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2015-04-24 07:06:36 -0500 answered a question Should the CloudSim link on http://gazebosim.org point to https://github.com/Cloudslab/cloudsim/?

Cloudslab/cloudsim is something totally different, it is for network simulations, not robots.

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2015-04-15 09:30:59 -0500 answered a question Gazebo5 simulator ball bearings leak through bowl walls

Thank you Andrei for your answer, I just did what you suggested and it worked.

I decreased the size of the polygons that constitute the mesh model by means of Blender program. See the result at the attached pictures.

With larger polygons image description

With smaller polygons image description

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2015-03-23 12:25:05 -0500 answered a question Are Gazebo 5 .deb packages broken?

I believe that is your system which has some inconsistency. Probably you did an update and then this problem arose.

I would recommend you to install gazebo5-common (sudo apt-get install gazebo5-common) If the a similar message appears indicating depends on xxx package, then try to manually install that xxx package. Repeat this process down until you are able to install. At that point, move back and install all the packages that gave you an error message, in the reverse order.

It works for me, at least ;-)

2015-03-23 11:07:04 -0500 answered a question Unable to create DepthCameraSensor when launching in remote computer

I finally found the solution to this problem.

The solution is to use the Xvfb with some specific parameters.

First, install Xvfb

sudo apt-get install xvfb

Then, start xvfb with the following parameters:

Xvfb -shmem -screen 0 1280x1024x24

Finally, launch gzserver exporting the DISPLAY to the one created by xvfb:

DISPLAY=:0 gzserver <your options here>

And that is all! Happy remote simulation!

2015-03-19 12:19:51 -0500 commented answer How to simulate a simple light sensor in Gazebo?

Thank you for your quick reply.

2015-03-19 11:33:30 -0500 asked a question How to simulate a simple light sensor in Gazebo?

Hi all, I would like to simulate a light sensor. The only solution I found for it is this old link at ROS answers. Is there any more modern way of doing it already implemented in the newest versions of Gazebo?

Thanks

2015-03-19 11:10:23 -0500 answered a question creating my own objects in gazebo

You can also have a look at this complete video tutorial

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2015-03-06 11:34:16 -0500 commented answer Unable to create DepthCameraSensor when launching in remote computer

Tested the Xvfb in order to create a virtual X system. Even if Xvfb works correctly, the depth sensor does not work and complains on not existing X. Any other idea to bypass the X?

2015-03-06 11:32:25 -0500 answered a question Want to install gazebo5 but has ROS indigo installed.

In order to have Gazebo5 with ROS Indigo you have to uninstall first the gazebo2 packages that ROS Indigo installed (ros-indigo-gazebo-*)

Then add the osrf repositories to your Linux package manager and follow the command provided by Jose Luis Rivero here

I'm using Gazebo5 with ROS and it works fine. When I installed it, I remember there was one of the ros-indigo-gazebo5-* packages that was not installed by default. Just check that all your ros-indigo-gazebo5-* packages are installed.

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2015-02-25 02:57:30 -0500 commented answer Unable to create DepthCameraSensor when launching in remote computer

Thanks Nkoenig for your reply. I understand what you mean. That would imply exporting the var DISPLAY to the active x-session of the remote computer (just to use its buffer). Based on your reply, what I am going to try is to enable the Framebuffer (http://hacklab.cz/2012/04/22/usefulness-linux-framebuffer-virtual-console) and set the DISPLAY to it.

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2015-02-24 04:44:00 -0500 asked a question Unable to create DepthCameraSensor when launching in remote computer

Hi, I am launching my simulation on a remote computer and setting my ROS_MASTER_URI to it. To avoid walking to the remote computer (which is at the other side of the room) I connect remotely (ssh) to it an launch the simulation there. Since I do not need the rendering, just the simulation, I use gzserver.

However, when I launch the world with gzserver remotely I get the following error:

gzserver my_world_with_a_kinect.world

[Msg] Waiting for master.
[Msg] Connected to gazebo master @ http://127.0.0.1:11345
[Msg] Publicized address: 192.168.100.106
[Err] [RenderEngine.cc:680] Can't open display: 
[Wrn] [RenderEngine.cc:92] Unable to create X window. Rendering will be disabled 
[Err] [DepthCameraSensor.cc:78] Unable to create DepthCameraSensor. Rendering is disabled.

Testing with rviz, I see nothing. The depth camera topics are not even created.

However, if I move to the remote computer and execute the same command everything works OK.

I know that been a remote connection, you don't have the Xs unless you connect with ssh -X <ip>. My computer is a Mac and does not have the Xs. Some people suggested me to install Xs but I cannot (for several reasons).

Additionally, I am running other remote simulations and evn if I get the 'Can't open display' error message, everything works fine.

The question is: how can I make the kinect work properly in such a remote environment?

2015-02-24 04:30:31 -0500 asked a question Gazebo5 simulator ball bearings leak through bowl walls

I have created a simulation where 1000 ball bearings are put inside a bowl. What happens is that some of the balls get through the walls of the bowl, leaking outside it. Most of the balls remain inside the bowl and react properly to interactions with them, but some others, go through the bowl.

Here there is a video showing the behavior Ball Leaking Video

The ball bearings model is just the model provided by Gazebo.

Can anyone give me a hint about how to avoid this behavior?

My system: - Ubuntu 14.04 - ROS Indigo - Gazebo5 (for ROS packages)

Attached: - The model of the bowl model.sdf

2015-02-24 03:03:08 -0500 answered a question not realistic simulatoin

I do agree with you Hsu, you approach is closer to reality and may be required in some simulations. From my experience the bounding box approach and center-of-mass calculated as homogeneous body has been good enough for what I needed. Is up to the user to decide, though.

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2015-02-23 09:20:47 -0500 answered a question not realistic simulatoin

The key to have realistic simulations is to provide a correct section <inertias> ... </inertias>

A proper section should look like this:

<inertia> <!-- interias are tricky to compute -->
      <!-- http://answers.gazebosim.org/question/4372/the-inertia-matrix-explained/ -->
      <ixx>0.000033719</ixx>       <!-- for a box: ixx = 0.083 * mass * (y*y + z*z) -->
      <ixy>0.0</ixy>         <!-- for a box: ixy = 0 -->
      <ixz>0.0</ixz>         <!-- for a box: ixz = 0 -->
      <iyy>0.001305175</iyy>       <!-- for a box: iyy = 0.083 * mass * (x*x + z*z) -->
      <iyz>0.0</iyz>         <!-- for a box: iyz = 0 -->
      <izz>0.001322294</izz>       <!-- for a box: izz = 0.083 * mass * (x*x + y*y) -->
    </inertia>
  </inertial>

Steps to follow:

0- Use Blender to automatically set the center of mass and arrange the axis of the object at that center (this will make later steps easier) 1- Use the tutorial chapulina has suggested to calculate the inertial parameters and set the model. Don't forget to set a correct mass value (the one you have now seems unrealistic) 2- Use Gazebo's option View->Center of mass/Inertia to observe if your inertias are correct (see figures attached for a wrong one an a correct one, for a spoon) 3- If they do not show correct, iterate

INCORRECT INERTIAS image description

CORRECT INERTIAS image description