[Mateusz]

Another successful movies, author says "VtolPathfollower all defaults"

Position Hold


Autonomous flight


Sounds pretty windy, but looks good.

I think I probably could have it flying rather good in Complementary mode if I tweak the PIDs.

Regarding your case though, I don't see how GPS would fly any better, if it does not fly well in Complementary in the first place. If your control PIDs are off, no matter what you do with sensors they won't be any use if your control loops are not tuned.

[hwh]

Another successful movies, author says "VtolPathfollower all defaults"
...

You don't recognize the backyard from other videos?   That's by Laurent, f5soh in this forum.

[Mateusz]

You don't recognize the backyard from other videos?   That's by Laurent, f5soh in this forum.

The point is that all those modes work in LibrePilot 15.09 and there is nothing wrong with the software. What might be incorrect though is expectation that GPS is able to magically fix everything, including tuned PIDs for control loops. It really must fly stable in Complementary mode in the first place, before adding more sensors. More sensors wont help if your control is lousy.  The LP software is pretty advanced and sometimes some tuning is necessary. It is the case for every build, that sometimes default parameters are not optimal for this build, as you can't just cover all, and require some extra care. If it works out of the box well lucky you, if it does not then it needs some patience and learning. Maybe some other system will have default parameters fitting your build, but you don't learn to solve problem this way, instead you changed conditions without knowing why it didnt work in the first place. If the problem happens again with other flight controller using similar algorithm (very likely uses PIDs and EKF), you still can't solve it. If I wanted an aircraft that is plug&fly I would buy DJI, guys there are really smart and make awesome products. It's just not my cup of tea. If you want help on forum, please ask you are welcome and everyone here is glad to help, but if you come to say it does not work, I give up or buy another product... it feels hopeless and strange

[f5soh]

You don't recognize the backyard from other videos?   That's by Laurent, f5soh in this forum.

 

I need to choose another place to fly 

[TheOtherCliff]

I'm using Beitian-880 GPS ... If I move the revo, the gps in GCS immediately goes red and shows no fix,

GPS problem (indoors there are multipath issues and you may loose your fix) or wiring problem (connection comes loose).

Red simply means that the GPS is telling the FC that it doesn't have a usable fix.

[micaelkarlsson]

I'm old and stuborn. I put togehter a hexa copter during weekend (kongcopter) and attached the flight controller to it. I have adjust the pids (read another thread here in forum) but I have the feeling it behave exact the same as with my small 450 quad. This weekend I was out and flew my APM2.6 based quad and brought my hexa but after a friend looked at it and we did some testning. I hold it over my head and he tried to controll it but we both had the feeling it it would crasch. Perhaps it is the antivibration plate who make the motorn sudently speed up and behave nervously?
Could i post a logfile here and someone could take a look at it?

[f5soh]

Not sure this is the best place for APM log analysis.

The sure thing, regardless of board/system used: Never hold a multicopter over your head, that not safe !

[micaelkarlsson]

Not sure this is the best place for APM log analysis.

The sure thing, regardless of board/system used: Never hold a multicopter over your head, that not safe !

No, I didnt mean the APM log. I meant Revo log. If I run the motors and collect some info in the logfile. If someone could help me analyze them.

[f5soh]

This weekend I was out and flew my APM2.6 based quad and brought my hexa but after a friend looked at it and we did some testning. I hold it over my head and he tried to controll it but we both had the feeling it it would crasch.

Sorry i understand you flew a APM with your friend

Whats your issue ?

[p25o1]

ok just to give my experience

i managed to get it to work



Openpilot revo running 15.02.01
V9 gps , zuul frame, 1900kva motos, 6" props, 4s, Kiss esc.

GPS is enabled as assisted flight option,
this way its only active when sticks are neutral.
allows me to fly in my usal mode, and have a safety net if i lose control :-)

it was a long process to get it working ,

it came down to getting the calibration process done 100% and keep the orientation of the quad consistent through out the process.
go to an open area to get a faster GPS fix.

doing all this multiple time using a laptop in an open filed is not ideal

so an android GCS will really really help.

[TheOtherCliff]

Unfortunately GPS setup is a picky technical thing to get it right.  A correctly set up quad with an easy GPS flight mode is much easier to fly than a quad without GPS, but you need to get it flying without GPS before adding GPS, and it is very important to be able to fly it without GPS in case there is a problem.

Instead of using Attitude mode with GPS Assist, I recommend that you try Velocity Roam mode.  Truly anyone can fly that the first time they try.

[Lazaros]

...The flight controller and the thin mu-metal plate is tight togheter with the frame but I didn't removed the rubber dampers. I really don't Think thats the issue.

Have you tried mu metal with an external mag ? Mu-metal is supposed to do an excellent job in magnetic shielding

[f5soh]

Mu metal is a bad good idea but in our application we still need to measure the world magnetic vector.
Put external Mag away from strong currents and mag is not disturbed anymore.

[micaelkarlsson]

Hi Lazaros !

No, I have not tried external mag. I have a UBLOX m8n and if I understand it right I should wait for next release of libre to be able to use that external mag wich is included in the GPS.
However I bought a Pixhawk and have mounted it on the hexacopter and what I can see so far everything is ok. Everything works perfect out of the box, same as with my two other APM flight controllers.  Pretty easy to install and configure and they work with GPS. I admit I'm not enough skilled to build and configure librepilot based multirotors.
Perhaps I save the Revo to another day or perhaps I sell it. It's soon summer here I want to spend most of the time outside and fly.

[Mateusz]

Regarding your Revo problem.

The LibrePilot software uses 3D magnetometer (all three axis of space), in contrast APM uses only 2D magnetometer.
It makes no difference with Complementary, but EKF benefits greatly from getting more data as it makes estimates more accurate. On another hand, less data as in 2D case, makes algorithm more robust to noise.

If you don't include noisy measurements, your estimates won't be affected. The EKF is designed to deal with noise but to certain level, it just mixes best of all sensors. If one of your sensors gives total crap it just wont make it better. As people hinted on forum, your nu-metal may distort subtle magnetic earth field, your internal magnetometer might be affected by switching components or power wires.

The solution for this is either not to use EKF, or use external magnetometer, twisted wires if necessary, proper outdoor calibration and no nu-metal thingy, that may distort subtle earth field.