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2023-02-21 05:06:38 -0500 marked best answer Python and C++ nodes in the same package

I have a package containing some C++ nodes. How do I add a Python node using rosbuild?

2022-10-19 07:34:05 -0500 commented question Speed up 'rostopic list'

have you found any solution to this? I am pretty sure it is some local network config on the ROS machine

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2022-09-19 06:59:14 -0500 commented answer Is there a topic for camera FOV info?

W is image width and h is image height in pixels. F_x and f_y are the focal lengths, from the camera matrix K[0][0] and

2022-06-30 03:17:28 -0500 commented answer Inverse of geometry_msgs/pose

Pose and Transform are equivalent. And it makes sense to avoid tf when needing the inverse of a pose sometimes.

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2022-01-04 04:33:37 -0500 commented question How to manage extrinsic sensor calibration dynamically with urdf?

Yes I was thinking about xacro/urdf actually I will check it out thanks! Feel free to post it as an answer

2022-01-04 04:19:00 -0500 asked a question How to manage extrinsic sensor calibration dynamically with urdf?

How to manage extrinsic sensor calibration dynamically with urdf? Is there a standard way of doing this in ROS? The idea

2021-12-20 04:23:44 -0500 marked best answer point_cloud2.read_points and then?

I have a topic publishing a point cloud of type sensors_msgs.PointCloud2. I can subscribe to it and read it using sensors_msgs.point_cloud2.read_points function but then I get and object of type "generator". How do I access the coordinates of the points in this object? I want to write a service that checks the maximum allowed height in some specific target areas (the point cloud represents the ceiling). I am using python.

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2021-10-27 09:04:34 -0500 commented answer How do I create dynamic launch files?

This is very very smart!

2021-10-05 08:33:03 -0500 commented question Problem working with vanilla cmake packages as dependencies in caktin_ws

@jdlangs the build error is basically function not defined because building stuff in catkin_ws tries to link against an

2021-09-28 03:56:37 -0500 commented question Problem working with vanilla cmake packages as dependencies in caktin_ws

@jdlangs I edited the question, robohive_ws is basically catkin_ws, forgot to rename all of them before posting the ques

2021-09-28 03:54:49 -0500 edited question Problem working with vanilla cmake packages as dependencies in caktin_ws

Problem working with vanilla cmake packages as dependencies in caktin_ws I have a pure cmake complex package that gene

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2021-09-23 11:06:29 -0500 edited question Problem working with vanilla cmake packages as dependencies in caktin_ws

Problem working with vanilla cmake packages as dependencies in caktin_ws I have a pure cmake complex package that gene

2021-09-23 11:05:02 -0500 asked a question Problem working with vanilla cmake packages as dependencies in caktin_ws

Problem working with vanilla cmake packages as dependencies in caktin_ws I have a pure cmake complex package that gene

2021-08-13 21:01:59 -0500 marked best answer What should I upload exactly to GitHub

I have been working on improving/changing an existing package. Now that I am done, I have a package ready for use in my system. What should I consider when uploading it to a repository?

bin folder should probably not be uploaded. But what about msg_gen? is there anything special I should consider? Is there also a tool that makes this process automatic?

2021-08-10 08:44:31 -0500 commented question Getting rotation angle from laser data

Ransac, line detection representing the wall from the lidar points, get the relative angle from the line coefficients an

2021-06-26 21:16:40 -0500 marked best answer Controlling transitions between states in SMACH

Hello, i started working with SMACH few days ago and I was wondering how I could control the transition between my states from external events. For example a transition would be triggered by the event "voice detected" or "light turned on" which could be published to a topic. I'm aware that it is possible to use acitonlib with SMACH but the tutorial is really confusing and not clear and there is no complete working example as far as I know. I'm also working with a central state machine where many smaller states are nested. Somebody has an idea how to implement event driven state transitions?

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2021-05-11 09:47:43 -0500 commented answer How to setup Intelisense on VS Code for ROS C++

As Samarth mentioned in his answer, this blog post really helps getting it setup correctly.

2021-05-11 09:28:38 -0500 commented answer How to setup Intelisense on VS Code for ROS C++

"The extension does not require additional configuration" is the biggest lie ever!

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2021-05-11 04:42:29 -0500 marked best answer Costmap2DROS transform timeout

I am trying to run amcl, move_base and map_server on my robot. Everything starts fine but after I get "Odom received" warning messages start to show up:

Costmap2DROS transform timeout. Current time: 1438775060.1538, global_pose stamp: 1438775056.1344, tolerance: 0.3000

and

[ WARN] [1438775074.022202129]: MessageFilter [target=map base_laser_link ]: Dropped 100.00% of messages so far. Please turn the [ros.costmap_2d.message_notifier] rosconsole logger to DEBUG for more information.

