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Old 08-12-2012, 10:31 PM   #1 (permalink)
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Default Advanced parameters glossary

Hi,

i will post tomorrow night an advanced parameter " walkthrough" for the Brain.

What i can say if it can help is that the combinationof PID gain is important and may vary a lot even with same helictopers and hardware, depending on settings, blades, flight style, and each parameter will somehow have an influence on the others. So it is important to use always, if possible, the 3 setups ability, and to keep one (let's say Setup 1) the same and operate changes on the 2 others to be able to identify, and understand the actions of each parameter.

A common error is to try to modify several parameters at the same time, which will not help you to achieve a good setting, it will only lead you to non working parameters and frustation. I did learn that from AC3-X usage

Now, to make it short:


Proportional Gain is the general correction strenght and interpretation of the tail stick input. The higher it is, the faster it reacts to our sticks inputs Too high gain will generate a tail oscillation. It's the Tail Gyro gain in the receiver parameter.

Integral Gain is a time value. It "schedules" the tail angular position control. It's exaclty like the Heading Hold gain on a regular gyro to make it simple.The higher the value is, the harder the tail is locked.
But too high value will give some bounces on hard stops or oscillations in hovering ( or both..).But it will also setup the consistency of pirouetting..

So The tail gets an input from the pilot. Proportional gain will command a tail movement, hard or soft depending on the Proportional gain. The Integral Gain will then check the angular position of the tail repeatly, on slow or fast cycles and detect the tail angular position.

Derivate gain will affect the stop behaviour of the tail, hard or smooth, based on prediction of the need of correction to stop the tail correctly depending of the flight characteristics needed ..

So once the tail angular position has been checked by the Proportional gain, it will react harder or smoother depending of it's prediction strenght ( value) and will either give a slow stop ( small drift), a smooth stop, a hard stop or a too hard stop ( bounce). We could vulgarize this setting with the " delay" of the GY 401 gyro for the people who have used one in the past, which helped the gyro to predict the amount of correction for the stop by giving a time value matching the servo speed abilities..

So it is important to start with basic wizard value and create new setups to select in flight and check the behaviour.

First of all, the cyclic must be set correctly before hoping to get a good tail setup.

I will describe the swash setups tomorrow as for now most of you have very good behaviour on the swash and are fighting against tail bounces.

So here we go for a basic setup example:

We start with the Proportional gain tuning ( Gyro Gain)
All other parameters must be "stock" from 3D setup wizard as the extreme 3D is a bit.. Extreme ( it was requested by customers anyway lol)

Rise the gain until the tail starts to oscillate. Reduce then not just a little, but by 1/3rd of the total gain (keeping high value will simply make Integral and derivate **** up totally lol).

So if you were at 40, and rised to 70 to have the tail starting to oscillate, don't reduce to 68, but reduce by 70/3 points which will be 47 / 48 .

Once done, we move to Integral gain. To set it up, make several Slow/ moderate climbing / descent to adjus the value until the tail does not " wag" when making up / down pitch manoevers. at limited pitch inputs ( for fast pitch you can work pitch precomp) For fine tunig, check the tail consistency in Pyro. Adjust until the Pyro consistency is allright, perfect test is in steady forward flight, make pyros left and right and once you have something looking . Once you have a suitable value, move to.. Derivate gain. Do not work out pitch precomp and cyclic precomp, you will adjust after a first setup of integral gain.

The derivate gain will affect the helicopter tail stop behaviour. So start with a low value and rise step by step. To test the pyro stop, never release the tail stick to have it get back to neutral as the tail will understand this as multiple left /right fast inputs ( spring of the stick). Start with slow pyros and then gradually move to fast pyros. Do not hesitate to " limit" the pyro rotational speed to 360% / S at the beginning for the setup, too fast Pyro will not allow you to identify the real tail behaviour in the stop process.

