e_moveit_config: example of MoveIt! configuration package generated with moveit_setup_assistant.

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Setup ur_ros_rtde

To utilize our software, you need to install ur_rtde and ROS2.

Install ur_rtde:

You can install ur_rtde running:

sudo add-apt-repository ppa:sdurobotics/ur-rtde
sudo apt-get update
sudo apt install librtde librtde-dev

Alternatively, you can manually build it:

git clone https://gitlab.com/sdurobotics/ur_rtde.git
cd ur_rtde
git submodule update --init --recursive
mkdir build
cd build
cmake ..
make 
sudo make install

Install Robot Operating System 2 (ROS2)

We recommend installing ROS2 humble using the official guide.

Additionally, install the following packages:

sudo apt install python3-colcon-common-extensions
sudo apt-get install ros-humble-controller-manager

(Optional) Install MoveIt!:

ur_ros_rtde ROS2 nodes were developed so that MoveIt! can be easily adopted for motion planning.

sudo apt install ros-humble-moveit
echo "export LC_NUMERIC=en_US.UTF-8" >> ~/.bashrc
(optional)
sudo apt install ros-$ROS_DISTRO-rmw-cyclonedds-cpp
echo "export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp" >> ~/.bashrc

Setup ROS2 interfaces

# clone ur_ros_rtde repository
git clone https://github.com/SuperDiodo/ur_ros_rtde.git

# build ur_ros_rtde
colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=Release

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How to use ur_ros_rtde

Our software is composed of three ROS2 nodes:

robot_state_receiver: provides robot data through topics and services (reference launch file: robot_state_receiver.launch.py).

command_server: discovers and loads ur_ros_rtde_commands plugins available in the ROS2 workspace. Each plugin starts a ROS2 action server for robot control (reference files command_server.launch.py, command_base_class.hpp).

dashboard_server: discovers and loads ur_ros_rtde_dashboard_commands plugins available in the ROS2 workspace. Each plugin starts a ROS2 action servers for robot control (reference files dashboard_server.launch.py, dashboard_command_base_class.hpp).

You can easily interact with ROS2 services and actions using header files provided in ur_ros_rtde_simple_clients. For further details and documentation, please visit ur_ros_rtde.

Test if everything is working:

1. Ensure that the optional packages are compiled.

2. In simple_ur10e_description generate UR10e urdf file from xacro files.

   # generate ur10e urdf
   cd ~/your_path/simple_ur10e_description/urdf
   sh generate_urdf.sh ur10e.xacro ur10e.urdf
   
   # build again the package to make the urdf visible
   colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=Release

3. Configure robot_state_receiver.launch.py:

   • set ip address with robot_ip
   • set robot_description_package = "simple_ur10e_description"
   • set urdf_file_name = "urdf/ur10e.urdf"
   • (optional) set launch_rviz = True if robot should be displayed in RViz

4. Launch robot_state_receiver:

   # type in a new terminal
   ros2 launch ur_ros_rtde robot_state_receiver.launch.py

   The first time RViz will be empty. To show the robot:

   1. Add a robot model: Displays\Add\RobotModel
   2. Set world in Fixed Frame
   3. Set /robot_description in RobotModel\Description Topic

5. Configure command_server.launch.py setting ip address with robot_ip

6. Launch command_server:

   # type in a new terminal
   ros2 launch ur_ros_rtde command_server.launch.py

7. Run test:

   WARNING! If everything was successfully configured the robot will start moving! Check for possible collisions with the environment!

   With test_command_server executable MoveL commands are sent to the robot. Starting from the actual pose it will move +10 cm on X axis, then -20 cm on X axis and finally +10 on X axis again.

   # type in a new terminal
   ros2 run ur_ros_rtde test_command_server

   Moreover, there is a second executable (test_trajectory_execution) which can be used to test trajectory execution. The robot will move as shown in the animated image (the robot is oriented towards Y-axis).

   

   # type in a new terminal
   ros2 run ur_ros_rtde test_trajectory_execution

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Adding new plugins to ur_ros_rtde

In ur_ros_rtde/src/base_commands and ur_ros_rtde/src/base_dashboard_commands several commands from ur_rtde RTDE Control Interface and Dashboard Client are implemented as ROS2 plugins. When launching command_server and dashboard_server these plugins are automatically loaded.

An example of commands that can be defined in custom ROS2 packages is reported in ur_ros_rtde_gripper_commands, an initial tutorial on plugin can be found here.

Basically:

1. create a ROS2 package containing a plugin.xml file in which the plugins are declared (use ur_ros_rtde_gripper_commands as example).
2. create new plugins as ur_ros_rtde_command or ur_ros_rtde_dashboard_command subclass. Below there is an example of the template for a ur_ros_rtde_command new plugin.

   #include <ur_ros_rtde/command_base_class.hpp>
   #include <pluginlib/class_list_macros.hpp>
   #include </* your action */>
   
   // < EXAMPLE OF ur_ros_rtde_command DEFINITION>
   ...
   // ----- PLUGIN INFO (CHANGE HERE!) --------
   #define PLUGIN_NAME "your_command"
   #define PLUGIN_CLASS_NAME YourCommand
   using action_type = /*action type*/;
   // -----------------------------------------
   
   void execute_function_impl(
       const std::shared_ptr<rclcpp_action::ServerGoalHandle<action_type>> goal_handle,
       rclcpp::Node::SharedPtr node,
       std::shared_ptr<ur_rtde::RTDEControlInterface> rtde_control,
       std::shared_ptr<ur_rtde::RTDEIOInterface> rtde_io,
       std::shared_ptr<ur_rtde::RTDEReceiveInterface> rtde_receive,
       std::shared_ptr<ur_rtde::DashboardClient> dashboard_client)
   { 
     // ---------- PLUGIN BEHAVIOUR ----------
     //      implement your plugin here!
     // -----------------------------------------
   }
   
   class PLUGIN_CLASS_NAME : public ur_ros_rtde_command
   {
   public:
     void start_action_server(
         rclcpp::Node::SharedPtr node,
         std::shared_ptr<ur_rtde::RTDEControlInterface> rtde_control,
         std::shared_ptr<ur_rtde::RTDEIOInterface> rtde_io,
         std::shared_ptr<ur_rtde::RTDEReceiveInterface> rtde_receive,
         std::shared_ptr<ur_rtde::DashboardClient> dashboard_client) override
     {
       auto bound_execute_function = std::bind(execute_function_impl, std::placeholders::_1, node, rtde_control, rtde_io, rtde_receive, dashboard_client);
       server_ = std::make_unique<command_server_template<action_type>>(
           node, PLUGIN_NAME, bound_execute_function);
     }
   
   private:
     std::unique_ptr<command_server_template<action_type>> server_;
   };
   
   PLUGINLIB_EXPORT_CLASS(PLUGIN_CLASS_NAME, ur_ros_rtde_command)

Basically, you have to add the include for an action that will be exposed with an action server, change the plugin info ad the implementation. The remaining part is the same for each plugin.

3. Compile the package and, if everything worked, command_server or dashboard server will automatically load the new plugins.

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Integration of ur_ros_rtde and MoveIt!

Setting launch_moveit = True in ur_ros_rtde/launch/robot_state_receiver.launch.py, several files from the associated MoveIt! configuration packages are automatically launched.

We recommend to use moveit_planning, a C++ library which includes utility functions for using ROS2 MoveIt! planning framework.

In moveit_planning instructions on the setup and its usage can be found.