Can MoveItPy be used with rclpy.node.Node?

[ymollard]

Hi,

The MoveItPy tutorials do not create a rclpy.node.Node instance:

moveit2_tutorials/doc/examples/motion_planning_python_api/scripts/motion_planning_python_api_tutorial.py

Lines 53 to 77 in 12edc7e

	def main():
	###################################################################
	# MoveItPy Setup
	###################################################################
	rclpy.init()
	logger = get_logger("moveit_py.pose_goal")
	# instantiate MoveItPy instance and get planning component
	panda = MoveItPy(node_name="moveit_py")
	panda_arm = panda.get_planning_component("panda_arm")
	logger.info("MoveItPy instance created")
	###########################################################################
	# Plan 1 - set states with predefined string
	###########################################################################
	# set plan start state using predefined state
	panda_arm.set_start_state(configuration_name="ready")
	# set pose goal using predefined state
	panda_arm.set_goal_state(configuration_name="extended")
	# plan to goal
	plan_and_execute(panda, panda_arm, logger, sleep_time=3.0)

In my opinion this is somehow inconsistent with rclpy tutorials that recommand to inherit from rclpy.node.Node here:
https://docs.ros.org/en/jazzy/Tutorials/Beginner-Client-Libraries/Writing-A-Simple-Py-Publisher-And-Subscriber.html

That makes integration of MoveItPy with other rclpy tools (subscribers, services, ...) more complicated for beginners who cannot rely on official ROS 2 tutorials to assemble with MoveItPy.

Is there a recommanded way to use the MoveItPy + rclpy.node.Node combo?

[sea-bass]

It seems like MoveItPy internally contains its own node and executor:

https://github.com/moveit/moveit2/blob/99227040ebe4bac4cc1a95afbe44ee9c543e3c02/moveit_py/src/moveit/moveit_ros/moveit_cpp/moveit_cpp.cpp#L55

You might be able to create something that subclasses from a node and stick the MoveItPy instance inside it as an attribute, but I haven't tried this myself.

[ymollard]

Yes, it works pretty well like this: https://gitlab.com/f2m2robserv/jazzy-ros-ynov/-/blob/main/src/tiago_pick_and_place/tiago_pick_and_place/pick.py

Shouldn't the tutos create a regular node like this instead? This is confusing for newcomers, they're told in regular ROS tutorials to create a node via class inheritance, but MoveItPy is not demonstrated this way.

[sea-bass]

Great to hear, and your example does look nice!

If you'd be willing to add a new tutorial on "Using MoveItPy in existing ROS 2 nodes", that would be a good addition to the currently small set of Python tutorials.