LOCKED IN FEEL
« on: November 06, 2017, 03:44:25 am »
Hello i would like to ask how to achieve a locked in feel when flying free style fpv here is my setup:

DYS excite 250 frame
20A esc
2600kv racerstar 1806
3s 2200
foxeer 1200tvl
eachines vtx
5x3x3 prop
cc3d


Re: LOCKED IN FEEL
« Reply #1 on: November 06, 2017, 03:50:34 am »
is it possible to achieve locked in feel in attitude mode or only in rate mode?

Mateusz

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Re: LOCKED IN FEEL
« Reply #2 on: November 06, 2017, 07:35:57 am »
is it possible to achieve locked in feel in attitude mode or only in rate mode?

Can you describe "locked-in", so it's easier to figure out what you expect and what is happening ?
I don't think anyone is able to help with the "feeling" it's very personal, but if you describe how it should behave, then we might help.
Which version of LP are you using ? Can you make video and tell what is wrong ? Are you using Always Stabilized When Armed feature ?

But to answer your question, I believe properly configured LP copter feels no different than properly tuned betaflght. My colleague gave his LP copter to BF pilot who said he feels no difference.

Re: LOCKED IN FEEL
« Reply #3 on: November 06, 2017, 07:55:23 am »
No drifts on maneuvers, quad seems to be fluid in motion, smooth, locked in / precise on maneuvers

im using latest libre pilot, so  any inputs on how to achieve this? higher P higher I D? higher all PID? i know PID but i want to hear from you guys so i can consolidate all information

thanks in advance

Re: LOCKED IN FEEL
« Reply #4 on: November 06, 2017, 08:16:48 am »
Aside from aerial photography where the pilot is willing to sacrifice some amount of quickness in control for more smoothness, there is really only one correct set of PID settings.

Tuning PIDs manually (CC3D doesn't have room for AutoTune code) is somewhat of a black art.  People do it differently and in my opinion many don't get the best PIDs, but do get acceptable PIDs.

If I'm not mistaken, CC3D (Complementary=Basic AttEstAlgo) will always have a problem with levelling (Attitude mode or camera gimbal) in some cases. E.g. if you fly a quad for several minutes in the same direction (really only happens in non-local FPV), you must bank it forward the whole time.  The problem comes in that after a while, it considers that bank angle to be level and you have to use more and more forward stick.  This happens with Attitude mode, but not with Rate mode.  Properly tuned PIDs (and other settings) minimize this, but don't eliminate it.  Revo FC has INS13 that adds 3D mag support that can do this more correctly.  This is one big reason why experienced FPVers fly various versions of Rate mode.
« Last Edit: November 06, 2017, 08:38:17 am by TheOtherCliff »

Re: LOCKED IN FEEL
« Reply #5 on: November 06, 2017, 09:05:52 am »
Thanks Cliff! very informative

Mateusz

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Re: LOCKED IN FEEL
« Reply #6 on: November 06, 2017, 09:38:00 am »
No drifts on maneuvers, quad seems to be fluid in motion, smooth, locked in / precise on maneuvers

im using latest libre pilot, so  any inputs on how to achieve this? higher P higher I D? higher all PID? i know PID but i want to hear from you guys so i can consolidate all information

Hi again,

  • drifts on maneuvers - On this one, I as far as I know in rate you are only using gyro and gyro by design, it's property has some drift that cannot be detected without other sensors. However if your copter is really unstable, you might need to tune PIDs or maybe you have vibrations ?
  • fluid in motion - Might be rates you set in advanced panel you should increase defaults to something like 900deg/sec, default is for general flying and you want higher for racer.
  • precise on maneuvers - I think you need to play a bit with expo curve, there is new expo curve probably coming, but testable in dev branch from mindnever which is a bit sharper in the middle, current expo is a bit too flat in the middle, but try playing with it, so you get more sensitivity.

Regarding increasing/decreasing gains, I don't know, really depends on copter setup

You didn't answer whether you use ASWA (Always Stabilized When Armed), it has bug and zeros I term at low throttle, which sometimes can cause problems when you dive and decrease throttle.
Consider testing with "next" branch which has this fixed.


Re: LOCKED IN FEEL
« Reply #7 on: November 06, 2017, 09:51:24 am »
Thanks for the info Mateusz

my quad is stable actually no over vibrations but sure there is vibes from
motors but very small and its tolerable have no effect on flight since i tested flying indoors no drift, i get drift outdoor when there is wind, so it think ill get my self GPS? or is there any other way to stay put and fight winds by just PID?

ill try the rates you recommend thanks

yeah thanks been playing with the expo since yesterday im just
finding my sweet spot


nice video i watched that before thanks!




no i dont use ASWA hehehe :)

Mateusz

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Re: LOCKED IN FEEL
« Reply #8 on: November 06, 2017, 11:40:04 am »
motors but very small and its tolerable have no effect on flight since i tested flying indoors no drift, i get drift outdoor when there is wind, so it think ill get my self GPS? or is there any other way to stay put and fight winds by just PID?

