Replies to This Discussion

Permalink Reply by Ron Curry on April 2, 2012 at 9:26pm

Ramesh,

I am also an experimental full size aircraft builder and, in the past, I've built or rebuilt several full size  airplanes as well as built a full size kit helicopter. Of course, when you are getting ready for you first real flight with one of these babies you exercise a lot of caution - mostly because the stuff cost a bunch of bucks but also because if you f*** up something important there is a good chance of getting killed!. Took me 2+ years to build my two seat full size helicopter from scratch and when I went to fly it I tested and tested and tested incrementally until I reached a point where I could no longer find a reason not to take a flight around the pattern. Of course, we don't need to take quite  as many precautions with RC aircraft (or do we! ;-) ) but certainly it reduces a lot of frustration and cost to be as careful as you describe (and follow the directions). I should mention that the guy I sold my helicopter to tried to teach himself to fly it and rolled it over and it did the funky chicken (short for it beat itself to death). No more  helicopter.

One thing I've found indispensable with multicopters is the hand test. Setup channel 6 on a knob or slider on your TX and to rate_KP and fire up while holding the ship overhead. Turn it up until it bounces when you tap it to the left or right. Note the value, make it permennnt and then do the same thing for stab_kp. Absolute easiest way to get in the ballpark for your ship. once you get it where it doesn't bounce and doesn't oscillate then go out in the yard and try it.  WAY better than trial and error flights.

It can be dangerous so BE CAREFUL though so don't go crazy on control inputs.

Of course you could build some sort of test fixture that does the same thing and it would be a lot safer but....

Cheers,

Ron

Cheers,

Ron

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Permalink Reply by Dave C on April 3, 2012 at 10:26am

Ron I look forward to the day when i can say I've built my own full sized helicopter, and yes caution will be the key I'm sure!

In the meantime I completely agree the hand test is invaluable for RC stuff, especially multi-copters.

Not only will you have a better tuned, safer beast to fly, but you learn so much about how the airframe handles, how external influences might affect it and most importantly how the P's I's and D's influence how it flies and responds.

I recommend to everyone, where possible, get your helmets/plain-glass welders masks/ safety goggles, gloves, body armour on, whatever makes you safe whilst you've got four spinning blades above your head and go for it - full throttle at times!

And as we all occasionally need reminding of what might happen, here's what happened to me 2 weeks ago...

I was trying out some new cheap HK prop savers, and one of them gave up while i was chucking 'the beast' about in the lounge. I had my helmet on, but no gloves. Prop saver gave up, prop came off, straight at me and hit the back of my hand. Even after flying, unpowered, for a couple of meters towards me it cut me twice, close together, and wrapped my other finger pretty well too, and obviously by this point it wasn't even attached to a motor. 

2 cuts, 3 weeks later - the first was 'to the bone'... Only pleased that this was my finger and not my lovely eyeballs ;)

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Permalink Reply by Maki, Eric J on April 3, 2012 at 8:13am

A note on safety for hand PID tuning: the more the better! 

Balistic shooting glasses are the mimimum safety gear I wear while I've been tuning PIDS with my quad in hand overhead (ever seen a prop come apart at 10k rpm?)  Blowing dust and grit in the air are another reason for glasses.  Gloves are unwieldy, but a long sleeve shirt works fairly well to turn potential puncture wounds into a torn shirt or mild scratch.  Props do come apart, prop adapters can come off the motor shaft, and control circuits can fail.  Eyeballs are cool, I like mine.

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Permalink Reply by Paul Emous on April 3, 2012 at 8:32am

Hey guys,

I have some issues with PID tuning as well. I use a carbon Y6 950mm frame with 850 motors and 10" props. Everything is pretty centre so no COG issues if I look at the copter.

Currently I use: Rate Roll / Pitch 0.120

when the copter takes of, it is fare from stable in the beginning and flies around (15 meters radius) trying to sort itself out without success. Any suggestions?

Thx.

Paul

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Permalink Reply by Brian McGrath on April 12, 2012 at 9:58am

Hi folks! Thanks for starting this kind of thread. I am starting a build of a Scarab YSiix (standard configuration - 775k motors, 10amp ESC, 2650mah 4S) and I am planning on using the APM2 as the flight control system. Any suggestions for starting setup?

 

Thanks!

 

Brian.

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Permalink Reply by Jason Tinacci on May 15, 2012 at 10:19am

Hi Rui, 

Any news on updated standard PIDs for the standard 3DR quad? There have been several releases since the last param file was posted in the wiki back in February?

Thanks,

Jason

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Permalink Reply by Rui Manuel Cravo Marques on May 15, 2012 at 10:45am

Hi Jason, I haven't posted anything since no one has been sending me configurations. I think the actual AC versions, since 2.4, by default have the PIDs' tunned for 3DR frame and motors. I'm flying different frames so my PID are no good for you, but if I can help you with anything please let me know. I'm waiting for a version with the best loiter dev team can get to update my firmware.

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Permalink Reply by Dave C on May 15, 2012 at 11:12am

One of my airframes is a 3dr, 850kv kit, I use completely stock params for rate and stab sometimes, and other times tune starting with rate_D for a more ninja feel. It flies pretty well either way, and most places in between. Best way to get it perfect is to start stock and use channel 6 to go 20% up and down from stock, see if you get any improvements. Do rate first and then stab. 

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Permalink Reply by JohnB on June 29, 2012 at 10:08am

Lets BUMP this thread!  Please do not let it die.

I'm a bit surprised at the lack of PID information in the Google doc file.. but that's ok.. we're on the bleeding edge.  I've seen videos with amazing results; I wish they would post their settings in the doc. 

I've got a Next Level 650 high-power quad with Cobra motors.  I'm struggling with Alt Hold right now.  Stabilize was great at default settings to my surprise.

On to tuning...

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Permalink Reply by Mike R. on July 5, 2012 at 1:17pm

I opened another thread on the board specifically asking for PID info/advice for hexas as I have a new 3dr one with 880 motors/11" props, and everything I read is geared towards the quads (randomly incorrect/inconsistent build instructions, jumping to 4-5 different docs to find one step that is missing from all the others, etc..)

I would love to see some hexa info from people who have them - seem to be few and far between so far...

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Permalink Reply by Rui Manuel Cravo Marques on July 5, 2012 at 2:12pm

I've been using an hexa lately (even tough I have a quad also), mine is a xaircraft diy x6 with x2212 sunnysky motors and 10" blades, about 550mm motor to motor and 1.6kg. My settings are almost default, I have just put STAB I =0, lowered STAB P = 3.0 and RATE P = 0.110 and RATE I = 0.015, RATE D = 0.001 and STAB D=0.09

This are the main parameters. However, it would be good if you show the rest of your specs, like motor to motor dimension and approx weight.

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Permalink Reply by James on July 5, 2012 at 3:32pm

i would like this thread to carry on too ..

heres a new one for the spreadsheet Rui, 

Flat Hexa 650mm

jDrones 880kv

APC 12x3.8

AUW 2.0 - 2,5Kg depending on load

STAB P 4.3; I 0; D 0 (can lower stab p in calm conditions)

RATE P 0.130; I 0.015; D 0.010

STAB YAW P 6.5; I 0

RATE YAW P 0.160; I 0.015; D 0.001 (not 100% perfect, but getting better)

this flies great with or without camera, with these settings its a bit aggressive for a camera platform but great for fighting the wind.

james

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