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How do I determine the order of ROS messages in Python

I am using ros-noetic. I am receiving ROS messages and putting them into a python Queue which is FIFO. I suspect but I am not sure that what is happening is the subscriber callbacks are called in a ...
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Can we create a custom ROS2 message datatype?

I have a datatype called alpha which is based on float64. Now I want to create a custom ROS2 message which has this datatype instead of adding float64. Is there a ...
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Cannot get the message using rosbag2 and rclpy

Good day everyone, I've been struggling with this for two days now. and I can't seem to find a solution. I have a dictionary with topic names and their types, what is the correct module to read the ...
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Set interface name without msg in ROS2

When creating custom message types in ROS1 (noetic), I can store the *.msg files in a subfolder named msg. In the CMake file, I ...
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Recursive message definition in ROS2

Hi, Is it possible to create a recursive message type in ROS2? E.g.: message Node.msg int64 id my_msgs/Node neighbors This is currently causing compiler errors in ROS2 Humble for me but I was ...
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Best Practices for Publishing Lots of Related Data

I am developing a system using ROS2 Foxy on Ubuntu 20.04 that interfaces with a Allen Bradley ControlLogix PLC, speaking EtherNet/IP. We pull data from it at 20Hz, and there is a large amount of ...
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1 answer
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Importing ROS msgs from a directory other than /msg

I'm trying to create a flexible way of defining enumerations for different datatypes, such that adding a new enum doesn't invalidate the message hash, thereby ruining the bag. Such that a traditional ...
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1 answer
276 views

Send a 2D array through topics in ROS2

What is a proper way of sending 2D arrays through topics? I want to send small ones (4x6 for example) and so far I created an array msg (float64[]) and then use the .reshape function in order to send ...
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1 answer
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Subscriber in /odom topic from gazebo loses first message

Hello! I have a robot in a gazebo environment that publishes the odometry data on the topic /odom. I have a node that subscribes to that topic and uses the odometry data. I save the data from the ...
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1 answer
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Adapting C++ Types in ROS Melodic

I'm trying to adapt a lot of code that already has data structures defined to ROS, so I decided to try using roscpp message adaptation since it seems like it could help make the transition easier. But ...
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1 answer
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Unitended change of message content

Hi there, I am running ROS Melodic on an Ubuntu 16.04 64-bit machine. While processing odometry messages from a rosbag file in a single node, I could not receive the expected output. While debugging ...
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1 answer
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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 ...
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Messages aren't built

I've downloaded a ROS package and I would like to use its messages in my program, however, for some weird reason the messages aren't built and thus I get an error. My package.xml has this: ...
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1 answer
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Subscribing multiple topics with different rate

Hey there, I´m currently new at ROS but made yet all the beginner tutorials at the ROS homepage. First I implemented a simple publisher and subscriber and it worked. Now I want to create something ...
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1 answer
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Understanding messages MDSum

I am trying to understand how the MD5Sum of the messages is being calculated following this link So far, I undestand that a plain message like std_msgs/Header translates to: ...
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1 answer
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Message for publishing roll, pitch, yaw without converting to quaternion

Hi there, I have been looking for a way to publish roll, pitch, yaw angles without change them to quaternions but I didn't find that kind of message after googling for a while. I know I can write my ...
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1 answer
18 views

ROS2 Custom Messages Not Found

While trying to run my python script, I get ModuleNotFoundError: No module named 'lightring_msgs'. I know the message types are being generated; the package files ...
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1 answer
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Looking for existing Electromyograph EMG/EEG, or voltage messages

I am in the process of implementing a ROSBag writer for an electromyograh device. Before implementing my own messages, I would like to know if such messages already exist. Basically I al looking for ...
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1 answer
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How to collect messages from all topics and put them into a csv file?

Hello everyone! I have a .bag file with recorded messages from 4 different sensors (2xIMU, 2xINEMO), which have been worked simultaneously. I need to collect all messages from all sensors' topics and ...
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Is there a possibility in ROS to check that the other machine messages publish in the topic without direct transfer of messages between the machines?

Hi, Is there a possibility in ROS to check that in the other machine messages publish in the topic without direct transfer of messages between the machines? I would like to transfer between machines ...
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1 answer
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Question re ACML_demo rosout messages

Hi All, I am fairly new to ROS, so forgive a rookie question. When I run amcl_demo.launch and view the output, I can see info such as "goal reached" and "got new plan", and I would ...
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1 answer
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Import variables from a message

Hello, In my code I would like to get a variable from my message and use this in my main. Whenever I run this code "x" is said to be 0.00. This should be a different number. In my message I ...
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1 answer
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ROS2 ament overlay issue with messages

I'm working on adding array parameter support for ROS2, and am having trouble with ament. I've added new types and values here and here. I then sourced ...
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Position, Velocity and Time

Is there a standard ROS message that can represent an object's x, y position along with its velocity at each position and time passed at the position? Originally posted by Divya Thomas on ROS Answers ...
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1 answer
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Message set for GNSS/INS ROS Driver (node) - Standardized

Hello, I am trying to develop a driver (node) for a commercial GNSS/INS unit. For that I think it is important NOT to use custom message sets, but rather standardized ones. I have found the following: ...
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1 answer
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Importing custom messages from other packages in Python

Hi all, I've been on this for hours now and I can't figure it out. It seems as if not this forum or the tutorials have a solution for this simple question. I have downloaded the Vesc stack here, ...
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1 answer
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ROS Answers SE migration: topic question

ubuntu 16.04 ROS kinetic as per http://wiki.ros.org/ROS/Tutorials/UnderstandingTopics, i have listed my verbose details on topics in use rn: ...
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1 answer
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Find node that logged an error?

