quadcopter shakes violently while flying

[quadMonkey]

hello, this is our first quadcopter build and we are having a problem with the flight, the quadcopter starts shaking immediately after takeoff, we checked the motors and ESC's and nothing seems to be out of place, the motors work great when activating them directly from the clean flight, we tried adjusting the PIDs, we cut the P in half and this helped just a tiny bit, the video attached is the flight after the PID adjustment, what can we do to fix this? and do you know what could be the problem ?

this is how it flew :

quadcopter properties:
f450 size frame
emax 2213 935KV
emax ESCs 25 amp
flysky fs-th9x transmitter
receiver fs-r9b
naze 32 rev 6 10dof
2.2 amp 3 cell turnigy battery

 

[moonpie57108]

If you are using Damped Light, try disabling it on the esc.

Have you balanced props?

Do the props track properly? - point Motor 1 Prop at Motor 2, and spin Motor 2 prop, watch as the blade comes around and its relationship to the height of the other blade. You are looking for a chance of height.

Is the naze hard mounted? Try hitting a local hardware store and grab some M3 (3mmx1.5mm about) silicone/rubber o-rings. Install above and below FC. I got some at a Ace Hardward in their metric section. I think some also just go straight to double back sticky tape to mount FC.

The Naze should have blackbox capability, enable it, it won't last long but you can get some logging out of your next flight.

 

[quadMonkey]

the propellers are all at the same height, as i understand that what you wanted to check
the naze is hard mounted on the quadcopter in its box using double stick tape
i will try to activate the blackbox on the naze hoping it will give some info but im still struggling to find the source of the problem

another question : should i try the default PIDs in the controller ? i used them at first and it was shaking and someone suggested to cut it in half, what do you suggest ?

 

[quadMonkey]

edit: i noticed that when i'm playing with it on the bench with no props, motors 2 and 3 seem to accelerate while motors 1 and 4 accelerate it happens no matter what pid i put in .... accept for one time when it magically stayed the same

 

[moonpie57108]

The prop check is just to check for a bent prop, it happens.

-What about balancing the blades for weight?

So the Naze is in a box and taped to the frame? That is fine, no need for o-rings.
-Is it centered in the frame?

ESC - Make sure all ESCs are running the same firmware and that are showing the same signal points (calibrated the same).
-Are you running Damped Light?

-Also, are you using Angle/Horizon/Rate mode?

It could be the pids, but I would think it would fly better than this off stock pids if you are not having vibration problems. Spinning up on a desk can cause the FC to do funny things because of the vibrations of sitting on a hard surface being in the air, in my experience. Though the only time I have had random motor accelerations on the desk was from Damped Light.

 

[quadMonkey]

i had a problem in the beginning with the ESC calibration, when we disconnected the battery instead of the motors completely stopping they kept running, we calibrated by disconnecting the power line from the ESC (red wire) and calibrating as usual
they start roughly at the same time now

we are currently using ACRO mode for flying
we did not balance the propellers since they came already balanced as we understood from the site

i just searched what damped light is and i don't suppose i'm using it, should we ?
we tried both PID the stock one and what was suggested still no signs of improvement

i would like to thank you for replying, you are helping us alot

 

[moonpie57108]

Not sure how your motors could keep spinning after disconnecting the battery . When you disarm or go to zero throttle, do the motors stop immediately or spin a little bit and more slowly stop? If they slowly stop, you aren't running damped light. If you have a way to balance the props, give it a try or at least check them. I have had balanced props that weren't even close. If you don't have a way to balance, look to add that to your tool bag at some point.

Can you give me to the link to the ESCs you are running?

Are you calibrating the ESCs through cleanflight? If there is a noticeable difference to when the motors start up, I would try calibrating again.

Granted the quad was oscillating badly, did it seem like it responding correctly to your inputs?

You could try reducing your gains further, but if the last adjustment did not make a difference, I would think it is not gain related.

Verify what we have for ESCs,
Update ESC firmware if possible
Calibrate ESCs

Using cleanflight with the props off, spool one motor up at a time, see if you notice one making a lot of noise or vibration as well.

 

[quadMonkey]

the ESC we are using : http://www.banggood.com/Emax-Simonk...-40A-ESC-For-Quadcopter-QAV-250-p-918126.html
25A

the motors do not stop immediately and slow down until stopping, and start at exactly the same time.
when activated using the cleanFlight they have exactly the same values, but when activated using the controller motors 2 and 3 have higher values
(note: all the motors sound the same)

when i flew it other than acceleration i did not feel it was responding to my input, but when i held it in hand and gave input it responded nicely

is reducing the gain the same as reducing the values in PID ? and what new values should we enter ?

and do you think that Updating the ESC firmware will do the trick ? i do not know what that means exactly but will read further incase it helps

 

[quadMonkey]

i have also noticed when in cleaflight that when i activate the motors from the controller motors 2 and 3 would accelerate without me giving further input to accelerate while 1 and 4 stay with the same values and don't change them if i don't give input

i flew it with very low P values as you can see and it made VERY small difference as flying with the default P

 

[moonpie57108]

Post a couple more pictures from cleanflight including a couple of your configuration tab and also one of the receiver table while your receiver powered on and all sticks centered.

 

[moonpie57108]

I was hoping they were BLHeli, you could still flash SimonK but I have never tried it on my escs and you would probably need a usb programming card for them, so we can pass on that at the moment.

