Hi Florian,

This was more of a simpler implementation choice then a design 
decision.  When robot_state_publisher was written all our joint states 
came from one node synchronously.  There's an open ticket to add this 
capability https://code.ros.org/trac/ros-pkg/ticket/4464

Tully

On 11/22/2010 05:58 AM, Weißhardt, Florian wrote:
>
> Hi,
>
> what's the reason/drawback for not having one robot_state_publisher 
> and one urdf that can deal with multiple joint_states messages for a 
> serial kinematic chain? ...which is, at least for me, the intuitive 
> understanding of a "global" /joint_states topic and a "global" urdf 
> description for the whole robot. Why dividing it into multiple subsystems?
>
> Regards,
> Florian
>
>
> -----Ursprüngliche Nachricht-----
> Von: ros-users-bounces@code.ros.org im Auftrag von David Lu!!
> Gesendet: Mo 22.11.2010 14:45
> An: User discussions
> Betreff: Re: [ros-users] robot_state_publisher with joint_states in 
> different messages does not compute tf for all joints
>
> 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.
>
> -David!!
>
> On Mon, Nov 22, 2010 at 6:44 AM, Weißhardt, Florian <
> Florian.Weisshardt@ipa.fraunhofer.de> wrote:
>
> >  Dear ros users,
> >
> >
> >
> > probably we figured out a bug in the robot_state_publisher (or are not
> > using it correctly):
> >
> >
> >
> > 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
> >
> > a)       the joint information for the whole kinematic chain is 
> published
> > in one joint_states message or
> >
> > b)       at least there are no joints connected to a serial chain and
> > published in different joint_states messages.
> >
> >
> >
> > 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.
> >
> >
> >
> > Is this a known behaviour (bug?) or are we missing something?
> >
> >
> >
> > Best regards,
> >
> > Florian
> >
> >
> >
> > _______________________________________________
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> > ros-users@code.ros.org
> > https://code.ros.org/mailman/listinfo/ros-users
> >
> >
>
>
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