[ros-users] Weirdness in URDF tutorials

Tue Dec 28 20:53:25 UTC 2010

I ran into a similar problem as well.  I didn't realize that
joint_state_publisher wasn't included in ROS and needed to be installed.  Of
course, it says right there it's needed and the warning tells you exactly
what you need to do.  However, when you're focused on the URDF, these things
sometimes slip by.  Maybe we should make this more obvious and explain
robot_state_publisher's and joint_state_publisher's roles better or even put
rosmake/rosrun tf view_frames steps in the tutorial somewhere?

- Chad

On Tue, Dec 28, 2010 at 1:59 PM, David Lu!! <davidvlu at gmail.com> wrote:

> 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 Is it possible that those tutorials are outdated and the URDF syntax and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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