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Convert double to std_msgs::Float64 for ROS topic

I have to publish a float64 value in a topic and I'm using C++. The problem is that the original value is a double, so I'm not able to find any way to convert the double into a float64 and publish it. ...
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1 answer
50 views

Is it possible to record or log specific topics in ROS2 without publishing?

I apologize if this is a somewhat naive question, but I don't really know much about ros2's architecture beyond basic utilization. I'm a student working in autonomous vehicle research, and my team ...
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1 answer
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Can't publish a message that is composed of several fields

Hey everyone, I am trying to publish a weather message that is composed out of several fields (temperature, pressure, wind velocity, water velocity and a general weather code), but it doesn't work. In ...
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Service Server and Publisher using same Node

So what i wanted to do is, send a service call to this service and then i wanted this service to publish to another topic. So i was experimenting this with the code as follows. But ofcourse lots of ...
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1 answer
65 views

Noetic python raw Image publisher (from video)

Hi everyone, I have spent nearly 2 full days with this problem now and have some extensive research, but just can't figure it out. My apologies for being a burden, I ussually hesitate to waste anyones ...
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1 answer
8 views

Publishing Marker arrow causes Segmentation fault (core dumped)

Hello, I am trying to publish a marker arrow and want to visualize it in rviz with a start and an end point. When I am using the points member as described here http://wiki.ros.org/rviz/DisplayTypes/...
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1 answer
103 views

ros2 publish frame_id

I created a simple image publisher node like the one below class MinimalPublisher(Node): ...
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2 answers
62 views

Calling publisher at a specific rate

Hi, I have a node that subscribes to a topic, does some computation and publishes the message on a different topic. The publish is implemented within subscriber callback function. While the subscribed ...
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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 ...
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1 answer
13 views

Publish clicked point in Rviz without using navigation stack

I wish to publish the clicked point in Rviz. I read that we need to be using the ROS navigation stack for this feature to work. However, my setup doesn't use laser scans and relies on aruco markers. ...
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2 answers
132 views

check if topic is being published to without subscribing

In our project we want to write a node to check sensor nodes for possible errors. One of the checked criterion is, if the topics of the node are actually published and not just have publisher. Is it ...
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2 answers
4 views

ros_tutorials roscpp talker/listener loses first message or two

This must've been seen before...I ran into it while trying to track down a lost message from a command-line app which publishes one message then exits. I'm running ros kinetic on Ubuntu 16.04.4. My ...
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1 answer
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Are ROS2 messages guaranteed to be received by a Subscriber in the same order they were published?

According to https://github.com/ros2/ros2/wiki/About-Quality-of-Service-Settings it's possible to vary the QoS settings of History, Depth, Reliability and Durability. However, I can't find any mention ...
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1 answer
3 views

PYTHON + ROS + V-REP

Hi I have got a problem with publish data. I want to publish msg.linear.x and msg.linear.y to V-REP via ROS. When I write in terminal ...
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1 answer
12 views

Rosbridgelb: Received a message without op

I'm using ROSBridgelb to publish "OccupancyGrid Message" from Unity to ROS. However I'm always getting the "Received a message without op" error. I made sure that there is no ...
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1 answer
9 views

Is there an option for a blocking publish() if any subscriber's queue is full?

I have an application where several image processing nodes need to be fed by previously recorded video as fast as possible, but without dropping any frames. To keep memory overhead down, I'm using ...
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1 answer
10 views

How to record NovAtel Raw Observation data in binary for post-processing

New here, is there a way to record raw binary data to a bagfile without using a ROS standard message? I would like to post-process using RTKLIB. Thank you Originally posted by damascus_west on ROS ...
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1 answer
8 views

writing a publisher and subscriber and unsure how to finish it

I am taking this edx course on robotics using ROS and our first project is "writing a node that subscribes to a topic and publishes to another. Your code will subscribe to a topic called '...
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1 answer
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The question about ros::publisher and ros::subscriber

I want to achieve receiving and transform data using rostopic at the same time or in a low time. I know that ros::subscriber can subscribe rostopic and receive the data included in topic. So I hope ...
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1 answer
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One time publish executable

Hi, Im trying to use a specific node (program A) as a test program being executed once taking the value to be published on a topic (lets call it "foo"). Program B is already subscribed to ...
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1 answer
6 views

Transfer octomap w/out ROS Message

Hey guys, is there a way to transfer a octomap between two nodes without using ROS messages? Due to high processing time I sourced out the octomap creating - and need the processed octomap in my main ...
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1 answer
4 views

how publish pose topic for RRRBOT?

how publish pose topic for rrrbot ? i cant undrstand this page turtle1 Originally posted by zakizadeh on ROS Answers with karma: 217 on 2017-04-13 Post score: -2
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1 vote
1 answer
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is rospy.Publisher.publish() thread safe?

Want to publish() in main and also in child thread on one rospy.Publisher(),is this safe? Originally posted by dyan on ROS Answers with karma: 7 on 2017-03-17 Post score: 0
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1 answer
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ERROR: Advertise a service already advertised in this node

Folks, I am subscribing to a compressed image published (or republished) by image_proc (it takes my rgb_raw, and publishes rectified rgb and mono images, including compressed versions). But when I ...
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1 answer
6 views

Subsribe and publish conversion problem

I'm trying to write an own Subscribe and Publisk node. I would like ti subscribe to the joystick and publish to my motors. For the publish i create with a launchfile to topics, I use the ...
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1 answer
27 views

Reducing the publishing rate of a topic from RosLaunch

Hi there, I have a custom-built robot which I am trying to control with move_it. I have written the urdf and generated the srdf using the move_it setup assistant. All the topics from my URDF are being ...
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1 answer
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NameError: global name 'NAME' is not defined

hello, I'm trying to publish data of my GPS but it appears this error NameError: global name 'hora' is not defined Anybody help me please :) My code is this: ...
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2 answers
47 views

How do Publisher/Subscriber Message Queues Work?

