Questions tagged [timestamp]

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How to deal with unsynchronized sensor data in a ROS2 bagfile?

I am using a ROS2 package for cooperative SLAM. After testing the package installation with official datasets like GrAco I recorded my own dataset with my vehicle. The main sensors I use are 3D-LiDAR ...
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DDS and Simulation Time

I am using a the eProsima Micro-XRCE-DDS agent (https://github.com/eProsima/Micro-XRCE-DDS-Agent) to send messages between my ROS2 application and the PX4 Autopilot (https://github.com/PX4/PX4-...
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rclcpp::Time epochs

I would like to get seconds, and nanoseconds from inside my node, so I have a timer_callback that executes each 100ms, to note seconds and nanoseconds of the rclcpp::Time ...
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Extract timestamp from bag for some topics without the time

Hi to all, unfortunately, I recorded a very long bag file containing some topics that have a timestamp and two topics that do not include it since I forgot to add it before to launch the ROS node. ...
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TF get the time of last transform

Hello! I want to check if the tf2_ros::Buffer received a valid transform from A to B in the last x seconds (to throw an error in case of time out). So something like ...
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TimeStamp of each topic

How is it possible to get the time of each rostopic used of my simulation? Precisely, I want to know when each topic is sent by a node and when is it received by the next node? Thank you for your ...
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2 answers
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How to publish array of velocities?

Hello guys, so I am very new to ROS and python. Now I understand the following: to publish on a topic, for example Twist() you write something like this and you publish one value for a couple of ...
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Work with tf data timestamped from bag file

I am replaying a bag file containing point clouds, and right now can only work on that bag file. Now rosbag play publishes the data with the original time stamps, ...
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Why there is no timestamp field in sensor_msgs?

Hi ! I've been looking into ROS2 sensor_msgs definitions for example sensor_msgs::msg::Imu and I see that there is no field for timestamp ! What is the reason for that ? In practice any measurement ...
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How to subscribe to multiple topic that has no header or how to add header into topics?

ROS Kinetic Ubuntu 16.04 Python 3.5.2 I am trying to use following script to subscribe to 2 topics and combining their data into a json file. ...
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no timestamps when publishing for fixed joints robot_state_publisher

Hi guys, I have the following problem: I wrote a launch file which launches my differential drive robot with 2 lidar sensors in gazebo and rviz. The odometry for my robot comes from the differential ...
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How to obtain time stamps for messages with no header

Hi all, I have a simple question. My problem is the following. I am listening to the move_base/cancel topic because I want to know the exact time at which a certain goal has been canceled. The message ...
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rosbag and parameters dump with unique timestamp in filename

Dear all, my problem is the following: I want to save a rosbag file and dump at the same time the content of the parameter server on a file. I want the file and the rosbag to have exactly the same ...
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How to solve different ros::Time error message

I have a total of N. 7 .csv files. Those files are the result of N.7 sensors mounted on an underwater system. After packing both custom and standard messages ...
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Semantics of `%time` timestamp in `rostopic echo -p` from bagfile?

When I print the topic data using rostopic echo -p -b filename.bag /topic_name, there are two timestamps in the output. One comes from the header of the message (...
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How to record robot odometry in multiple bagfiles after resetting the robot's computer without resetting its odometry and timestamps?

I'm running the nodes rosaria, rosaria_client , hokuyo node and avt_vimba camera to record some datasets of routes around campus roads with rosbag in a Pioneer 3AT robot. The robot runs Ubuntu 14.04 ...
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How to attach the exact timestamp to "/gazebo/link_states" msg?

Hi all, I made a simulated environment and robot in Gazebo. Since Gazebo publishes the robot pose w.r.t. the world, I'd like to use this information to "simulate" a localizer. So far, this ...
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How to extract images from a bagfile properly

Currently I have a bag file which recorded a camera view topic. Now I want to extract the image date with its corresponding time stamp. I am able to get the png form of the image data using the ...
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laserscan to pointcloud timestamp issue

Dear all, I want to convert laserscans (sick lms511) to pointcloud2. I have found a topic on how to perform this conversion here : https://answers.ros.org/question/11232/how-to-turn-laser-scan-to-...
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IK - Invalid pose every single time for Baxter

...
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How to prevent data time travel?

Hi community. I have some trouble in stereo camera data logging that some old data pushed after newer one. The way to save this data is like this: prepare empty list and push new data in each ...
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1 answer
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TF behaviour showing delay when using ros::Time::now() vs. ros::Time(0)

My situation is that I have /tf topic publishing the following frame transforms: A to B B to C C to D My goal is to create a simple C++ program which extracts the ...
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4 answers
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Get timestamp during roslaunch

Hi ROS community! Is there a way to get the date/time to pass on as a (string) parameter, when roslaunching a node? The idea is to pass a filename as parameter to a node, which will have a specific ...
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Rosbag API and TF transforming tools

I am currently writing some tools in Python to visually judge the quality of the odometry. For this I record a bag with odom topic as well as tf, lidar scans and wheel encoders. Then I loop over the ...
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What is a timestamp?