It really depends what you want to do. Flying racer with rate is completely different experience than flying Attitude with autonomous functions.
When you fly rate, the controller will by-pass outer-loop (we have dual-loop PID controller) and will use just gyro alone (inner loop only) without any other sensor, so whole system works like single loop PID controller. When you fly Attitude it will use both loops and can use all sensors. For INS13 you need all sensors, not just GPS. Actually GPS is the least important sensor with least accuracy. You also need Magnetometer and Barometer properly calibrated and functional. Autonomous flight modes are just more complex and tricky.

Also keep in mind that while flying Attitude you will learn bad habits towards Rate style. If you just want to fly racer, stick to Rate and Complementary Basic. If you want autonomous flight-modes for photography or other tasks, well that's big topic in itself and you might consider INS13. Also GPS does not work indoors or close to tall buildings, due to multipath reflections which confuse it and you would get spikes hard to filter out as they look as valid signal.

If you have a racing copter, stick to Rate, much more fun and more control over copter, sharper turns, it's actually the proper way to fly it.
Just check rates you have and expo on roll, pitch, yaw.

mr_w

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Re: LOCKED IN FEEL
« Reply #9 on: November 06, 2017, 01:01:00 pm »
@Mallowsthecat

Do you have some reference build to compare yours with, or this is based on "locked in feel" talks on web? For example, I have hesitated to try copters builds by other people, using other firmware for quite some time, actually until I was sure that my piloting skills were good enough that I'd not only notice the difference, but good enough so I could see what exactly I have to change on my LibrePilot builds.

What I came with so far,  is .. (maybe I have said that in some other thread here):
1. To beging with, PIDs must be really tuned. Autotune does this well. Except if there are excessive vibrations. Sometimes you also need to play with Autotune's smoothquick feature. This is easy to do if you use TX pot for changing it.
2. ASWA (AlwaysStatbilizeWhenArmed, or Airmode in other firmwares) must be turned on. That is really mandatory. If it was only me, I'd make it be ON by default.
3. Expo and rates: you need to have fine control, but also ability to be fast when required. Given the limited TX stick travel, you are bound to use high rates and suitable expo setting.

Now about some unfortunate stuff with LibrePilot:
- if you use 16.9 release, ASWA mode will be broken. It will give impression that it is working, but not quite what you expect it to do. You need to use next to have it fixed.
- expo - as Mateusz said, but I will rephrase - LP expo curve sucks. It is not good at all. You can play with it, but it won't give good results, well not even nearly comparable to other firmware (Betaflight for example.).

This is as of today. All of this might change soon, or not. The more we talk about it, the bigger chance it gets fixed :)

Re: LOCKED IN FEEL
« Reply #10 on: November 06, 2017, 01:11:15 pm »
If I'm not mistaken, in LP 16.09 you can simulate a correctly working ASWA by simply increasing the throttle trim so that the motors always spin at lowest throttle stick.

mr_w

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Re: LOCKED IN FEEL
« Reply #11 on: November 06, 2017, 01:49:54 pm »
If I'm not mistaken, in LP 16.09 you can simulate a correctly working ASWA by simply increasing the throttle trim so that the motors always spin at lowest throttle stick.

yes, I forgot that one - you are right, that is completely valid workaround for 16.9

(although, this is possible only because of other code changes that went into LP at the same time with ASWA).


Re: LOCKED IN FEEL
« Reply #12 on: November 06, 2017, 04:32:04 pm »
LP expo curve sucks. It is not good at all. You can play with it, but it won't give good results, well not even nearly comparable to other firmware (Betaflight for example.).

I don't use expo.  I feel that it defeats reflexes / muscle memory because different stick angles have different sensitivity.  That said, what is wrong with the LP 16.09 expo?  It would seem to be something fairly straight forward to implement.  :)

Mateusz

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Re: LOCKED IN FEEL
« Reply #13 on: November 06, 2017, 05:44:04 pm »
LP expo curve sucks. It is not good at all. You can play with it, but it won't give good results, well not even nearly comparable to other firmware (Betaflight for example.).

I don't use expo.  I feel that it defeats reflexes / muscle memory because different stick angles have different sensitivity.  That said, what is wrong with the LP 16.09 expo?  It would seem to be something fairly straight forward to implement.  :)

Expo allows to have more fine control in the middle of the stick. At least that's what it is suppose to do.
LP expo is indeed exponent function, which is real exponent, but that's not really what you  want for flying. Other firmware like BetaFlight uses something called SuperExpo, which is not real exponent function, it's something else but has similar shape, though more favourable properties in the middle of the stick.
Two functions ported and rendered here https://mashu.shinyapps.io/Rates/  (Give it up to 1min to render and you can pull sliders).
You can see our LP function has middle too flat (unresponsive) while that pseudo-expo function from BetaFlight has more favourable behaviour. It just feels better and we both are flying this code, it's in @mindnever's branch for Omnibus. I hope this can be merged soon.

Of course this is nerdy detail and people used to fly great with old code, which in fact comes from OP, but it would be nice to have that better behaving expo :)

Re: LOCKED IN FEEL
« Reply #14 on: November 06, 2017, 07:56:49 pm »
Flat at center stick like that would suck very badly, and there is always a flat spot.

BF isn't good either.  It lets you configure it so that the curve doesn't go through the corners of the graph.
« Last Edit: November 06, 2017, 07:59:50 pm by TheOtherCliff »