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2015-10-31 12:30:45 -0500 marked best answer The inertia matrix explained


I'd like to find some documentation about the inertia matrix in Gazebo/ROS (this topic is located in between).

Here is the ROS wiki page:

Basically, what I do not understand, is that the inertia matrix could not be independent from the mass. How a discrepancy between a dummy inertia matrix and the real inertia matrix could impact the simulation?

Thanks in advance for any doc that could help me to understand this part of the robot models.

2015-10-31 12:30:34 -0500 marked best answer Inertia again: significant figures


I'm facing really bad bugs which seem to be related to inertia. I'm trying to understand the issue with Gazebo and found that the inertia tensors are [0] for the smaller parts:

image description

This is consistent with my bugs, since with the large arm parts, it works more or less, but with the gripper, that becomes crazy. The small parts of the arm and the gripper have 1e-4 values for the inertia tensor.

Here is a short video:

The joint 3 is moved to 1.0 rad, the next links should stay in line (at 0 rad), but they don't. If you stay long enough (several tenth of second), they finally go to there stable position.

So I wonder how many figures are considered in Gazebo. What are the best practice for simulating this kind of robot? (we could imagine to use a simple kinematic simulation for this part of the body, as they have a low contribution to the overall behavior)

Any inputs will be helpful.

This question is related to:

2015-10-31 12:30:33 -0500 marked best answer How to tune the render of COLLADA files in Gazebo?


I have build a robot model for the youBot from COLLADA files provided by KUKA. I would say that everything is fine, but I am somehow disappointing by the display of the robot parts (see screenshots bellow).

I don't know anything about 3D so I do not have the word to tell precisely the problem. I would say that the colors are too bright, preventing to see the shape of the parts. Moreover, this feeling is not consistent between Gazebo and rviz. Only the orange of the arm in Gazebo is fine. The black and the grey do not let the user to imagine the edges.

I had a look at the COLLADA files but did not notice anything. They contains tags for black, orange and grey. I have checked the parts in meshlab. The meshes are fine. Unfortunately meshlab does not read the color. The files can be found in this repo:

The wheels have been simulated with simple spheres and the display is fine too.

So, is there any way to improve this? I would say ideally without modify the COLLADA files. Maybe the light is not correct (I use the standard world file).

Thanks for your answers!

image description

image description

2015-10-31 12:30:32 -0500 marked best answer Fail to start effort_controllers/JointVelocityController (ros_controllers)


I managed to make the effort_controllers/JointPositionController successfully works, but some of my joints need to be controlled using the velocity.

When using this type, I get the following error message:

gzserver: /home/arnaud/Documents/catkin_ws/src/ros_control/hardware_interface/include/hardware_interface/joint_state_interface.h:71: double hardware_interface::JointStateHandle::getVelocity() const: Assertion `vel_' failed.
Aborted (core dumped)

Any idea of how to fix this? It looks like a run-time error.

Thx in advance.

2015-10-31 12:30:32 -0500 marked best answer Can a graphics card speed up Gazebo?

I am running Gazebo on a laptop which is geared with 2 graphics cards, one Intel (low spec and low power consumption) for one nVidia (more powerful).

I do not see any performance gap between the two, and neither between the nVidia closed source driver and the open source one (Nouveau, shipped with Ubuntu 13.04).

So I wonder if a graphics cards can improve the performance of Gazebo and how. It looks like all processes are supported by the CPU (around 60% - 70% of use for the 4 cores).

2015-10-31 12:30:30 -0500 marked best answer How to start and stop Gazebo 1.9?


This is a serious question. I faced very strong issues with Gazebo and I just find a way to manage them. This was related to the way I start and stop Gazebo (from ROS in my configuration).


  • stop from the Gui, using close window, unable to restart Gazebo properly afterwards. Gazebo should be closed using Ctrl+C from the console which started it (even if it is OK to do that within rviz)
  • AND click reset before aborting the main process

My questions are therefore:

  • what are the best practice for start/stop
  • is there a way to reset automatically the simulation

Thx in advance for your answer.

2015-10-31 12:30:30 -0500 marked best answer Display center of mass, what is the meaning of the green lines?


