Toilet Bowl

[Kilby]

Hey gang,

So I have a small problem that I don't seem to be able to solve. I'm gettings some pretty bad toilet effect on my F550 Hexa w/WK. The build is pretty new (last couple months) and to be honest, I don't know that this problem hasn't existed in some form since I've built it. At this point, I've tried to change the settings in the assistant (mounting & autopilot) and also rotated the GPS on it's mount (that worked on an old build). Nothing seems to help it out. I've double checked that the craft is balanced and that my mounting settings are as close as possible. Still, no matter my efforts, I get a counterclockwise toilet bowl about 20-30 feet across.

The only other thing that I can think of is the GPS mounting itself. For this build, I've lowered the GPS unit so that i sits just a couple of cm off the main frame plate, dead center. Could I need to raise that up a few more cm with a longer mount? I have noticed that it seems to take longer than normal to get full sat lock, so maybe the mount needs to be raised?

Anyone have any input? To paint a full pic of the craft, it's an F550 with Avroto motors pushed out on extensions that make the frame more of a 650 than a 550. I'm spinning 11x5 graupner and the whole thing sits on an Aeroxcraft landing gear kit with my own gopro gimbal. Currently I'm on the newest 5.12 FW, but the problem existed on 5.02 before I upgraded.

Thanks!

-Terry

 

[soundmind]

Hi terry, have you tried offsetting your gps for magnetic declination?

Baltimore MD declination is 11 degrees 10 min west, so try and mount the gps with a 11 degree counter clockwise offset.

i had the same problem in Auckland NZ ahd when mounter my gps 19 degrees clockwise (19degree east declination) it solved it.

you could also try to hard mount your gps on an arm without the little stand-off, its is believed that the standoffs introduce vibration so hard mounting may also improve it either on the centre plate of on an arm to get away from all the emi.

cheers
theo

 

[Kilby]

Hey Soundmind,

I did try to offset the GPS, but I went in the opposite direction (clockwise). Thinking back now, it did seem that the problem got a little worse when I tried that, so your recommendation might have some legs. I'll give that a try today when I get home from work.

 

[Elliott000]

I have found on my hexa, that with imu z axis of zero and some clockwise rotation of my compass the thing flies better as a whole. Good luck man

 

[Kilby]

That would make sense, Elliott. Check out the true magnetic north for your location. A small clockwise rotation of the GPS sounds right for you, probably the same amount counter clockwise for me should do the same thing.

BTW.. my imu z axis is more or less 0 to begin with, so not much I can do about that, but thanks for the info!


View attachment 5218

 

[Droider]

Aye up Kilby.. post some pics


Dave

 

[Kilby]

I'm in the office for another hour, but I'll give it a go and post some supporting photos then.

 

[OneSkidShort]

One thing you may try (worked for me) is after you've fiddled with gains and it doesn't help, try and change your Z settings for the imu to tell it your CoG is actually lower than the correct settings. I had a real fun time trying to settle my toilet bowl till I played with the Z settings. Your mileage may vary.

 

[Kilby]

Thanks Bill, but that was one of the first things I did. I've seen a few others on here post about that, so I wanted to give it a go while I had the assistant open.

I had this problem on an old quad once and I just rotated the GPS and all was well again. I tried that this time, but I'm hoping I just rotated it the wrong direction. We'll see tonight when I get home.

 

[Kilby]

I tried the rotation, but it made just the slightest difference. Not enough to cure my problem. I ended up moving the GPS out on one of the booms and it seems like things are working out now. There was little to no wind, and I didn't turning all the gains back since testing, but it held pretty well all in all. I'll do some more tuning tomorrow and I'm hoping everything will be just right again.

 

[soundmind]

@kilby

i think the little carbon stick they provide with the wkm is from the devil......and they cause some weird hi frequincy vibe, i reckon gps hard on a arm on some doublesided foam tape or even some align gyro gell is the way to go.....

dont forget to change your x y setting for gps......

let us know how it goes...

 

[Kilby]

I was able to put it out on the arm and it seems right now. One of the big things I wanted to make sure I did with the install was give it the ability to be moved easily. I ended up bolting 2 servo x-horns through the arm and mounting it to the top with double-sided tape. So far so good.

 

[Bella7821]

Here's the easiest way I've found to solve the toilet bowl issue.
First off, the GPS works perfectly just velcro to an arm.
Set the GPS offset to the magnetic declination( east declination turn the GPS right and West turn it left. Then calibrate and hover. go forward about 50ft and turn the GPS just a tad in the opposite direction of whatever way it's drifting. Bring it back and land and re- calibrate. Do this a few times until it tracks pretty straight and that should totally solve the toilet bowl issue.
If you go fly far from home, just re-calibrate again when powering up.
This worked great for me.


View attachment 5246

 

[Dewster]

Hi terry, have you tried offsetting your gps for magnetic declination?

Baltimore MD declination is 11 degrees 10 min west, so try and mount the gps with a 11 degree counter clockwise offset.

i had the same problem in Auckland NZ ahd when mounter my gps 19 degrees clockwise (19degree east declination) it solved it.

you could also try to hard mount your gps on an arm without the little stand-off, its is believed that the standoffs introduce vibration so hard mounting may also improve it either on the centre plate of on an arm to get away from all the emi.

cheers
theo

Man... I learn something new everytime I visit this forum. Great answer!

 

[soundmind]

Man... I learn something new everytime I visit this forum. Great answer!

I cant take all the credit for that, been speaking to quinton from multiiwii in AU and some other Guys who fly locally .....so a community solution at its best...