If you still get some bounces on each direction, don't start to mess up wit the " Stop gain". Start with increasing the tail stick spring tension of your transmitter ( it is very common on Spektrum and Futaba transmitter that the spring is a bit soft so when you make a tail pyro stop, your thumb or fingers give an erratic input to the tail stick out of center.. Once you can feel a bit better difference, you need to go in the control advanced setup and increase a little the dead band of tail to make sure the Brain will not react on a mistaked interpretation of the tail stick position due to potentiometer precision in the stick or thumb wobbling or small uncontrolled stick movements. 4 / 5 % seems to work better than 2% in most cases.

Once this is done and the tail is acting better, then you can play with the " Stop gain" and see how it helps.

Then, when you have something steady, end up tunig with forward flight with climbing ( adding pitch) to adjust the Pitch precompensation and then just high / low pitch changes to fine tune.
Proceed now for rolls and adjust the cyclic precomp. Just make sur to tick the checkboxes in the advanced configuration of the cyclic and pitch precomp if you wish to set these values.

I will have to re read myself tomorrow afternoon to make sure i did not make many mistakes inthe explanations and to make sure the parameters names are the correct ones for PID / DMA feed forward that are used on AC3x unit. In any case, proceeding this way should help you to have a work base.

You can also use a 250 class setup for the 450's and a 450 class setup for 500's to see the variations from the basic wizard in flight and get some inspiration

The Brain is a very powerfull unit and to allow the flight characteristics it offers, it is needed to make several test and tuning flights. Some other FBL systems might offer very good results out of the box, but when you search for the " little more" thing then you have to pay for it with patience and fine tuning

Thomas is in hollidays for a small week, i do not have the pretention to know the parameters effects as good as he does, so i can only give practical tips to work out the setup for now.

No doubt he will modify the presets or make any change that would be needed eventually once there is enough parameters feedback to make more " plug and fly" presets especially for the tail

Best regards,

Fabien

Best regards,

Fabien
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Old 08-12-2012, 10:45 PM   #2 (permalink)
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Awesome, thanks! Lots to chew on there. Can you comment on what increasing and decreasing each value does to the model? For example, my stock stop gain is already 0%, with a derivative gain of 10%. My stops are way to hard and bounce as well. So I assume I need to reduce, not increase derivative?

For pre-comp, my starting value is -20%. To I increase or decrease this number to increase pre-comp?

For tail I gain, I'm at 55 now, and still climbing. Main tail gain found it's way down to 47 in the process of increasing I.

For elevator bounces, I increased to 80 and it helped, but is still there. So I assume I need to go higher?

Thanks!
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Old 08-12-2012, 11:30 PM   #3 (permalink)
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Hi,

i'll try to get more in details tomorrow evening as it's 6 am here lol ! Need to go to bed )))

For precomp,it is very simple It is in fact computing digitaly a precompensation of the torque to ask the tail to anticipate the upcoming torque generated by a fast pitch or cyclic movement.

For checking it, just do it on the bench to know the value you have to put ( this can generate an unsolvable tail bounce if not setup in the right direction, you will understand why right below..

Check with motor disconnected or with a receiver battery( security, security), put your helicotper to level approx and power transmitter / Brain, linked to the computer in advanced mode to tweak the values.

Put your swahsplate to be at 0% pitch and move pitch to max. chek the tail behaviour. It must add some pitch on the tail to compensate the torque. You will know straight away if you need positive or negative pre compensation value. If you have "reversed" value, your heli will have a tendency to have the tail reacting late to the pitch or cyclic input.

Concrete example:
On a Protos 500, rotor is spinning clockwise. It means that if you give a fast pitch input, the heli will "try" to rotate on the yaw counter clockwise.
To coutneract this manually, you would need to give a momentum tail input in clockwise direction to compensate that momentum excess of torque.
So just check in which direction the tail rod is moving when you give a clockwise tail input, and put positive or negative to have same direction reaction.

Pitch precomp will give same direction precompensation command for both positive and negative pitch ( the pitch positive or negative will generate an anticlockwise torque.

