[WIP] adaptive hover-throttle for altitude control

[cmic0]

Describe problem solved by the proposed pull request
This PR is a first draft for an altitude controller that takes into account parametric uncertainty of MPC_THR_HOVER by exploiting an online hover-estimator.
With the current architecture, the user has to properly set MPC_THR_HOVER to the actual hovering throttle to get reasonable altitude tracking performances. If such parameter is not properly set, the user may experience poor altitude-tracking performaces or even worse flight instability.
Further discussion about this issue is referenced in this issue.

The (draft)-solution suggested here takes inspiration from Adaptive Robust Control designs, where an adaption law is used for estimating the new operating point.
A projection-type adaption law is used to estimate the hover throttle, which replaces the static feedforward action defined by MPC_THR_HOVER.

With the adaption law in place, problems such as

• changes in vehicle's payload
• higher hover thrust when batteries are low
• parametric uncertainties

should be fixed.

This is PR is a draft to test the behavior of the adaption law, further work to have a clean architecture is still required.

Open questions for discussion:

• which initialization value use for the MPC_THR_HOVER?
• Should the parameter be updated after the flights?
• How to provide the info to the landing estimator?

References:

• Robust and Adaptive Control With Aerospace Applications

• Adaptive Robust Control (ARC) for an altitude control of a quadrotor type UAV carrying an unknown payloads

• Advanced Motion Control: From Classical PID to Nonlinear Adaptive Robust Control

Test data / coverage
I'm currently testing in SITL with a joystick to evaluate the effects of the hover estimator against the original implementation. Flight testing logs will be provided soon (still need to get them from the vehicle).
During the tests the hover estimator was published in vehicle_local_position_setpoint/hover_estimation.
Hover estimator is enabled by setting MPC_HOV_EST_ENto 1.
Tuning parameters:
MPC_HOV_ADT_RATE
MPC_HOV_EST_P

FYI @MaEtUgR @bresch

[stale]

This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.

[bresch]

Closing as there is no further work on this PR. I'll open a new one once I have something working (work in progress here: Auterion/Flight_Control_Prototyping_Scripts#3)

[MaEtUgR]

Hover thrust estimator added in: #13981