Hi all, I can't seem to find any documentation on this, but it I want to understand more deeply how messaging queues work. My understanding is that each node has its own publisher and subscriber ...
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1 answer
20 views

publish numpy matrix to topic

Hello together, I would like to publish a 10x10x10 numpy-Matrix in one publishing step. Therefore I would like to know how I can declare the numpy.ndarray as a ...
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1 answer
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Is it possible to publish/subscribe as root?

Hello smart people, I have made a ROS node that makes use of an FTDI library that requires that I run the executable as root to have access to the usb device that the node reads data from. The trouble ...
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1 answer
20 views

How to publish a 2 dimensional array of known values

Hello, I'm stuck at my program to publish a 2 dimensional array. The array kinda looks like this: int deptharray[4][5] = { {0, 0, 0, 0}, {0, average11, average21, average31, average41}, {0, average12, ...
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1 answer
3 views

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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1 answer
2 views

advertise() function parameter for vector type

I'd like to publish a vector (cpp) in my publisher, and I do not want to create my own message. Is there already a built-in type for it? What I mean is to replace ...
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2 answers
4 views

publish multiple data on one topic

Hello, Is it possible to publish multiple data i.e angle for servo1 and angle for servo2 on one topic ? If yes, please show me answer how to do it. Thanks in advance. Edit: Thank you sir for your ...
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1 answer
9 views

How to subscribe to a topic, while publishing to another

Hey guys, I want to write a basic controller for a quadrotor. For a target_position it should take the current_position from a simulated quadrotor, calculate an error between the two and send the ...
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1 answer
5 views

Pusblishing to topic problem (Mavros)

I'm trying to push to the override RC for mavros. I checked the message type first rostopic type mavros/rc/override giving mavros_msgs/OverrideRCIn I then check the parameters for this message type ...
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1 answer
73 views

/joint_states topic and publish rate

I want to read the joint states of a robot from the /joint_states topic, preferably at 1kHz. The problem is that when I increase the publishing rate X of the joint ...
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1 answer
3 views

problem with publish in fork() process

When I use fork() function, then the publish function of Publisher do not work, do any one who has met this problem, I am grateful that you can tell me something, thanks :-) the code ...
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1 answer
12 views

My node of ROS keeps dying. Subscribe a gazebo topic and publish in a ros topic

Hi, I have created a node in ROS so I can subscribe a topic of gazebo, analyse the information and then use it. I have a callback function for the subscription and I put the information in a certain ...
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1 answer
23 views

Two ROS computers - roswtf: WARNING The following nodes are unexpectedly connected:

I'm unable to publish on /turtle1/cmd_vel with second controller computer, but it works fine on 1 computer. It works fine to send /clear service commands on 1 and 2 computer configurations. Controller ...
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1 answer
35 views

Can't publish or use time in my class constructor

I am creating a class that subscribes to an Odometry message and in the corresponding callback function updates an OccupancyGrid message which is published to a topic. I've got all this working just ...
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1 answer
109 views

Publish Joint_State with Python to RVIZ

I have a robot that I built in URDF that I am visualizing in RVIZ. I can control the joints using the gui tool or a rostopic pub command, but I am unable to build a publisher node to interface with ...
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1 answer
32 views

Publishing a collision object to MoveIt!

I am using MoveIt! for controlling an ABB IRB1600 robotic arm. Currentyl I am able to execute trajectories with the robotic arm. The problem is that the arm moves through objects, instead of around. ...
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2 answers
5 views

publish array velocities in a topic?

Hi Ros users! I have just done a .cpp wich publish velocities in a opic (p3dx/cmd_vel) Here it is: ...
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1 answer
29 views

Publish multiarray Python msg

When I press a button of my joystick, I save one point [x y z r p y] if I press again I save another point. Here, I save two points: [[0.29845908995953135, 0.210860533103541, 1.2190388918130415, -2....
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1 answer
26 views

rostopic hz output more than real frequency

Hi All, I have a callback function that takes point clouds from a openni device at a frequency of 30 Hz. Inside that function I do some computations with it and then I publish the outcome of my ...
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2 answers
8 views

Empty connection header topic

I am trying to use a driver that reads the name of the incoming topic from the connection header. When I publish data from a C++ node, it is always empty but when I use ...
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1 answer
14 views

Rqt_myPlugin can't subscribe node

Hello guys, I have a GUI as a rqt plugin and I want to subscribe a topic but I can't see my rqt_plugin node on the rqt_graph. The topic which i want to subscribe is in the same machine, which I want ...
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2 answers
14 views

Publish Image msg

Hey all, I'm working on a code which publishes images coming from a camera (atm a video is used for testing). To publish those Images I would like to use the sensor_msgs. In the following is the code ...
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1 answer
2 views

How to publish ROS program?

Like windows programs, hos to publish a single simple "setup" install package on ROS so that I can reduce server configuration work when transfer to other machine? Is anyone has experience ...
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