Question: Local FPV Group Cant Solve - Yaw Issue, Halp!

[LucidFPV]

Hey guys,

I just finished building my third quadcopter from all brand new parts top to bottom. I take it out for a maiden and a few test fights and noticed some unstability. When I started testing I ran into an issue with only my yaw.

Issue:

When I hard yaw one direction, after completing the yaw move the quad would counter this by snapping back the opposite direction nearly 90 degrees some times. High pitch sream and after landing motors are extremely hot. All this sounded like a PID tuning issue. I tried spending a couple batteries tunning but everything I did made it worse or only changed a bit and not nearly enough. I've looked around to find other solutions, re-flashed my FC, tried flipping between gyros to see if one was the issue {dual gyro board}, messing with PIDs/Filters, messing with controller settings and no luck. Posted all this and video of the issue to my local FPV group and of the 100 people no one could come up with a solution and suggested posting else where or trying to get a new FC. I would like to avoid spending another $120 for a FC that I've flown 5-6 packs on only testing this issue. Any ideas?

Link to video of the issue for review below and if you need anything else to trouble shoot let me know! If I can't find a solution, I'll try reaching out to the manufacturer for replacement or buy a new one.

Quad Components:

FC/ESC: iFlight Succex-D F7 V2.1 TwinG 30x30

RX: ImmursionRC Ghost

VTx: Flywoo Goku VTX625

Battery: GNB 1350mah

Motors: T-Motor V2207 - 1950kv

Camera: Runcam Pheonix 2 micro

Controller: FrSky Taranis X9D+ 2019 version

 

[wafflejock]

Hey guys,

I just finished building my third quadcopter from all brand new parts top to bottom. I take it out for a maiden and a few test fights and noticed some unstability. When I started testing I ran into an issue with only my yaw.

Issue:

When I hard yaw one direction, after completing the yaw move the quad would counter this by snapping back the opposite direction nearly 90 degrees some times. High pitch sream and after landing motors are extremely hot. All this sounded like a PID tuning issue. I tried spending a couple batteries tunning but everything I did made it worse or only changed a bit and not nearly enough. I've looked around to find other solutions, re-flashed my FC, tried flipping between gyros to see if one was the issue {dual gyro board}, messing with PIDs/Filters, messing with controller settings and no luck. Posted all this and video of the issue to my local FPV group and of the 100 people no one could come up with a solution and suggested posting else where or trying to get a new FC. I would like to avoid spending another $120 for a FC that I've flown 5-6 packs on only testing this issue. Any ideas?

Link to video of the issue for review below and if you need anything else to trouble shoot let me know! If I can't find a solution, I'll try reaching out to the manufacturer for replacement or buy a new one.

Quad Components:

FC/ESC: iFlight Succex-D F7 V2.1 TwinG 30x30

RX: ImmursionRC Ghost

VTx: Flywoo Goku VTX625

Battery: GNB 1350mah

Motors: T-Motor V2207 - 1950kv

Camera: Runcam Pheonix 2 micro

Controller: FrSky Taranis X9D+ 2019 version

Is the FC soft mounted? What I mean is is the FC just on rubber grommets that are on screws that are held into the frame (kind of want the FC to float a bit so it doesn't feel all the jerks of the quad)

I ask because I had a really really similar kind of behavior just doing some near the ground testing and it turned out even though I did have a "soft mount setup" as described above the nyloc nuts on the top of the stack were wrenched down too much and so the screws were knocking around the FC and causing yaw glitches. In my case just loosening the nyloc nuts on the top of the soft mount stack was enough to get things working better (could also potentially remove the noise in the gyro with filters but easier to make a few physical adjustments and see how things work and generally has more of an effect than tweaking sliders/PID values, although for this case a filter may have a big effect if setup "properly", with blackbox data to show where the noise is I mean).

Also suggest go back to default PIDs from iFlight, PID adjustments from what MFG gives you should be something to tweak out the little wobbles or adjust the feel of the flight but it shouldn't be so out of wack it twists like this, this is something physically wrong IMO.

 

[LucidFPV]

Is the FC soft mounted? What I mean is is the FC just on rubber grommets that are on screws that are held into the frame (kind of want the FC to float a bit so it doesn't feel all the jerks of the quad)

I ask because I had a really really similar kind of behavior just doing some near the ground testing and it turned out even though I did have a "soft mount setup" as described above the nyloc nuts on the top of the stack were wrenched down too much and so the screws were knocking around the FC and causing yaw glitches. In my case just loosening the nyloc nuts on the top of the soft mount stack was enough to get things working better (could also potentially remove the noise in the gyro with filters but easier to make a few physical adjustments and see how things work and generally has more of an effect than tweaking sliders/PID values, although for this case a filter may have a big effect if setup "properly", with blackbox data to show where the noise is I mean).

Also suggest go back to default PIDs from iFlight, PID adjustments from what MFG gives you should be something to tweak out the little wobbles or adjust the feel of the flight but it shouldn't be so out of wack it twists like this, this is something physically wrong IMO.

Hey!

Yes it is soft mounted but I can check the tightness to the nuts and ensure it’s not super squished.

Im on stock PIDs as adjustments didn’t help much, although I’m not good/experienced at tuning sadly. Normally stock has been fine.

when you say physically wrong, what do you mean? Like maybe motors are mounted correctly or something wrong with the frame?

 

[holtneil]

I was wondering if the esc setting are wrong for the motors and it making them twich in flight and knocking the gyro the motors should not be very hot , brushless motors have a timing setting that's adjusted in the esc if not the esc has to match the motor setting it needs to work with out getting very hot , may be worth a look at but I do agree with wafflejock it's gyro related

 

[LucidFPV]

I was wondering if the esc setting are wrong for the motors and it making them twich in flight and knocking the gyro the motors should not be very hot , brushless motors have a timing setting that's adjusted in the esc if not the esc has to match the motor setting it needs to work with out getting very hot , may be worth a look at but I do agree with wafflejock it's gyro related

You know what, I dont know if I messed with my ESC settings after I built it... Do you have a suggestion that might be good for this build?

 

[LucidFPV]

Also small update, been talking to iFlight about this issue as well and they said my tune may be a bit off for the build. They suggested a few things,
1) Turn on I Term Relax if its off and set Axes to RPY / Type to Setpoint / Cutoff to 10
2) Adjust PIDS for Yaw to P = 50 / I = 90 / D = 0 / Feedforward = 40

I plan to make these changes tonight and see if that changes anything. Along with that (or after i can test this) I'll try going though the ESC setup as @holtneil suggested. Maybe my settings are off their as well, just need to figure out what good setting are for the ESC first.

 

[LucidFPV]

Update: I tried their suggested setting with no improvement. I took a blackbox log to look at the yaw move and I see the overcorrection part now. The only thing I dont get is why it delays so hard on the end of my yaw move. my set point is already coming down but my I term is pushing so hard still keeping the gyro scaled up. Then at some point it stops and pushes to hard the other way and I get overshoot. Any ideas on how to get the tail end to track better?

 

[Dugdog47]

Make sure there isn't a screw touching a motor somewhere.