Unstable hovering

All discussions related to the Loco Positioning system
sali0
Beginner
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Joined: Wed Oct 19, 2016 7:53 pm

Re: Unstable hovering

Post by sali0 »

Apologies, I didn't know that you have to turn off the rosbag before you turn off RVIZ to get a proper rosbag. Here is another one that perfectly shows the issues we are experiencing.

https://drive.google.com/file/d/0BzQzuQ ... sp=sharing
sali0
Beginner
Posts: 24
Joined: Wed Oct 19, 2016 7:53 pm

Re: Unstable hovering

Post by sali0 »

Bumping, as we still have not found the issue, and it seems no one else is experiencing this.

Also, which topic is the drones xyz position being published to? Is there a way we could get a csv file with a table of the position over some period of time from a rosbag? Thank you.
arnaud
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Joined: Tue Feb 06, 2007 12:36 pm

Re: Unstable hovering

Post by arnaud »

Hi,

Something strange about your bag: It seems that the setpoint in Z is also going down and even becoming negative. Is that wanted?
arnaud
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Re: Unstable hovering

Post by arnaud »

About the other question: you can extract data from a ros bag, either as text (yaml): http://answers.ros.org/question/9102/ho ... -from-bag/. Or there seems to be some tools: https://gist.github.com/marc-hanheide/4 ... 4bf9e5e9f5. I have previously used rostopic and then extracting the data with a script.

The setpoint is /crazyflie/goal and the returned position from the Crazyflie is /crazyflie/crazyflie_position.
sali0
Beginner
Posts: 24
Joined: Wed Oct 19, 2016 7:53 pm

Re: Unstable hovering

Post by sali0 »

Hello Arnaud,
Yes the changing Z setpoint is exactly the issue we are seeing. We have been seeing this issue ever since we started using tdoa with our drones. My team and I are inexperienced though, and we could not find what is causing the issue. We have another rosbag where the drones setpoints are drifting along the x axis. Have you any idea what may be causing these issues? Thanks!
arnaud
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Re: Unstable hovering

Post by arnaud »

Ah I see, this issue is caused by something in ROS, not by the Crazyflie or its ranging mode (TDoA).

The topic /crazyflie/goal is generated by one of your ros node. To find which one you can use "rostopic info /crazyflie/goal" it will tell you which node is publishing the topic. You can also use rqt_graph to see how things are connected.
sali0
Beginner
Posts: 24
Joined: Wed Oct 19, 2016 7:53 pm

Re: Unstable hovering

Post by sali0 »

Hello Arnaud,

Thank you for the call you did with me last week. As frustrating as it was, it really was simply just the xbox controller having a tilt on the joystick. This was quite the learning experience. Thank you so much for the help.
arnaud
Bitcraze
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Joined: Tue Feb 06, 2007 12:36 pm

Re: Unstable hovering

Post by arnaud »

Glad that it works!

Yes this is a very frustrating problem, I have had it when working on the LPS. I am always careful with axis deadzone now :).
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