Embedded Motion Control 2012/FAQ

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Ubuntu

I installed Ubuntu, but my wireless internet is not working.

You're wireless card is not supported by Ubuntu 10.04. One possible fix is to download the latest wireless drivers here, see Where to download bleeding edge. This page also contains detailed info on how to install the drivers. This basically boils down to:

  1. Extract the tar ball into a folder
  2. Open a terminal, and cd to the directory
  3. Compile the driver against the kernel:
    make
    This may take a while.
  4. Install the driver: 
    sudo make install
  5. After a reboot, your wireless should be working.

Note: Since you build the driver against the kernel, you need to rebuild it after every kernel update, i.e., you have to again do the compilation and installation step described above.

I installed Ubuntu, but my screen is flickering (IBM Lenovo T60).

The preinstalled Ubuntu driver seems not doing his job properly, please use this driver to solve the problem http://support.amd.com/us/gpudownload/linux/legacy/Pages/radeon_linux.aspx?type=2.4.2&product=2.4.2.3.9&lang=us&rev=9.3&ostype=Linux%20x86

The following command shows the supported packages: 

sh ./ati-driver-installer-9-3-x86.x86_64.run --listpkg

Result (among others): 

Ubuntu Packages:
	Ubuntu/7.10
	Ubuntu/8.04
	Ubuntu/8.10
	Ubuntu/9.04
	Ubuntu/gutsy
	Ubuntu/hardy
	Ubuntu/intrepid
	Ubuntu/jaunty
	Ubuntu/source

Unfortunately, Ubuntu 10.04 is not supported by this driver and therefore, installing this driver will results in an error like this: 

Error: ./default_policy.sh does not support version
default:v2:i686:lib::none:2.6.32-41-generic; make sure that the version is being
correctly set by --iscurrentdistro

Try to install the driver by using the following command: 

./ati-driver-installer-9-3-x86.x86_64.run --buildpkg Ubuntu/9.04

The driver for Ubuntu 9.04 is runnning without problems on my T60 with Ubuntu 10.04. Since this solution still caused some problems, I now installed Ubuntu 11.10 which seems to work well...

I try connect to the svn but I need the GNOME keyring password.

  1. Go to console 
    cd ~/.subversion
    nano config
  2. Go to [auth] and enter below [auth] the following "password-stores =".
  3. Press ctrl+x and save the file with the same name (config).
  4. Open a new console and now it works fine.

I start the jazz_simulator but my maze is blinking very fast (HP Elitebook 8540w).

  1. Go to "System" --> "Administration" --> "Hardware Drivers".
  2. Remove the "ATI/AMD proprietary FGLRX graphics driver" (Ubuntu recommended to install this)
  3. Restart Ubuntu

RViz

I cannot display odometry information in RViz

In order to visualize the odometry information, RViz needs a tf (transform) from /odom to /base_footprint which is not published by the simulated controller. Since this tf is not available on the real robot either, we will not add it to the simulator. If you really want to visualize the information, or need the transform for some other reason, you will have to publish the tf yourself. See http://ros.org/wiki/tf for more info.

I've got an error with RViz and it doesn't start

If the error looks like this: 

  The program 'rviz' received an X Window System error.
  This probably reflects a bug in the program.
  The error was 'BadDrawable (invalid Pixmap or Window parameter)'.
 (Details: serial 22 error_code 9 request_code 136 minor_code 3)
 (Note to programmers: normally, X errors are reported asynchronously;
  that is, you will receive the error a while after causing it.
  To debug your program, run it with the --sync command line
  option to change this behavior. You can then get a meaningful
  backtrace from your debugger if you break on the gdk_x_error() function.)
  [rviz-6] process has died [pid 1978, exit code 1].

The following solutions can be tried:

In section 3.4 Segfault during startup from RViz troubleshooting page.

Open a terminal without Gazebo running and just type: 

  export OGRE_RTT_MODE=Copy


If this does not work, just follow the next steps: 

1 rosrun rviz rviz --sync ( add the --sync it even says in the error message)
2 don't give up even with sync it will fail,maybe...try it 2-3 times
3 if it still fails do rosmake rviz rviz and repeat step 1

Graphics drivers issues

Using the wrong graphics drivers may cause Gazebo and/or rviz to crash. To solve this problem, please follow the following steps:

  • First try installing/updating the graphics driver using Hardware Drivers (System->Administration->Hardware Drivers)

You can test the driver from working properly by launching AMIGO in Gazebo and looking at the pointcloud data. This data should be refreshed when AMIGO for instance drives around or if you draw a big block in front of AMIGO.

Global Q&A

Group 2
Q: Can it be assumed that all corners are 90 degrees?
A: Yes, it can (but be aware that in practice it may be 88 or 92 degrees as well...).
Q: Do arrows insinuate driving direction only or do they provide information on next crossroads as well?
A: The camera can only look in front of the robot meaning that arrows to the left or right in a corridor are hard to recognize. They will be placed in spots where you drive towards them. They only give information about the driving direction at the location of the arrow.

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