✨ Your First C++ MoveIt Project Tutorial (#262)

Co-authored-by: Shuhao Wu <[email protected]>
Co-authored-by: Nathan Brooks <[email protected]>
Co-authored-by: Anthony Baker <[email protected]>
Co-authored-by: Stephanie Eng <[email protected]>

Author: 5 people

doc/tutorials/quickstart_in_rviz/launch/demo.launch.py

@@ -21,6 +21,9 @@ def generate_launch_description():
         MoveItConfigsBuilder("moveit_resources_panda")
         .robot_description(file_path="config/panda.urdf.xacro")
         .trajectory_execution(file_path="config/gripper_moveit_controllers.yaml")
+        .planning_scene_monitor(
+            publish_robot_description=True, publish_robot_description_semantic=True
+        )
         .to_moveit_configs()
     )
 

doc/tutorials/quickstart_in_rviz/quickstart_in_rviz_tutorial.rst

@@ -232,12 +232,8 @@ Saving Your Configuration
 +++++++++++++++++++++++++
 RViz enables you to save your configuration under ``File->Save Config``. You should do this before continuing on to the next tutorials.
 
-Next Tutorials
-++++++++++++++
-* To easily control your robot using C++, check out the :doc:`Move Group C++ Interface </doc/examples/move_group_interface/move_group_interface_tutorial>`
 
-* To easily control your robot using Python, check out the :doc:`Move Group Python Interface </doc/examples/move_group_python_interface/move_group_python_interface_tutorial>`
+Next Tutorial
++++++++++++++
 
-* To create your own ``*_moveit_config`` package, check out the :doc:`Setup Assistant </doc/examples/setup_assistant/setup_assistant_tutorial>`
-
-* Save and restore robot states from a database or from disk using :doc:`warehouse_ros </doc/examples/persistent_scenes_and_states/persistent_scenes_and_states>`
+In :doc:`Your First MoveIt Project </doc/tutorials/your_first_project/your_first_project>`, you will create a C++ program using MoveIt to plan and execute moves.

doc/tutorials/tutorials.rst

@@ -13,4 +13,5 @@ In these tutorials, the Franka Emika Panda robot is used as a quick-start demo.
 
    getting_started/getting_started
    quickstart_in_rviz/quickstart_in_rviz_tutorial
+   your_first_project/your_first_project
    pick_and_place_with_moveit_task_constructor/pick_and_place_with_moveit_task_constructor

doc/tutorials/your_first_project/hello_moveit.cpp

@@ -0,0 +1,51 @@
+#include <memory>
+
+#include <rclcpp/rclcpp.hpp>
+#include <moveit/move_group_interface/move_group_interface.h>
+
+int main(int argc, char* argv[])
+{
+  // Initialize ROS and create the Node
+  rclcpp::init(argc, argv);
+  auto const node = std::make_shared<rclcpp::Node>(
+      "hello_moveit", rclcpp::NodeOptions().automatically_declare_parameters_from_overrides(true));
+
+  // Create a ROS logger
+  auto const logger = rclcpp::get_logger("hello_moveit");
+
+  // Create the MoveIt MoveGroup Interface
+  using moveit::planning_interface::MoveGroupInterface;
+  auto move_group_interface = MoveGroupInterface(node, "panda_arm");
+
+  // Set a target Pose
+  auto const target_pose = [] {
+    geometry_msgs::msg::Pose msg;
+    msg.orientation.w = 1.0;
+    msg.position.x = 0.28;
+    msg.position.y = -0.2;
+    msg.position.z = 0.5;
+    return msg;
+  }();
+  move_group_interface.setPoseTarget(target_pose);
+
+  // Create a plan to that target pose
+  auto const [success, plan] = [&move_group_interface] {
+    moveit::planning_interface::MoveGroupInterface::Plan msg;
+    auto const ok = static_cast<bool>(move_group_interface.plan(msg));
+    return std::make_pair(ok, msg);
+  }();
+
+  // Execute the plan
+  if (success)
+  {
+    move_group_interface.execute(plan);
+  }
+  else
+  {
+    RCLCPP_ERROR(logger, "Planing failed!");
+  }
+
+  // Shutdown ROS
+  rclcpp::shutdown();
+  return 0;
+}

