[WIP] Intuitive manual position control by mapping stick input to acceleration

[MaEtUgR]

Describe problem solved by the proposed pull request
This is a first draft for a more intuitive manual position controlled flight by stick. Mapping the stick input to velocity generally results in a too agressive flight behavior so often tight acceleration limits have to be applied which result in a too long braking distance and a percieved delay in executing stick inputs.

Describe your preferred solution
Mapping the stick inputs to an acceleration looks promising to solve a big part of the listed problems. It feels more intuitive and guarantees gentle vehicle behavior when being gentle on the sticks while allowing to brake hard in emergency cases by pulling the stick all the way to the oposite side of flight direction.

This task requires changes to the position controller to track an
acceleration setpoint which me and @bresch are working on.

Test data / coverage
This is a draft and not yet ready to fly on a real vehicle. I'm currently testing in SITL with a joystick to see what changes to the position controller make sense to execute these setpoints.

Additional context

• @bresch 's related acceleration feed-forward pr: MC position control - Add acceleration/thrust feedforward to velocity PID controller #12052
• First messy branch I used to thinker around: https://github.com/PX4/Firmware/tree/new-manual-position

resolves #12999

[LorenzMeier]

Awesome!

[hamishwillee]

This is just Position mode MC? When this goes in, can you remind me that we will need to update https://docs.px4.io/master/en/flight_modes/position_mc.html (and a few other pages)

[Pedro-Roque]

This sounds good! But on the other hand we need a good estimation of the acceleration.

I can try to help with this!

[xdwgood]

Looking forward to its merger, in fact many customers want this feature...Better control feel, better PX4 😃

[MaEtUgR]

This is just Position mode MC?

@hamishwillee Yes, it's thought as a replacement option for the current implementation of the manual position mode. At first it will for sure not be default. I will inform you about the behavior and configuration options. Thanks for thinking ahead 👍

This sounds good! But on the other hand we need a good estimation of the acceleration.

@Pedro-Roque Certainly would be good to have a useful acceleration estimate but this pr produces acceleration setpoints to be used in a feed-forward manner for the attitude setpoint generation and is not dependent on a good acceleration estimate.

many customers want this feature...Better control feel, better PX4

@xdwgood Exactly what I've seen as well. Thanks for the confirmation from your side.

[Pedro-Roque]

This is just Position mode MC?

@hamishwillee Yes, it's thought as a replacement option for the current implementation of the manual position mode. At first it will for sure not be default. I will inform you about the behavior and configuration options. Thanks for thinking ahead 👍

This sounds good! But on the other hand we need a good estimation of the acceleration.

@Pedro-Roque Certainly would be good to have a useful acceleration estimate but this pr produces acceleration setpoints to be used in a feed-forward manner for the attitude setpoint generation and is not dependent on a good acceleration estimate.

many customers want this feature...Better control feel, better PX4

@xdwgood Exactly what I've seen as well. Thanks for the confirmation from your side.

Right, I understood now how you do it after going a bit through the code. Sounds good! Will keep an eye on it

[MaEtUgR]

After rebasing unsuccessfully and realizing that it will probably not be mergeable anytime soon because of risk I'm breaking this down into small pieces. Sorry @Stifael for not listening in the first place (#12072 (comment)).
The first part that should be easy to review is here: #13247
I'll update you with the follow-ups.

[LorenzMeier]

I'm closing this.