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Hello list,

Trying to get a trajectory controller working, but am unable to get a working action client. As a first test I tried to add it to the rrbot example from gazebo_ros_demos. As the rrbot_control.yaml I use the following:

  # Publish all joint states -----------------------------------
    type: joint_state_controller/JointStateController
    publish_rate: 50  
  # Trajectory Controller  (not together with the position controllers)
    type: effort_controllers/JointTrajectoryController
      - joint1
      - joint2
      goal_time: 0.0
      stopped_velocity_tolerance: 0.01
      joint1: {trajectory: 0.01, goal: 0.01}
      joint2: {trajectory: 0.01, goal: 0.01}
      joint1: {p: 100.0, d: 75.0, i: 0.0, i_clamp: 0.0}
      joint2: {p: 100.0, d: 25.0, i: 0.0, i_clamp: 0.0}
      state_publish_rate:  100
      action_monitor_rate: 100
      stop_trajectory_duration: 0.0

With an properly adapted launch file both controllers are loaded and started. All is well I think, but I have a problem creating a simple actionclient to use them. I actually do not know how to start the client (in Python). The client starts but noting happens, if keeps waiting for the server. The relevant line (i think) in my client is:

arm_client = actionlib.SimpleActionClient('rrbot/joint_trajectory_controller', FollowJointTrajectoryAction)

The first parameter is wrong, but what should it be? Is there an additional parameter needed in the yaml file?

Thanks in advance, Sietse

PS. Using melodic (from source) on debian test

Originally posted by Sietse on ROS Answers with karma: 168 on 2018-10-17

Post score: 0


1 Answer 1


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This is all very sensitive to which namespaces have been declared, where topics are located, etc.

What is the output of rostopic list | grep -i goal after you've started your simulation?

Originally posted by gvdhoorn with karma: 86574 on 2018-10-17

This answer was ACCEPTED on the original site

Post score: 1

Original comments

Comment by Sietse on 2018-10-17:

And that solved my problem, thanks!


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