Hex behaving wierdly
« on: August 31, 2017, 08:24:46 am »
Hi, I have been using Librepilot for a couple of years with quads, but recently purchased a Kingkong Hex300, bnf.  I am using it with a modded Eachine transmitter, and IA6B receiver, using PPM.  I have had problems with the hex from the start.  I have never been able to run the motors using the Wizard ... they just will not run.  After replugging the battery on Wizard at motor calibration, however, there only seems to be ten confirmatory beeps, instead of the expected twelve.

Bear in mind that this hex has been set up at least a dozen times on Llbrepilot, and the motors have never spun up on Wizard.  As a result, I have set them manually, and have never had a problem with this method. 

When setting them manually, however, after pressing home after the first beep, I never get a beep or series of beeps for the six ESC,s jus a short musical tone.

I had it flying perfectly, until a pretty heavy crash.


It has been impossible to set up since then.. number one motor was not spinning, and on checking, the PCB had a fault, and was not supplying a signal to that motor, so I jumped a wire from the number one motor output on the FC to the number one ESC and fixed that.  I then notice that the PCB was not powering the receiver, so another jumper wire fixed that.

I have now set it up on Librepilot using Generic Hex, with the FC angled 90 degrees to the right, so yaw has been set to -90 degrees. 

The motors have been calibrated manually, and all react to the sliders properly.

The motors are set to idle at arming.  No 1 motor needs more to run smoothly than the other 5, ie the other five run smoothly at about 1035, while number one needs about 1060. 

I also had a faulty motor at number 5, and have replace it with a similar size but slightly different kv, that is, the other five are 2280, while the replacement is 2300.

When I arm it, all the motors are running smoothly, and if I move the controls, the quad reacts to the movements while still on the ground correctly. 

However, when I try to take off, at very slow throttle opening, it will lift about a foot in the air, then all of a sudden, the motors will rev, the quad will leap into the air about a foot or so, then violently flip forward onto its back.

I thought, when number on motor was not running, I may have had a problem with the ESCs, but the motors all react properly on manual calibration, so surely this points to the ESCs being ok.

I have replaced the FC with a new one, but no change.

I have spent a week solid on this, and am about to turn it into parts.

To me, it appears that the FC thinks the quad is upside down, and tries violently to correct that, but then, wouldn't that affect the way it behaves to the controls before it becomes airborne?  The FC is the right way up, just facing 90 degrees to the right. 

Can someone suggest something?

thanks Dave.

f5soh

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Re: Hex behaving wierdly
« Reply #1 on: August 31, 2017, 09:02:56 am »
Instant violent flip at take off can be a FC orientation problem, motor position.
Check the motor assignment using the testing output option so the starting motor matches the motor's name (VtolMotorNE, VtolMotorE...)
Of course, double check rotation en prop mount CW/CCW.


If the hex lift off completely at take off and next do a flip, there is a hardware issue with one motor.

Please post your config file, just in case you did something wrong.
File > Export UAV settings

Re: Hex behaving wierdly
« Reply #2 on: August 31, 2017, 10:34:14 am »
Thanks, UAV files attached

Dave.

f5soh

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Re: Hex behaving wierdly
« Reply #3 on: August 31, 2017, 01:25:41 pm »
This config file is empty (or all defaults), please redo the Export UAV Settings while the board is connected.
You didn't mention the FC used.

Re: Hex behaving wierdly
« Reply #4 on: September 01, 2017, 01:58:03 am »
Thanks, re-did export with fc connected and the file is attached.

I am using CC3D at the moment, but started with CC3D Atom.

Dave.

f5soh

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Re: Hex behaving wierdly
« Reply #5 on: September 01, 2017, 09:33:59 pm »
Different neutral for the first motor is not a really good indicator and maybe this motor have issues when you try to takeoff.

Do you have a video ?
Is the hexacopter doing a instant flip or flip after the takeoff ?

Re: Hex behaving wierdly
« Reply #6 on: September 02, 2017, 07:31:23 am »
It's in bits again at the moment, but I will re-assemble it and try to post a video in the next day or so.

thanks Dave.

Re: Hex behaving wierdly
« Reply #7 on: September 02, 2017, 08:31:25 am »
Ok, couple of short vids of th hex's behaviour.  The movement on the ground is me gently moving the controls:

Files were too big for posting here, so links are for Youtube:





thanks Dave.



« Last Edit: September 02, 2017, 05:08:37 pm by TheOtherCliff »

f5soh

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Re: Hex behaving wierdly
« Reply #8 on: September 02, 2017, 10:57:46 am »
Not really sure but how is mounted / oriented the FC ?
Looks like the FC arrow point to motor 1 instead between motor 1 and motor 6 according to the USB port in your transparent/yellow case ?



You should fix the physical orientation or set the Virtual Attitude Orientation in Attitude tab with some custom Yaw value like -30° or -45° matching the angle in frame.
https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/2818092/CC+Attitude+Configuration

Re: Hex behaving wierdly
« Reply #9 on: September 04, 2017, 10:35:22 am »
Hi, the FC is aimed 45 degrees to the right, and position in Librepilot is set to yaw -45%.

f5soh

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Re: Hex behaving wierdly
« Reply #10 on: September 04, 2017, 11:36:44 am »
Sorry, last config file you posted didn't show the modification.

If you align the case with the top plate (red) border the orientation should be be set to Yaw: -37° (degrees)

Re: Hex behaving wierdly
« Reply #11 on: September 04, 2017, 11:40:00 am »
Verify that it is correct by watching the displays in the Flight Data tab.  The large PFD/HUD in the upper left side should show "more brown dirt" when you tip the hex forward.  The roll should be OPPOSITE of the way you tilt the hex.  The little multicopter in the lower left should act exactly as expected, but can be confusing if you have moved the hex in the yaw direction since starting the GCS and hex.

Your video shows classic symptoms of one of:
- FC rotation mounted incorrectly including inverted (and not correctly compensated for in RotateVIrtual)
- motor numbers not ordered correctly (ESC plugs into FC incorrect order)
- wrong props on wrong motors
- motors spinning in the wrong direction
Two wrongs do not make a right.  Sometimes we see people putting the wrong prop on a motor that is spinning the wrong way but this usually causes yaw problems.

Another issue is that you must balance your props because the gyros go crazy if there is too much vibration.  I haven't seen this be as violent as your issue though.

Another test is to take the props off, run it in Rate mode and see how the motors respond when you manually rotate it, and when you apply roll or pitch controls.