ros2 topic echo /odom --> None value on fastdds

[william00kim]

Robot Model

Turtlebot4 Standard

ROS distro

Humble

Networking Configuration

Discovery Server

OS

Ubuntu 22.04

Built from source or installed?

Installed

Package version

ros2 humble 2.6

Type of issue

Networking

Expected behaviour

Hello,

I am a user currently working with a TurtleBot4.

I am experiencing an issue where running ros2 topic echo /odom on the TurtleBot works correctly, but when I connect my laptop (running Ubuntu 22.04) to the TurtleBot’s Wi-Fi (Access Point mode) and run the same command on the laptop, no data is displayed.

Currently, both the TurtleBot and the laptop are connected to the TurtleBot’s Access Point. The ROS_DOMAIN_ID is the same on both devices, and the TurtleBot is configured to act as the discovery server. The discovery server is set as TurtleBot_IP:11811.

Could you please advise what might be causing this issue? I would appreciate your prompt response.

Actual behaviour

?

Error messages

goguma@goguma:~$ ros2 topic echo /odom

To Reproduce

I am experiencing an issue where running ros2 topic echo /odom on the TurtleBot works correctly, but when I connect my laptop (running Ubuntu 22.04) to the TurtleBot’s Wi-Fi (Access Point mode) and run the same command on the laptop, no data is displayed.

Other notes

There is no /odom echo in Labtop

[william00kim]

ubuntu@ubuntu:~$ ros2 topic echo /odom --once
header:
stamp:
sec: 1753912162
nanosec: 361636326
frame_id: odom
child_frame_id: base_link
pose:
pose:
position:
x: -0.00022088455443736166
y: 3.4157508821408555e-07
z: -8.09820085123647e-06
orientation:
x: -0.004056487698107958
y: -0.019141877070069313
z: -3.713493424584158e-05
w: 0.9998085498809814
covariance:

• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
  twist:
  twist:
  linear:
  x: 0.0
  y: 0.0
  z: 0.0
  angular:
  x: 0.0
  y: 8.770104642508159e-09
  z: -1.347061073797562e-10
  covariance:
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0
• 0.0

---

ubuntu@ubuntu:~$

up: turtlebot4 down: labtop___________

goguma@goguma:~$ ros2 topic echo /odom --once

[smatarCPR]

Hello @william00kim
Thank you for reaching out on the Turtlebot 4 Github page. I am very sorry to hear that your Turtlebot unit is not meeting expectations. based on the details provided I have the following questions/recommendations:

• The odom topic comes from the Create3 base unit on the Turtlebot. If you SSH into the Raspberry Pi are you able to echo the topic and receive data reliably? What about other topics from the Create3 such as wheel_ticks and battery_state
• Are other topics also unechoable or is it only the odom topic? Are you able to test topics from the Pi such as the laser scan topic?
• Setting up a discovery server requires that the Create3 be factory reset and completely cutoff from wi-fi. Were you able to do so?
• On the offboard computer are you able to verify the Discovery Server settings? What is the output of printenv | grep ROS?

Looking forward to hearing from you soon.
Best Regards,
Saif

[william00kim]

I would like to communicate without using Wi-Fi, by having the TurtleBot Raspberry Pi operate in AP (Access Point) mode. Currently, the Discovery Server is not working, so I switched to Simple Discovery. However, the issue still remains: topics from the Raspberry Pi can be echoed, but topics from the robot itself cannot be echoed.

I am using Fast DDS, and the fastdds.xml file is currently empty/default.

On the TurtleBot Raspberry Pi (ubuntu):

ubuntu@ubuntu:~$ printenv | grep ROS
ROS_VERSION=2
ROS_PYTHON_VERSION=3
ROS_SUPER_CLIENT=False
ROS_DOMAIN_ID=0
ROS_LOCALHOST_ONLY=0
ROS_DISTRO=humble
ROS_DISCOVERY_SERVER=

On the laptop (goguma):

goguma@kimgoguma:~$ printenv | grep ROS
ROS_VERSION=2
ROS_PYTHON_VERSION=3
ROS_DOMAIN_ID=0
ROS_LOCALHOST_ONLY=0
ROS_DISTRO=humble

ubuntu refers to the TurtleBot Raspberry Pi, and goguma refers to the laptop.

Thank you.

[smatarCPR]

Hello @william00kim ,
Thank you for providing these details. I have the following questions/recommendations regarding the current setup.

• On the Raspberry Pi environment variables I notice that the ROS_SUPER_CLIENT has been set to FALSE. Are you able to update the setup.bash file, to set this variable to TRUE. Please also do the same on the kimgoguma computer.
• With the switch to Simple Discovery, the Create3 must now be connected to a 2.4 GHz wi-fi network. The Raspberry Pi Access Point only supports 5.0 GHz. This means that the Create3 is unable to connect to this network for the purposes of Simple Discovery.

It is recommended in this case that a Discovery Server be used as the Raspberry Pi does not have the capability of generating dual-band network . Another detail worth mentioning is the use of the Creat3 Republisher - when using a discovery server the Create3 republisher is used to have the Raspberry Pi republish the Create3 topics onto the Discovery Server - see here for more details - https://turtlebot.github.io/turtlebot4-user-manual/software/create3.html#create-3-republisher

Are you able to verify that for the Create3 the namespace _do_not_use was set?

Looking forward to hearing from you soon.
Best Regards,
Saif M.