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ardrone not responding to the image tags.

asked 2012-01-14 08:58:30 -0500

this post is marked as community wiki

This post is a wiki. Anyone with karma >75 is welcome to improve it.

I ran some tests on the ardrone to identify the tags .The camera of the ardrone quit well recognizes the tags.This was evident since there was a tag identified on the image window outlining the tag with a green line.I have some pictures of tag identification,since I have only one karma,I am not able to upload.

These are the commands which are executed for the tag identification and the flight of the ardrone.

rosrun ardrone_brown ardrone_driver //synching the computer with the ardrone wifi and acquiring connection

rosrun ar_recog ar_recog image:=/ardrone/image_raw //directs the camera feed of the ardrone to the ar_ecog

rosrun image_view image_view image:=/ar/image //this windows shows the image window of the ardrone which is monitored by ar_recog .It is able to recognize image tags and outline it in green outline

rosrun nolan3d //this is the target follower which indeed communicates with the ardrone is the topic info

metallo@ubuntu:~$ rosnode info /nolan_3014_1326654517968 
Node [/nolan_3014_1326654517968]
 * /cmd_vel [geometry_msgs/Twist]
 * /rosout [rosgraph_msgs/Log]

 * /tags [ar_recog/Tags]

Services: None

contacting node http://ubuntu:60922/ ...
Pid: 3014
 * topic: /rosout
    * to: /rosout
    * direction: outbound
    * transport: TCPROS
 * topic: /cmd_vel
    * to: /ardrone_driver            //note here it communicates with the ardrone driver
    * direction: outbound
    * transport: TCPROS
 * topic: /tags
    * to: http://ubuntu:58952/
    * direction: inbound
    * transport: TCPROS

rosrun drone_teleop this I set the ardrone on flight)

This is where I discovered the problem.I held the tag in an optimal distance in-front of the drone.The tag I held was a big one ( 8.5 inches x 11 inches).But the drone does not seem to fly to it and neither align itself to the tag when held close it .

any suggestions please.. hope the question is more informative now..

Here is what I did. I made sure the drone was on air. Then I started the node Nolan3D package by running the python program in its bin.Then I held the image tag.The drone did not fly to me and even when the image tag was close , it was not able to align its movement according to the tag.

Any suggestions please.

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Please be more specific. Which OS and distribution of ros are you running? What are the exact commands you're running, and possibly any relevant output? What are you using to generate tags? Maybe add a screenshot if it's relevant. See: for how to ask good questions.
ahendrix gravatar imageahendrix ( 2012-01-14 17:42:26 -0500 )edit
I have edited the question and please let me know,if you need any more info.I was not able to upload the pictures,since I have only one karma.
metal gravatar imagemetal ( 2012-01-15 05:55:42 -0500 )edit
I suggest you mark any new questions as not "Community Wiki" so you can get karma (a mod can mark it as community wiki if appropriate after it's been created). You could use a service such as imgur, flickr or any other image sharing service to link to pictures in your post.
Eric Perko gravatar imageEric Perko ( 2012-01-15 06:49:06 -0500 )edit
I will make note of that Eric and other than that could you please give your perspective on the problem I have with ARDRONE and the tags.
metal gravatar imagemetal ( 2012-01-15 07:09:25 -0500 )edit

2 answers

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answered 2012-01-15 07:07:24 -0500

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This post is a wiki. Anyone with karma >75 is welcome to improve it.

It looks like the drone_teleop node is continuously publishing to cmd_vel, which is probably overriding any commands sent by the nolan3d node. Try stopping the drone_teleop node once your AR drone is in the air.

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stopping the might make drone to fall.but I will try and will let you know.There is a topic /ardrone/takeoff .I should be publishing to that may be.
metal gravatar imagemetal ( 2012-01-15 07:28:27 -0500 )edit
thanks Ahendrix the drone is able to follow the tag little bit.The thing is once it sees the tag it moves away so far that it losses its glimpse of the tag.
metal gravatar imagemetal ( 2012-01-15 08:56:51 -0500 )edit
The nolan3d node looks like it's still experimental. You may have to adjust some of the parameters to get it to run for you. I would start by playing around with stopping_dist (you'll have to edit the code). If you're feeling ambitious, you could add dynamic_reconfigure capabilities it.
ahendrix gravatar imageahendrix ( 2012-01-15 09:11:50 -0500 )edit
I reduced the stopping_distance,I am yet to test it.I dont understand what do you mean by dynamic _reconfigure. Could you please be more precise
metal gravatar imagemetal ( 2012-01-15 09:17:57 -0500 )edit
I can confirm that teleop and nolan will "fight" for control of the drone (with the likely outcome being paralysis). A trick I've used is to use bash to launch teleop, then nolan, then teleop. Then you can control-C once the drone's in the air and Control-c again if something goes awry.
tjay gravatar imagetjay ( 2012-01-16 05:08:02 -0500 )edit
dynamic_reconfigure is a framework for adjusting node parameters on-the-fly. see: and . You can find a great deal of documentation on ros with google or<stack or package name>
ahendrix gravatar imageahendrix ( 2012-01-16 10:12:03 -0500 )edit

answered 2012-01-17 08:14:44 -0500

Arjun gravatar image

When you hold up the ar-tag, try to not place your fingers on the surface of the tag. I've noticed that the ar-recog sometimes fails to recognize the tag if there are fingers on the surface. This is just a tip in addition to the solution proposed by "tjay" above.

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Asked: 2012-01-14 08:58:30 -0500

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Last updated: Jan 17 '12