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Simple action client freezes at waitForServer(), command line possibility?

asked 2013-04-09 04:29:23 -0500

updated 2013-04-14 21:28:37 -0500

Hi all,

I have followed the instructions and setup a navigation stack for my robot. I can control it very well with Rviz. However, when I wrote a program similar to the 'Simple Action Client' in the tutorials, the program waits forever at the waitForServer function. So sending goals through Rviz works, but simple action client does not. Any idea how I could debug this?

Also, is there a way to know through commandline whether the move_base action server is up? Perhaps, through the topics or services. I can see that most of the familiar move_base topics are running. Like I said earlier, I can control the robot through RViz. I would just like to verify the action server is running through commandline.

Edit April 10,2013: Does successfully sending commands through Rviz mean that the move_base action server is running? To me running the navigation stack implies running:

rosrun move_base move_base

with all the parameters in a launch file. Is that sufficient to start the move_base action server?

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answered 2013-04-09 04:45:31 -0500

dornhege gravatar image

There is no verification afaik, besides looking at the topics.

You can try to connect to the server via a simple tool and test if something replies:

rosrun actionlib axclient.py /my_action
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What type of topic should '/my_action' be? Since Rviz sent a goal to the topic /move_base_simple/goal which is of type 'geometry_msgs/PoseStamped', I tried that. However I get an error similar to 'assert('Goal' in topic type)', which is quite self evident.

Shanker gravatar imageShanker ( 2013-04-09 23:21:48 -0500 )edit

I then tried the topic '/move_base/goal' which is of type '/move_base_msgs/MoveBaseActionGoal'. I then do get the GUI, however there is a red error on the bottom of the GUI box which says 'No Goal and Disconnected from server'. I've tried to fill the fields in but it makes no difference.

Shanker gravatar imageShanker ( 2013-04-09 23:24:51 -0500 )edit
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I think it's just move_base. The /move_base_simple is not using actionlib.

dornhege gravatar imagedornhege ( 2013-04-10 00:43:05 -0500 )edit

Right. I have added an edit to my question. It relates to how to start the move_base action server. I would appreciate if you could look at it. Thanks..

Shanker gravatar imageShanker ( 2013-04-10 02:23:57 -0500 )edit

In the actionclient GUI, is 'Disconnected from server' the default/start statement?

Shanker gravatar imageShanker ( 2013-04-10 02:24:37 -0500 )edit

move_base should be the node to run "everything". It might not come up properly if misconfigured, but there should be warnings. Thus, when rviz works usually the actionclient also works, although it's not 100% guaranteed as rviz uses another mechanism.

dornhege gravatar imagedornhege ( 2013-04-10 07:15:07 -0500 )edit

That's what I thought as well. Rviz works perfectly, yet the autoclient does not. Also, the simple action client does not work as well. It waits indefinitely as I mentioned at waitForServer().

Shanker gravatar imageShanker ( 2013-04-14 21:25:00 -0500 )edit

/move_base should be the action to connect to. There should be actionlib related topics in the move_base node. If not, something is wrong.

dornhege gravatar imagedornhege ( 2013-04-14 23:42:06 -0500 )edit
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answered 2013-04-19 02:25:29 -0500

I have discovered that my problem was that I was simply connecting to the wrong server. My application generates several servers and clients and it was a mistake. The answer to how one connect externally is through the GUI mentioned in the accepted answer.

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Asked: 2013-04-09 04:29:23 -0500

Seen: 1,789 times

Last updated: Apr 19 '13