MAVSDK-Python set PX4 local position with mocap commands


I am trying to implement a single camera relative position detection for a quadcopter. Let’s say, I get a rotation and translation matrix that describes the necessary rotations and translations required to get from camera coordinate system to quadcopter coordinate frame. I would then like to us MAVSDK-Python, to set the quadcopter local position in relation to that camera (assuming I know the location and orientation of the camera or set it to arbitrary location and orientation), so that I can control the quadcopter without the GPS signal.

Can this be done with the information I have? I looked into the mocap commands, but was unable to understand the message format required to implement them:

If I understand correctly, I should set local position with set_attitude_position_mocap() but how are the other 2 used?

If the above stated works, can I then switch my quadcopter to offboard mode and set desired location with offboard.set_position_ned() to set the x,y,z and yaw?

I will be grateful for any advice or recommendations.

Do the comments here help in any way?

I was planning to generate proper Python docs for the API.

Hi @JulianOes
Thanks for the quick response.

Thanks for hint, it seems that all this documentation can be a bit overwhelming for a newcomer like me.

So if I understand correctly, I can set
q = mavsdk.Quaternion(w, x, y, z)
position_body = mavsdk.PositionBody(x_m, y_m, z_m)
pose_covariance = float('nan')­
message = mavsdk.AttitudePositionMocap(time_usec, q, position_body, pose_covariance)
and then
await drone.mocap.set_vision_position_estimate(message)

So the Quaternion and PositionBody I can set to values calculated from rotation and translation matrix.
Given the correct PX4 configuration this would then give quadcopter position information, and it could hold the position I continuously send with drone.offboard.set_position_ned(message2), correct?

What happens when I set pose_covariance = float('nan')­ can the PX4 operate stably with pose_covariance = NaN? Maybe this is less MAVSDK question and more of a PX4 Autopilot question.