So at Zero pitch the tail servo will not move at all.
If you go positive it must give a clockwise input
if you go back to zero it comes back to neutral
if you go negative pitch it must again give a clockwise input.

Same methodology for Cyclic Precomp

This is why, if it's setup with an erratic way ( positive instead of negative), you will generate a .. bounce on the tail whatever you do

Then for the tail stops you need to work with derivative and integral and leave the tail stop to 0%. Now, i have to admit , i wonder if the Stop Gain is a stop Gain or a stop delay and i have to ask Thomas for that matter.

For Cyclic, every time you will touch the Proportional gain, you will have to adjust Integral and Derivative also. Normally you should be able to higher the integral gain and reduce derivative maybe ? I'll give mroe details tomorrow but as PID result is the combination of the 3 values sometimes it can happen to end up with fuzzy values and grear results lol !

I'll work on the manual tomorrow afternoon and hope to put the most important explanations by editing my first post in the night.

Best regards,

Fabien
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Old 08-12-2012, 11:45 PM   #4 (permalink)
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Hi Fabien,

First I have to say congratulations on the launch of an excellent FBL controller. I've tried many different ones and can honestly say that for once a product has exceeded my lofty expectations!!

My only question so far is the Governor spoolup adjustment. I am using YGE ESC's v4.23 (vbar gov ready) and am using Heli Mid+ plane Fast. Gov performance is excellent...but startup is harsh. I want to use the YGE's built in soft-start. Setting Ramp Spoolup to 5 or 10 and decreasing startup to 5s or 10s works fine on my X4/120LV 6s...but is not working on my X7 12s setup 160HV..i get hard kick ...blades fold.
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Old 08-12-2012, 11:46 PM   #5 (permalink)
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You rock and thank you for the very detailed explanation. And thanks for loosing sleep for the brain early adopters. (-:

Looking forward to the rest of your extremely informative posts
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Old 08-13-2012, 06:51 AM   #6 (permalink)
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Hi Guys,
thanks for your messages

I'm not related to MSH but for some reasons i'm happy to help on this little " Brain" if i can

Best regards,

Fabien
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Old 08-14-2012, 02:07 AM   #7 (permalink)
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I don't find any prop gain for the tail.. am I blind?
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Old 08-14-2012, 02:18 AM   #8 (permalink)
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Quote:
Originally Posted by Berserkertom View Post
I don't find any prop gain for the tail.. am I blind?
Its the main tail gain controlled by your TX.
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Old 08-14-2012, 02:38 AM   #9 (permalink)
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... somehow this makes sense

Thank you... time for the third coffee to make it better Somehow I was getting used to make a fixed setting of the tail gain independent of the TX.
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Old 08-14-2012, 02:46 AM   #10 (permalink)
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Quote:
Originally Posted by Fabien View Post
Rise the gain until the tail starts to oscillate. Reduce then not just a little, but by 1/3rd of the total gain (keeping high value will simply make Integral and derivate **** up totally lol).
Should I keep heli in hover and rise gain until tail starts to oscillate or should I do it in forward flight?
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Old 08-14-2012, 05:57 AM   #11 (permalink)
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Lot's of information but well explained. I was holding off on setting up my Brain , following posts and trying to learn more about it. With all the posts and feedback I feel i'm about ready to install mine. I have 4 BX units currently and have not had to do much to them..
so a more advanced fbl unit is a little out of my comfort zone. With more explanation I feel confident that I will have positive results.
Looking forward to the "Brain"
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Old 08-14-2012, 06:35 AM   #12 (permalink)
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Quote:
Originally Posted by njs77 View Post
Should I keep heli in hover and rise gain until tail starts to oscillate or should I do it in forward flight?
Hi,

you can rise the gain by increments of 5% until it starts oscillating, and then drop a little the value before going on fast forward flight to see if you have oscillations at high speed.
Be very carefull like with ANY tail gyro in this case and make sure you are flying in a safe and large flying field, and make sure in your transmitter to have a switch alowing you to get back to " standard" gain value in case it oscillates too much in fast forward flight, so yuo cna switch back if you feel it start to oscillate too fast

Always remember that The proportional gain is the input of general gain if i can translate this this way ad that the integral gain will setup the repeat delay to check the angular position of the unit / tail and the derivative gain is the anticipated amount of correction that will be applied for the correction.

