LibrePilot Forum
Users => Vehicles - MultiRotors => Topic started by: QAV Jim on September 10, 2016, 02:23:49 am
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Hello. I'm new to FPV. I've been flying RC planes the majority of my adult life, 25 years or so. I flew helicopters for a short period. I'm hooked on FPV.
My first and only build is the QAV 250 with the CC3D. I've been flying for a month of so. I've got it flying pretty OK in rattitude mode but things are not quite right in rattitude. Additionally, acro+ is not flyable...yet. I need help.
My primary concerns:
#1
When in rattitude mode and cruising around, the quad is not steady; it wobbles (mainly forwards and backwards) while in forward flight, not a lot but enough to make video annoying. I've dialed in some expo on the flight controller thinking it was my stick inputs, but I don't think it is the problem.
#2
When in acro+ mode, it is flyable but too sensitive even with 50% expo on the flight controller.
#3
In acro+ mode, there are times when the pitch inputs go crazy (not predictable, or so it seems). What I mean is that it will pitch steeply up (or down, depending on the input) but not in proportion to the input. It's like it "pops a wheelie" for no reason. I can push it down with the control sticks but it is not the desired effect considering the transmitter inputs. In one instance, just flipping the switch from rattitude to acro+ made it do the "pop a wheelie" thing with barely any stick input.
I tried to attach a video but couldn't; not sure why. I'd like to get the flight smoothed out. I'd also like to fix the acro+ mode but don't know what to do to fix it. My goal in the end is to get tight flips into my flying but with smoothness in between.
I've also attached a screen shot of my settings.
Note: Bank 1 I use for rattitude. Bank 3 I use for acro+ (well I don't really use it because I don't fpv in acro+ yet).
I appreciate any input and your time.
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Hello
Your PIDs are low on pitch, I would use easy tune to set the pid right or you could use the new auto tune on the test release.
Also use damping on esc to on small quads
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Hi Jim.
About wobble, you have too low integrals. Please, enable Advanced Stabilization by selecting the checkbox and change the Integral inner loop values for pitch and roll at "Proportional x 3" (at least). I usually set P x 4.
Acro+ is not a linear actuator, you must expect an increasingly aggressive behavior while moving the stick to the maximum deflection, like a sort of expo. It's made to have a well balanced behavior during normal flight, and crazy flip for advanced acro maneuvers. Also, it adds a smooth behavior when you stop any fast rotation.
On Bank3, try to set rate mode response to 200-220 for roll and pitch instead of 300. You can lower the acro+ factor in the basic page if you're not comfortable when smashing on the sticks.
For all I know, you can not attach a video file, but you can put the youtube link ;)
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@ liftbag: I didn't think about a youtube link. Great Idea:
https://www.youtube.com/watch?v=YBRcGI5YdgE
So, to understand what your saying about the "I", if "P" is 216 (roll) and 321 (pitch), "I" should be 648 (roll) and 963 (pitch) if I'm at 3 X P and more if it is 4 X P?
As for acro+, I do understand that it get's increasingly crazy away from center, but at rate or acro+, it does the same pitching. And I'm talking very minimal stick input. It's sporadic where I'll be doing a circuit in LOS and then all of a sudden it doesn't like the pitch stick input and pitches up or down, depending on stick input.
I'm hoping if I fix the "I" and change the rate mode response as suggested, it will solve the problem.
@ hawkview: Can you provide links to the auto tune or easy tune? I found a link to Optune but I don't have a laptop or a transmitter with knob/slider. And my time flying is limited. It would take a while to find that oscillation factor to be able to use Optune. Are the auto tune/easy tune different?
OMG, I'm so appreciative of the input. FPV rocks!
Jim
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@ liftbag: I didn't think about a youtube link. Great Idea:
https://www.youtube.com/watch?v=YBRcGI5YdgE&feature=youtu.be
So, to understand what your saying about the "I", if "P" is 216 (roll) and 321 (pitch), "I" should be 648 (roll) and 963 (pitch) if I'm at 3 X P and more if it is 4 X P?
As for acro+, I do understand that it get's increasingly crazy away from center, but at rate or acro+, it does the same pitching. And I'm talking very minimal stick input. It's sporadic where I'll be doing a circuit in LOS and then all of a sudden it doesn't like the pitch stick input and pitches up or down, depending on stick input.
I'm hoping if I fix the "I" and change the rate mode response as suggested, it will solve the problem.
@ hawkview: Can you provide links to the auto tune or easy tune? I found a link to Optune but I don't have a laptop or a transmitter with knob/slider. And my time flying is limited. It would take a while to find that oscillation factor to be able to use Optune. Are the auto tune/easy tune different?
OMG, I'm so appreciative of the input. FPV rocks!
Jim
You have to adjust rate mode response to tame the rate/acro+ behavior. If 200 deg/S is too much, lower again till you feel comfortable with.
EasyTune requires a knobble like OPTune, then dont seems to be an option for you.
AutoTune is a flight mode that through an evaluative flight routines, generates an optimized PID set on one of the Bank available.
Actually it is implemented in the 16.09-RC1, but still there is no gui. Info here: https://librepilot.atlassian.net/wiki/display/LPDOC/AutoTune
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Did I understand the P/I relationship correctly. In other words take the P and multiply it by 3 or 4?
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Did I understand the P/I relationship correctly. In other words take the P and multiply it by 3 or 4?
Yes, you did :)
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Thanks. I'm retuning as we speak and then will go test.
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Acro+ test this morning with new PIDs and other settings (see the settings in the attached document). The problem still exists but maybe it's because I moved the maximum rate limit to 720!!! Was that not smart?
With the new settins, it felt a little better flying but still sensitive and nimble. I started moving too fast for LOS in forward motion so I started pulling back and back then..., "pop a wheelie"! I'm gonna tune the maximum rate limit to 300 again.
