Added basic Ignition Gazebo tutorial and restructure simulation index (…

…#2356) (#2362)

* Added basic Ignition Gazebo tutorial and restructure simulation index

Signed-off-by: ahcorde <ahcorde@gmail.com>
Co-authored-by: Chris Lalancette <clalancette@openrobotics.org>
(cherry picked from commit ef89d38)

Co-authored-by: Alejandro Hernández Cordero <ahcorde@gmail.com>

source/Tutorials.rst

@@ -83,7 +83,7 @@ Simulation
 .. toctree::
    :maxdepth: 1
 
-   Tutorials/Simulators/Webots/Setting-up-a-Robot-Simulation-Webots
+   Tutorials/Simulators/Simulation-Main
 
 Miscellaneous
 -------------

source/Tutorials/Simulators/Ignition/Setting-up-a-Robot-Simulation-Ignition.rst

@@ -0,0 +1,224 @@
+.. _SimulatorsIgnition:
+
+Setting-up a Robot Simulation (Ignition Gazebo)
+===============================================
+
+**Goal:** Launch a Simulation with Ignition Gazebo and ROS 2
+
+**Tutorial level:** Intermediate
+
+**Time:** 20 minutes
+
+.. contents:: Contents
+   :depth: 2
+   :local:
+
+Prerequisites
+-------------
+
+First of all you should install ROS 2 and Ignition Gazebo.
+You have two options:
+
+ - Install from deb packages. To check which versions are available from deb packages please check this `table <https://github.com/ignitionrobotics/ros_ign)>`__.
+ - Compile from sources:
+
+   - :doc:`ROS 2 install instructions <../../../Installation>`
+   - `Ignition install instructions <https://ignitionrobotics.org/docs>`__
+
+Tasks
+-----
+
+1 Launch the simulation
+^^^^^^^^^^^^^^^^^^^^^^^
+
+In this demo you are going to simulate a simple diff drive robot in Ignition Gazebo.
+You are going to use one of the worlds defined in the Ignition Gazebo examples called
+`visualize_lidar.sdf <https://github.com/ignitionrobotics/ign-gazebo/blob/main/examples/worlds/visualize_lidar.sdf>`__.
+To run this example you should execute the following command in a terminal:
+
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        ign gazebo -v 4 -r visualize_lidar.sdf
+
+.. image:: Image/gazebo_diff_drive.png
+
+When the simulation is running you can check the topics provided by Ignition
+Gazebo with the ``ign`` command line tool:
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        ign topic -l
+        /clock
+        /gazebo/resource_paths
+        /gui/camera/pose
+        /gui/record_video/stats
+        /model/vehicle_blue/odometry
+        /model/vehicle_blue/tf
+        /stats
+        /world/diff_drive/clock
+        /world/diff_drive/dynamic_pose/info
+        /world/diff_drive/pose/info
+        /world/diff_drive/scene/deletion
+        /world/diff_drive/scene/info
+        /world/diff_drive/state
+        /world/diff_drive/stats
+
+Since you have not launched an ROS 2 nodes yet, the output from ``ros2 topic list``
+should be free of any robot topics:
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        ros2 topic list
+        /parameter_events
+        /rosout
+
+2 Configuring ROS 2
+^^^^^^^^^^^^^^^^^^^
+
+To be able to communicate our simulation with ROS 2 you need to use a package called ``ros_ign_bridge``.
+This package provides a network bridge which enables the exchange of messages between ROS 2 and Ignition Transport.
+You can install this package by typing:
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        sudo apt-get install ros-{DISTRO}-ros-ign-bridge
+
+At this point you are ready to launch a bridge from ROS to Ignition.
+In particular you are going to create a bridge for the topic ``/model/vehicle_blue/cmd_vel``:
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        source /opt/ros/{DISTRO}/setup.bash
+        ros2 run ros_ign_bridge parameter_bridge /model/vehicle_blue/cmd_vel@geometry_msgs/msg/Twist]ignition.msgs.Twist
+
+For more details about the ``ros_ign_bridge`` please check this `README <https://github.com/ignitionrobotics/ros_ign/tree/ros2/ros_ign_bridge>`__ .
+
+Once the bridge is running the robot is able to follow your motor commands.
+There are two options:
+
+* Send a command to the topic using ``ros2 topic pub``
+
+ .. tabs::
+
+    .. group-tab:: Linux
+
+       .. code-block:: console
+
+        ros2 topic pub /model/vehicle_blue/cmd_vel geometry_msgs/Twist  "linear: { x: 0.1 }"
+
+* ``teleop_twist_keyboard`` package. This node takes keypresses from the keyboard and publishes them as Twist messages. You can install it typing:
+
+ .. tabs::
+
+    .. group-tab:: Linux
+
+       .. code-block:: console
+
+        sudo apt-get install ros-{DISTRO}-teleop-twist-keyboard
+
+ The default topic where ``teleop_twist_keyboard`` is publishing Twist messages is ``/cmd_vel`` but you can remap this
+ topic to make use of the topic used in the bridge:
+
+ .. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        source /opt/ros/{DISTRO}/setup.bash
+        ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r /cmd_vel:=/model/vehicle_blue/cmd_vel
+
+        This node takes keypresses from the keyboard and publishes them
+        as Twist messages. It works best with a US keyboard layout.
+        ---------------------------
+        Moving around:
+           u    i    o
+           j    k    l
+           m    ,    .
+
+        For Holonomic mode (strafing), hold down the shift key:
+        ---------------------------
+           U    I    O
+           J    K    L
+           M    <    >
+
+        t : up (+z)
+        b : down (-z)
+
+        anything else : stop
+
+        q/z : increase/decrease max speeds by 10%
+        w/x : increase/decrease only linear speed by 10%
+        e/c : increase/decrease only angular speed by 10%
+
+        CTRL-C to quit
+
+        currently:	speed 0.5	turn 1.0
+
+3 Visualizing lidar data in ROS 2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The diff drive robot has a lidar.
+To send the data generated by Ignition to ROS 2, you need to launch another bridge.
+In the case the data from the lidar is provided in the Ignition Transport topic ``/lidar2``,
+which you are going to remap in the bridge.
+This topic will be available under the topic ``/lidar_scan``:
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        source /opt/ros/{DISTRO}/setup.bash
+        ros2 run ros_ign_bridge parameter_bridge /lidar2@sensor_msgs/msg/LaserScan[ignition.msgs.LaserScan --ros-args -r /lidar2:=/laser_scan
+
+To visualize the data from the lidar in ROS 2 you can use Rviz2:
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        source /opt/ros/{DISTRO}/setup.bash
+        rviz2
+
+Then you need to configure the ``fixed frame``:
+
+.. image:: Image/fixed_frame.png
+
+And then click in the button "Add" to include a display to visualize the lidar:
+
+.. image:: Image/add_lidar.png
+
+Now you should see the data from the lidar in Rviz2:
+
+.. image:: Image/rviz2.png
+
+Summary
+-------
+
+In this tutorial, you launched a robot simulation with Ignition Gazebo, launched
+bridges with actuators and sensors, visualized data from a sensor, and moved a diff drive robot.

source/Tutorials/Simulators/Simulation-Main.rst

@@ -0,0 +1,16 @@
+.. _SimulationMain:
+
+Simulation Tutorials
+====================
+
+These set of tutorials will teach you how to configure different simulators with ROS 2.
+
+.. contents:: Contents
+   :depth: 2
+   :local:
+
+.. toctree::
+   :maxdepth: 1
+
+   Webots/Setting-up-a-Robot-Simulation-Webots
+   Ignition/Setting-up-a-Robot-Simulation-Ignition