So ou will have to adjust in fast forward flight, then i would recommend you to fine tune he integral gain with doing pyros in forward flight at the beginning, fine tune the stop behaviour with the derivative gain, and get back to fine tune proportional gain if to finalise adjustements once you are satisfied with I and D gains.

BEst regards,
Fabien

Best regards,

Fabien
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Old 08-14-2012, 10:18 AM   #13 (permalink)
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Hi,

i am working on the advanced manual, and to make it "easy" to read, i wonder if something like a big organigram ( like chargers menus organigrams) would help ?

This akes a bit of time to put together but it could be used as well as a manual as a troubleshooting and setup guide ?

BEst regards,

Fabien
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Old 08-14-2012, 12:25 PM   #14 (permalink)
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Thanks Fabien for time you spend to help us understand how to configure this module.
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Old 08-14-2012, 01:04 PM   #15 (permalink)
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Quote:
Originally Posted by Fabien View Post
Hi,

i am working on the advanced manual, and to make it "easy" to read, i wonder if something like a big organigram ( like chargers menus organigrams) would help ?

This akes a bit of time to put together but it could be used as well as a manual as a troubleshooting and setup guide ?

BEst regards,

Fabien
I think thats a great idea. Anything helps. Documentation on advanced settings is lacking across most FBL units. I believe the BeastX has the most comprehensive FBL manual available. I believe this is a key reason why they were successful. Simple Setup and well documented tuning guides. The vbar owes much of its success to Mr Mel's videos..

The CGY750's manual is a great example of what not to do in contrast. There is alot of information and was detailed yet it confused people more than encouraged!

I personally would love to see a wiki which would let others contribute to so that burden is well distributed!

FYI Mods please make this thread sticky!
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Old 08-14-2012, 06:50 PM   #16 (permalink)
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Quote:
Originally Posted by njs77 View Post
Should I keep heli in hover and rise gain until tail starts to oscillate or should I do it in forward flight?
I think the BX tail setup process may work here.

Increase gain until it wags in hover, then drop ~5%
Fly faster and faster circuits/eights reducing gain if there is any oscillation in the tail (often audible), once you are done with those flat out try reverse (and hurricanes)

Basically move through whatever fast forward and backward things your skill will allow from least to most demanding on the tail reducing TX gain as you go. This prevents any catastrophic oscillations.
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Old 08-14-2012, 09:21 PM   #17 (permalink)
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Thanks for the info , this will be pure gold when the unit arrives ina few days
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Old 08-24-2012, 08:14 AM   #18 (permalink)
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Keep up the good work.


Thanks for that explanation.
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Old 08-24-2012, 08:26 AM   #19 (permalink)
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Hello,

I'm sorry it's in french, but some times ago I posted a basic explanation of how a closed loop system works.

http://www.murmureurs.fr/index.php?p...mode-d-emploi.

The very first version of this article was posted on Fabien's forum when he was doing the french support for A2Pro (dragonus and excellium) !

It explains the P, the I and the D using simple examples.
But keep in mind PID is just a starting point ;-)

If I had time I'd do a set of videos to explain it better (in french, my spoken english is not good enough for that ). Problem is that for now : "tempus fugit" (and "euros fugit" too) ;-)

Thomas.

[EDIT] Google translate in english :

http://translate.google.fr/translate...mode-d-emploi.

quiet funny sometimes
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Old 08-24-2012, 09:56 AM   #20 (permalink)
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Hi Thomas,

I'll include some of your PID's explanations in the glossary when i have finalised the rewriting of it with a small manual

Best regards,

Fabien
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