doc/tutorials/your_first_project/rviz_1.png

@@ -0,0 +1,264 @@
+Your First C++ MoveIt Project
+=============================
+
+This tutorial will quickly get you writing your first ROS project with MoveIt.
+
+Prerequisites
+-------------
+
+If you haven't already done so, make sure you've completed the steps in :doc:`Getting Started </doc/tutorials/getting_started/getting_started>`.
+
+This tutorial assumes you understand the basics of ROS 2.
+To prepare yourself for this please complete the `Official ROS 2 Tutorials <https://docs.ros.org/en/{DISTRO}/Tutorials.html>`_ up until "Writing a simple publisher and Subscriber (C++)".
+
+Steps
+-----
+
+1 Create a package
+^^^^^^^^^^^^^^^^^^
+
+Open a terminal and `source your ROS 2 installation <https://docs.ros.org/en/{DISTRO}/Tutorials/Configuring-ROS2-Environment.html>`_ so that ``ros2`` commands will work.
+
+Navigate to your ``ws_moveit2`` directory you created in the :doc:`Getting Started Tutorial </doc/tutorials/getting_started/getting_started>`.
+
+Change directory into the ``src`` directory, as that is where we put our source code.
+
+Create a new package with the ROS 2 command line tools:
+
+.. code-block:: bash
+
+  ros2 pkg create \
+   --build-type ament_cmake \
+   --dependencies moveit_ros_planning_interface rclcpp \
+   --node-name hello_moveit hello_moveit
+
+The output of this will show that it created some files in a new directory.
+
+Note that we added ``moveit_ros_planning_interface`` and ``rclcpp`` as dependencies.
+This will create the necessary changes in the ``package.xml`` and ``CMakeLists.txt`` files so that we can depend on these two packages.
+
+Open the new source file created for you at ``ws_moveit2/src/hello_moveit/src/hello_moveit.cpp`` in your favorite editor.
+
+2 Create a ROS Node and Executor
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This first block of code is a bit of boilerplate but you should be used to seeing this from the ROS 2 tutorials.
+
+.. code-block:: C++
+
+  #include <memory>
+
+  #include <rclcpp/rclcpp.hpp>
+  #include <moveit/move_group_interface/move_group_interface.h>
+
+  int main(int argc, char * argv[])
+  {
+    // Initialize ROS and create the Node
+    rclcpp::init(argc, argv);
+    auto const node = std::make_shared<rclcpp::Node>(
+      "hello_moveit",
+      rclcpp::NodeOptions().automatically_declare_parameters_from_overrides(true)
+    );
+
+    // Create a ROS logger
+    auto const logger = rclcpp::get_logger("hello_moveit");
+
+    // Next step goes here
+
+    // Shutdown ROS
+    rclcpp::shutdown();
+    return 0;
+  }
+
+2.1 Build and Run
+~~~~~~~~~~~~~~~~~
+
+We will build and run the program to see that everything is right before we move on.
+
+Change directory back to the workspace directory ``ws_moveit2`` and run this command:
+
+.. code-block:: bash
+
+  colcon build --mixin debug
+
+After this succeeds, **open a new terminal**, then source the workspace environment script in that new terminal so that we can run our program.
+
+.. code-block:: bash
+
+  cd ~/ws_moveit2
+  source install/setup.bash
+
+Run your program and see the output.
+
+.. code-block:: bash
+
+  ros2 run hello_moveit hello_moveit
+
+The program should run and exit without error.
+
+2.2 Examine the code
+~~~~~~~~~~~~~~~~~~~~
+
+The headers included at the top are just some standard C++ headers and the header for ROS and MoveIt that we will use later.
+
+After that, we have the normal call to initialize rclcpp, and then we create our Node.
+
+.. code-block:: C++
+
+  auto const node = std::make_shared<rclcpp::Node>(
+    "hello_moveit",
+    rclcpp::NodeOptions().automatically_declare_parameters_from_overrides(true)
+  );
+
+The first argument is a string that ROS will use to make a unique node.
+The second is needed for MoveIt because of how we use ROS Parameters.
+
+Lastly, we have the code to shutdown ROS.
+
+3 Plan and Execute using MoveGroupInterface
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In place of the comment that says "Next step goes here," add this code:
+
+.. code-block:: C++
+
+  // Create the MoveIt MoveGroup Interface
+  using moveit::planning_interface::MoveGroupInterface;
+  auto move_group_interface = MoveGroupInterface(node, "panda_arm");
+
+  // Set a target Pose
+  auto const target_pose = []{
+    geometry_msgs::msg::Pose msg;
+    msg.orientation.w = 1.0;
+    msg.position.x = 0.28;
+    msg.position.y = -0.2;
+    msg.position.z = 0.5;
+    return msg;
+  }();
+  move_group_interface.setPoseTarget(target_pose);
+
+  // Create a plan to that target pose
+  auto const [success, plan] = [&move_group_interface]{
+    moveit::planning_interface::MoveGroupInterface::Plan msg;
+    auto const ok = static_cast<bool>(move_group_interface.plan(msg));
