Simulation
==========

Apart from being used with a real robot, the ROS driver can be used with ros2_control's mock hardware or the URSim simulator (which is equivalent from the driver's perspective).

Additionally, the robot can be simulated using
`Gazebo Classic <https://github.com/UniversalRobots/Universal_Robots_ROS2_Gazebo_Simulation>`_ or
`GZ Sim <https://github.com/UniversalRobots/Universal_Robots_ROS2_Ignition_Simulation>`_ but that's
outside of this driver's scope.

.. _usage_with_official_ur_simulator:

Usage with official UR simulator
--------------------------------

The easiest way to use URSim is the `Docker
image <https://hub.docker.com/r/universalrobots/ursim_e-series>`_ provided by Universal Robots (See
`this link <https://hub.docker.com/r/universalrobots/ursim_cb3>`_ for a CB3-series image).

To start it, we've prepared a script:

.. code-block:: bash

   ros2 run ur_client_library start_ursim.sh -m <ur_type>

With this, we can spin up a driver using

.. code-block:: bash

   ros2 launch ur_robot_driver ur_control.launch.py ur_type:=<ur_type> robot_ip:=192.168.56.101 launch_rviz:=true

You can view the polyscope GUI by opening `<http://192.168.56.101:6080/vnc.html>`_.

When we now move the robot in Polyscope, the robot's RViz visualization should move accordingly.

For details on the Docker image, please see the more detailed guide :ref:`here <ursim_docker>`.

Mock hardware
-------------

The package can simulate hardware with the ros2_control ``MockSystem``. This emulator enables an
environment for testing of "piping" of hardware and controllers, as well as testing robot's
descriptions. For more details see `ros2_control documentation
<https://control.ros.org/rolling/doc/ros2_control/hardware_interface/doc/mock_components_userdoc.html>`_
for more details.

.. note::
   Some driver functionalities currently don't work with mock hardware:

   * The TCP pose broadcaster does not work.
   * The passthrough trajectory controller does not function when calling the follow joint trajectory action.
   * The force mode controller also does not respond when trying to start force mode.
   * The GPIO controller cannot verify that it has changed the state of an I/O pin, so it will report a failure when trying to set an I/O pin.