Wookong-M on a RC-Carbon 900 mm boom

BorisS

BorisS

Drone Enthusiast
same page as you Ken. No wind outside today so i am testing inside were the 900 hexa is creating its own wind. Cant get the wobbles out.

vid: http://sprealinvest.at/hexa900indoor.mov

and he is attacking very strangl on the throttle today. Starting off the motors they spin up very fast second time started up they run smooth strange one.

didnt have that with the old firmware. Only thing i change was timig to middle which reduced the heat of the ESCs and BAT in my eyes
 
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R

RTRyder

Merlin of Multirotors
I've been all the way up to 500% on the gain and still not eliminated the wobble. I backed it down to 410 and it's OK but the Droidworx/MK AD6 is much smoother in the wind, to bad its so much less stable than the WKM in vario A/H and autolevel. I did a couple quick test flights with the AD6 earlier and WOW what a difference after flying the WKM for a week, flying the Mk seems like work. I also have some weird compass board problem going on with the Mk at the moment it swivels side to side in a P/H hover and descending from tree top height in position hold it suddenly swung hard to the left and started to fly backwards while looking like it was going to keep rotating. I clicked out of GPS immediately and brought it back in but man did that surprise me! I'll have to pop the dome off and have a look, may have something to do with having the stack off it recently and then putting it all back together (I hope) I'd rather not have to buy yet another MKMag board.

At this point it's beginning to look like eliminating the wobble on the WKM is going to take a firmware fix. I'm not the only one seeing it and there aren't many that have one flying on a large frame yet but I think as more people do start swapping to big multis there's going to be a lot more reports of the problem. Still, not bad for version 1.0 if thats' the only thing I can find wrong with it after wringing it out for two weeks trying everything I can think of to make it misbehave.

Ken
 

BorisS

BorisS

Drone Enthusiast
Yeah i guess they understood though DJI guy offering his options in RCgroups

our current algorithm is optimized for try its best to hold the position and fight against any turbulence in the air. and it is more resistant to wind. the price to pay is it will change its attitude more frequently. but what you get is the more stable and more control in the wind(instead of being blow away by the wind).
there will have 2 solutions:
1.optimize for attitude stability,instead of position and velocity stability, we can add another parameter to user to tune.
2.Use DJI 3 axis gimbal(totally new design, dynamic accuracy will be less than 0.05 degree) which will come out in 2 months, weight will be about 800g and will be good for pana GH2 size camera

but i guess option 1 will probably be on the costs of loosing a little of that ease of fly the WK-M has compared to the MK. But a parameter like that if i understand it correctly would be very good to trim the WK-M for the given conditions and what results one if after.
 

BorisS

BorisS

Drone Enthusiast
funny though with the 900mm Hexa 4kg 410% gain no chance he already looses it on the ground starting with oscillations. Around 300 is max for me.
 


D

Dixter

Member
DJI on a Droidworx

Boris, Now that you have had some time with your DJI I was wondering if you would recomend the DJI on a Droidworx frame... either a hex or octo... do you think the DJI and Droidworx is a good fit??

thanks
 

BorisS

BorisS

Drone Enthusiast
Dixter,

i cant say yet. I dont think that WK-M is ready for bigger frames yet. The parameters thus variables you can alter might be enough to get a smaller quad or hexa flying like on rails but they still have issue with bigger birds. If there is absolutely no wind and i have it of the ground 3 meters the thing is a beauty. If a little wind sets in its over.

But dont get me wrong. I think the hardware is more capable (I don't know the internals processor etc., didn't dare to open it :)), than any other boards out there. So they have the basis and they announced that they will add some more options to get big frame less aggressive in the wind. In my eyes the MK tends to drift more (manual mode) in the wind and regulates later. The wk-m is straight on it in it attitude mode and that in my eyes causes these wobbles.

When it comes to plain flying the WK-M is far ahead of the MK. It is so easy to fly its joke. Flew with a MK in the mean time I was scared again like the first couple times.

The best advice i can give you is to wait a little longer. There a several bigger builds out there and DJI is getting more and more request to alter there firmware to make it more suitable for big frame heavy lifts. I was just reading that this new firmware will be out in 2 weeks.

hmmm and now every one is getting pissed off beause they just lowered the price again. Follow the RCgroups thread on the DJI wk-m its pretty funny whats going on :)
 

BorisS

BorisS

Drone Enthusiast
Dixter,

if you can really wait. Its getting a little strange at the moment. Just read all the posts in the DJI thread and they are starting to produce their own ESCs with which they say the performance of the system will get better. Now one of the key points was to use any ESCs available and they are offering max 30a ESCs which is bull in my eyes.