+    return std::make_pair(ok, msg);
+  }();
+
+  // Execute the plan
+  if(success) {
+    move_group_interface.execute(plan);
+  } else {
+    RCLCPP_ERROR(logger, "Planing failed!");
+  }
+
+3.1 Build and Run
+~~~~~~~~~~~~~~~~~
+
+Just like before, we need to build the code before we can run it.
+
+In the workspace directory, ``ws_moveit2``, run this command:
+
+.. code-block:: bash
+
+  colcon build --mixin debug
+
+After this succeeds, we need to re-use the demo launch file from the previous tutorial to start RViz and the MoveGroup node.
+In a separate terminal, source the workspace and then execute this:
+
+.. code-block:: bash
+
+  ros2 launch moveit2_tutorials demo.launch.py
+
+Then in the ``Displays`` window under ``MotionPlanning/Planning Request``, uncheck the box ``Query Goal State``.
+
+.. image:: rviz_1.png
+   :width: 300px
+
+In a third terminal, source the workspace and run your program.
+
+.. code-block:: bash
+
+  ros2 run hello_moveit hello_moveit
+
+This should cause the robot in RViz to move and end up in this pose:
+
+.. image:: rviz_2.png
+   :width: 300px
+
+Note that if you ran the node ``hello_moveit`` without launching the demo launch file first, it will wait for 10 seconds and then print this error and exit.
+
+.. code-block:: bash
+
+  [ERROR] [1644181704.350825487] [hello_moveit]: Could not find parameter robot_description and did not receive robot_description via std_msgs::msg::String subscription within 10.000000 seconds.
+
+This is because the ``demo.launch.py`` launch is starting the ``MoveGroup`` node that provides the robot description.
+When ``MoveGroupInterface`` is constructed, it looks for a node publishing a topic with the robot description.
+If it fails to find that within 10 seconds, it prints this error and terminates the program.
+
+3.2 Examine the code
+~~~~~~~~~~~~~~~~~~~~
+
+The first thing we do is create the MoveGroupInterface. This object will be used to interact with move_group, which allows us to plan and execute trajectories.
+Note that this is the only mutable object that we create in this program.
+Another thing to take note of is the second interface to the ``MoveGroupInterface`` object we are creating here: ``"panda_arm"``.
+That is the group of joints as defined in the robot description that we are going to operate on with this ``MoveGroupInterface``.
+
+.. code-block:: C++
+
+  using moveit::planning_interface::MoveGroupInterface;
+  auto move_group_interface = MoveGroupInterface(node, "panda_arm");
+
+Then, we set our target pose and plan. Note that only the target pose is set (via ``setPoseTarget``. The starting pose is implicitly the position published by joint state publisher, which could be changed using the ``MoveGroupInterface::setStartState*`` family of functions (but is not in this tutorial).
+
+One more thing to note about this next section is the use of lambdas for constructing the message type ``target_pose`` and planning.
+This is a pattern you'll find in modern C++ codebases that enables writing in a more declarative style.
+For more information about this pattern there is a couple of links at the end of this tutorial.
+
+.. code-block:: C++
+
+  // Set a target Pose
+  auto const target_pose = []{
+    geometry_msgs::msg::Pose msg;
+    msg.orientation.w = 1.0;
+    msg.position.x = 0.28;
+    msg.position.y = -0.2;
+    msg.position.z = 0.5;
+    return msg;
+  }();
+  move_group_interface.setPoseTarget(target_pose);
+
+  // Create a plan to that target pose
+  auto const [success, plan] = [&move_group_interface]{
+    moveit::planning_interface::MoveGroupInterface::Plan msg;
+    auto const ok = static_cast<bool>(move_group_interface.plan(msg));
+    return std::make_pair(ok, msg);
+  }();
+
+Finally, we execute our plan if planning was successful, otherwise we log an error:
+
+.. code-block:: C++
+
+  // Execute the plan
+  if(success) {
+    move_group_interface.execute(plan);
+  } else {
+    RCLCPP_ERROR(logger, "Planning failed!");
+  }
+
+Summary
+-------
+
+* You created a ROS 2 package and wrote your first program using MoveIt.
+* You learned about using the MoveGroupInterface to plan and execute moves.
+* :codedir:`Here is a copy of the full hello_moveit.cpp source at the end of this tutorial<tutorials/your_first_project/hello_moveit.cpp>`.
+
+Further Reading
+---------------
+
+- We used lambdas to be able to initialize objects as constants. This is known as a technique called IIFE.  `Read more about this pattern from C++ Stories <https://www.cppstories.com/2016/11/iife-for-complex-initialization/>`_.
+- We also declared everything we could as const.  `Read more about the usefulness of const here <https://www.cppstories.com/2016/12/please-declare-your-variables-as-const/>`_.
+
+Next Step
+---------
+
+TODO