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Old Aug 30, 2014, 10:40 PM
Redjestird Youser
SidewaysLS4's Avatar
Joined Jan 2009
3,877 Posts
You said you recalibrated the IMU under the 'tools' tab, yes? I had a tail drift that was cured with that, but an atti-only drift...don't know how that could be related, might be worth a shot doing that (if you haven't already).

Unless you have a spare Vbar w/pro firmware you can mount to see if you have some vibration issues going on with the spectrum analyser?
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Old Sep 01, 2014, 03:18 PM
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Well after doing a factory reset yet again and setting everything up for a third (or forth?) time, all seems to work OK. Took it out to the field yesterday, gained some altitude and flipped into ATTI mode with intentions of flipping back to manual quickly. To my surprise, it self leveled without any aggressive kicks in any direction and floated in a nice level hover. Did some circuits in ATTI mode and mostly seemed good.

I say mostly because I now have a followup question: There were some light gusts of wind throughout the day, and occasionally when I would come out of forward flight and try to level out, the entire heli would bob back and forth aggressively like a troubled teen at a Pantera concert. Seemed like it was trying to over correct, similar to tail wag with gyro gain too high. I would save it by going back into FF and veeeerrry slowly easing back on the elevator until level. Would this be a symptom of too high corrective gains in the software (all adjustments are left at 100% per the suggestions)? Could it have been from a gust of wind? Although from what YouTube videos I've seen, even in ATTI mode the heli would still stay level but just drift off in the direction of the gust.

I'm so close.

Additional info: Head speed is about 2650 , measured with an optical tachometer by one of the guys on the field... so I don't know if head speed would have any factor in the bobbing as it typically does.
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Old Sep 01, 2014, 06:36 PM
Redjestird Youser
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Joined Jan 2009
3,877 Posts
Your headspeed is more than ok. If it is bobbing in atti like it has too much gain...it probably does. On my heli I have the gain as low it will go on aileron (40), 55 on elevator. And this is with tricking the unit into giving less effective gain (set the 6.5 degree setup stage at 5 degrees/as low as it would go, numerically '40' there also). And it flys just fine like this and has solid GPS position holding in wind. I think DJI purposely made the gain ranges in the NAZA like so, to not steal sales from the ACE series for pro photography apps. Or at least that's my theory, lol.

Best bet is keep dropping the gain 5 points at a time while studying the heli to see if has any rocking in calm/no wind conditions. Once it stops rocking, you should be good to go. If it keeps rocking and you cant go lower, lower the '6.5' degree head geometry setting lower to get that effective gain lower.
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Old Sep 01, 2014, 06:43 PM
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United States, VA, Roanoke
Joined Dec 2012
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Hi. Mine was kicking pretty good. I lowered the autopilot gain to 80, and the agility to 20% and it's much better. It still has some issues. If I take the GPS gain lower than 80 it starts to drift badly.

On the setup page mine control is set to 40 and in getting 6.7 as the lowest pitch as measured on the blade over the tail. When set to normal I get 0*. How can you get closer to 5?
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Old Sep 01, 2014, 10:46 PM
Redjestird Youser
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Joined Jan 2009
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Quote:
Originally Posted by Mapoff View Post
Hi. Mine was kicking pretty good. I lowered the autopilot gain to 80, and the agility to 20% and it's much better. It still has some issues. If I take the GPS gain lower than 80 it starts to drift badly.

On the setup page mine control is set to 40 and in getting 6.7 as the lowest pitch as measured on the blade over the tail. When set to normal I get 0*. How can you get closer to 5?
That is interesting how yours drifts, especially what sounds like a ton of cyclic authority available to the NAZA from what you describe. I'll say I cant think of why that would be.

Getting the measured degrees...it's all servo arm/swash/grip geometry. I happen to use a "PNP" 3 bladed head, which happens to use a good amount of servo travel vs. grip angle. At '40', it just happens to measure exactly at 5 degrees. I would actually still like to reduce the head system's mechanical gain even more as I feel I could use a bit more aileron gain reduction...but not going that far just yet, I like the way it functions in atti and gps. It does get a bit busy in wind, but not enough for me to put forth the effort, yet.

You can move the link balls on the servo arms inward a hole, put longer balls on the outer swash ring, maybe shorter balls on the inner swash ring if possible, or longer balls/arms on the grips themselves to increase the mechanical resolution and get that 6.7 degree lowest measured pitch lower with what the NAZA is signaling to the servos at that setup stage. There's a few pics of the head setup I have and how the relationship to the servos/swash/grips looks like to get a gander how these parts are "ratio'ed" to each other on my heli in this thread: http://www.rcgroups.com/forums/showthread.php?t=1794952


What sort of heli or head is this?
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Old Sep 02, 2014, 03:37 PM
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Mine is an rjx head. I'm using shorter ball links to get less travel on the maximums.
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Old Sep 02, 2014, 03:38 PM
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Mine is doing pretty good but has a left to right oscillation. It's really almost like a diagonal oscillation. There is no info on autopilot agility, velocity tracking, autopilot gain, and it seems like there is another one I'm missing.

I want to tone mine down. When wind hits it, it's trying to hard to get level again.
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Old Sep 02, 2014, 04:36 PM
Redjestird Youser
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Joined Jan 2009
3,877 Posts
Quote:
Originally Posted by Mapoff View Post
Mine is an rjx head. I'm using shorter ball links to get less travel on the maximums.
What size heli? You lost me on the less travel on maximums part...got a pic?



Quote:
Originally Posted by Mapoff View Post
Mine is doing pretty good but has a left to right oscillation. It's really almost like a diagonal oscillation. There is no info on autopilot agility, velocity tracking, autopilot gain, and it seems like there is another one I'm missing.

I want to tone mine down. When wind hits it, it's trying to hard to get level again.
I'll bet less gain might do the trick
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