Ardupilot failing to hover with yaw deflection

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1

Now this is a bit bigger problem than i had with datalogs and factory settings are useless.

my Y6 configuration camera copter is unable to do agressive stable yawing without falling down (seems to be somewhat controlled falling since it does not flip, but drops straight down)

I have Mikrokopter BL-Ctrl 2.0 ESC-s with 360KV T-motor BL-motors.

I did trim down the pwm frequency for motors but that did not change anything. (since the same configuration motors and escs fly perfectly with naza controller I adjusted it to 400Hz as is naza)

My battery is 8Ah 5S lipoly (turnigy nanotech)

The last flight does not show the falling very well, but i had multiple flights (best ones with alt hold) that show clearly how the y6 starts losing altitude when going to a bit larger yaw movement and throttle goes up while the quad comes down.

I am not very sure how to address this issue. I could head to pid and limit the yaw action to safe value, but that seems to be a hack and not addressing the real problem.

At the same time I am not sure what the issue is. Since my hover throttle is less than 50% (less than 1.5ms high time) I should have more than enough power left to do very aggressive flying.

Also I have triple checked all the motor positions and rotations and am not very sure where to look next.

I added a log that shows my problem very clearly. It loses altitude way before it loses throttle.

The tests are done over a nice piece of grass, so the legs stop motors and props hitting the ground and they work pretty nice. A little vibration has come in since props have gotten a bit rough life.

y6 weight is about 4-5kg and should go 1 kg up to get 50% hover thottle.

Any help to get my camera rig flying would be very welcome.

PS i have been flying 3DR quad for a while and that flies like a charm.

2

I ran testing and de-tuning yaw and got to point where fast stick deflection to right is perfectly ok, but fast stick deflection to left drops front left beam down and with that goes the copter.

It does not happen when I got rotating slowly, but any fast movement to that direction brings quad down. Stab yaw is 1 and rate yaw P is 0.22, I 0,02

3

And of course the log file is wrong. Will post the correct one tomorrow… Tlog vs dataflash log… did not notice the file extension…

4

Log file shows how the pitch changes strongly if yaw is changed. Also one can see that motor 6 output behavior is a bit weird as well.

Still no idea about how i should address this issue.

5

After further tests i discovered that mikrokopter esc-s are having problems with very fast pwm with changes. Not sure if this is the issue since only one leg creates problems in fast yawing but it seems that i might have gotten a little closer to the problem.

does anyone have any experience with arducopter and mk esc?

also, i still confirm that same motor esc configuration flies fine with dji naza.

6

And way too much testing later, the problem lies in 5s lipoly voltage, prop size and motor configuration. Same problem came up with different escs but when lipoly or prop are changed, it works like a charm.

This is not a cool problem, but it seems that I am getting to the end of the rabbit hole.

Tomorrow i am getting full new set of props AND motors and will fix it. Hopefully. Will post follow-up as well.

I really hope that no beginners get this kind of problem. Not the beginner grade stuff.

7

So, since the motor or driver change makes everything working we decided to go for driver change.

I would like to post the picture as attachment, but 256kb file limit is stupid. Also for forum admins the forum works like dead cat…

so as you can see the new drivers do not fit the designated area, but i should get the machine running today.

I could have changed the motors, but weight that would add, was bigger than drivers.

We did try different props but the same kind of motor stalling at some fixed speed came up there too. Also with a different driver that had 50A constant drive current. (different from mikrokopter blctrl 2.0)

So, if your quad falls out of the sky by doing fast movement, check your motor and driver configuration. It just might die on fast throttle changes. (no smoke, but designated speed will never be achieved)

Also as i found out y6 is capable of stabilizing if one arm motors are switched. it will then yaw nicely to one direction but will not be able to do nice yaw to other direction. Found it out from other y6 flyers. Just something that beginners should be aware of.

Not sure if I will post any more updates.

best regards,
cmc

8

Today I did a full autonomous flight, and everything works. success.

9

[color=#004000]Please keep civilized behavior![/color]
The size limit is not stupid but to prevent overly large files from stacking up on the server.
And there is no need to post pictures which are bigger than the average screen size of users!