I have had my number 2,3 motor output dance in cleanflight (CF) while controlling tx as well. It was a vibration issue for me. It was a hard mount flight controller (FC), one piece frame, strong motors.

As well as more pictures out of CF, post a couple of the quad, including the FC and wiring.

Also lets re-calibrate escs:

a - verify in CLeanFlight throttle signal. Zero throttle = 1000 and max throttle =2000. Adjust your throttle end points in TX to get here.
b - minimum command on config tab CF should be 1000, max throttle 2000.
c - go to the motor tab and click i understand the ricks to enable motor testing
d - increase master throttle to max (2000)
e - plug main battery in
d - once beeping stop, move master slider to (1000)
e - at this point it should a final beep sequence and you are done.

 

[quadMonkey]

in the past couple of days we made some improvement
so we don't know how exactly but it started flying without all that noise in the video, there was still noise, we started the G-TUNE and it got the P to 10 (that's the maximum it can give apparently)
we increased the P to 11.5 and now it flies with minimum oscillation, some noise but not a lot, tomorrow we are tuning the D and I gains

we did not re-calibrate the ESC and don't know how exactly that problem got fixed

on another note, is P gain more that 10 normal ? and what ranges of I should we try to get the optimal numbers... as i understand the I should be less than the P

and i would like to thank you alot for helping us,
we will be sending a video of the flight after all the tuning is done

 

[quadMonkey]

note : on the other try as my friend suggests the problem was fixed by turning the P gain up to 4 instead of 2

 

[moonpie57108]

in the past couple of days we made some improvement
so we don't know how exactly but it started flying without all that noise in the video, there was still noise, we started the G-TUNE and it got the P to 10 (that's the maximum it can give apparently)
we increased the P to 11.5 and now it flies with minimum oscillation, some noise but not a lot, tomorrow we are tuning the D and I gains

on another note, is P gain more that 10 normal ? and what ranges of I should we try to get the optimal numbers... as i understand the I should be less than the P

Keep upping the P gain till it starts to twitch. Too much p will give a very tight quick oscillation.

Based on Weight, Arm Length, Motor KV, Which rev of firmware on Flight Controller......(list goes on) there is not much for a normal gain.

 

[AH-1G]

hello, this is our first quadcopter build and we are having a problem with the flight, the quadcopter starts shaking immediately after takeoff, we checked the motors and ESC's and nothing seems to be out of place, the motors work great when activating them directly from the clean flight, we tried adjusting the PIDs, we cut the P in half and this helped just a tiny bit, the video attached is the flight after the PID adjustment, what can we do to fix this? and do you know what could be the problem ?

this is how it flew :

quadcopter properties:
f450 size frame
emax 2213 935KV
emax ESCs 25 amp
flysky fs-th9x transmitter
receiver fs-r9b
naze 32 rev 6 10dof
2.2 amp 3 cell turnigy battery View attachment 27735

What is the loop time number set to in Clean Flight?

 

[Dave747]

Hard to see in the video but if the battery is on top, try to locate it under the CofG. It happened once to me.

 

[Paul Atherton]

I had a very similar issue, caused by too much dampening on the flight controller. I had mounted the FC to the frame using insulating material which was too soft, so vibrations were induced into the Naze32. I removed the dampening material and used some double sided foam for mountaing instead and the issue was instantly resolved.

 

[quadMonkey]

Hi, we tried to fly inorder to tune the D and I ,also to use GTUNE for P, GTUNE did not give a good result and after tunning the i value we increased the D value to 170, we tried to fly it using angle mode and it was like a slug, so the D value is higher than we need, but the quadcopter still shakes and oscillates in turns
According to previus answers it is suggested to put the battery inside the quadcopter rather than on it and have shock resistence to the FC, we are going to do that then try again
Note : we also tried to tune the rc rate and the expo which made it alot faster,
Flying it usig horizon after all this tunning made it balance itself very slowly

We are not sure if we should buy a shock resistence plate for the FC, should we?

 

[quadMonkey]

the LOOP in naze32 at the moment is 1000, we want to try and get it to 1200 if

 

[moonpie57108]

RC Rate and Expo will only make the multirotor feel faster or slower to my knowledge based on your moving the sticks and won't probably help much with the oscilation trouble.
Rate = Higher rate will increase the overall movement or speed to which the craft reacts
Expo = Allows you to smooth out the center and push the more aggressive movements to the extreme stick positions. It makes center stick "softer" to help with slower movements.

As you adjust these PIDs, watch your motor temps, after flowing for a period of time on new settings, check your motors for overheating. They might get warm, but if you feel like they are hot, you may have adjusted too far.

To Paul's point, how is the FC mounted? You could have too little or too much dampening. If you are using a foam, you could try 3M or similar double back sticky tape or you could even try hard mounting it.

To Dave's point, I don't know if you will have room to put your battery on the bottom with this frame, it looks like a F450 style frame with no clearance underneath. If you cannot move the battery, make sure it is mounted firmly. If you can move the battery around after you strap it in, it is too lose and fast control movements could cause the battery to move back and forth would only add another problem too the ordeal.

In Horizon mode, the slow "balance" (I assume this is slow self level) - This is probably too high of a D term. Low D speeds up correct, High D slows down correction.

we increased the P to 11.5 and now it flies with minimum oscillation, some noise but not a lot, tomorrow we are tuning the D and I gains

If it is has gotten better at 11.5, what about say 12, 13, 14, 15?