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cmd_vel topic can be manipulated but no messages are received

asked 2018-10-29 10:41:47 -0600

Dylan gravatar image

updated 2018-10-29 12:22:34 -0600

Using ROS Kinect + Gazebo 7 I'm controlling an AR.Drone. Everything works fine, I can move the drone using the teleop_twist_keyboard or using a Python script done by me, but when I try to see the cmd_vel topic (rostopic echo), this happens:

rostopic echo /quadrotor/cmd_vel

WARNING: no messages received and simulated time is active.
Is /clock being published?

/clock is being published, and /quadrotor/cmd_vel is the name of the topic. What can I do? To move the drone using the teleop_twist_keyboard I use the following:

rosrun teleop_twist_keyboard teleop_twist_keyboard.py cmd_vel:=/quadrotor/cmd_vel

and I can also publish in that topic like:

rostopic pub -r 10 /quadrotor/cmd_vel geometry_msgs/Twist  '{linear:  {x: 0.1, y: 0.0, z: 0.0}, angular: {x: 0.0,y: 0.0,z: 0.0}}'

I hope you can help me. Thanks!

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answered 2018-11-02 08:16:08 -0600

wentz gravatar image

This has nothing todo with gazebo, but with ROS. Have you tried to echo cmd_vel while operating the quadrocopter with teleop_twist_keyboard? (Just try it ;)) This text "WARNING: no messages received and simulated time is active. Is /clock being published?" Simply means that there are no messages sended, but is not an error. Which is quite normal.

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Asked: 2018-10-29 10:41:47 -0600

Seen: 41 times

Last updated: Nov 02