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Difference between joint_trajectory_action and follow_joint_trajectory

asked 2019-07-18 02:37:54 -0500

Victor Wu gravatar image

updated 2019-07-18 09:44:47 -0500

gvdhoorn gravatar image

I want to find out if there is any difference between joint_trajectory_action and follow_joint_trajectory.

I used to use joint_trajectory_action as the action_ns in the controllers.yaml file under (project)_moveit_config/config folder. Matching this name, when I create the action client in my program I did:

actionlib::SimpleActionClient<control_msgs::FollowJointTrajectoryAction> ac("joint_trajectory_action",true);

This will work for me both for just RViz simulation and driving the real ur3.

Then I changed to use the new ur_modern_driver, when I try to bring up the RViz, it will always that it is waiting for the /joint_trajectory_action to come up and Action client not connected: /joint_trajectory_action. I then tried to use follow_joint_trajectory as the action_ns in the controllers.yaml file. Then when the RViz was brought up it did not complaint and I can launch the


to plan and execute using moveit in simulation. However, when I try to run my program to control the real ur3 then it complaints that it cannot connect to the action server and hence cannot execute trajectory for my program.

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I would suggest to add a bit more context / tell us where you found references to these two names.

gvdhoorn gravatar image gvdhoorn  ( 2019-07-18 03:05:25 -0500 )edit

I used to use joint_trajectory_action as the name in the controllers.yaml when using the ur_modern_driver. Eversince I started to use the new driver, it does not seem to work and I have to change it to follow_joint_trajectory in the controllers.yaml but then the RViz simulation doesn't work. So I really want to find out what is wrong or how am I confused.

Victor Wu gravatar image Victor Wu  ( 2019-07-18 03:13:41 -0500 )edit

Then please write this in your main question text.

Describe how you used to set things up, then how you set them up now, which contexts this was in, etc.

Eversince I started to use the new driver

"the new driver": we don't know what you are using, so this reference doesn't tell us much.

the RViz simulation

and pedantic, but: RViz is not a simulator, only a visualisation tool.

gvdhoorn gravatar image gvdhoorn  ( 2019-07-18 03:26:22 -0500 )edit

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answered 2019-07-18 22:35:45 -0500

Victor Wu gravatar image

I am sorry for the fuss. I have found the problem. It has nothing to do with any version of the ur_modern_driver. I have found that there was a remap of follow_joint_trajectory to joint_trajectory_action in the previous (project)_planning_execution.launch file and that is all it is about.

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Asked: 2019-07-18 02:37:54 -0500

Seen: 283 times

Last updated: Jul 18 '19