More Stereo Web Cams.

After looking for some stereo webcams I found two of them that look very interesting. The first one is called Minoru and it has been used by ROS users. It seems to work good enough for it's price $$$$ so I will buy it in order to start using the VSLAM stack.

This is the webpage of the minoru stereo webcam http://www.minoru3d.com/

The second one is one called Hydra webcam, from nVela. It looks a very nice stereo webcam and it is synchronized. It allows the user to control it with low level programs and it includes C++ codes to make different image treatment. The main software that this camera includes is only for windows but the manufacturers say they will launch a Linux and Mac version too.

This is the webpage of the Hydra stereo webcam http://www.nvela.com/hydra.html

This is an interesting set of questions about VSLAM by the ROS Users community:
http://ros-users.122217.n3.nabble.com/Questions-about-VSLAM-td1784417.html

This is a video of how was implemented the Minoru webcam on ROS.
http://www.ros.org/news/2010/04/v4l2stereo-and-minoru-stereo-webcam-integrated-with-ros.html

this is an aplications with a pendulum.
http://www.youtube.com/watch?v=_37S3q2Z-qk

This is an intersting page about the Minoru webcam, it's hardware and the code to use it.
http://code.google.com/p/sentience/wiki/MinoruWebcam

This other page is about the monocular vision odometry, it might be usefull to make odometry readings with a monocular camera.
http://www.hessmer.org/blog/2010/08/17/monocular-visual-odometry/

VSLAM

Now I have successfully installed Ubuntu Maverick Meerkat and Ros Diamondback I will proceed to install the VSLAM Stack.

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Having problems with the VSLAM/setup.sh directory

Message:

root@oscar-Presario:/opt/ros/diamondback/stacks# . VSLAMDIR/setup.sh
bash: VSLAMDIR/setup.sh: No such file or directory

I'll see next week what's happening with this problem.
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I still don't know how to solve this problem but I'm going to rosmake the VSLAMDIR diretory in orded to start using it. I hope that everything goes well, but if not I will come back and check this issue.

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After many hours and all night compiling it finally finished. I hope that it is normal to last so long because if not it might be a problem of lack of memory RAM or something about my PC.



Now I will start to try VSLAM.

Economic restrictions.

By now I should have the stereocamera to test it with the VSLAM package of ROS. But i've been unable to purchase one.

By now I will actualize my Ubuntu Version, Install the latest version of ROS and instal VSLAM.

When roscd FAILS

Today I tried to use roscd just after running the roscore program, and the terminal said that it didn't know any command named roscd. Well after looking up at the commands on the setup.sh and the different .bashrc files (user and root) I discovered that they were in order.... and the terminal didn't recognize the roscd command.

The solution to this problem is to resource the rosbash package to your .basrch file. Yo can do this by typing this command:


export ROS_ROOT=/opt/ros/diamondback/ros:/
export PATH=${ROS_ROOT}/bin:${PATH}
export PYTHONPATH=${ROS_ROOT}/core/roslib/src:${PYTHONPATH}
export ROS_PACKAGE_PATH=/opt/ros/diamondback/stacks
if [ ! "$ROS_MASTER_URI" ] ; then export ROS_MASTER_URI=http://localhost:11311 ; fi
source ${ROS_ROOT}/tools/rosbash/rosbash

Now the problem is to solve it for root.

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Ok i solved the problem.

I need to change the file manually of the setup.sh located at opt/ros/cturtle.

I only needed to change cturtle by diamondback on that file.

It looked like this:

export ROS_ROOT=/opt/ros/cturtle/ros:/
export PATH=${ROS_ROOT}/bin:${PATH}
export PYTHONPATH=${ROS_ROOT}/core/roslib/src:${PYTHONPATH}
export ROS_PACKAGE_PATH=/opt/ros/cturtle/stacks
if [ ! "$ROS_MASTER_URI" ] ; then export ROS_MASTER_URI=http://localhost:11311 ; fi

And it needed to be change to this:

export ROS_ROOT=/opt/ros/diamondback/ros:/
export PATH=${ROS_ROOT}/bin:${PATH}
export PYTHONPATH=${ROS_ROOT}/core/roslib/src:${PYTHONPATH}
export ROS_PACKAGE_PATH=/opt/ros/diamondback/stacks
if [ ! "$ROS_MASTER_URI" ] ; then export ROS_MASTER_URI=http://localhost:11311 ; fi

It solve the problem

Videre Camera.

Discussion in a ROS Forum about wich stereocamera should we use that is compatible with ROS:

http://ros-users.122217.n3.nabble.com/Stereo-camera-recommendation-td1633371.html

The brand to use is called Videre.

This is the Videre Website:

http://www.videredesign.com/

This is the link at ROSWiki for the Driver of that camera:

http://www.ros.org/news/2010/07/videre-stereo-camera-driver-from-ua-ros-pkg.html

Stage

http://www.ros.org/wiki/stage

move_base_stage Tutorial

Following the tutorial of amazing ROS in: http://www.ros.org/wiki/move_base_stage/Tutorials/stage%20and%20navigation%20stack

...

Well trying the tutorial everything went fine until I followed the step #5. At the last command I recieved an error message like this:



So I went to the .cc code and found the part of the code where that error message was generated:



I coulnd't find where actually the error was, so I decided to change the !=4 to !=3 and see what happens...

After making stage I ran the willow.world once again...

It didn't work, I changed the values first and then the message and it didn't change, I also rosmake stage and nothing... It seems to bee usign another code, because in all the extension of the model.cc there is no other message like that, I also might be reading a copy of that code in another part... so I will follow all the instructions again and see if it works well...
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roscp is a useful commandline tool for copying files from one package to another.
pr2 throws a robot on map =D

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map_server
Provides the map_server ROS Node, which offers map data as a ROS Service. It also provides the map_saver command-line utility, which allows dynamically generated maps to be saved to file.
Maps manipulated by the the tools in this package are stored in a pair of files. The YAML file describes the map meta-data, and names the image file. The image file encodes the occupancy data.

http://www.ros.org/wiki/map_server
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Other resources:

Navigator Stack and Stage:
Simple tutorial that sets up navigation stack and rosstage. Can be used by any new beginner just to see how awesome and simple ROS is