Still working on my inertia issues, I wonder what is the meaning of the green lines displayed in the center of mass view:

image description

Precisely here:

image description

It is related to the orientation of the inertia, but I did not find it in the documentation and I do not find it obvious.


2015-10-31 12:30:23 -0500 marked best answer How to control robots models?


Sorry if there is an obvious answer to this question, but I did not find it after a very long search.

I would like to know how to control the robots models which are packed with Gazebo. That's easy to add them into the world, and I did not find how to go further.

I have read the tutorial of course. It looks like I have to modify the robot description to add some plugins. That makes sense for defining a new robot, but for using a model, it seems complicated.

If you could give me hint, that would be appreciated.

Thanks a lot.

2015-10-31 12:30:12 -0500 marked best answer From the debs Gazebo wants to remove ros-hydro-desktop-full

Hi folks.

The Gazebo ROS integration tutorial suggest to install ros-hydro-desktop-full. OK. And then, to install gazebo. But this last package suggest to remove the previous one.

Do we have to keep gazebo-prerelease?


arnaud@hercules:~$ sudo apt-get install gazebo
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  ffmpeg fltk1.3-doc fluid freeglut3-dev gir1.2-gtk-2.0 libasound2-dev
  libatk1.0-dev libav-tools libavahi-client-dev libavahi-common-dev
  libavcodec-dev libavdevice53 libavfilter2 libavformat-dev libavutil-dev
  libbullet libbullet-dev libcaca-dev libcairo-script-interpreter2
  libcairo2-dev libcf0 libdbus-1-dev libflann-dev libflann1.7 libfltk-forms1.3
  libfltk-images1.3 libfltk1.1 libfltk1.1-dev libfltk1.3 libfontconfig1-dev
  libgdk-pixbuf2.0-dev libgl2ps-dev libglib2.0-dev libgtk2.0-dev
  libharfbuzz-dev libhdf5-7 libjasper-dev libjs-sphinxdoc libjs-underscore
  libnetcdf-dev libnetcdfc++4 libnetcdfc7 libnetcdff5 libogg-dev
  libpango1.0-dev libphonon4 libpixman-1-dev libpulse-dev libpyside-dev
  libpyside-py3-1.1 libpyside1.1 libqhull-dev libqwt-dev libqwt5-qt4 libqwt6
  libsdl-image1.2 libsdl-image1.2-dev libsdl1.2-dev libshiboken-dev
  libshiboken-py3-1.1 libshiboken1.1 libslang2-dev libswscale-dev
  libtheora-dev libusb-1.0-0-dev libv4l-dev libvtk5-dev libvtk5.8 libwebp4
  libxcb-render0-dev libxcb-shm0-dev libxcomposite-dev libxcursor-dev
  libxft-dev libxi-dev libxinerama-dev libxml2-dev libxml2-utils libxrandr-dev
  libxrender-dev libxss-dev libyaml-cpp-dev libyaml-cpp0.3 phonon
  phonon-backend-gstreamer python-epydoc python-jinja2 python-kitchen
  python-matplotlib python-matplotlib-data python-opengl python-pydot
  python-pyparsing python-pyside python-pyside.phonon python-pyside.qtcore
  python-pyside.qtdeclarative python-pyside.qtgui python-pyside.qthelp
  python-pyside.qtnetwork python-pyside.qtopengl python-pyside.qtscript
