[gionibravo]

Hello,

I am new in this hobby which i like very much.

I just built my first quad with the following setup:

 - Reptile 500 frame
 - SunnySky 2212-13 980kV motors
 - Turnigy dlux 30A ESC
 - 1045 Props
 - 3000 mAh 3S LiPo
 - Revolution Board

I built the quad as best as i could.
I made the wizard, than i made all the calibrations, including the temperature calibration.
I balanced the CG as best as i could.
Then i have made the first flight.
I was impressed that the quad was able to fly pretty good
But i noticed 2 problems

STABILITY

Drifting
After I take off the quad seem to drift forward, backwards and sideways as well, but mostly forward. I trimmed the stick at maximum, but with no effect.
In flight it feels pretty manual, like a 40$ quad from ebay, I want a more assisted feel. I played a bit with the PID tunning on bank 2, but I don`t know the best way to do it,
mostly because all tutorials i can find are on different platforms.

Throttle
Another problem is I can`t make the quad hover. It just ascends or descends.
On the throttle stick i found the spot where it slowly ascends and the spot where it slowly descends, there is no spot in between.
Its either ascending or descending.

ALTITUDE HOLD
I tried altitude hold mode, but it just bursted up and down rapidly.
I tried altitude vario mode, but it just ascended really fast, in bursts (throttle stick in the middle), i got scared and put the throttle at 0, but then the motors stopped so it crashed.
That was my mistake, I should`ve switch to manual throttle mode.

So this being said, now i am waiting for my replacement arm and motor.
After I get them I hope I will have enough information to fix these problems.
I really want to squeeze the best experience that i can from this controller.
But the information on the internet is pretty specific for certain situations.
I could`t find something that suited my situation.
So I beg you, experienced craftsmen, help this newbie guy.   

[Mateusz]

STABILITY

Drifting
After I take off the quad seem to drift forward, backwards and sideways as well, but mostly forward. I trimmed the stick at maximum, but with no effect.
In flight it feels pretty manual, like a 40$ quad from ebay, I want a more assisted feel. I played a bit with the PID tunning on bank 2, but I don`t know the best way to do it,
mostly because all tutorials i can find are on different platforms.

#1 are your PIDs tuned ? https://librepilot.atlassian.net/wiki/display/LPDOC/TxPID
#2 Is the copter well balanced, are the propellers damaged/balanced ?
#3 Do you have vibrations ? Did you try increasing filtering in sensor tuning (GCS->Stabilization->Expert) ?

Throttle
Another problem is I can`t make the quad hover. It just ascends or descends.
On the throttle stick i found the spot where it slowly ascends and the spot where it slowly descends, there is no spot in between.
Its either ascending or descending.

There is a throttle curve in GCS->Vehicle, you can flatten a bit middle to have more resolution in that area, at expense of high and low throttle being more step. I do that for altitude hold, so I can find the spot more easily.
https://librepilot.atlassian.net/wiki/display/LPDOC/Vehicle+Configuration

ALTITUDE HOLD
I tried altitude hold mode, but it just bursted up and down rapidly.
I tried altitude vario mode, but it just ascended really fast, in bursts (throttle stick in the middle), i got scared and put the throttle at 0, but then the motors stopped so it crashed.
That was my mistake, I should`ve switch to manual throttle mode.

Altitude is maintained by PID controller, which means it may be optimal for one copter, but not for another. Sometimes may need some tunning, as there are no universal values that fit every build.
Have you checked https://librepilot.atlassian.net/wiki/display/LPDOC/Altitude+Hold ?

[@marc]

As for the Altitiude Hold, the Default Values are not good for a big Quad. I have one similar to yours, here are my AH values as a starting point for you:

[startrek66]

For throttle curve see link
https://r.tapatalk.com/shareLink?url=https%3A%2F%2Fforum%2Elibrepilot%2Eorg%2Findex%2Ephp%3Ftopic%3D2043%2E0&share_tid=2043&share_fid=1037713&share_type=t


Inviato dal mio SM-G800F utilizzando Tapatalk

[startrek66]

Altitude hold performance depend directly by quality of baro sensor. Read this link

https://forum.librepilot.org/index.php?topic=311.0

I hope that help you.


No need to quote all previous post

[hwh]

... I trimmed the stick at maximum, ...

In addition to all the advice given above, if you touched the stick trims you need to set them all back to center and then rerun the transmitter wizard.  Never touch the trims when using a flight controller of any kind.

[gionibravo]

Thank you all for all the feedback. After I get the new arm for my frame, i will try all what you guys told me, and i will get back to you with the result.

I really appreciate all the tips u guys gave me. And I thank you very much!!

Sent from my Nexus 6P using Tapatalk

[TheOtherCliff]

I have this same setup.  I suggest that you use default PIDs.  Do not use some cloud PIDs or someone else's PIDs until you try default PIDs.

