Hallo Reiner,
I think we have a lot in common, especially when it comes to flying helicopters and our age-related reaction times. Like you, I’m successfully training with a 250mm helicopter in my backyard.
Our interests in autopilot are also similar. The focus is on helping with attitude stabilization.
I’ve been working with the Arduino software for a little over a year, although I haven’t really used it in a helicopter yet.
I’m convinced the software is very sophisticated when combined with the right hardware flight controller. But it’s also very complex, so making your own modifications can be very risky, especially with helicopters.
Here, however, the software also offers good help via so-called LUA scripts, where you don’t change the Arduino firmware itself, but instead run scripts on the FC for initially simple functions. I’m convinced this is easy to learn for someone like you, although I haven’t tried it myself yet. The only requirement is a sufficiently powerful FC based on an STM H7 controller, of which there are plenty recommended here.
Hy Juergen and all the others !
Besides the very interesting technical diskussion, I want to say thank you for the “worm welcome” in this forum.
In german forums, language and behavior are pretty rough, people tend to insult each other. The respectful and cultivated conversation here is very pleasant !
On topic :
I think, i will order an MATEK STM32-Board as recommended above. It’s not open source, but i think this doesn’t matter, because i have no intention to modify hardware.
Loading Ardupilot will be possible for me, i hope, and for experimenting with own software, i had the idea to do it in python.
Clicking on the icons of other users, i can read a bit about the persons, their professional history and so on. but i can find no way, to edit such a text on my profile.
A good choice for any Ardupilot vehicle.
Hallo Reiner,
Exceptionally answer in german
Es gibt auch freundliche deutschsprachige Foren, ich bin in so einem als Moderator tätig :-))
Wenn Du Deinen Profilbutton oben rechts anklickst, öffnet sich ein Menü mit einer Symbolspalte rechts. Dort das unterste Symbol das Persönchen (profile) anklicken. Es öffnet sich Deine Profilübersicht.
Dort gibt es wieder eine Menüzeile mit dem Zahnrad (Preferences) ganz rechts. Anklicken. Es erscheint unterhalb dieser Menüzeile eine weitere Untermenüzeile. Dort den 3.Eintrag “Profile” anklicken.
Und schon kannst Du unter “About Me” weitere Eingaben zu Deiner Person machen und weiter unten auch zusätzliche Angaben, Profilbild etc ändern.
Darf ich Fragen aus welcher Region Du kommst?
Ist es unhöflich, deutsch zu antworten ?
South of munich, near starnberger see.
was a bit tricky, adding more lines in profile. now i did only two lines, and it works 
Hy Juergen,
in your profile, you mention experience with gps. your’re the expert for my question.
i cant’t find detailed information, how ardupilot does “position hold”.
even in theoretical view, it see no possibility, to measure the horizontal position by gps with enough resulution. we need, as a proposal, +/- 10 cm if we talk of “stabilisation”. gps never gives such precise values. even fusioned with acceleration and filtered in x and y, there is no way.
optical systems, like 2-dimensional correlation (like the mouse does it), are critical too. when flying over surfaces with no optical characteristics, like short gras or a street surface, or still water, it will (and does in my experiments) not work.
so : how does position hold work ??
Hy Reiner,
Oh, it is correct that I worked long time in the field of GPS but not on the +/- 10cm level so I am not your expert in this.
So I can’t answer what algorithm ardupilot is using for “position hold” but also it is an interesting question and hopefully one of the ardupilot developers can answer this in simple words for us oldies.
The EKF3 fuses data from baro, GNSS (GPS), accelerometers, gyros and compass to do the very accurate position hold.
thanks a lot for this answer.
since baro is not important for horizontal moves, and gyro / compass will not resolve horizontal position in first view, acc seems to be the most important signal.
is there any writen dokumentation besides the code, which explains in simple words the structur of this fusion-method ?
@kannix I am glad that you are receiving a warm welcome from our community. I am the code co-maintainer for the helicopter vehicle. @Ferrosan is the other code maintainer for helicopters. Most of us do this in our spare time so don’t feel offended if you don’t hear from us immediately.
Regarding your question on GPS, as @amilcarlucas elluded to, the code uses an Extended Kalman Filter (EKF) to provide position and velocity estimates. It also provides attitude estimates as well. As you know, it does this through sensor fusion. The details of the EKF can be found in our wiki here. In my personal experience, the EKF with a regular GPS was able to achieve +/-30cm and the EKF with a Real-Time Kinematic GPS was able to achieve +/-3cm. The RTK GPS uses a base station to provide corrections for the GPS on the vehicle. It is very impressive.
wow, this is reraly very impressive !
the kalman filter is, in my eyes, beyond “hobby”-software programming. i didn’t know that the estimates made by this filter can reach such high resolutions. I tried it with fusion of acc and gps, then filtered by simple digital filters, and better than 1m was never reached. i will read - and try to understand - the theory behind your link. thank you one more time !
@abenn1 :There are ten or more flightcontrollers available on matek-page.
The only one dedicated especially to helicoters is a type for flybarless helis, a function i don’t need.
which one do you use ?
I use H743WING in my 3 helis. To my knowledge no flight controller is model-specific (even though their names may imply it), for it’s the Ardupilot version that determines what type of model it’s good for. I also use a H743WMN in a fixed-wing aircraft.
The H743WING just fits between the side frames of my Align TRex 500s, but I prefer it over the H743WMN because it has a power distribution board and can run directly of a 6S LiPo. It also has an SD card slot so can store more logs than the WMN.