  python-pyside.qtsql python-pyside.qtsvg python-pyside.qttest
  python-pyside.qtuitools python-pyside.qtwebkit python-pyside.qtxml
  python-qt4-dev python-qwt5-qt4 python-sphinx python-tz ros-hydro-actionlib
  ros-hydro-actionlib-msgs ros-hydro-actionlib-tutorials ros-hydro-amcl
  ros-hydro-angles ros-hydro-base-local-planner ros-hydro-bfl
  ros-hydro-bond-core ros-hydro-bondpy ros-hydro-camera-calibration
  ros-hydro-camera-calibration-parsers ros-hydro-camera-info-manager
  ros-hydro-carrot-planner ros-hydro-clear-costmap-recovery
  ros-hydro-collada-parser ros-hydro-collada-urdf ros-hydro-common-msgs
  ros-hydro-common-tutorials ros-hydro-compressed-depth-image-transport
  ros-hydro-compressed-image-transport ros-hydro-convex-decomposition
  ros-hydro-costmap-2d ros-hydro-cv-bridge ros-hydro-depth-image-proc
  ros-hydro-diagnostic-aggregator ros-hydro-diagnostic-analysis
  ros-hydro-diagnostic-common-diagnostics ros-hydro-diagnostic-msgs
  ros-hydro-diagnostic-updater ros-hydro-diagnostics ros-hydro-driver-base
  ros-hydro-driver-common ros-hydro-dwa-local-planner
  ros-hydro-eigen-conversions ros-hydro-eigen-stl-containers
  ros-hydro-executive-smach ros-hydro-fake-localization ros-hydro-filters
  ros-hydro-gazebo-msgs ros-hydro-gencpp ros-hydro-genlisp
  ros-hydro-geometric-shapes ros-hydro-geometry
  ros-hydro-geometry-experimental ros-hydro-geometry-msgs
  ros-hydro-geometry-tutorials ros-hydro-gmapping ros-hydro-image-common
  ros-hydro-image-geometry ros-hydro-image-pipeline ros-hydro-image-proc
  ros-hydro-image-rotate ros-hydro-image-transport
  ros-hydro-image-transport-plugins ros-hydro-image-view
  ros-hydro-interactive-marker-tutorials ros-hydro-interactive-markers
  ros-hydro-ivcon ros-hydro-joint-state-publisher ros-hydro-kdl-conversions
  ros-hydro-kdl-parser ros-hydro-laser-assembler ros-hydro-laser-filters
  ros-hydro-laser-geometry ros-hydro-laser-pipeline ros-hydro-librviz-tutorial
  ros-hydro-map-msgs ros-hydro-map-server ros-hydro-message-filters
  ros-hydro-message-generation ros-hydro-mk ros-hydro-move-base
  ros-hydro-move-base-msgs ros-hydro-move-slow-and-clear ros-hydro-nav-core
  ros-hydro-nav-msgs ros-hydro-navfn ros-hydro-navigation
  ros-hydro-nodelet-core ros-hydro-nodelet-topic-tools
  ros-hydro-nodelet-tutorial-math ros-hydro-octomap ros-hydro-opencv2
  ros-hydro-openslam-gmapping ros-hydro-orocos-kdl ros-hydro-pcl
  ros-hydro-pcl-conversions ros-hydro-pcl-msgs ros-hydro-pcl-ros
  ros-hydro-perception-pcl ros-hydro-pluginlib-tutorials
  ros-hydro-polled-camera ros-hydro-python-qt-binding ros-hydro-qt-dotgraph
  ros-hydro-qt-gui ros-hydro-qt-gui-app ros-hydro-qt-gui-core
  ros-hydro-qt-gui-cpp ros-hydro-qt-gui-py-common ros-hydro-random-numbers
  ros-hydro-resource-retriever ros-hydro-robot-model ros-hydro-robot-pose-ekf
  ros-hydro-robot-state-publisher ros-hydro-ros ros-hydro-ros-comm
  ros-hydro-ros-tutorials ros-hydro-rosbash ros-hydro-rosboost-cfg
  ros-hydro-rosbuild ros-hydro-rosclean ros-hydro-rosconsole-bridge
  ros-hydro-roscpp-tutorials ros-hydro-roscreate ros-hydro-rosdoc-lite
  ros-hydro-roslang ros-hydro-roslaunch ros-hydro-roslisp ros-hydro-rosmake
  ros-hydro-rosmaster ros-hydro-rosnode ros-hydro-rosout ros-hydro-rosparam
  ros-hydro-rospy-tutorials ros-hydro-rostest ros-hydro-rostopic
  ros-hydro-rosunit ros-hydro-roswtf ros-hydro-rotate-recovery
  ros-hydro-rqt-action ros-hydro-rqt-bag ros-hydro-rqt-bag-plugins
  ros-hydro-rqt-common-plugins ros-hydro-rqt-console ros-hydro-rqt-dep
  ros-hydro-rqt-graph ros-hydro-rqt-gui ros-hydro-rqt-gui-cpp
  ros-hydro-rqt-gui-py ros-hydro-rqt-image-view ros-hydro-rqt-launch
  ros-hydro-rqt-logger-level ros-hydro-rqt-moveit ros-hydro-rqt-msg
  ros-hydro-rqt-nav-view ros-hydro-rqt-plot ros-hydro-rqt-pose-view
  ros-hydro-rqt-publisher ros-hydro-rqt-py-common ros-hydro-rqt-py-console
  ros-hydro-rqt-reconfigure ros-hydro-rqt-robot-dashboard
  ros-hydro-rqt-robot-monitor ros-hydro-rqt-robot-plugins
  ros-hydro-rqt-robot-steering ros-hydro-rqt-runtime-monitor
  ros-hydro-rqt-rviz ros-hydro-rqt-service-caller ros-hydro-rqt-shell
  ros-hydro-rqt-srv ros-hydro-rqt-tf-tree ros-hydro-rqt-top
  ros-hydro-rqt-topic ros-hydro-rqt-web ros-hydro-rviz
  ros-hydro-rviz-plugin-tutorials ros-hydro-rviz-python-tutorial
  ros-hydro-self-test ros-hydro-sensor-msgs ros-hydro-shape-msgs
  ros-hydro-shape-tools ros-hydro-smach ros-hydro-smach-msgs
  ros-hydro-smach-ros ros-hydro-stage ros-hydro-std-srvs
  ros-hydro-stereo-image-proc ros-hydro-stereo-msgs ros-hydro-tf
  ros-hydro-tf-conversions ros-hydro-tf2 ros-hydro-tf2-bullet
  ros-hydro-tf2-geometry-msgs ros-hydro-tf2-kdl ros-hydro-tf2-msgs
  ros-hydro-tf2-py ros-hydro-tf2-ros ros-hydro-tf2-tools
  ros-hydro-theora-image-transport ros-hydro-timestamp-tools
  ros-hydro-trajectory-msgs ros-hydro-turtle-actionlib ros-hydro-turtle-tf
  ros-hydro-turtlesim ros-hydro-urdf ros-hydro-urdf-parser-plugin
  ros-hydro-urdf-tutorial ros-hydro-urdfdom ros-hydro-urdfdom-headers
  ros-hydro-vision-opencv ros-hydro-visualization-marker-tutorials
  ros-hydro-visualization-msgs ros-hydro-visualization-tutorials
  ros-hydro-voxel-grid ros-hydro-xacro shiboken sphinx-common sphinx-doc
  tango-icon-theme tcl8.5-dev tk8.5-dev x11proto-composite-dev
  x11proto-randr-dev x11proto-render-dev x11proto-scrnsaver-dev
Use 'apt-get autoremove' to remove them.
The following packages will be REMOVED:
  gazebo-prerelease ros-hydro-desktop-full ros-hydro-gazebo-plugins
  ros-hydro-gazebo-ros ros-hydro-gazebo-ros-pkgs
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 5 to remove and 0 not upgraded.
Need to get 0 B/37,4 MB of archives.
After this operation, 13,8 MB disk space will be freed.
2015-10-31 12:29:06 -0500 marked best answer pr2_gazebo_plugins, ROS and Gazebo 1.9

