Tutorials for ur_ros_rtde

The proposed software is composed of three ROS2 nodes:

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

• CommandServer ) discovers and loads ur_ros_rtde_commands and ur_ros_rtde_extension plugins available in the ROS2 workspace. Each plugin starts a ROS2 action server. Reference files:
  • command_server.launch.py
  • ur_ros_rtde/include/ur_ros_rtde/command_base_class.hpp
  • ur_ros_rtde/include/ur_ros_rtde/extension_base_class.hpp
• DashboardServer ) discovers and loads ur_ros_rtde_dashboard_commands plugins available in the ROS2 workspace. Each plugin starts a ROS2 action server. Reference files:
  • ur_ros_rtde/launch/dashboard_server.launch.py
  • ur_ros_rtde/include/ur_ros_rtde/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.

Run examples

Ensure that the ur_ros_rtde_tutorials package is compiled.

Retrieve robot state

To retrieve the robot state RobotStateReceiver must be used.

1. Configure robot_state_receiver.launch.py:
   • set ip address with robot_ip
2. Launch robot_state_receiver:

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

At this point, the robot state can be accessed using topics and services.

1. Print joint states:

    # type in a new terminal
    ros2 topic echo /joint_states
    

Visualize the robot in RViz

RobotStateReceiver does not require any URDF of the robot, but URDF files are required to visualize the robot in tools like RViz. If a ROS2 description package of a UR robot is already available, skip to step 2 and use that package instead of simple_ur10e_description.

1. 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
    cd <ros_workspace_path>
    colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=Release --packages-up-to simple_ur10e_description
    

1. 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"
   • set launch_rviz = True

When setting launch_rviz to True a robot state publisher node is started which will publish TF for each robot link based on the joint states.

1. Launch RobotStateReceiver:

    # 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`
4. Click on `File\Save config` to save the actual configuration of RViz

Activate robot commands

In ur_ros_rtde commands are defined as plugins and exposed as action servers. To make available these action servers the CommandServer must be started:

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

2. Launch CommandServer:

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

1. List the available commands (more info at ur_ros_rtde):

    # type in a new terminal
    ros2 action list
    

The file command_server.launch.py can also be used to define a blacklist of plugins which must not be loaded. By default, the plugins implemented in ur_ros_rtde_gripper_commands are disabled, since they rely on the presence of specific hardware.

Move the robot

In this tutorial package are provided 3 examples which can be used to move the robot:

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