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Discussion in 'Cinestar 6' started by Gary McCready, Sep 7, 2013.
Casey, I never made it through college either. I hope you don't grow up like me.
Please clarify..... MK refers to nick, roll and yaw which I understand even though I do not fly MK. But you mention here, tilt...... Is that simply the motor offset on each and every arm.... or am I missing something in translation here?
Can someone provide a link to the forum thread and / or video? It did not come up in search for me.
Thanks for that valuable info Casey.... I have seen similar motor data results from my iOSD which is connected to my DJI WKM on my 800mm Hex.....while this 3 deg offset concept can provide faster yaw response I am wondering if this also somehow helps to resolve unrequested random yaw issues? My hex will tend to yaw on it's own in a crosswind which wreaks havoc with my aerial video work at golf courses where the intent is to video straight down the fairwary all the way to the flag..... w/o looking off to on side or the other (2 axis BG system).
I think this is it...
To put the above document in layman's terms.......
While the X configured Hex remains a simple challenge to resolve in all flight modes, control challenges begin to crop up with a Hex, Octo etc. since counter-torques no longer neutralize naturally, i.e., mechanically.
The simplest example is where the Hex is "I" configured such that the front motor slows down for forward flight while motors M3 and M5 speed up. This creates a situation where mechanical counter-torques are naturally out of balance such that more complex programming is required to regain control of neutral yaw.
Graydon, that's a very intriguing situation.
Applied to an octocopter, this got me thinking.
My pedestrian reaction to this would be to utilize a mixer config with the 'nose' of the copter between two booms, and treat the copter as though it was a quad in a '+' config, with pairs of motors at NSEW. This way, directional motions would always happen with counter-rotating props, not introducing any yawing side effects.
Am I right?
Shaun? Somebody smart? Anybody? Anybody?
As usual, standard disclaimers apply (college dropout, did math on slate tablet, had lamb chop sideburns at one time, etc...)
Here's a little sketch of what I'm talking about. This assumes odd props and even props rotating opposite one another.
Steve...... makes sense to me but for some reason the commercially sold flight computers don't see to do it that way as far as I can tell. Keep in mind that failsafe design conventions suggest that a mechanical design be made as stable as possible before resorting to electrical control methods..... so I intend to implement the 3 degree motor offsets first and foremost.
But for anyone wishing to do custom programming, I noticed that the new WooKong controller opens the door so you can customize control to your particular requirements.... and some of that math looks quite similar to the special euclidean methods in the previously mentioned google document appearing this this thread.
I have also heard rumours that the Mikrokopter 3 degree wedges help, not only to improve yaw response but to eliminate random yaw issues that seem to occur more often in when flying a Hex or Octo in crosswinds..... Hoping those rumours are true.... I had quite a struggle maintaining a straight forward heading while doing aerial videos of a golf course from tee-off to pin..... the 2 axis BG controlled camera kept trying to look off to the left or right depending upon cross-wind direction.