Micro tuning techniques - different than larger quads


#1

I thought maybe this would be deserving of a dedicated thread. Coming from a world dominated by larger quads - I have personally experienced that micros tune with a slightly different set of rules than larger high powered brushless quads.
I have my first silverxxx firmware build still needing bench time over a bad tune. It’s a 2s setup with a dm007 board. When I ran it with 1s motors - it was way overpowered - my brushless tuning instincts were right on the money - and I had it flying buttersilk smooth in a few adjustments. Well those motors melted down (of course) and a month later I still don’t have it reigned in on the new motor prop combo.
I feel I’m pretty decent at tuning when I work all the way up from scratch - adjusting p up from low values while d & i are turned down. Then raising d, then raising i. But I stink at taking a poorly tuned micro and adjusting it in from a starting point of a bad tune. Anyone else feel that way? Should I just commit to applying the while long process (feels longer with silverxxx firmware cause I can’t do the thing we do with betaflight to adjust values with a 3 position switch) or do all you gurus have words of wisdom or basic principles of correcting a bad tune vs tuning from scratch.

So here are some things I’ve noticed that are different about brushed micros (maybe it will help someone else)

They sometimes take a lot of p and even more d.
If it feels twitchy or too mechanical, I raise d even more.
Sometimes all the I in the world won’t overcome environmental effects and too much causes oscillation.
Parrot and gemfan props suffer a lot more prop wash and usually cant be tuned out like hubsan clears can.
I have to crank super rates up higher than large brushless to get the same rotational feel.
I feel like faster loop times open a larger tuning window.
Dang near any setup can be made to feel good in the air - if you can’t get it there - wipe it all and tune up from scratch.
You have to know what your tuning goal is - an acro machine or the “boxed” micro feel. Betaflight/cleanflight default setting are way more aggressive than any boxed micro. A lot has to be adjusted if you want that nano qx feel.

Agree, disagree, any tips to add?


Brushed micro tune?
Identifying flight characteristics for Noobs
#2

I don’t have any details on the brushed parts (didn’t fly any brushed micros with recent firmware for a long time), but I wanted to add that the part about raising P also seems to be true for most of my brushless micros.

Edit: Let me add - more D also helps for brushless micros, BF stock settings are waaay too low. Currently trying to tune the BOBO 95 - it’s a bit of a pain thanks to the EMAX Femto (very sensible gyro). But now that the FC is held in place with Kyosho Zeal (I had to cut a lot of pieces and play tetris, since 3mm Zeal was just too much and I didn’t want to ruin the low profile of the build) it’s getting better and better.


#3

I liked reading your ideas on how to tune a quad… I think so far you are right on the money!

I’ve only tuned one micro brushed quadcopter so far - i tuned it with the idea of agressive flips and rolls and speed in mind… ended up with a 3:30 4 minute flight time flying “fast” landing at 3.7v - motors fairly warm to the touch…

From stock betaflight tune on a 115mm brushed with 8.5mm motors at 63g*, I turned up the P a little on Roll, Pitch, and Yaw, and left the I gains alone entirely.

I did notice that increasing D was needed to smoothen out the robotic feel that too much P had added…

This is as much as I know on tuning… Hopefully when I get a little free time i can build a few more models to try out how to tune those too… Tuning… patience is a must during this process lol


#4

Yep, it takes a bit of patience and issues are sometimes rather hard to track down (brushless machines are slightly worse IMHO since you have some more options to fail) - especially if you don’t have blackbox on the machine you are tuning.

But this process is nevertheless so much better than what we had roughly 1.5 years ago - I mean, stock PIDs are usually flyable now, it wasn’t always like that.


#5

I can only imagine! - I am so thankful it is as simplified as much as it is at this point. It would SUCK having to tune something that wasn’t already flyable lol

(Not looking forward to brushless tuning - going to have to get a windows* tablet capable of running betaflight for that shiz. lol I can’t tune brushless in my backyard sadly)


#6

Yeah that’s the truth and it did. But it taught incredible “tuning from scratch” skills. It’s always interesting to see the difference between tuning from scratch and making adjustments off of a stock tune. Brushed quads still seem to tune more similar to the days before active braking brushless.

My best results on brushed quads have always been produced by the following long scratch way.

Preflight - get the highest rates you will ever fly with and enter them in. Very important.

First flight: pick roll or pitch axis and lower P to 20, drop I to 10 and D to 5. Have increasing P value assigned to a switch and get in the air - flying with sharp back and fourth action on that axis till the response to the commanded motion feels/sounds really “crisp.” It’s a learned feeling, but there tends to be a range where you start to feel it - and I push that range to the top ( that’s a personal preference thing- stop where you like it). Land and save.