As the title says, when a ROS error (or warning, or info) message is printed, how do I find out which node it came from? Originally posted by Jacob.Beck27 on ROS Answers with karma: 13 on 2017-08-21 ...
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1 answer
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Is there a package for topic diagnostics/message rate tracking and warning?

I am interested in having something like a package with general nodes that subscribe to topics and publish warnings when messages aren't being sent or are coming in at the wrong rates and that ...
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1 answer
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Compiler error when trying to read message values

Here is my SWrite.msg file int16 id int16 pos int16 time Here is my CMakeLists.txt ...
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1 answer
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Problem at timing in communicating nodes?

Hello ROS community, I'm really newbie to ROS and what I am trying to do is to make an architecture in which there is a Simulator that compute his trajectory in every moment and a Controller that get ...
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1 answer
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Are messages sent once over a network or once per subscriber?

I'm looking for a general answer because this issue is going to come up all the time but here is the specific version of my question: I have a mobile base with a stereo camera. It sends SensorData/...
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1 answer
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Two messages with the same sequence number

I have a bag file with a lot of messages on different topics. I've just found out that I have two messages with the same sequence number, but they were published to different topics. I thought that ...
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1 answer
5 views

ROS Message Best Practices

Hey there guys, I am quite new to ROS and have not been involved in bigger projects. However I am confronted with creating one on my own. Working through the tutorials and some literature some of my ...
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1 answer
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Do all messages share a base class?

I would like to create a map of a topic name to a template function that constructs a message in the context of publishing to a topic. Essentially I would be following the pattern described in this SO ...
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1 answer
11 views

Publish Joint position step by step

Greetings, I need an advice about how to perform my robot simulation. I have a node that subscribe a topic and use the data subscribed to create a vector with all the angle that a joint has to reach ...
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1 answer
8 views

rostest fails when run using "catkin_make run_tests"

Hi all, I have a node and some_test.test file like this: ...
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1 answer
2 views

What is more efficient: writing to disk or message passing a huge amount of data as an array between a Python node and CPP node?

Does anyone have experience with the following scenario: A Python node that needs to pass a large amount of float values (an array of images) as a multidimensional ...
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2 answers
4 views

How to profile message activity?

Are there any tools for profiling or collecting statistics on the types of message activity per node? I'm trying to troubleshoot some nodes consuming excessive amounts of CPU, and to help diagnose the ...
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1 answer
13 views

Change frame_id in messages

I use kitti_player and robot_localization. kitti_player publich messages with framed_id "/kitti_player" but in robot_localization I get an error "frame_ids cannot start with a '/' &...
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1 answer
12 views

Get (remote) node name(-space) when receiving a message

Hi all, when I subscribe to a topic, is there a way to get the name / namespace of the publishing node on reception of a message? I know about ...
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1 answer
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Must Compile Message and Service Several Times To Work

Folks (sorry for the upper case in advance...they just to make sure people understand those are examples of my code), What is the proper way to create a CMakeList.txt file that includes messages and ...
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1 answer
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Message definition namespaces

In message definition naming is the syntax always: package/messagedef.msg Suppose one wants to have sets of messages for different vehicles (perhaps the hardware is sufficiently different that this ...
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1 answer
14 views

How to find list of messages published on particular topic?

I am using turtlebot in gazebo which uses "scan" message for publishing laser scan data, by using rostopic type scan command I can find out type of the ...
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1 answer
2 views

compile node which uses messages defined in an other machine

Hello everybody I have a problem. I am using INDIGO. I am using as ROS MASTER my own account on my pc in communication with ROS running in a virtual machine. The problem is that I would like to ...
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1 answer
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Unreliable subscribers based on launch order

How do you ensure your node subscribes to a topic? I'm finding launch order effects if a node is able to successfully subscribe. For example, say node A publishes /A/topic, and node B consumes it. I ...
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1 answer
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rospy sensor_msgs.msg.BatteryState is not found

For some reason I'm not able to import the BatteryState message with rospy. This is the only message I've encountered that seems to be missing. http://docs.ros.org/indigo/api/sensor_msgs/html/msg/...
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1 answer
3 views

Using Synchronizer to batch up image messages

Given the code on this page, if I have a message file batched_image.msg that looks like: ...
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1 answer
21 views

rosserial connection not working with custom messages! [SOLVED]

Hi community! I've got a problem, as the title suggests, with my custom messages used in arduino. I publish here the arduino code and explain later: ...
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1 answer
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publish c structs

Hey guys, I'm searching for a way to publish my own c struct. In my code I use a struct like: struct test { int a; int b; int c; float d; } ; and I want a ...
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