rospy.get_param('~namespace') problem [closed]

asked 2013-03-15 04:16:34 -0500

Rizqa gravatar image

updated 2016-10-24 08:34:39 -0500

ngrennan gravatar image

I am trying to control a dynamixel ax-12 servo by using kinect.. I just use one servo I followed the tutorials in pi_robot package

When I start robotis.launch, it works fine.. But when i start dynamixels.launch to control my servo.. it has problems..

[WallTime: 1363352924.628046] /dev/ttyUSB0 controller_spawner: waiting for controller_manager None to startup in /ax12_controller/namespace...

Traceback (most recent call last): File "/home/rizqa/trunk2/pi_tracker/bin/", line 251, in manager = ControllerManager()

File "/home/rizqa/trunk2/pi_tracker/bin/", line 78, in __init__ manager_namespace = rospy.get_param('~namespace')
File "/opt/ros/electric/stacks/ros_comm/clients/rospy/src/rospy/", line 378, in get_param return _param_server[param_name] #MasterProxy does all the magic for us

File "/opt/ros/electric/stacks/ros_comm/clients/rospy/src/rospy/",line 117, >in __getitem__ raise KeyError(key) KeyError: '~namespace'

I'm not sure why the controller_manager None to start up..

dynamixel.launch ( for a while, I just one servo )

  <param name="robot_description" command="cat $(find pi_tracker)/urdf/b_robot.urdf" />
  <param name="/use_sim_time" value="False" />

  <node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher">
    <param name="publish_frequency" value="50.0"/>

    <!-- Define the namespace for all our controllers -->
    <arg name="ax12_namespace" value="ax12_controller" />

    <!-- Start the ax12 controller manager -->
    <node ns="$(arg ax12_namespace)" name="ax12_manager" pkg="pi_tracker" type="" required="true" output="screen">
        <param name="port_name" type="str" value="/dev/ttyUSB0" />
        <param name="baud_rate" type="int" value="1000000"/>
        <param name="min_motor_id" type="int" value="1"/>
        <param name="max_motor_id" type="int" value="1"/>
        <param name="update_rate" type="int" value="10"/>

    <!-- Load joint controller configuration to parameter server -->
    <rosparam ns="$(arg ax12_namespace)" file="$(find pi_tracker)/params/dynamixels_params.yaml" command="load"/>

    <!-- Start individual joint controllers -->
    <node ns="$(arg ax12_namespace)" name="pi_tracker" pkg="pi_tracker" type=""
          args="--port /dev/ttyUSB0
        output="screen" />

    <!-- Start the ax12 joint state publisher -->
    <node ns="$(arg ax12_namespace)" name="ax12_joint_state_publisher" pkg="pi_tracker" type="" output="screen">
        <rosparam file="$(find pi_tracker)/params/dynamixels_params.yaml" command="load"/>

How could this problem solved..?? thanks..

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Closed for the following reason question is not relevant or outdated by tfoote
close date 2015-11-26 03:08:07.454289


I have solved the problem..

Rizqa gravatar image Rizqa  ( 2013-03-16 02:09:25 -0500 )edit

Please state how you did this as an answer so others can benefit.

tfoote gravatar image tfoote  ( 2013-06-12 11:43:15 -0500 )edit

Same problem here. Sad that answer was not provided.

Tõnu Samuel gravatar image Tõnu Samuel  ( 2014-03-31 02:30:47 -0500 )edit

The reason why you are unable to read the ros param set under node is because, the name got changed i.e. attached with the name of node.

For example, if you consider the following <node name="testnode" pkg="asdf" type=""> </node>

Then your parameter name will be /testnode/params. So now if you read using rospy.get_param(' /testnode/params'), you should be able to read it without any issue.

tek raj gravatar image tek raj  ( 2020-04-20 05:14:12 -0500 )edit