Going on they will also release some motors that they recommend etc. but those will only have 700 grams at 70% throttle ! Thats a little strange wouldn't be suitable for any AP frame setups on the market.
 

D

ddmt

Member
I would guess after blaming and creating their own ESC, we'll see their own version of motor, frame, camera mount. Hey actually DJI will sell all of those "soon" :D
Boris, what's the weight of your frame? I have the X4/X8 frame from rc-carbon, but it's quite heavy. That's why I'm using mk.de Hexa XL frame for my hexa. Still waiting for my WKM.
 

J

jes1111

Active Member
As I'm sure has been mentioned on the RCG thread (which I haven't read), ESC performance is increasingly critical to stable flight as your frame gets larger. All ESCs that were designed for fixed wing aircraft have an input filter which basically smooths/ramps the acceleration. This amounts to a significant (in electronics terms) delay between the FC commanding a new throttle setting and the ESC responding completely. The longer your arms (and therefore the higher the moment of inertia), the more this delay will show up, manifesting itself as slow initial reaction and then overshoot - a.k.a. the wobbles.

I'd like to see if it has the same problems with large frames when using firmware-modified ESCs (which basically remove the input filtering and therefore the delay).
 

D

ddmt

Member
Yes, I can understand we can't really expect too much from the off-the-shelf escs like the hobbywing (and other oems). The WKM is actually pretty damn good with the current limitation of the esc response speed. I guess that's why OpenPilot make their own fast esc.
 

BorisS

BorisS

Drone Enthusiast
@ddmt i will get you the weight infos a little later.

@ Jess111 well that exactly what they are planning but in a strange way :)

---------------
DJI Response the altered ESCs

a new firmware that can let you choose weather you want to optimize for position hold or attitude hold will be out in less than 2 weeks.
and also, in current firmware, most people still get very satisfying result in windy condition even for AP. most people who does not get perfect result from WKM is because of the wrong esc, motor, props, voltage combination, that's why we are developing our own ESC, and will sell in combo with motor and prop, which can provide thrust at about 700g each(@70% throttle), at the same time get 9 g/w efficiency

---------------

Response from some very cool RCgroups Forum guy.

Frank you guys have to consider that for a full blown AP platform additional weight automatically will be added. People want some form of Vid downlink. Preferred option is a second receiver (for things like slew mode) for the camera mount control and not a student teacher setup. Additional i guess your GH2 3 axis gimbal includes a basic lens. If we step into the area of wide angle or basic teles you can add another 300 to 500 grams. Either the outcome will be very restrictive plattform what the customers can install on the copter or you will approach 80 % + throttle to get the bird in the air. I can tell you that a 20% throttle reserve for taking up camera equipment that can be worth up to 2000 $ 3000 $ will be a rough one for people who love their equipment !
-----------------
HI Boris,

higher lifting power can be achieved too, but with lower efficiency.

Frank

-----------------

What this comes down to is that there will not be a suitable solution for real heavy lift setups 30A will not be enough.
 


BorisS

BorisS

Drone Enthusiast
by the way jess got the 14 x 4 all cool solid for the price, but they could have left out the glossy finish :) Not balanced but i never had i prop that was ! These XOAR are certainly not !

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BorisS

BorisS

Drone Enthusiast
I can only mention it one more time for everybody reading this thread.

WAIT UNTILL YOU YOU BUY A WK-M

Things are turning out to be a little different than expected and before you don't see a video footage from a none home grown DJI multirotor being able to produce wobble free vids dont buy.
Not saying the plattform dosent allow, but its not there yet and in combo with the strange approach DJI is taking at the moment lets see if it will.
 

BorisS

BorisS

Drone Enthusiast
For me the experience got somewhat better today though with these lighter props 10 grams CF still trying to find the right gain settings. Flying with a 900mm inside i just don't want the gain controls on the radio. Keep in mind my bird does create its own wind and turbulences in such a small (relative) place/room.

Only Tilt compensation Roll still deactivated. AV 130

http://sprealinvest.at/900mmCF10gram.mov

http://sprealinvest.at/900mmgoproCF10gram.mov

Hope for tests outside soon.
 


BorisS

BorisS

Drone Enthusiast
so finally got the time to fly outside today.

http://sprealinvest.at/firstWKMirrsee.mov

little rough still at some points but i just started tweaking it. Lets see how good it gets till Sunday. Only Roll compensation is on. Switched off Tilt and straped that axis down since AV was aacting strange again and i couldnt deal with figuring why .

(edit) light winds and gusts
 
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