Flying just takes practice.    The best you can do is to get it to drift as little as possible.  Like driving a car if you take you hands off the wheel it will drift into one ditch or the other. 

Throttle is the same way.  There is one exact stick location where vertical is mostly motionless.  Any little bit above or below and it is climbing or descending.  Adding some "exponential" will make this center spot a little wider and easier to hold, but I recommend that you try without expo.

Vibration is an issue that beginners try to ignore.  You absolutely must balance each new prop that you put on it.  You also must rebalance any prop that gets a chip out of it.

For starters use what ever stab mode is set up to be Attitude with manual throttle.  Take off from a level place and don't let it get more than waist high.  Never change your transmitter trims.  Does it drift?  If so, use Configuration->Attitude->Settings->RotateVirtual to correct it.  If it is drifting forward you subtract from Pitch.  If it is drifting left you subtract from Roll.  Etc.  Start with changes of 3 or so and see how that works.
Repeat.  After a few times, it should hover without much drift at all.  Now it is a lot easier to learn to control the throttle.

When you get it flying well and have learned to hover it, you can change from Manual to ALtitudeVario for your Attitude thrust mode (better than Hold because you can drift up or down, but center throttle stick is Hold).  Baro must be covered with open cell foam to keep light and tiny puffs of air out.

Good Luck. 

[gionibravo]

Thanks for the tips.

As soon as i replace the broken arm, I will do the following:

1. Balance motors and props. (Already did that)
2. Set PIDs to default, than try to hover it, correct any drift with RotateVirtual.
3. Set an expo on thrust to help me get find the hovering spot.
4. Try alt hold and vario, my revo board was shipped in a case and some foam on the baro, so i think that s enough, if the alt won`t be hold as i desire, i will try and change the settings in GCS. I will start with flachskopp values and go from there.
5. I will use TxPID to tune my PIDs untill i get the locked in feeling.

Is there something i missed?
What about the sensor filtering? Should I use that as well?
How about the TxPID, is easytune any good, or should i use normal Kp, Ki for pitch and roll?

I want to use it for photography, getting a locked in feeling and a very easy to control craft is crucial for me.

[startrek66]

Your check list is ok. Remember the throttle curve. You can check the quality of baro using a scope tab in gcs.

Inviato dal mio SM-G800F utilizzando Tapatalk

[TheOtherCliff]

The version called "next" (and the coming release) have AutoTune built in.  When you use it, it sets the PIDs for you.  AutoTune has a feature called SmoothQuick that you use after tuning.  You configure SmoothQuick onto an accessory0-3 knob (transmitter auxiliary channel configured as an accessory0-accessory3 in the FC) and adjust the knob for smoother flight.  You can even leave the SmoothQuick knob permanently configured so you can always change it.  See AutoTune wiki.  There is a forum user who builds next and posts it if you can't build it yourself.

Another thing, automated GPS position hold (velocity roam is more useful) and baro altitude hold (altitude vario is more useful) can be a little jumpy depending on GPS used (DJI/Naza has smoother settings built in) how the GPS is configured and how well the baro is covered and configured.  GPS and baro are good to keep you in one place, but for smoothest photography you may want to use simple Attitude mode with manual throttle with very slow and smooth fingers.

[gionibravo]

The version called "next" (and the coming release) have AutoTune built in.  When you use it, it sets the PIDs for you.  AutoTune has a feature called SmoothQuick that you use after tuning.  You configure SmoothQuick onto an accessory0-3 knob (transmitter auxiliary channel configured as an accessory0-accessory3 in the FC) and adjust the knob for smoother flight.  You can even leave the SmoothQuick knob permanently configured so you can always change it.  See AutoTune wiki.  There is a forum user who builds next and posts it if you can't build it yourself.

One knob for PID tuning sounds very good, but the process to obtain this looks very complicated.
I think it s easier for me to use easytune on TxPID or just classic tune with trial and error. 

I will do my best to tune this quad for the most stable flight, i will add gps for return home function, and if i am not happy with the result i will switch with DJI Naza and I will keep this one for a later FPV racer.

[TheOtherCliff]

It's not really even one knob for PID tuning.  It's one knob to change the tuned PIDs more towards smooth or more towards quick.

[gionibravo]

I understant.. but still it seems complicated. But ehat about filtering for acc and gyro. On the tooltip sais that it should make the quad more stable.. but how do i know if i should add it or not, and how much.

Sent from my Nexus 6P using Tapatalk

[TheOtherCliff]

Gyro and Accel filters are only useful to fix vibration issues.  They slow down the quad reaction.  That can be done other ways, like setting the two max rotation rates.

I would say don't use them unless you are fighting vibration issues that you can't fix with a good rebalancing of props.