I've been tuning the octocopter this evening, I started with Stab at 1.000 and Rate at 0.25.
I tuned the rate by hovering then giving sharp stick inputs and watching for the bounce as I release the stick to centre. I turned up Rate P until the bounce was just present then back down a little so no bounce on releasing the stick.
During this I found the controls very wolley and needing loads of stick input.
Moving on to STAB I increased it via channel 6 up to 2.8 (still got to get this right but waiting for batteries to charge now) As I increased STAB the sticks became much more responsive, The octo seems fairly good until wind catches it then its a bit of a sod to control.
Am I doing this correctly, how do I got about tuning yaw ?
This oct has loads of power, it lifts at quarter stick so I expected the values to be less than default but If I remember correctly default rate was somewhat less than I have now,
Any help would be appreciated.
Thanks
Replies
I'm having a night mare !
I'm doing something wrong in tuning, but I don't know what. I thought I had the Rate dialed in but as I add stab its becoming unstable, so I reduce rate and get some stability back but that effects return to level it stops way short of being level after centering the sticks.
I did get to a stage when rate P was at 0.15 and Stab at 1.6 where there was no wobble but I was at full stick just to correct the hover.
So here's my tuning method, please tell me where I'm going wrong. All tuning is done in Stabalise mode.
1. Set a base value of Rate 0.25 Stab 1.0
2. Adjust Rate P and put in a sharp stick movement then stick back to centre. Watch for a wobble as it returns to level. Reduce Rate P until the wobble just disappears.
3. Begin to increase STAB and repeat the same procedure
and thats about as far as I've got. Its a perfectly still day here and Ideal for testing.
Help would be appreciated, I've obviously got something very basic wrong in my method.
Those are pretty wild settings! That stab_I is way too high in my opinion.
Did you make a note of the defaults before you started tuning? They are pretty close to reasonable for most air frames, as a good starting point:
Rate_P 0.130 (increase/decrease in 0.010 increments, <0.05 you will find sloppy unless you have a very powerful machine)
Rate_I 0.030 (increase/decrease in 0.005 increments - can be at zero for 'careful' flying) only use this OR Stab_I not both together in my experience anyway.
Rate_D 0.002 (increase/decrease in 0.001 increments - can be at zero)
Stab_P 4.000 (increase/decrease in 0.200 increments, <0.05 you will find sloppy unless you have a very powerful machin
Stab_I 0.030 (increase/decrease in 0.005 increments - can be at zero - only use this OR Rate_I not both together)
Stab_D 0.002 (increase/decrease in 0.001 increments- can be at zero)
loiter_p to 1.2 (increase/decrease in 0.100 increments - you'll need at least 0.5 in my experience even in no wind situations)
Also try work through the spread sheet attached below, thanks to Angel for that one.
Let me know how you get on.
Mark: I fly a large octo as well. Your rate looks pretty spot on. You should set your stab_i gain to zero and focus on getting stab_p dialed in. stab_p is around 1.75 for my octo. Once you get that where you want it, you can play with trading off a little (like .01 at a time) stab_p for some stab_i for better response in wind or with cg issues. You definitely shouldn't be tuning all your stab response into the Stab_I gain though. Start with P.
Stab_I will help in the wind. Just to be clear, stab_i is how quickly the copter adjusts for wind / CG, and stab_i_max is how much it is allowed to correct for wind/CG. So if you get stab_i dialed in to where it is correcting with the appropriate speed and it still isn't quite correcting enough, you can increase stab_i_max. Maybe start with increments of 5 on stab_i_max.
I am flying 14x4.7 props with AXI 2826/12 motors (LOTS of power), but I still require a higher rate_p setting because of the sheer size and weight of the copter. You are correct in having your value a little higher than the defaults.
Good luck!