Second flight: Assign D to the switch and fly with the same motion till with the switch activated till it feels/sounds butter smooth. You’ll know when you hit it. It comes in just like the warm feeling after a shot of Captain Morgan’s. There is not as big of a range on D (it’s a matched value to the p you selected), so I stop when I find it. Land and save.

Third flight: Assign I to the switch and fly. Set a bank angle and punch throttle/ drop throttle rapidly. Look for it to hold attitude. Then deactivate switch so it stops increasing I. Now pull a flip. If you are still to low on I, then you will hear the motors pulse at the apex of the flip. Raise it up some if needed. Land and save.

4th, 5th, 6th flights - same thing as 1,2,3 for either roll or pitch.

7th flight - attack yaw. I’ve never had to lower below stock on anything - so P gets assigned to the switch and I raise looking for that crisp feeling with abrupt movement, and a sharp sound to start and stop the motion. When it gets to high, it will start to bounce up bad on both the start and stop of motion. I stop at a manageable amount of bounce up. Land and save

8th flight - add a hair of D to tame the bounce up. Too much and you will hear the motors dig too long trying to stop the motion.

9th flight - address yaw bounce back if it’s there. (Different than the bounce up) If it is there on short sharp stick inputs - add I.

On yaw, if you like sick fast rates, and you take off and yaw spin till its going really really fast - it’s gonna bounce back. Don’t try to tune that out. Our small motors don’t have that much authority.

Flight 10 - fpv process to check I maintaining attitude, and to make sure D has bounce back on flips and any mechanical feeling reigned in.

So 10 flights just to tune for me (the first time - I like to run the gauntlet twice and compare). But when I take the time - it’s always way way different then where I end up adjusting from stock… and I like the way it flies significantly more! That’s the old school tuning method as I learned it years ago. And if you think it’s exhausting to read it - you’re right! Hahaha


#7

How do you assign the values to a switch? I usually loose interest in tuning after flying, unplugging battery, plug in cable, make some guess adjustments and repeat.


#8

It’s not the most intuitive procedure with the betaflight/clean flight gui but it is possible. I’ll seek out a decent YouTube video describing it and link it here.


#9

Confession: I have not watched this video myself - but it’s the right topic and I’m sure Bardwell does not disappoint! I probably should - I bet I would even learn something new from him about a process I have done for years! Hahaha

I remember cresting the learning curve long ago on in flight adjustments - it felt steep at the time but was well worth it. That’s before the University of JB (Joshua Bardwell) existed though. Tutorials were scarce then and not so well produced.


#10

I’m going to have to watch this.
Thanks!


#11

Cool video… thanks. I have a DX6 transmitter… does anyone know how to set it up to use 1 switch to decrease the value of another switch like he does in this video?


#12

For some reason I am getting the feeling it’s a taranis thing? I know taranis is open source, I am not too sure if spektrum radios can accomplish this. I hope someone proves me wrong tho lol


#13

I know the DeviationTX TXs can do it with mixers, don’t know about the dx6, but I’d guess it probably can.


#14

There is no need to be able to adjust everything at once. ESPECIALLY at first. It’s going to take you a whole pack just to reign in each value one at a time. I’ve been doing this for years and fiddled with a set up like that. I just don’t operate that fast. Plus, it only changes 1 value point per second. A three minute flight with takeoff and landing time just doesn’t afford that kind of room. Start simple. One axis, one value, and 1 three position switch.


#15

I used MWOSD for PID tuning a lot - still have to try the fancy lua scripts for the Taranis :slight_smile:


#16

This is a great thread with lots of good tuning advice and techniques for brushed micros. Thanks @NotFastEnuf for getting it going!


#17

should we be tuning in acro mode, or angle mode? lol I am once again giving the good old PID tune a try again and having better luck with tuning off a stock betaflight tune, but I am still curious as to which is best for tuning…


#18

This quote is from bardwell himself
"The transmitter setup will be different in Spektrum, and honestly I am not sure whether it is possible to reproduce it or not. The ability to do complicated programming like this is one of the benefits of the Taranis. But maybe it is possible in Spektrum too… I’m just not a Spektrum user."

I haven’t tested it out yet but I am thinking he is right, there are only 2 aux switches that I know of on the dx6…


#19

You do all your tuning in acro. When she is good and solid - you can switch back over to angle. At that point - you adjust leveling strength. A perfectly tuned quad in acro may oscillate like the world is coming to an end just because of that setting being off when you activate angle. I haven’t set up angle in a long time but I remember I liked the values much lower than stock setting. I think it’s like 50 or something - anything above 20 caused me problems. Sweet spot for me was about 18 to 19.


#20

Makes sense man! I’ve been tuning in Acro but wasn’t sure. Cant wait until 2moro to finish tuning it :smiley: