Questions tagged [topic]
The topic tag has no usage guidance.
222
questions
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Intermittent Communication Freeze in ROS2
Our team encountered a peculiar issue while developing with ROS2. We are using the iron version of ROS2, and during intensive communications between multiple nodes (short time intervals but not large ...
CommunityBot
- 1
0
votes
0
answers
5
views
Velocity topic in ign-gazebo
I am having trouble understanding whether and how it's possible to retrieve the velocity of links from the simulator. When I launch any URDF, using ign topic -l, I expect to see the topic where the ...
- 1
0
votes
3
answers
266
views
How to show topics using python in ROS2
Hi, everyone.
Like the title, I want to show topics using python in ROS2.
First I thought use a ros2 topic list command through a ...
CommunityBot
- 1
0
votes
2
answers
44
views
Multiple times same node and same topics
In ROS1 Noetic my students like to launch multiple times:
the same node;
the same topics.
What is the exact effect of these multiple declarations ?
For Node, is-it a problem ?
When you create ...
CommunityBot
- 1
0
votes
1
answer
31
views
How to publish data to a topic different than the one listened to
I want to execute a ROS2 command say:
ros2 topic pub --smth /obj std_msgs/String "sometext"
from a package node (written in Python) that is execute using ...
0
votes
1
answer
20
views
How to make rosnodes communicate in different docker containers
I'm using ROS2 Iron in Docker on my robot. The problem is that nodes can't communicate with each other. What have been done:
I've run two containers in Docker with Ros Iron:
...
- 113
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1
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128
views
Ros2, topics still persist after subscribers/publishers go out of scope
I have a map plugin I've made for rqt_gui that I am going to be using to visualize location information from n number of ROVs/autonomous vehicles. So far I am able to find and create subscribers to ...
CommunityBot
- 1
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votes
0
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15
views
repeated topic, use namespace vs one topic only, scalability
The setup is as following:
It has several Raspberry Pi and to each several Arduino are attached that have each one sensor.
...
- 1
0
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1
answer
26
views
Get data from Hardware Component to other package outside of ros2_control
I am currently writing a package that will calculate the linear acceleration and angular velocity (geometry_msg/Twist) for driving from A to B. I am now facing the ...
- 1,934
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125
views
gz topic not publishing
I have a fresh installation of Ubuntu 22.04 in a VM VirtualBox, fully updated.
I compiled Gazebo Harmonic from source code and followed the "Building your own robot" tutorial creating the ...
CommunityBot
- 1
0
votes
1
answer
40
views
rqt_graph sees more nodes and topics than ros2 topic list and ros2 node list
I'm migrating a ROS1 application to ROS2 and am at the stage where I have some nodes converted and running. The main workhorse node, though, runs fine (as in not crashing) but it doesn't show up when ...
0
votes
1
answer
275
views
Get robot position wrt world frame in ROS2-Gazebo Garden
I'm trying to understand how I can possibly get the global position of a model in a Gazebo simulation through ROS2.
I've seen that Gazebo publishes data to the ...
- 25
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2
answers
13
views
How to create a node to share data between different robots
I am trying to build a data structure (cloud system) able to receive and send data and instructions from/to different kind of robots (e.g. drones,turtlebots). My idea is to create a node to which ...
CommunityBot
- 1
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0
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16
views
0
votes
1
answer
404
views
How to get a topic name in a callback function (Python, Ros2)
I have two cameras subscribing camera1/image_raw and camera2/image_raw respectively. And both subscribers call image_callback when they received any topic. I want to show camera1 image in window1 and ...
- 903
1
vote
3
answers
649
views
ROS2 data exchange over network
I have a question regarding ROS2 data exchange over the network.
Let’s assume, I have two hosts that are running some ros nodes over the same network, using ROS_DOMAIN_ID=0, so I broadcast all topics. ...
0
votes
0
answers
57
views
Does rclpy supports intraprocess communication?
I wanted to know if rclpy supports intraprocess communication or is there a way to do intraprocess in rclpy with python based libraries?
Thanks,
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144
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ROS2: RQT can not get message class for a user defined message
I can build a package used to define interfaces like messages, service and actions. I think everything is fine since I can show them using the usual command
...
- 33
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1
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147
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no new messages for rostopic hz /camera/aligned_depth_to_color/image_raw in ros noetic inside docker
steps to reproduce the problem
In the first terminal type: ...
- 976
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0
answers
56
views
VRX wamv position using ROS2
I need information about the instant position of the wamv (osrf/vrx).
Using ROS1 + Gazebo11 it works in general properly:
...
0
votes
0
answers
96
views
Communication problem of ros2 humble
On the ROS2 humble version, we publish messages using the topic method, and there is a probability that the node subscribing to the topic will not receive the message. This situation usually occurs ...
0
votes
0
answers
57
views
navsat_transform_node imu topic data mapping problem
I ran into the problem of mapping the /imu/data topic of the navsat_transform_node node in the robot_localization package. the node has a very strange behavior - when mapping imu data to the /...
- 1
0
votes
2
answers
20
views
rqt_plot not publishing showing anything
rqt_plot not publishing anything even thought there is data being published on the topic "mytopic". When I do rostopic echo /mytopic I get continious ...
Gudjohnson
0
votes
1
answer
382
views
ros2 topic list doesn't work in sudo mode
Hi all,
I'm using Ubuntu 22.04.1 LTS with Linux 5.10.0-18-rt-amd64, with ros2 humble debian release.
I try to launch ros2_control from sudo terminal, but I can't see the ros2 topics outside ( from ...
dei
0
votes
1
answer
63
views
Subscribing and publishing to the same topic (/map) in a single python ros node
My goal is to process a PointCloud2 and visualize it in RViz. I have rosbag data collected. This rosbag file includes /map, /tf, /ssl_slam/trajectory topics. The /map topic is in the form of ...
hunterlineage1
1
vote
1
answer
124
views
Processing pointcloud2 using ros node with both publisher and subscriber
I am trying to process a pointcloud2 being generated by the /map topic, which I play from a rosbag file containing the topics /tf, /map, /ssl_slam/trajectory topics. By process, I mean I want to ...
hunterlineage1
0
votes
1
answer
137
views
[ROS2 Foxy] Topics sometimes subscribed to and sometimes published to
I have two Nodes who communicate with a Float32 message topic.
The typical sequence of events are:
Node A starts
Node B starts
Node A waits to subscribe to topic T
Node B creates topic T publisher
...
Fubbis
0
votes
1
answer
25
views
ROS2 topic name validation
Is there a way to validate topic names in rclcpp? For ROS1 I was using the validate function defined here.
Is there anything that is equivalent in C++ for ROS2?
...
a.g
0
votes
1
answer
106
views
ROS2 Resolve topic names rclcpp
In ros1 cpp I was able to resolve a string containing the topic name to the actual topic name that accounts for remappings using the following block:
...
vinny
0
votes
1
answer
734
views
ROS2 nodes stay alive and keep publishing after shutting down
Hi,
I am currently working with ROS2 Galactic on Ubuntu 20.04.3 LTS (Focal Fossa) on a project of mine.
The problem:
After stopping my launch file and shutting down my computer, the next time I open ...
Brulf
0
votes
1
answer
81
views
ros2 topic pub from launch file
Hello everyone,
Does anyone know if it is possible in ros2 to directly start from launch file a simple node that publishes a message?
In ROS1 it was easily possible like this:
...
Raposa
1
vote
2
answers
111
views
[ROS2] Retrieving QOS settings for a topic
Hi,
since a subscriber can receive a topic message only if its QOS profile is compatible with the QOS profile of the publisher, is there a way to retrieve the DURABILITY and the RELIABILITY settings ...
0
votes
3
answers
8
views
How to subcribe 2 image topics with 1 node in same time?
Hi buddy,
My name is Toan. I am a newbie in ROS. Now, i'm using Kinect Camera and trying to subcribe 2 image topics with 1 node. But seem like my code is wrong something. If i try to subcribe 1 node ...
ToanJunifer
0
votes
5
answers
43
views
Is there a way to subscribe to a topic without setting the type?
I try to create some UI to allow users to select a topic and visualize the data published on that topic. To get started I wanted to have only one field for the topic name and connect to it with python....
Felix Kaser
0
votes
1
answer
11
views
how can i save rostopic in array?
Hi guys. I need help.
I want to make nodes that 'subscribe topic - save in array' and 'read array - publish topic'.
(in my case it is geometry_msgs::Pointstamped)
But there are no references and ...
Ray_Shim
0
votes
3
answers
55
views
What is the actual meaning of ros::spin()
I know that ros::spin can make the subscriber and publisher run in loop to publish or receive data.
But I dont know which part in the program is running in loop or ...
Bill5785
0
votes
2
answers
64
views
trajectory_msgs/JointTrajectory Exception :AttributeError: 'str' object has no attribute 'positions'
I wrote a python script to publish a JointTrajectory message. It results in an Exception: AttributeError: 'str' object has no attribute 'positions'.
The python script:
...
GUENNI
0
votes
1
answer
49
views
Read /rosout/msg with seperate Python script
Hello!
I am currently working on a project where I navigate a TurtleBot3 to several positions in a room. The TB3 navigation is triggered by publishing messages to a specific topic (/tb3_hsc/command). ...
anonymous55390
0
votes
1
answer
4
views
Does ROS2 support keyed topic?
Hi everyone,
As stated in the title, does ROS2 have topic with keys? I have been studying ROS2 for few weeks and I have looked around but cannot find anywhere stating about keyed topic in ROS2.
Maybe ...
Sapodilla
0
votes
1
answer
4
views
How can I round /scan topic values?
Hello!
I am student and I really want to send /scan topic values to rtabmapviz. I am using ROS kinetic, /scan is topic created by RPLidarNode. Unfortunately I think that I need rounded values, because ...
tominkoooo
0
votes
2
answers
4
views
When exactly is a connect callback of a publisher called?
Hi all,
I would like to know when precisely the connect_cb is being invoked, specified in
...
CodeFinder
0
votes
1
answer
6
views
Number of TCP connections for a "bidirectional" topic?
Hi all,
I have a (possibly) simple question: assume if I have two nodes A, B that communicate over a topic "/my_topic", i.e., both nodes subscribe and publish to "/my_topic" using ...
CodeFinder
0
votes
1
answer
16
views
How to increase frequency of /diagnostics topic published by epos_hardware node?
Dear ROS community,
I am using the epos_hardware ROS package as a hardware interface between an effort controller and a EPOS2 motor controller coupled with a Maxon EC90 motor. The set up is working ...
indraneel
0
votes
1
answer
22
views
In publish raise ROSSerializationException(str(e))
In my package that I created, there are 3 nodes currently. I also generate a custom message which is "AnchorScan".
First node does some stuff and only publishes from ...
elcinerdogan
0
votes
3
answers
323
views
how to point and click on rviz map and output the position
Can any one tell me how to use mouse to click on a map in Rviz and get the position of this area. Then output it.
Originally posted by Rikardo on ROS Answers with karma: 75 on 2013-07-25
Post score: ...
Rikardo
0
votes
1
answer
17
views
What is the proper convention for published topic names?
Hi, I'm working on a wheeled robot using rosserial and I am publishing wheel encoder counts and velocities. I was wondering if there was a proper way to write the topic names I am publishing. For ...
geistmate
0
votes
1
answer
11
views
How to subcribe both Image topic and Text topic in the same time?
Hi buddy,
I am newbie in ROS. And this is the first time i'm trying to subcribe 2 topics type, 1 for Image topic and 1 for Array of ints topic. And i have a problem on it.
This is my source code:
<...
ToanJunifer
0
votes
1
answer
45
views
How to send Array Message from Arduino to ROS Topic?
Hi Buddy,
I'm newbie in ROS and i trying to send data from arduino to Ros Topic. I have send string and integer type. But in Array type i have a small problem. This is my source code:
...
ToanJunifer
0
votes
2
answers
22
views
How many nodes can publish to a single topic?
hello every body. I'm new in Ros and I have a simple question.
How many nodes can publish to a single topic?
thank you.
Originally posted by hamed ghasemi on ROS Answers with karma: 3 on 2018-10-07
...
hamed ghasemi
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votes
1
answer
1
view
how to calculate difference of two messages in callback function on same topic
Hi Sir,
I am actually reading my hand pose from a Leap Motion sensor and I want to calculate how much the hand moves in X direction.
My question is how to read the message in callback function(as you ...
stevensu1838