Quad X - not flyable - devil inside??

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acid_g
Posts: 4
Joined: Sun Apr 17, 2011 3:59 pm

Quad X - not flyable - devil inside??

Post by acid_g »

Hi,

I'm pretty new to the multicopter scene. I just finished the prototype of a Quad in X-mode, but it's just not flyable. As soon as the WMP realizes any movement the Quad starts kicking around - that much that even when the throttle is at about 20%, some motors get full power. I tried to reduce the P progressively to 0,1 but it still is not flyable.
Latest result:
Image
I cut myself, because I hold it in my hand and it started kicking...

My configuation:

Before that, I had a NK connected and if I turned on the autolevel during lowest possible throttle, it just flipped over and crashed, because one motor started to pull at full power. Both, gyro and ACC were calibrated before that. So i decided to remove the NK and test it again. At about a value of 2 for P in Roll and Pitch it was quite stable in my hand, but flying with this configuration resulted in another crash.

When I connected the Arduino to my PC, I noticed that even when only the Quad is armed, but no throttle is applied, the WMP started capturing some vibrations. I already balanced the Props, so i made another dampening for the WMP board and mounted the adapterboard with rubberbands onto a really soft foam material.
The gyros themselves are working fine:
Image
In the screenshot you also can notice that P for Roll and Pitch is lowest possible, but still everytime I try to fly it results in a crash, because it oversteers.

Does anyone know a solution to my problem?

Here are some Pictures (again, its a Prototype!!! ==> ugly build - ready to crash again :mrgreen: )

ImageImageImage

If some Informations are missing,just ask ;)

Thanks,
acid_g

ziss_dm
Posts: 529
Joined: Tue Mar 08, 2011 5:26 am

Re: Quad X - not flyable - devil inside??

Post by ziss_dm »

Hi,
1) Remove I and D (Zero them)
2) Check your motor connections. I mean that ESC connected to correct Arduino channels for your configurations.
3) Check sensor(s) orientation
http://www.rcgroups.com/forums/showthread.php?t=1340771
When the gyro is mounted correctly:
tilt left => negative values
pitch back => negative values
yaw left => negative values

4) Try to follow instructions in this post (pre-flight checks)
http://www.rcgroups.com/forums/showthread.php?t=1348268
Setting start point Pitch/Roll PID:
P at the default setting (4)
I at zero
D at zero

Hold the carefully and and increase throttle util the Tri becomes light - near hover point.
Try to lean the Tri down onto each motor axis
You should feel a stiff reaction against your pressure for each axis. If not you have a config issue.

Be carefulll, though, in case you have sensor orientation issues or motors not connected correctly the quad could go wild in your hands. So increase throttle really carefully. ;)

Regards,
ziss_dm

acid_g
Posts: 4
Joined: Sun Apr 17, 2011 3:59 pm

Re: Quad X - not flyable - devil inside??

Post by acid_g »

1. I and D is set to 0
2. Connection is correct, looked it up here
3. Sensor orientation is correct. Negative Values for tilt/yaw left and pitch back
4. I can't turn throttle up to hover, because when throttle is just enough to turn it on, it escalades and kicks. P is at the default setting (4). Reduction of the P-value just gives the possibility to keep it in your hands, but it's far away from flying stable.

Kayle
Posts: 141
Joined: Sun Feb 13, 2011 6:45 pm

Re: Quad X - not flyable - devil inside??

Post by Kayle »

Hi,

Do you have done the throttle range setting to your esc?

Greetings kayle

miniquad
Posts: 65
Joined: Wed Mar 23, 2011 8:17 pm

Re: Quad X - not flyable - devil inside??

Post by miniquad »

@acid_g, it's good to try to dampen sensor vibration with some foam. But make sure the sensor board is not moving with vibration. It's a good idea to secure the sensor board, so it does not move around due to motor vibration. I was reading on aeroquad thread the other day, a guy was having a unflyable quad when he sandwiched the sensor board between foam pads, but once he screwed the board to the body with some rubber dampers, the problem was gone. You might want to try some thick foam tapes to secure the sensor board.

gompf
Posts: 8
Joined: Sun Feb 06, 2011 2:50 am

Re: Quad X - not flyable - devil inside??

Post by gompf »

Hi acid_g,
have you tried how it behaves with only 1/2/3 ESCs connected/under load with motor(s)? Maybe an (broken) ESC is injecting noise to the 5V line. Is your buffer foam from an ESD protection (slighty conductive)?

regards,
gompf

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quax
Posts: 47
Joined: Mon Mar 14, 2011 12:28 pm
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Re: Quad X - not flyable - devil inside??

Post by quax »

Maybe this information helps:

viewtopic.php?f=8&t=162

I had the same problem, but the problem was the WMP and not the assembly.

acid_g
Posts: 4
Joined: Sun Apr 17, 2011 3:59 pm

Re: Quad X - not flyable - devil inside??

Post by acid_g »

Sorry for not responding for such a long time... was quite busy

I removed the dampening and put the WMP on some foam tape. It's hold in place quite stiff now.
After that, I tested it out, but there was no improvement.

I cut three of the four wires of the BECs, so only one is left for powering the system.
After that it stopped kicking on minimum throttle and was quite stable in my hand.
I didn't try to fly right now, because there still is some kicking when more throttle is applied, but i think it's because of the config...

I'll keep you up to date...
Thanks for your help so far!


//EDIT:
It works!!! Even better than I imagined!
Sometimes it doesn't initialize correctly, so i have to reset and calibrate again. But after that it flies like a charm.
I tried again with the NK, but i think it produces too much noise for the WMP. I noticed that the signal of the NK is stuck at elvel when I tilt the quad form one side to the other. I think it's broken...ELV ACC is on its way...

acid_g
Posts: 4
Joined: Sun Apr 17, 2011 3:59 pm

Re: Quad X - not flyable - devil inside??

Post by acid_g »

Next Problem:

Just got my ELV ACC and connected it like this:
ImageImage

I think my quad didn't like it... it commited succide instantly^^
In detail: same problem as described before, it starts kicking when throttle is applied, no matter if hover-mode is on or off.
I couldn't make any improvement by changing the BECs.
In Multiwiiconfig, the signal seems OK.

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