I am new to the forum, not new to forum software as I am active member on multiple sites. I decided to join here to read some more about Oscar's posts about Blackbox PID tuning as I am currently trying to take that on myself with my new custom DIY ZMR 250 CF frame build. I got hooked on quads when I ordered a cheap Syma X5 and flew it for a few weeks; then I needed to upgrade to something with more power for lifting a SJ cam which I ended up getting the Syma X8 because of the good experience with X5. Then I bought everything needed to build a custom 250mm racer/FPV; still waiting on the FPV gear to arrive (VTX, Cam, VRX) BUT trying to get this thing somewhat tuned with my SJCam + LOS. I can see it has major tuning issues, but what a learning curve as well.

Anyway; Hope to be around for a bit. Thanks for the awesome site!

Welcome! You have obviously caught the bug and this won't be your first build.

Oscar has a great forum here. Lots of nice people and plenty who are prepared to share their skills and knowledge.

welcome bud, feel free to ask any questions

Hoping that my VTX/Cam arrived today and gonna order goggles from US (thinking of Quanum V2) then I'll be able to record. Right now, I'm trying to fix COG and look at Black box following some of Oscar's write-up. 

I am a Process Engineer at a thermoforming factory so tuning and controlling processes is what I do just have to learn the process and how the PID works and the effects of changes (timing, causes, etc) plus the whole human input that can also be the error.

Right now my 250 moves around a bit while trying to hover, and when I go into rate mode it tends to lean forward on its own. Wondering if that is my board alignment or COG.. will tell with time I suppose.

(05-Jun-2017, 09:28 PM)NitrousZ28 Wrote: Hoping that my VTX/Cam arrived today and gonna order goggles from US (thinking of Quanum V2) then I'll be able to record. Right now, I'm trying to fix COG and look at Black box following some of Oscar's write-up. 

I am a Process Engineer at a thermoforming factory so tuning and controlling processes is what I do just have to learn the process and how the PID works and the effects of changes (timing, causes, etc) plus the whole human input that can also be the error.

Right now my 250 moves around a bit while trying to hover, and when I go into rate mode it tends to lean forward on its own. Wondering if that is my board alignment or COG.. will tell with time I suppose.

If you can hover, the board alignment is correct.
The flight controller will compensate for a COG that isn't perfect.

"Error" in this process is the difference between the commanded rate of rotation on each axis and the actual rate of rotation as measured by the gyro. "Command" is what the human inputs via the radio's sticks.

If the quad wants to keep moving in a particular direction when the sticks are centred, the first thing you should check is that the pitch, roll and yaw channels are at 1500 when they are centred. If they are, but they jitter between (say) 1498 and 1502 then you should add RC Deadband and Yaw Deadband to tell the flight controller to ignore small movements from the centre position. The deadband is applied either side of the mid point, so a deadband of 5 is +5/-5.

If they are not at 1500, you should use your radio's subtrim function to make them centre at the correct value. You should also make sure that all sticks go from 1000 at the minimum to 2000 at the maximum by using the radio's travel adjustment or scale (depending on what your particular radio calls this adjustment).

(05-Jun-2017, 09:58 PM)unseen Wrote: If you can hover, the board alignment is correct.
The flight controller will compensate for a COG that isn't perfect.

"Error" in this process is the difference between the commanded rate of rotation on each axis and the actual rate of rotation as measured by the gyro. "Command" is what the human inputs via the radio's sticks.

If the quad wants to keep moving in a particular direction when the sticks are centred, the first thing you should check is that the pitch, roll and yaw channels are at 1500 when they are centred. If they are, but they jitter between (say) 1498 and 1502 then you should add RC Deadband and Yaw Deadband to tell the flight controller to ignore small movements from the centre position. The deadband is applied either side of the mid point, so a deadband of 5 is +5/-5.

