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sensor_msgs/JointState Message ERROR

HI, I use sensor_msgs/JointState in python to subscribes information about what the current joint values are. But I got this error in terminal

[ERROR] [1566284941.404363788, 1746.419000000]: Client [/joint_positions_node_3931_1566284941324] wants topic /myfirstrobot/joint2_position_controller/state to have datatype/md5sum [sensor_msgs/JointState/3066dcd76a6cfaef579bd0f34173e9fd], but our version has [control_msgs/JointControllerState/987ad85e4756f3aef7f1e5e7fe0595d1]. Dropping connection.

Asked by garychang on 2019-08-20 02:25:54 UTC

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Answers

The topic you're subscribing to (ie: /myfirstrobot/joint2_position_controller/state) is not a topic that carries sensor_msgs/JointState messages, but control_msgs/JointControllerState.

Those are two different messages and you cannot subscribe to a topic with control_msgs/JointControllerState messages with a subscriber that expects sensor_msgs/JointState.

HI, I use sensor_msgs/JointState in python to subscribes information about what the current joint values are

The state topic does not have messages that "current joint values", but the internal state of a ros_control joint controller.

The typical topic for joint states would be joint_states, and is typically published by drivers, not by controllers.

Asked by gvdhoorn on 2019-08-20 02:47:00 UTC

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THANKS for reply!!

Yes, I got joint_states in rostopic list .So I wondering is there any function could get value in python ?

/clock /gazebo/link_states /gazebo/model_states /gazebo/parameter_descriptions /gazebo/parameter_updates /gazebo/set_link_state /gazebo/set_model_state /gazebo_gui/parameter_descriptions /gazebo_gui/parameter_updates /joint_states /myfirstrobot/cmd_vel /myfirstrobot/joint1_position_controller/command /myfirstrobot/joint1_position_controller/pid/parameter_descriptions /myfirstrobot/joint1_position_controller/pid/parameter_updates /myfirstrobot/joint1_position_controller/state /myfirstrobot/joint2_position_controller/command /myfirstrobot/joint2_position_controller/pid/parameter_descriptions /myfirstrobot/joint2_position_controller/pid/parameter_updates /myfirstrobot/joint2_position_controller/state /myfirstrobot/joint_states /myfirstrobot/odom /rosout /rosout_agg /scan /tf /tf_static

Asked by garychang on 2019-08-21 04:47:18 UTC