The meaning of manually written ""

I am doing “3 Publisch & Subscribe to TF data” of “TF” course. In this case we are learning how to write a py-file to broadcast/publish TF data. But I find that even though without this manually written py-file, we can still see turtle1 and turtle2 in rqt_tf_tree and rviz.
If we add “coke_can” in name_list in this py-file, rqt_tf_tree will add “coke_can” as well. But why “turtle1” and “turtle2” always show themselves? Where has this defined? Even though I set the name_list in “” just as [“coke_can”], “turtle1” and “turtle2” remain. As a result, what is the meaning of this manually written “”? Just add ‘‘other’’ objects to present?

The manually written “” is here:

#! /usr/bin/env python
import rospy
import time
import tf
from turtle_tf_3d.get_model_gazebo_pose import GazeboModel

class MultiTfBroadcast(object):
def __init__(self, robot_name_list, loop_rate=5.0):

    self._robot_name_list = robot_name_list
    self._gazebo_model_object = GazeboModel(self._robot_name_list)

    # hz
    self._rate = rospy.Rate(loop_rate)

    # We start the Tf broadcaster
    self._broad_caster_tf = tf.TransformBroadcaster()

    # Leave enough time to be sure the Gazebo Model logs have finished
    rospy.loginfo("Ready..Starting to Publish TF data now...")

def handle_turtle_pose(self, pose_msg, robot_name, reference_frame_data="/world"):

    self._broad_caster_tf.sendTransform((pose_msg.position.x, pose_msg.position.y, pose_msg.position.z),
                                        (pose_msg.orientation.x, pose_msg.orientation.y,
                                         pose_msg.orientation.z, pose_msg.orientation.w),

def start_loop(self):

    while not rospy.is_shutdown():
        for robot_name in self._robot_name_list:
            pose_now = self._gazebo_model_object.get_model_pose(robot_name)
            if not pose_now:
                robot_name_msg = "The " + \
                    str(robot_name) + \
                    "'s Pose is not yet available...Please try again later"
                self.handle_turtle_pose(pose_now, robot_name)

def main():

rospy.init_node('publisher_of_tf_node', anonymous=True)
multi_tf_broadcast_obj = MultiTfBroadcast(
    robot_name_list=["turtle1", "turtle2", "coke_can"])

except rospy.ROSInterruptException:

if name == ‘main’:

Hello @MeineLiebeAxt,

as I understand from you post you are executing the script after having modified this line here:

multi_tf_broadcast_obj = MultiTfBroadcast(
    robot_name_list=["turtle1", "turtle2"])

into this:

multi_tf_broadcast_obj = MultiTfBroadcast(

and you are wondering why in the new version of your file the TF’s for turtle1 and turtle2 are also being published. Did I understand your question correctly?

The answer is they should not be published. So something else must be causing this issue.

To start, please confirm a few things:

  • You have saved your new script and the line above is like so:
multi_tf_broadcast_obj = MultiTfBroadcast(
  • You have stopped all ROS nodes running in every Webshell before you run you new code. To do so switch to every Webshell and press Ctrl + C.

  • Confirm that when you execute the script you see these lines printed out to the console:

user:~/catkin_ws/src/tf_exercises_pkg$ rosrun tf_exercises_pkg
[INFO] [1665562839.223504, 0.000000]: Retrieveing Model indexes
[INFO] [1665562839.256574, 481.781000]: Final robots_index_dict =  {'coke_can': 1}
[INFO] [1665562840.266317, 482.797000]: Ready..Starting to Publish TF data now...

The second INFO log shows the name of the objects who’s TF’s will be broadcasted in lines above it is just coke_can. In that case you should only see the TF for coke_can being published.

Hope this helps,


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