What is a timestamp? How is it related to the 3D location of an object? Why is it useful? Originally posted by Rai on ROS Answers with karma: 30 on 2017-03-13 Post score: 0 Original comments Comment ...
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find 3D location of the sensor when a depth image arrives

Hey buddies! I went through the forum and couldn't find a satisfying answer. Sorry, if I reopened an already-answered question. Basically, I need to write a ROS node that will print the 3D location of ...
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Publish at the time of a vector

Dears, I have a vector containing double type numbers representing the ros time that I recorded from a previous simulation. I need to publish data of a node at this given time. I try to explain better:...
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difference between usage of rostime::Now & toSec for Matlab

Hello everyone, i have some troubles and hope that you can help me. I want to use the time that i got from ROS in Matalb. First i used the command ros::Time::now(); and i got for each frame a ...
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Turtlebot-Gazebo-Demo: Gazebo sends wrong timestamps

Hi all, I get some warnings when I start the turtlebot gazebo amcl demo. Here is the warning: ...
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1 answer
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Format console timestamp

Hi, We are facing non-human looking timestamp output in the console: [ INFO] [1465210897.698024206]: Some log msg while nicely readable in the log files: ...
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1 answer
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ueye_cam timestamp is 3600 seconds old - How to correct?

I'm running a ueye_cam node as follows: ...
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1 answer
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TimeSynchronizer compilation error

Hi, I am trying to implement a simple approximate time synchronizer that synchronizes two topics, Imu data and a twist message from an xbox controller I have not even departed from the structure of ...
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1 answer
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Extract header timestamp of Image message

Is the extraction of a timestamp from the header of a sensor_msgs::Image that easy: ...
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1 answer
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urg_node timestamp way too far in the future

I am trying to get the urg_node to publish scans to the default topic (laser) and the default frame_id (laser). It all works fine when I couple the commands: ...
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differential_drive_controller publishing with wrong timestamps

Hello, I'm using the differential_drive_controller plugin in urdf of my robot: ...
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1 answer
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What does "timestamp" of "header" in hokuyo's scan data?

I'm wondering what timestamp in hokuyo's sensor_msgs::LaserScan does mean. Is the time at first scan ray is measured? Or is the time at last scan ray is measured? I know there is calibration function ...
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1 answer
258 views

tf error: Lookup would require extrapolation into the past

Hi, all. I want to convert a pose from "odom" to "map", I am using codes as follows. ...
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1 answer
21 views

Playback of rosbag file at the same rate that messages are stored in rospy

Hi, I am trying to playback data that I have stored using rosbag in rospy. Is it possible to playback the rosbag file in rospy at the same rate that it is recorded? I know that I can do this from the ...
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1 answer
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Extract time from .bag file

Hi, I am trying to process some bag files and, while I am able to get the timestamp for each message, I am not able to get the actual time the message was received. Is it possible to get it? I am ...
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2 answers
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make tf from rosbag data raw

Hello, I am trying to make tf tree from rosbag file and raw topics like /imu/data and /scan without tf topic. At the time when record the bagfile, we don't know the tf jet and now we want to make the ...
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1 answer
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what is the Timestamp?

1-Can someone please explain what exactly is the timestamp that is sent along with every message regardless of the data type ? This number is huge and its in the range of 4.7x10^18 . 2- For ...
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1 answer
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Get message metadata within rosjava

Using rosjava, how would one get the timestamp and other metadata for a message? Answering in the form of an adaptation of the Listener class in the rosjava tutorial would be particularly useful. ...
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1 answer
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rosbag API C++: Message Header Stamp sec and nsec are always zero?

The "sec" and "nsec" values in the message header are always zero when recording using "rosbag::write". I provide a valid Time for the second parameter, but that only ...
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1 answer
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How to write to a file different parameters from different CallBacks with same timestamp?

Hello I would like to write to a text file different parameters obtained from different topics (scan, raw_imu, odom). I obtained some parameters in different CallBacks like scanCallback poseCallback, ...
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1 answer
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timing problem with laser scan (synchronizing with odometry)

Hi guys, I've got a timing problem with my laser scans. I receive laser scan data through a tcp socket (it's simulated laser data from another system in the network). While the robot is standing still ...
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1 answer
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Is sensor timestamp can modify robot_pose_ekf accuracy?

Hello, I'm using a visual odometry working on a workstation connected by wifi to the Turtlebot. I have synchronized the time in the workstation related to the turtlebot with: sudo ntpdate tutlebot_IP ...
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1 answer
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strange dates in ROS' bags

hello everyone. I'm trying to record the messages published to two topics inside a bag. The creation of .bag file is created correctly, but when I write rosbag info subset.bag this is what I get: ...
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1 answer
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Why does ROS_INFO_STREAM print two time stamps?

When I use ROS_INFO_STREAM, it prints two timestamps: [ INFO] [1348651448.232151821, 1323877497.479939999]: Hello World! What do they represent? I looked at the ...
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ROS Answers SE migration: ROS timestamps

Hey, I am using 2 machines for our robot and in order to properly use the tf package, we have to synchronize the clocks between them, because ROS uses the systems time for adding timestamps. If the ...
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Stereo Camera syncronization

Hi all, I'm using the uvc_camera package and its stereo_node to grab frames from my 2 webcams. Now I'm trying to have a measure of the sync error of the 2 frames doing the following: write ...
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