This is the intended behavior. The standard approach to fixing it is to create a node that merges the two JointState messages. Alternatively, you could use two separate URDF and two separate robot_state_publishers. <div><br>
</div><div>-David!!<br><br><div class="gmail_quote">On Mon, Nov 22, 2010 at 6:44 AM, Weißhardt, Florian <span dir="ltr"><<a href="mailto:Florian.Weisshardt@ipa.fraunhofer.de">Florian.Weisshardt@ipa.fraunhofer.de</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div lang="DE" link="blue" vlink="purple">
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<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">Dear ros users,</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">probably we figured out a bug in the
robot_state_publisher (or are not using it correctly):</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">We are running a robot_state_publisher subscribed to
the /joint_states topic and using a urdf robot_description. The transformation
from joint_states with urdf to tf transformations works only if</span></font></p>
<p class="MsoNormal" style="margin-left:36.0pt"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial"><span>a)<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">the
joint information for the whole kinematic chain is published in one
joint_states message or</span></font></p>
<p class="MsoNormal" style="margin-left:36.0pt"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial"><span>b)<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">at
least there are no joints connected to a serial chain and published in
different joint_states messages.</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">In our case e.g. there is a gripper attached to an
arm. Both have rotary joints defined and are publishing joint_states in two
different joint_states messages, but tf can only be computed for the arm, not
for the gripper.</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">Is this a known behaviour (bug?) or are we missing
something?</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">Best regards,</span></font></p>
<p class="MsoNormal"><font size="2" face="Arial"><span lang="EN-GB" style="font-size:10.0pt;font-family:Arial">Florian</span></font></p>
<p class="MsoNormal"><font size="2" face="Frutiger 45 Light"><span lang="EN-GB" style="font-size:11.0pt"> </span></font></p>
</div>
</div>
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