Some swashplates, like those found on SAB Goblin 280 and 380, are flat, meaning the servo link balls are at a height lower than that of the pitch control link balls, as opposed to many which have the arms curve up to put them all on the same level. As it is currently, pairing the Brain with a flat swashplate would result in interactions between collective and cyclic, specifically giving any cyclic input would add uncommanded positive collective as well, as lower servo speeds are too fast, on account of the flat swashplate. To tune out this interaction I am forced to decrease lower travel limits on all cyclic servos and apply an asymmetric pitch curve in the radio to compensate for the resulting difference in positive and negative collective, hardly an ideal solution. I suggest adding a feature in the software to accommodate flat swashplates such as these.
A good mechanical setup is a basic prerequisite before configuring flight controllers.
In fact, with electronics and firmware/software it is not possible to "compensate" for any kind of mechanical setup problem without creating other consequences and interactions.
For a job well done, it would not be enough just to automatically and nonlinearly compensate for servo excursions, but also to work on reducing the speed of servos that will have to move less than those that will have to make a greater excursion and path.
Remember that servos are not linear motion devices, and the further you get from center the less movement you get per degree of rotation.
It is therefore essential that at zero pitch the servo horns are perfectly at 90° to the main shaft.
For this reason, for example, compensating via software positive excursions of the collective pitch versus negative excursions could be done by the flight controller only by "starring" and shifting the perfect 90° position of the servo horns and would have negative consequences on the operation of the cyclic pitch.
For all these reasons it is much, much, much better for the model manufacturer to make and supply a swashplate with correct mechanical geometries to replace the incorrect one.
To the best of our knowledge, no other flight control unit manufacturer has to date made what you are asking for, probably for the same reasons
I thought it was all sorted.
https://www.msh-electronics.com/forum/support/sab-goblin-280-fireball-swash-type/
The solution is for the model manufacturer to make and supply a swashplate with correct geometries to replace the incorrect one.
Or that a model accessory and upgrade manufacturer make a swashplate with correct geometry and supply it as an upgrade (for a fee).
@customercare Which, if we are to be honest with ourselves, are pretty unrealistic expectations, with the redesign and retooling and all, for a model that's been already out for some years. To be fair I didn't have much expectations making my suggestion here either. But however improbable it might've been, I figured here I have the highest chance of success since I was able to come up with that solution without modifying the hardware, however inelegant it may be, and wanted to see if you guys can implement a more ideal solution software wise.
@calvinliang11361 the solution to the "problem" you've identified has been avaliable for years. You need this lower part of the swasplate along with longer swashplate guide and longer servo-swash links. All avaliable from the well-known SAB clone manufacturer.
I bought it a while ago just out of curiosity.
Yes, you can feel the difference if you really, really want to - like when you're hovering and swinging left-right, you will notice that the helicopter will start to slowly climb up with the original, flat swasplate and it climbs up a bit less with this "upgrade".
But there's absolutely no noticeable difference in normal flight, and it's unnecessary unless you're using your 380 for F3C competitions. Go buy and check for yourself if you don't believe me - it's not that expensive.
@maciej-j-wnuk I'm glad there's a simple hardware solution for you, but not for me, as the copter I have is the 280, and believe you me I have tried looking.