Hi folks. I'm currently working on a robot and found an URDF file including Gazebo plugins. This file is based on pr2gazeboplugins. I'm working on Gazebo 1.9. I managed to spawn my robot in Gazebo but the topics are not feed.

I have read in the document about PR2/Gazebo:

Note: This tutorial refers to a previous version of Gazebo that is no longer fully supported. In the future this tutorial needs to be updated to use the new gazeborospkgs interface.

Does it mean that the description file should be adapted to gazeborospkgs? I just want to be sure before breaking everything.

Thx in advance for your answer!

2015-10-31 12:13:09 -0500 marked best answer Initializing controller failed (RRBOT tutorial)

Hi folks.

I'm working on the tutorial of Gazebo 1.9 with rrbot and currently facing the following error messages.

From the controller start launch file:

[INFO] [WallTime: 1375388998.774908] [0.000000] Loading controller: joint1_position_controller
[ERROR] [WallTime: 1375389000.170747] [28.387000] Failed to load joint1_position_controller
[INFO] [WallTime: 1375389000.171134] [28.387000] Loading controller: joint2_position_controller
[ERROR] [WallTime: 1375389001.195123] [29.373000] Failed to load joint2_position_controller

And from the Gazebo launch file:

[ERROR] [1375388999.165926429, 27.406000000]: Exception thrown while initializing controller joint1_position_controller.
Could not find resource 'joint1' in 'hardware_interface::EffortJointInterface'.
[ERROR] [1375388999.166263170, 27.406000000]: Initializing controller 'joint1_position_controller' failed
[ERROR] [1375389000.189563304, 28.401000000]: Exception thrown while initializing controller joint2_position_controller.
Could not find resource 'joint2' in 'hardware_interface::EffortJointInterface'.
[ERROR] [1375389000.190056911, 28.404000000]: Initializing controller 'joint2_position_controller' failed

I have followed the tutorial step by step and used the gazeborosdemos package.

Thank for the help.

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2014-09-04 07:23:51 -0500 marked best answer How to simulate a mecanum wheel in Gazebo?


All my technical problems are hopefully behind me. I can now address core simulation questions.

The robot I'm working on (youBot) is equipped with "mecanum wheels". I did not this kind of wheel before. They allow the mobile platform to move in any direction.

The URDF files I found have implemented this part with simple wheels and casters. This is far from the real moves of the youBot, which "glides" on the ground.

Any idea of how to simulate this kind of wheels with a simplified model? (I guess that simulating the full dynamics of the wheel will be too heavy )

2014-08-02 01:49:49 -0500 commented answer gazebo(os x 10.9): No valid hardware interface element found in joint

I have posted an issue in the roscontrol bug tracker:

2014-07-26 06:37:20 -0500 commented answer gazebo(os x 10.9): No valid hardware interface element found in joint

Same isseu here ... did you report it somewhere?

2014-06-15 14:28:11 -0500 commented answer Gazebo crashes when spawning a robot with urdf.

I am still interested in the bug fix!

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2014-06-08 00:26:09 -0500 commented question "Getting remote endpoint failed" let Gazebo-Gui crash

In fact, empty_world is fine. I am not able to start it after a first attempt to spawn a robot. After a reboot, it works. My bug is triggered by $ roslaunch rrbot_gazebo rrbot_world.launch.

2014-05-27 14:48:08 -0500 commented answer "Getting remote endpoint failed" let Gazebo-Gui crash

I have exactly the same message than described above. When I start gzserver alone (as described in your link), it works. The issue is triggered when Gazebo is started from ROS (looks like). Not corrected by the last update (a few minutes ago).

2014-05-26 14:25:11 -0500 commented question "Getting remote endpoint failed" let Gazebo-Gui crash

Exactly the same issue here, and posted on the ROS forum: (for reference)

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2014-04-16 23:15:08 -0500 marked best answer Joint effort limits and realistic behavior


So I'm done with the description of my robot and I'm not satisfied with the final result. The movements are far from what I have seen on the videos. The description is based on values provided by the manufacturer.

One of my assumption is that I do not understand the "joint limit effort" value. I have used the torque value given for the actuators. The robot looks too weak to move properly. What value should be used for this?

Additional remark. According to the wiki, this information is mandatory for revolute joints, but it has not been defined for the rrbot.

Link to the URDF wiki, here.

This is a first assumption and I may post a more general question later.

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2014-01-20 14:09:40 -0500 commented answer Spawning Erratic robot in Gazebo 1.9 with ROS groovy

For my repo, you should run ```rosrun youbot_teleop```

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2014-01-02 05:39:52 -0500 answered a question rospack could not find the controller_interface package

From ROS answer:

sudo apt-get install ros-hydro-ros-controllers
2014-01-02 05:33:55 -0500 commented question rospack could not find the controller_interface package
2013-12-13 04:47:47 -0500 commented question rospack could not find the controller_interface package

OK, thx, let's do this.