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General Topics => Beginners Zone => Topic started by: TKSP33DY on January 10, 2016, 09:30:21 PM



Title: Need help with quadcopter build
Post by: TKSP33DY on January 10, 2016, 09:30:21 PM
Hey,
I am very new to making my own RC quads but i have flown quite a lot of them.

I have built my quad with reference to this link (http://fpvcentral.net/2013/03/high-performance-quadcopter-for-120-step-1-the-shopping-list/)

and i need help as i have been trying to configure the Hobbyking kk 2.0 chip with the correct PI tunings.

Online, many people have gotten values of P at 50 and I at 75 whereas when i started experimenting with those values i ended up breaking a prop.

I have tried lots of combinations of P and I values over months and not achieved flight yet. Please help?
I need to get the quad flying before 2nd Feb.


Title: Re: Need help with quadcopter build
Post by: SK1701 on January 11, 2016, 06:24:00 AM
You should be able to fly the quadcopter even with the default PI values. You will only need to tune them for better flight performance.

If you mean your quadcopter is flipping when you try to fly, check the following:

motor rotation direction
Correct props on motors.
kk boards orientation
ESCs plugged in the right order
kk firmware update


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 11, 2016, 08:08:39 AM
With those high values of P and I my quadcopter keeps flipping. In fact with my current values of P Gain: 8 and I Gain: 1 it is very unstable. I read online that in this case i should try to decrease the values but when i reach P and I Gain at 0 then it only flies in one direction.

Can you please elaborate on kk board's orientation.

My motors are spinning in the right direction and im using the correct props on the motors.

Also What do you mean by plugging the ESCs in the right order? All I did was connect it so that I got the motor spinning in the right direction.


Title: Re: Need help with quadcopter build
Post by: SK1701 on January 11, 2016, 09:24:53 AM
I meant the order in which the ESC signal leads are connected to the kk 2.1s output pins. And the orientation is just that the buttons should be towards the back and the LCD towards the front of the quad. With a high P gain, the quad shouldn't flip. It will just oscillate a lot. Even I had this issue with my quadcopter flipping at takeoff despite the motors and propellers all being correct. I fixed it by flashing the latest firmware version to the kk 2.1. This can be done using a USBasp or an Arduino. Which firmware version do you have on the kk now BTW?


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 11, 2016, 10:53:32 AM
Im currently using FW 1.6

I'll try to increase the P gain slowly then and keep you updated with the results.


Title: Re: Need help with quadcopter build
Post by: SK1701 on January 11, 2016, 11:44:46 AM
1.6 was the one I had major issues with. Try flashing to 1.19S1 or RC911 AIO R4 before doing anything else.


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 11, 2016, 01:46:47 PM
Is there a particular place where i should get the firmware from? And between them both which one would you prefer?

I just tried re calibrating my ESCs. The oscillations reduced but my P and I gains are around the same value.


Title: Re: Need help with quadcopter build
Post by: SK1701 on January 11, 2016, 07:05:31 PM
You can get the Steveis firmware (1.19S1) here (http://www.rcgroups.com/forums/showthread.php?t=2298292). The other option is RC911's KK2.1++ AiO R5, which I prefer, from here (http://www.rcgroups.com/forums/member.php?u=432613). The reason I like this firmware better is the SL mix mode that performs like horizon in cleanflight, i.e. self levelling near centre stick and acro at the extremes.

You can flash it using an Arduino as described here (http://www.rcindia.org/multirotors/updating-kk-firmware-with-an-arduino-(on-a-mac)) or here. (http://blog.oscarliang.net/flash-kk20-16-firmware-upgrade-arduino/) You can also use a USBasp tool to flash it very easily using this (http://lazyzero.de/en/modellbau/kkmulticopterflashtool) software.

Recalibrating the ESCs won't do anything as long as you did it once. Just upgrade the firmware and try.


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 11, 2016, 07:09:27 PM
Alright, thanks for the help.  :salute:
Just ordered a USBasp cable and adapter from eBay.
Will keep you posted with updates.


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 15, 2016, 09:50:33 AM
Flashed stevies fw 1.19S1 on it and added the vibration absorbing foam between the board and the body and it doesn't oscillate anymore.
still have to work on the trims to get it to fly perfectly.
Thank you so much!


Title: Re: Need help with quadcopter build
Post by: SK1701 on January 15, 2016, 10:16:43 AM
You're welcome! And congratulation!  :thumbsup: It is a great feeling to have your quad in the air.

Just FYI, I don't think you need to trim the quad. Without GPS, all quads have a tendency to drift and you need to correct it manually to keep it in position. However, if you notice a continuous drift in the same direction, you may need to set ACC trim on the kk, especially if it was not perfectly level when you did the ACC calibration. The most important step now is PI tuning. Check out this (http://oddcopter.com/2013/01/06/easy-diy-quadcopter-build-part-4-tuning/) page for info on PI tuning.


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 15, 2016, 10:56:24 AM
Hey
I was just tuning my quad and when i raised the throttle above 50% motor3 cutoff and soon motors 2 and 4 also cut off.
Did i do something wrong?
ive tried to reconnect everything but the problem still persists.


Title: Re: Need help with quadcopter build
Post by: SK1701 on January 15, 2016, 04:04:34 PM
Could be bad solder joints between the motors and ESCs or the ESC power leads to the PDB/wiring harness. If you are using bullet connectors, check your soldering again. And now if you try to spin up the motors on the ground what happens?


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 15, 2016, 04:16:25 PM
I think it was because the heat shrink tubing for 2 of the wires had come off and they might have touched. Solved that issue and its up and flying again.

Is there any solution to stop it from swaying? Whenever i get it in the air I need to be on the sticks continuously to correct it otherwise it sways back and front. I dont think its because of the gains because it goes in front for 3 meters before coming for another 3 and that keeps repeating.


Title: Re: Need help with quadcopter build
Post by: TKSP33DY on January 22, 2016, 02:48:19 PM
Hey,
I got it flying again but ended up breaking my last set of props. I was using 3 blade 7x4.5 hobbyking props
I bought 4 2 blade 8x4.5 inch props and now my quad wobbles alot on the ground. In the air the wobble is much more manageable but on the ground it is impossible to take off straight.
Is it because my props arent compatible or do I just need to repeat the PI tuning?
Im currently using turnigy 1100kv brushless outrunners.


Title: Re: Need help with quadcopter build
Post by: Darshan for multirotors on January 22, 2016, 03:02:14 PM
You will need to set the PID settings according to your new props. Different props affect the quad differently.