Help with oscillations

[Legend FPV]

Ok so I know that there are a million cures for mid throttle oscillations, and I also know that often times they are there to stay and there is nothing to be done about them. I have tried everything from swapping all 4 motors, swapping the frame with a brand new one, soft mounted motors, and flight controller. Tuned and retuned and I still have these oscillations in my videos. They are much better than they were but they are still there. It is very frustrating as you all know. I am running betaflight 3.2 with dynamic filter enabled, both notch filters disabled, and still the problem persists. What am I missing? Is it the tune? I just swapped out flight controllers in hopes that it will fix the issue. It is my last option really as everything else has been fixed! I used to have a cheap SP racing F3 that had the crappy MPU6500 chip in it. I have replaced it with the LUX V2 which has the MPU 6000 chip which is supposedly better when it comes to noise. Any help or advice would be greatly appreciated. On a side note, if you like my videos, go ahead and Sub just throwing that in there. Happy Flying!

 

[theGreenOrange]

It very well may be your camera lens. Replace the lens with a known good quality lens, they are cheap.

 

[theGreenOrange]

Oh, and the video isn't showing up for me.

 

[Legend FPV]

It very well may be your camera lens. Replace the lens with a known good quality lens, they are cheap.

The lens in my Gopro session 5? Surely that is the best quality you can get as far as that goes. If you are talking about my runcam 2 lens, I am using a Gopro lens for that as well. I also put some foam on the back of the sensor as that was super shaky at one point but is fixed now. I really only see the oscillations in the HD footage. I inserted another one of my vids that shows the same issue. Thanks for the reply back BTW!

 

[Legend FPV]

You can see them more about midway though the vid

 

[theGreenOrange]

It would be easier to tell what is going on without the music. Sounds like it could possibly be D_term oscillation but it is hard to hear exactly what is happening. Have you looked at the BlackBox D_term graphs? You could try lowering your D-terms. Also you could lower the D_term setpoint weight slider. If it gets worse when you lower the D_term then it is probably excess P gain.

 

[theGreenOrange]

I don't know if you have seen this already but it is a pretty detailed and concise talk on PID tuning. It has some good examples of what excess P and D gain sound like.

 

[Legend FPV]

It would be easier to tell what is going on without the music. Sounds like it could possibly be D_term oscillation but it is hard to hear exactly what is happening. Have you looked at the BlackBox D_term graphs? You could try lowering your D-terms. Also you could lower the D_term setpoint weight slider. If it gets worse when you lower the D_term then it is probably excess P gain.

So in theory, would raising the slider help reduce the oscillations? I just cant see it being too high of P because they are set fairly low compared to other builds I have done. They are all different though as I am sure you know. I have messed with them before to see but maybe I never went low enough. I will try stock pids and see if they are still there. I have a LUX v2 installed, just waiting on my PPM receiver to get here. Hopefully I dont have to even worry about it after thats done. Thanks for the advice man! I really appreciate it.

 

[Legend FPV]

I don't know if you have seen this already but it is a pretty detailed and concise talk on PID tuning. It has some good examples of what excess P and D gain sound like.

No I have not seen that but will definitely check it out. I forgot to mention that I have not checked the logs. The LUX has an SD slot so I will check them once I get it in the air again.

 

[theGreenOrange]

So in theory, would raising the slider help reduce the oscillations? I just cant see it being too high of P because they are set fairly low compared to other builds I have done. They are all different though as I am sure you know. I have messed with them before to see but maybe I never went low enough. I will try stock pids and see if they are still there. I have a LUX v2 installed, just waiting on my PPM receiver to get here. Hopefully I dont have to even worry about it after thats done. Thanks for the advice man! I really appreciate it.

I know lowering the setpoint weight slider can help with D_term oscillation if lowering the D_gain doesn't do the trick. To me, it looks like it is D_term related probably but the BlackBox would help know for sure.

I'm not sure what effect raising the setpoint weight slider would have if your oscillations are P_term related. Usually in this case you would lower P gain or increase D gain.

 

[Legend FPV]

I know lowering the setpoint weight slider can help with D_term oscillation if lowering the D_gain doesn't do the trick. To me, it looks like it is D_term related probably but the BlackBox would help know for sure.

I'm not sure what effect raising the setpoint weight slider would have if your oscillations are P_term related. Usually in this case you would lower P gain or increase D gain.

I believe my D gain was set lower than it was stock. It is at 25 in the video. I have since raised it to 31. Here is a raw video I had maybe you can hear the oscillations. This was my most recent vid without music. It was done after my frame and motor swap.

 

[theGreenOrange]

It looks pretty good to me in that last video. The only oscillation I noticed was in propwash situations.

 

[Legend FPV]

It looks pretty good to me in that last video. The only oscillation I noticed was in propwash situations.

Well at that point I had done some extensive tuning and repairs to get it to fly smoother. I really only noticed them when I would give it full throttle. It was hard to get a good run in because it was in my back yard.

 

[Legend FPV]

It looks pretty good to me in that last video. The only oscillation I noticed was in propwash situations.

The tree line is the best reference point for what I am talking about. It seems like the roll axis is fluttering a little when I give it about 75% throttle. My TPA is at 48% so surely thats not the issue either.

 

[MCCV]

The tree line is the best reference point for what I am talking about. It seems like the roll axis is fluttering a little when I give it about 75% throttle. My TPA is at 48% so surely thats not the issue either.

Have you ever been able to fix this issue, i have exactly the same problem, i have tried pretty much every PID combination possible, i have replaced my motors and props, soft mounted everything with custom tpu parts. Yet i still get these oscillations of about 5hz