A couple of things I need to confirm:
#1
I checked the "Used Advanced Configuration" box, saved it, disconnected the Flight Controller (FC), and then reconnected. When I saved from the advanced tab and reconnected, the advanced box was still ticked. When I saved the advanced configuration but went to basic to adjust expo, saved, and disconnected from the basic tab, when I reconnected, the "Use Basic Configuration" was ticked when all I had done was move expo (I didn't click the basic box). I don't know if this affects anything. The last time I disconnected I did it from the advanced tab just to make sure it all took.
#2
Am I correct to assume that the "attitude mode response" settings in the advance tab only affect rattitude mode (or attitude if I were using it)?
#3
If I'm correct in #2 above, to get more responsiveness out of rattitude, do I just increase the degrees in "attitude mode response" settings?
#4
Because rate mode is giving so much problem controlling at near center stick, I'm thinking to match the "rate mode response" to the "attitude mode response" settings and then move up from there. Good idea?
#5
Is there anyway to adjust where in the stick motion in Acro+ engages the extra control? I see a place in the expert tab for rattitude but not for acro+.
Thanks.
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Hi
Interesting thread.
If I may :
#4 - if I remember right , settings of 70 for pitch n roll were a good starting place for me when learning rate mode flight.
#5 - yes , back on the basic page - acro slider.
(Also , I suspect that flying in ratitude mode may be a hindrance to getting to grips with rate / acro modes. )
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Frustrating with a capital "F"!
So this last round of testing:
#1
When I came back from flying, the FC did keep the settings. It looks like I have to disconnect from the advanced tab and not the basic tab. RESOLVED
#2
In rattitude mode, I decreased the "attitude Mode Response" setting for pitch to see if it will help with the input just in case it is my own fingers causing the low frequency wobble in pitch in forward motion. I also increased expo. Still does the wobble.
#3
I switch to rate mode instead of acro+ to see if maybe I was getting into that acro+ area on the sticks causing the excessive pitch into a wheelie thing. I also decreased pitch and roll to match rattitude in the "rate mode response". Flying rate was definitely more docile (too docile in fact)...but...it still did the "pop a wheelie" thing but just slower and more subdued.
In fact, the more I fly in rattitude, the more aggressive I'm becoming with the input and I notice it is also doing "the pop a wheelie" thing just to a lower degree than I first experience in rate mode.
So I've tripled the "I" and still am getting the "wheelie". I have the latest version of Librepilot installed. I'm sure I just don't have the PIDs right.
I have the QAV angled extension arms (does that matter?). I can't take them off because I don't have any 5" props. Also, am running the E-max 2300kv motor/ESC combo with the 6x3 blades getfpv sells.
Note: I also have a Blade QX3 350 and am perfectly capable of flying it on its most aggressive mode. This pop a wheelie thing is semi unpredictable which is making flying fpv in rate mode something I'm not yet willing to try.
Thanks again for the input and time.
Jim
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Wait, do you have the motor tilted, how much degrees?
Inviato dal mio iPhone utilizzando Tapatalk
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it says in the ad, 10 degrees.
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it says in the ad, 10 degrees.
Have you set pitch rotate virtual to -10 deg?
Inviato dal mio iPhone utilizzando Tapatalk
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No. Where is that located?
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Found it. Done. Batteries are charging. Let's see what happens. Thanks.
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Put in the -10. It hovers better. The wind had picked, though, so it was hard to gauge what improvements were gained, if any. I kind of liked it when it was off 10 degrees because it was easier to keep it in forward motion without having to feed in some much forward input from the transmitter stick. Either way, it still pitches up but not as bad.
One notable thing, in the wind, it oscillated. I haven't had oscillation issues until flying today in the wind.
I'll keep working on the PID. That's got to be where the issue lies. It looks like what I need to do is borrow a laptop, take it to the park, and start from scratch, get it to oscillate in no wind, and then use the PID calculator.
I didn't know about PID adjustments until after I made the purchase, had I known...nah, I still would have made the purchase.
Any additional direction to resolve the issue is appreciated.
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Old thread, but this may help someone.
When you are flying forward and decide to slow down but it "Pops a wheelie", that is caused by PIDs being too low. The "I" term on roll and pitch in particular.
You should never use your transmitter trims. Ever. It is OK if you must, but put them back to ZERO and fix what is wrong. If Attitude mode drifts, you need to adjust GCS->Configuration->Attitude->Settings->RotateVirtual
RotateVirtual:
if it is drifting forward you subtract from pitch
if it is drifting left you subtract from roll
etc
If your FC is not mounted in the same plane as your props (commonly called race mount motors) then you must adjust RotateVirtual as above. If the motors are tilted 10 degrees forward then it is drifting forward very fast and you start by subtracting 10 degrees from pitch. After this, in a hover, the prop blades will be level and it will not drift, but the main body will be leaning backward 10 degrees. This is normal.
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Old thread, but this may help someone.
When you are flying forward and decide to slow down but it "Pops a wheelie", that is caused by PIDs being too low. The "I" term on roll and pitch in particular.
It is helpful to the original poster. Thanks.
Since I last commented on this thread, I purchased a Taranis and used transmitter nobs and Optune to find my current PIDs. Though it flies better, it's still not right. It will still "pop the wheelie" but is more predictable and less aggressive when it does it.
I'm at work and would like to post my current PIDS and a short video and get suggestions on where I need to go when I get time. Life is crazy busy right now.
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EzTune / OpTune is currently the best way to tune CC3D, but pop a wheelie sounds like you could just assume a bit bigger UOV and use those numbers, or just increase the pitch and roll "I" term till it is better or oscillates a little.
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Attached are my current PIDs