Use twist topic

[lidiaxp]

I would like to perform some tests in your but without using the pre-defined controls. Is it possible to use the topic "/control_manager/cmd_twist_out", that is a ? If yes, how can I release it? Because when I send a command to it by rostopic pub, the UAV does not make any movement.

Thank you in advance

[klaxalk]

Hey, the supported topics and services are listed here: https://ctu-mrs.github.io/docs/system/uav_ros_interface.html. The mentioned cmd_twist_out is being published by the control manager just to report on the current velocity reference.

Use the control_manager/velocity_reference topic if you want velocity control. However, many of our control layers will still be active, in this case, the SO(3), SE(3) feedback, and the MpcTracker reference generator.

[lidiaxp]

I tried:

rostopic pub /uav1/control_manager/velocity_reference mrs_msgs/VelocityReferenceStamped "header:
  seq: 0
  stamp:
    secs: 0
    nsecs: 0
  frame_id: ''
reference:
  velocity: {x: 10.0, y: 0.0, z: 0.0}
  altitude: 0.0
  heading: 0.0
  heading_rate: 0.0
  use_altitude: false
  use_heading: false
  use_heading_rate: false"

But the UAV just movement a few centimeters. There are a topic similar to cmd_vel which we send a value and UAV still movement until we send 0? Or I am using the topic control_manager/velocity_reference in a wrong way?

[klaxalk]

Well, if you publish just one message, the controller times out shortly after that. Check the logs. You need to publish this repeatedly, so, in the case of rostopic pub, add -r 10. That will make the message being published at 10 Hz.

[klaxalk]

To clarify, the timeout is there to protect you from yourself. Without the timeout, the UAV would continue at the desired velocity even when your publisher node crashes. And that would be very dangerous. So typically, velocity input for robots times out the messages.

[lidiaxp]

Thanks so much for your help. The flag -r is exactly what I was looking for