Get drone's reference state with MAVSDK-Python

Hey,I’m new to drone development.And I’m trying to write a drone instability detector by calculating the difference between reference state and observed state with MAVSDK-Python.
I can get done’s observed station by System.telemetry.position() and System.telemetry.attitude_quaternion(). But how can I get the reference state of the drone?
I’ve read the c++ documentation but found nothing useful.
Any reply would be appreciated:)

Hello! :blush:

I am not sure what you mean by “reference state of the drone”. Which MAVLink message would you expect to receive?

Thanks for reply!
Well I’m not clear which MAVLink message it is.
I once used V-REP in a quadcopter simulation, in which it used a virtual ball to represent the drone’s reference state. It shows the drone’s target position and attitude, which are used in PID algorithm.
I need the reference state because I’m working on a drone stability detector. And in a paper, the author used PX4 + gazebo + mavsdk to calculate the difference between reference state and observed state, and further finished the detector.
In a word, the reference state is the drone’s target position and attitude.
If there exists another way to detect the stability of the drone, I’ll be happy to know about it.
Thanks again! :grinning: