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_publish er/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