[ros-users] Weirdness in URDF tutorials

David Lu!! davidvlu at gmail.com
Tue Dec 28 18:59:19 UTC 2010


Hey Björn,
The tutorials were just finished last month, so they're up to date as far as
I know.

It looks like you have everything figured out, but I couldn't tell because
of the last "I still need to figure out why".

Things will appear white and at the origin when there isn't a proper
transform to the link. If you're still running into that problem, make sure
that rxgraph looks the way you would expect, with joint_state_publisher
 connected to robot_state_publisher.

-David!!

2010/12/28 Björn Giesler <bjoern at giesler.de>

> Hi,
>
> Addendum: My logs had the message
>
> ERROR: cannot launch node of type [robot_state_publisher/state_publisher]:
> Cannot locate node of type [state_publisher] in package
> [robot_state_publisher]
>
> because robot_state_publisher hadn't been built yet. It seems after doing
> "rosmake robot_state_publisher state_publisher", everything is the way it
> should be -- now I still need to figure out why...
>
> Regards,
> Björn
>
> Am 28.12.2010 um 17:21 schrieb Björn Giesler:
>
> > Hi,
> >
> > I'm trying to create a URDF model for my robot, which happens to be an
> R2-D2 replica so I was thrilled to find the wiki contains a series of
> tutorials that create a R2-D2 URDF. I'm trying to follow the tutorial on my
> robot's computer, a Zotac Zbox (NVIDIA ION-based) which I'm connecting to
> via VNC.
> >
> > Is it possible that those tutorials are outdated and the URDF syntax and
> semantics have changed? It seems that transforms and materials don't behave
> the way they should.
> >
> > This is how the second tutorial step should look like according to the
> wiki:
> >
> > <PastedGraphic-2.tiff>
> >
> > and this is how it looks on my machine:
> >
> > <PastedGraphic-3.tiff>
> >
> > Notice that the cylinder is OK, but the second shape (a .6x.2x.1 box) is
> rotated and also white. The URDF file I used is unmodified from
> urdf_tutorial, and its text is exactly as posted in the wiki.
> >
> > The first thing I noticed was that the coordinate assignment looks off
> causing the box to be higher than wide instead of vice versa. So I tried to
> just put a couple of colored boxes in the x, y, and z directions to see what
> the proper assignment was. I got as far as one box, the URDF file is this:
> >
> > <?xml version="1.0"?>
> > <robot name="R2-D2">
> >  <link name="base_link">
> >    <visual>
> >      <geometry>
> >       <cylinder length="0.6" radius="0.2"/>
> >      </geometry>
> >      <material name="white"><color rgba="1 1 1 1"/></material>
> >    </visual>
> >  </link>
> >
> >  <link name="redbox">
> >    <visual>
> >      <geometry>
> >       <box size=".1 .1 .1"/>
> >      </geometry>
> >      <origin xyz="1 0 0"/>
> >      <material name="red">
> >       <color rgba="255 0 0 0.5"/>
> >      </material>
> >    </visual>
> >  </link>
> >
> >  <joint name="base_to_redbox" type="fixed">
> >    <parent link="base_link"/>
> >    <child link="redbox"/>
> >  </joint>
> > </robot>
> >
> > ...so it's a red box at xyz="1 0 0". This is how it looks like:
> >
> > <PastedGraphic-4.tiff>
> >
> > So the box is there, but it's not red...
> >
> > Can anyone tell me what's going on here?
> >
> > Thanks a lot in advance,
> > Björn
> > --
> > Björn Giesler
> > bjoern at giesler.de
> > Verschlüssel Deine Emails -- oder schreibst Du Deine Briefe außen auf den
> Umschlag?
> > Meinen Schlüssel findest Du auf
> http://giesler.biz/~bjoern/downloads/bg.asc -- schick mir Deinen!
> > Mehr Informationen findest Du auf http://www.gnupg.org/index.de.html
> >
> > _______________________________________________
> > ros-users mailing list
> > ros-users at code.ros.org
> > https://code.ros.org/mailman/listinfo/ros-users
>
> --
> Björn Giesler
> bjoern at giesler.de
> Verschlüssel Deine Emails -- oder schreibst Du Deine Briefe außen auf den
> Umschlag?
> Meinen Schlüssel findest Du auf
> http://giesler.biz/~bjoern/downloads/bg.asc -- schick mir Deinen!
> Mehr Informationen findest Du auf http://www.gnupg.org/index.de.html
>
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>
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