They come from the Costmap2D plugin. I runned tf_monitor and I got:

RESULTS: for all Frames

Frames:
Frame: /base_footprint published by unknown_publisher Average Delay: -0.0456822 Max Delay: 0.10752
Frame: base_front_laser_link published by unknown_publisher Average Delay: -0.545968 Max Delay: 0
Frame: base_link published by unknown_publisher Average Delay: -0.545971 Max Delay: 0
Frame: base_rear_laser_link published by unknown_publisher Average Delay: -0.545966 Max Delay: 0
Frame: odom published by unknown_publisher Average Delay: -0.108352 Max Delay: 0.0916446

All Broadcasters:
Node: unknown_publisher 82.2074 Hz, Average Delay: -0.360456 Max Delay: 0.10752

What could be the problem causing the timeout?

When viewing the frames, I see that robot_state_publisher publishes with 50 Hz but somehow all published links have a delay of -0.5 seconds, which cannot be possible!

image description

I kept looking at it in real time with tf_monitor and the time of the most recent transform from robot_state_publisher is -0.5 for some time, then it jumps to +0.5. This is very confusing.

I kept tf_monitor running for few minutes and it seems like the delays are increasing:

RESULTS: for all Frames

Frames:
Frame: /base_footprint published by unknown_publisher Average Delay: 2.57823 Max Delay: 17.9659
Frame: base_front_laser_link published by unknown_publisher Average Delay: -0.408636 Max Delay: 0.626485
Frame: base_link published by unknown_publisher Average Delay: -0.40864 Max Delay: 0.626482
Frame: base_rear_laser_link published by unknown_publisher Average Delay: -0.408634 Max Delay: 0.626486
Frame: odom published by unknown_publisher Average Delay: 3.65717 Max Delay: 16.6323

All Broadcasters:
Node: unknown_publisher 82.0346 Hz, Average Delay: -0.124652 Max Delay: 1.20379
2021-05-06 14:13:05 -0500 marked best answer Understanding the bytes in a pcl2 message

I am using python in order to publish pointclouds. Prior to this I'd like to run some segmentation using python-pcl and colorize each cluster. Unfortunately, the only function that creates a pcl message from a numpy array does so without considering color (only x, y, z).

pcl2.create_cloud_xyz32(header, nx3_numpy_array)

Therefore, I want to create a ros message then tweak it manually to change the color of each point. Here is an example message:

header: 
  seq: 1535
  stamp: 
    secs: 1524593497
    nsecs: 322609179
  frame_id: "gripper_depth_camera_rgb_optical_frame"
height: 480
width: 640
fields: 
  - 
    name: "x"
    offset: 0
    datatype: 7
    count: 1
  - 
    name: "y"
    offset: 4
    datatype: 7
    count: 1
  - 
    name: "z"
    offset: 8
    datatype: 7
    count: 1
  - 
    name: "rgb"
    offset: 16
    datatype: 7
    count: 1
is_bigendian: False
point_step: 32
row_step: 20480
data: [0, 0, 192, 127, 0, 0, 192, 127, 0, 0, 192, 127, 0, 0, 0, 0, 0, 0, 0, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

It is easy to understand why x, y and z require 4 bytes each (float 32)

But why does rgb come at 16 and not 12? following the logic, z also needs 4 bytes, and the next free spot is at an offset of 12 and not 16.

Also why does rgb need 16 bytes? (point_step is 32 so one point requires 32 bytes from which 16 are for rgb). The color values themselves need only one byte each so this is confusing. Also, if we say the are float32 values, 16 bytes means 4 values, is the fourth value the transparency (RGBA?)

Here is an example from an XYZ only pointcloud where my understanding fits:

header: 
  seq: 5
  stamp: 
    secs: 1524583199
    nsecs: 372246980
  frame_id: "gripper_depth_camera_rgb_optical_frame"
height: 1
width: 231
fields: 
  - 
    name: "x"
    offset: 0
    datatype: 7
    count: 1
  - 
    name: "y"
    offset: 4
    datatype: 7
    count: 1
  - 
    name: "z"
    offset: 8
    datatype: 7
    count: 1
is_bigendian: False
point_step: 12
row_step: 2772
data: [125, 207, 94, 190, 220, 24, 98, 190, 254, 67, 60, 63, 69, 231, 92, 190, 6
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2021-04-23 09:48:31 -0500 answered a question is it possible to use a nodelet manager across multiple namespaces?

The way I made it work is by specifying the full path to the nodelet manager when loading a nodelet from a namespace fo

2021-04-22 11:42:16 -0500 commented question is it possible to use a nodelet manager across multiple namespaces?

@mugetsu have you figured out a way how to do this?

2021-03-17 08:36:18 -0500 asked a question Generate debian package with custom CMake args

Generate debian package with custom CMake args I am trying to package the software I am using for a cleaner deploy proce

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2021-02-11 10:10:29 -0500 commented answer Is there a way to read from a text or yaml file and pass its data to <arg> tag?

This really doesn't address the problem the OP is having.

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2020-12-02 01:51:51 -0500 marked best answer Local costmap is empty

I am trying something with the simulation of navigation with Turtlebot but with different frame_id's and topics. I checked that the laser data is being relayed to /scan and that my TF tree is consistent and that amcl and move_base are using the right frame_id's and subscribing to the right topics. Even with those conditions and with the laser detecting obstacles, my local costmap is empty (full of zeros) but the global costmap is just fine. Is there some other parameters I should consider that could influence the local costmap?

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