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Hi guys,

I have followed the tf tutorials and implemented all the instructions to get the second turtle to follow the first turtle which in turn is controlled via the keyboard, however, when I launch the start_demo.launch, the second turtle starts twirling continuously even without moving the first turtle.

When I move the first turtle, I can see that the second turtle changes its movement slightly while still rotating. I am not sure what the problem is. I have attached an image showing the pdf file created by rosrun tf view_frames and the turtlesim. Heres what I get:

$ rosrun tf view_frames Listening to /tf for 5.000000 seconds Done Listening Exception AttributeError: AttributeError("'_DummyThread' object has no attribute '_Thread__block'",) in <module 'threading' from '/usr/lib/python2.7/threading.pyc'> ignored dot - graphviz version 2.26.3 (20100126.1600)

Detected dot version 2.26.3 Exception AttributeError: AttributeError("'_DummyThread' object has no attribute '_Thread__block'",) in <module 'threading' from '/usr/lib/python2.7/threading.pyc'> ignored frames.pdf generated

Any help would be much appreciated.

regards,

Khalid

image description


Originally posted by K_Yousif on ROS Answers with karma: 735 on 2013-01-16

Post score: 0

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1 Answer 1

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This is the same issue as in this question and this question.

The dummy thread stuff is just a python bug that does no harm. Here's the ticket. Supposedly, ubuntu will distribute the fix in the future. There's a patch for it out there if you really want to fix it, though.


Originally posted by thebyohazard with karma: 3562 on 2013-01-17

This answer was ACCEPTED on the original site

Post score: 3


Original comments

Comment by K_Yousif on 2013-01-17:
Thanks alot. the problem is fixed now by replacing transform.setRotation( tf::Quaternion(msg->theta,0, 0) ); with transform.setRotation( tf::Quaternion(0, 0, msg->theta) ); in the turtle_tf_broadcaster.cpp

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