This is a problem I've run into as well. The way I usually fix it is
to write a node that aggregates the joint state messages and send out
a new stream with all the joints. But I agree, robot_state_publisher's
lack of memory is a problem sometimes.
-DL!!

On Fri, Oct 1, 2010 at 8:07 AM, Axelrod, Benjamin <baxelrod@irobot.com> wrote:
> I am using the robot_state_publisher to convert my joint angles to tf
> transforms.  However, it seems that the robot_state_publisher doesn’t like
> it when you send it different joints at different times.  In other words,
> robot_state_publisher doesn’t maintain any state…
>
>
>
> For example, my urdf has 2 joints:
>
> Base -> joint1 -> link1 -> joint2 -> link2
>
>
>
> If I send it joint1, then at a later time I send it joint 2, I get this
> error:
>
>
>
> Node: /robot_state_publisher
>
> Time: 1285876513.251897000
>
> Severity: Error
>
> Location:
> /home/arm_user/darpa_arm_software/stacks/robot_model/robot_state_publisher/src/robot_state_publisher.cpp:RobotStatePublisher::publishTransforms:78
>
> Published Topics: /rosout, /tf
>
> Could not compute link poses. The tree or the state is invalid.
>
>
>
> But if I send both joints at once, then everything is fine.  This seems like
> a major limitation to me.  Am I missing something?
>
>
>
> I am using boxturtle.  And am using robot_state_publisher running as a node.
>
>
>
> Thanks,
>
> -Ben
>
>
>
> Ben Axelrod
>
> Research Scientist
>
> iRobot Corporation
>
> 8 Crosby Drive, Mail Stop 8-1
>
> Bedford, MA 01730
>
> (781) 430-3315 (Tel)
>
> (781) 960-2628 (Fax)
>
> baxelrod@irobot.com
>
>
>
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