If they are not at 1500, you should use your radio's subtrim function to make them centre at the correct value. You should also make sure that all sticks go from 1000 at the minimum to 2000 at the maximum by using the radio's travel adjustment or scale (depending on what your particular radio calls this adjustment).

Thanks for the reply, my research had found ththe subtrim stuff and when I did the setup of my FS-i6 I got them all to 1500; but did notice a 2 or 3 number jitter so my deadband are both at 10 already to ensure this isn't the issue.

My board alignment is 90* CW so that the USB on the F3 faces to the left for easy access. The only other thing I notice in setup menu is that the board is showing a 1-2* forward pitch like the standoff aren't the same size in the front as the back.. I added 2 degrees of pitch to board alignment but it didn't really help. I have now changed that back to 0* but had to trim backward alot to get it to stop leaning forward.. but once I go into self-level it begins doing it again. I will have to check the board and standoff I think to make sure. Does it sound like a few degrees out of alignment could cause that?

I havent used the Quanam goggles, but AFAIK they don't come with DVR, battery or even VRX!
I recently got the Eachine Goggles Two, which are great, 1080p (1920 x 1080 px,) diversity antenna's, HDMI input an built in battery, probably the best goggles for under $150.

Under $100 I would go for the EV800D, the 800 x 480px screen can be removed from the box and attached to a ground station tripod. Alternatively the VR-D2 goggles have an adjustable screen for different eyesight, maybe glasses wearers too? These 2 have DVR in built, are both $89.99 and come ready to go with battery etc.

Oh and welcome to the greatest FPV forum there is!

(06-Jun-2017, 12:52 AM)NitrousZ28 Wrote: ... My board alignment is 90* CW so that the USB on the F3 faces to the left for easy access. The only other thing I notice in setup menu is that the board is showing a 1-2* forward pitch like the standoff aren't the same size in the front as the back.. I added 2 degrees of pitch to board alignment but it didn't really help. I have now changed that back to 0* but had to trim backward alot to get it to stop leaning forward.. but once I go into self-level it begins doing it again. I will have to check the board and standoff I think to make sure. Does it sound like a few degrees out of alignment could cause that?

A tilted board would impact the accelerometer but not the gyro I believe.  Since in rate mode you're effectively telling the board to ignore the accelerometer this probably wouldn't impact since the gyro is simply telling the FC the rate of rotation and not the actual position. Once you turn it back to self-leveling mode it starts reading the accelerometer, recognizes the forward pitch, and tries to correct. That's probably why you see additional problems in self leveling mode that you aren't seeing in acro/rate.

Edit: Oh yeah... and welcome! as you can tell people here love to jump in and help

Welcome nitrous! Hopefully you get the drifting issue figured out.
Are you using the trim buttons on the Tx while in level mode? This could be a cause for it to drift in acro/rate mode as all trim buttons should remain centered on the controller (I disable mine)
Just some brainstorming.
Only drifting issue I have faced similar to this was in a brushed micro where vibrations were the culprit, what loop times are you using?

(07-Jun-2017, 04:16 PM)Drone0fPrey Wrote: Welcome nitrous! Hopefully you get the drifting issue figured out.
Are you using the trim buttons on the Tx while in level mode? This could be a cause for it to drift in acro/rate mode as all trim buttons should remain centered on the controller (I disable mine)
Just some brainstorming.
Only drifting issue I have faced similar to this was in a brushed micro where vibrations were the culprit, what loop times are you using?

I believe you mean the Gyro/PID update/loop frequency so that would be 2/1khz on a SP Racing F3. It allows me to choose 8/2khz max if I desire, but not sure that looptimes are the issue at hand. I left them default because I was not sure what the update speeds were for my RS20A 4 in 1 ESC. I have the RS20A running in DSHOT150 and seem to get fairly clean motor outputs in Blackbox.

I am gonna go take a flight outside this morning and try to post the blackbox in tuning section I suppose, see if what I have been doing is similar to what others may think.