Include APA parameters in Adjustments tab

[Carticiak]

Current Behavior

Currently, only traditional TPA parameters are adjustable using the Adjustments framework.

Desired Behavior

Add adjustments for APA_POW and FW_REFERENCE_AIRSPEED.

If minimum cruise speed is adjustable, it sees fit that I should be able to adjust this for the APA while tuning mid-flight.

Who does this impact? Who is this for?

Folks experimenting with the new airspeed based TPA

[sensei-hacker]

I don't know if we'll do that or not, but since you're testing APA I wanted to make you aware of two things:

Be careful not to over-tune your base PIFF, leave it some room to work.

Also, we plan to make some changes. The RC4 code scales the I-term, which may tend toward over-control at low speeds. We'll probably be changing it to scale P, D, and FF but not I. So watch for over-control in the RC4 version.

Also, double check your pitot set up -the sock is removed, any tubes are properly connected, etc. The RC4 code isn't robust in the face of bad sensor data. That's the other thing we plan to work on.

[b14ckyy]

my 2 cents on this request:
Since TPA, especially the factor and the time constant, does vary a lot between aircraft builds and has to be tuned by trial and error, it makes sense to have that as in flight tunable parameter.

But for APA, you basically have just 2 adjustable factors. The Reference airspeed that you just set once (where you do the autotune at) and the APA_POW factor that adjusts the speed range.

Afaik the curve itself is based on a physical formula how control authority changes with airspeed. We are just testing right now for more reasonable constraints at super low speed in near stall regimes and to protect from sensor failure.
For 95% of planes that don't fly faster than 200kph, a change or fine tune should not be necessary or even make a difference.

The only way to see if the APA_POW is correct or not, would be to do a flight and maneuvers at different speeds and then you have to analyze the logs to compare the setpoint tracking at different speeds. Based on the errors at high and low speed you can literally calculate the value on point or just take it from that chart:

So if you are on spot at cruise speed but then you have a 10% error between setpoint and gyro rate at 150kph, you need 10% higher or lower FF at that speed to correct for that. So you change your APA_POW to a value that gives you the desired 10% higher or lower attenuation.

Its a one time thing that you cannot really feel or notice in flight at all.

[Jetrell]

@b14ckyy

For 95% of planes that don't fly faster than 200kph, a change or fine tune should not be necessary or even make a difference.

Exactly.
There is a relationship between apa_pow and fw_reference_airspeed .
It's for this reason when fw_reference _airspeed is increase for faster planes that have a higher cruise speed. That it also requires apa_pow to be lowered considerably more. (below 70 if the reference airspeed is increased higher)
So it ensures the lower speed end of the curve doesn't reach its scaling limit before the airplane reaches its touchdown speed.

Using the present RC4 implementation with planes that can reach speeds faster than 200km/h. It's more important to tune apa_pow to account for the lower end of the speed curve than the top end. The top end will just fall inline, with just a little lower stabilization responsiveness.
But this too is also dependent on how tight the user tunes the base gains at the fw_reference_airspeed. If they are real tight. apa_pow would require lowering even more on faster airplanes.

This is why I haven't said anymore in the other thread. Because people presently need to work with the code Shota wrote. Not wish it was different, and tune according to how they want it to work, rather than what it actually requires to work.

However I'm not against @Carticiak request to have apa_pow in the OSD adjustments. It would make it easier to get the tune correct, When I was testing this. I must have took off and landed 20 times while getting the tune correct on just one of the test planes. That's more than most people care to do.

[b14ckyy]

I suggest we keep it as it is for now. We will add fw_reference _airspeed and apa_pow into configurator for easier access. additionally you guys do some final tweaks and optimizations of the feature. After the release we can then monitor how and IF people even need to tune it in real life scenarios.

Its great to have a lot of values adjustable in flight with the Adjustment feature but on the other hand its already so full and so cluttered, that you would actually need to land and change the setup multiple times to do all the in flight tuning you can or want to do.

At the moment, untill we have a better solution, like an OSD Menu controlled with 2 channels over radio push buttons, I would even prefer to declutter and simplify the adjustments, instead of adding more barely needed functions.