Interesting Z axis settings..

[DucktileMedia]

Well, i realize this was unlikely but thought maybe with people saying a setting of 0 worked.... I have a friend on here with an almost identical setup as mine, really only difference was the camera and his flew rock solid. Which was teh only reason i bought the DJI WKM in the first place. I still have yet to make mine fly that nice. I am also skeptical that there are not a very few sources for these MEMS and ALL manufacturers end up using the same components. There is also a possibility that these MEM gyro/acc. were never meant for anything more than cell phone usage and we are just asking too much to have every single one be exactly the same. Another one of my random thoughts as to why none of us can make the same things work as well as the other.

 

[Kari]

Hi Ken,


You have flashed new set of esc:s? Would you like to share what esc:s you’re using now? I have lately tested a lot my setup with different esc:s. Last was with HK 30A blue series with flashed with SimonK fw. With them my CS6 was flying very smooth, but i found it having a little weird behavior with them, had a lot of toilet bowling, white flashes, bad altitude hold, drifting gps... even though i went through very many gain setups and it is flying really smoothly otherwise. I have noticed before this it has always flown pretty well with same gains P/R around 250 Y/V 180-200 and attis 70-80 and disturbed gain 160 not depending so much which esc:s there is.


Before flashed HK 30A:s i tried HobbyWing pentiums 40A with factory fw which were so far overall best working setup i've had yet. It had very solid gps and altitude hold and relatively smooth flying in wind and very good in calm. (And this was right before i only replaced esc:s to flashed HK:s, nothing else changed than auw few g:s) I also had some weirdness with Pentiums, it had pretty much difference in flights even in same day how it was flying. Sometimes it was very smooth even in gusts and 2 hours later is was much more restless and wobblier even if the air was calmer and had very same settings. Actually that was why i changed to flashed if i could find something there.


I have been thinking if there is a problem in gps or imu unit but it doesn't seem to make sense for me, also been thinking if there is a problem with motors but it doesn't seem to make sense either other than to problem with difference between flights. I will try soon with other motors (tiger 770kv) with slightly higher kv rating if that makes difference. Now i have QC3328(700kv), 11x5 graups, auw around 5kg with 4s 8000mAh. I also noticed that with Pentiums nonlinear throttle curve it would hover in manual mode at 50% but with flashed HK:s linear curve throttle needs to be around 70-75%.


Kari

The WKM is VERY sensitive to disc loading and flight weight and though I have yet to figure out exactly how they interact with each other there is definitely a relationship as well as with the axis measurements. In your case it sounds like the gain settings need to be tweaked for the weight difference which has a bigger effect than the axis measurements in my experience. I have one of my WKM on a large quad frame with Avroto motors, Graupner 11 x 5 props, a single 4S 5000 pack and an RTF weight of roughly 2800 grams, this seems to be the ideal setup as far as all around stability and GPS hold. When I installed a set of Droidworx landing gear and an AV130 the increase in weight sent it off the cliff as far as stability went, I could not find the sweet spot for gain settings until I ADDED more weight and went to a larger prop to get back to the proper disc loading. It either was far too soft and wobbly or would oscillate badly in anything other than a steady hover until I made the changes then I was able to dial in the gains so it flew acceptably well but not as nice as it did before I added the landing gear and camera mount. Eventually I put it all back the way it was and it's back to the smooth stable flyer it was at the start.

Today I reflashed a new set of ESCs for the CS6 WKM and in the process of testing them out noticed that it flew quite differently without the weight of the Nex 5n on the AV130 so I strapped a second 4S 8000 pack to the camera platform not wanting to risk the 5n if things went wrong. The pack being substantially heavier than the 5n the additional weight changed the Z axis CoG measurement enough that the effect was immediately noticeable. A tweak of 2 CM on the Z axis as a SWAG at the change seemed to put things back to close to normal so I have to say that it depends a lot on the setup if you will see a difference with the correct axis measurements or not, it was noticeable to me on the 825mm Cinestar frame but I don't see as much difference when I make a change to the same setting on the much lighter 550mm WKM quad with Avroto motors.

Ken

 

[Kari]

This is interesting (and off topic sorry), i went back to 40A HW pentiums with factory firmware and GPS hold is super solid, no toilet bowl, no drifting, no white lights even with very harsh flight. It's very smooth now but it was even slightly smoother with SimonK and loved silky smooth sound of motors. Going to try flashed 40A:s next, don't know why it would make difference but you never know..

Kari

 

[Dewster]

Just had this thought. Is it possible, just a question, that DJI's z measurement is completely meaningless and not even part of a formula for helping with stabilization? I think it may be possible that this parameter is a placebo of sorts and just sits in it's field with no links to other parts of the software. When changing my system from 3s to dual 4s, i noticed the heli flew like crap because I now had a lot of weight up top. Spinning a smaller prop faster made for smoother flight but it jitters like crazy in the air no matter what. Before I only used 1 3s battery and it flew without the oscillations in the air. I adjusted the Z for what seemed like the right CG for both batteries. I have tried so many different settings I have almost given up on making it fly the way it used to. As a test I will lower my batteries below the frame plate and leave the Zat 0 just to see for myself.

I noticed the same thing. I used to have my battery suspended about an inch or two below the center of gravity of the craft (not the landing gear). It flew pretty stable in the wind with the Z axis set at zero. I relocated my battery so that it's flush in contact with the bottom frame and have great results on calm wind to light breeze days. The craft goes through it's twitch manuever when it's windy now. I did notice when my gains were set higher for roll, attitude and pitch that it behaved smoother in the air. Has anyone tried setting remote gains on their transmitter? I might give it a try so I can adjust on the fly for windy days.