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Old Jun 29, 2012, 09:11 AM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,584 Posts
P,
You are correct. Tobias did a "virtual accelerometer" in TT-copter code with gyros only released back in about 2006. You had to do a steady hover when first launching so the gyros would calibrate. It auto-tunes the PID inflight. I notice he now has a GPS version for about $600 listed on his website.

--Tobias' TT-Copter that self-levels without an accelerometer or manual PID adjustments: http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Ftt-rc.ath.cx%2FSHOP%2FCAT-TT-Copter frame, motors and ESC's extra; board only=~$220 http://www.rcgroups.com/forums/showthread.php?t=1017583

The X-BL had a similar "virtual accelerometer" code scheme before they implemented accelerometer hardware. It worked very well too. The X-BL hardware implementation is still one of the best out there. It snaps to level as soon as the ACC is switched on.

Good to point out that most accelerometer code implementations move from self-level to gyro rate as the stick movement is increased for higher pilot induced angle of attack and resulting agility. If you only use small pitch and roll inputs and let go, most will then snap back to level quickly.

Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index


Quote:
Originally Posted by Percolator View Post
you never flew tt-copter so dont assume anything..

the software blew away most the DIY or kk software. but support was only on german sites. but never an issue
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Old Jun 29, 2012, 09:31 AM
Quad Whisperer
Joined Jul 2008
943 Posts
Quote:
Originally Posted by Akcopter View Post
Hey so does that mean autolevel is half-cooked on the current firmware...I dont have the board yet ,but looking at the experience of some rcg users here, the autolevel function does not seem to work the way it is supposed to..so does that mean without the AHRS algo that kaptien Kuk stated the tricopter go crazy with autolevel on,,, plz reply fast.. anyone......
No, it works. It is just not as fast as it can be. This was stated in my first post in this thread. The crazy tricopter where caused by wrong adjustments.

Quote:
Originally Posted by Percolator View Post
its funny but if you look at first version tt-copter it doesn't use any acc chip and it auto levels and handles great. when it comes down to it, software prevails
Auto-level with only gyros is possible, by removing the I-term (heading hold) and relying on aerodynamic forces, the same force that makes it balloon in forward flight. Se this video with my old firmware (no heading hold) for the KK1:

Quad Hands Off Hover And Some Flying (6 min 21 sec)


With I-term even the smallest error will add up over time and tilt it.

With gyros without drift it is possible with true auto-level (AHRS), but in real world we need to correct gyro drift with accelerometers, since they are the only way to sense the direction of gravity.

Accerelometers: slow reaction + gyros (fast reaction) = grreaat
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Old Jun 29, 2012, 09:34 AM
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Quote:
Originally Posted by kapteinkuk View Post
No, it works. It is just not as fast as it can be. This was stated in my first post in this thread. The crazy tricopter where caused by wrong adjustments.



Auto-level with only gyros is possible, by removing the I-term (heading hold) and relying on aerodynamic forces, the same force that makes it balloon in forward flight. Se this video with my old firmware (no heading hold) for the KK1:



With I-term even the smallest error will add up over time and tilt it.

With gyros without drift it is possible with true auto-level (AHRS), but in real world we need to correct gyro drift with accelerometers, since they are the only way to sense the direction of gravity.

Accerelometers: slow reaction + gyros (fast reaction) = grreaat
lets not confuse people with a balanced quad with no hands versus actual software autolevel algorithms with NO ACC chip

i give you a famous tt copter video with only software making it autolevel
not to mention toby as a young teenager back then this was huge development in my eyes!

TT-Copter QuadroCopter schwebt alleine (4 min 59 sec)
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Old Jun 29, 2012, 09:50 AM
Multi rotors=No Paycheck left
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United States, CA, San Diego
Joined Apr 2011
3,409 Posts
Would this board do well on a large Hexa? I had planned on using this on a small spider quad that I want to start using for FPV....but the FC that i was going to use on my hexa needed to be sent in for warranty repairs and i have no clue how long it will take to get back.

So..just curious if this would be good on a large craft?
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Old Jun 29, 2012, 11:03 AM
not insane; Mom had me tested
hallstudio's Avatar
Marietta Ga.
Joined Apr 2005
820 Posts
lets not dog the auto stable. it is great for the new pilot learning new skills in a open field. it saved MY butt. i was flying my tri about 200 foot from me when i got bit by somthing. took my eyes of the tri to swat the bug when i looked back i had no idea where the tri was pointing and it was heading toward the ground. fliped auto on gave it some gas then started a slow yaw turn till i figured out where it was pointing.
auto is also great for filming stationary objects and doing hard ascents and decents.
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Old Jun 29, 2012, 12:09 PM
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United States, AZ, Scottsdale
Joined Sep 2011
518 Posts
Quote:
Originally Posted by kauaicuda View Post
I think it flies great on auto level mode, I have no problems whipping it around the sky, I just found that the settings were kind of counter-intuitive.
I find that having autolevel disabled flies best for me. Perhaps it is because I am used to the leveling algorithms of multiwii and arducopter, but it could just be that I haven't tuned it correctly. With higher P values my quad is more controllable but even with the sensor calibrated it levels at a significant angle. With higher I values it becomes unstable very quickly (perhaps conflicting with my gyro PIDs). What PIDs are you using for both gyro and acc? I am trying to tune in autolevel on an 8" quad-x.
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Old Jun 29, 2012, 04:35 PM
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Australia, NSW, Sydney
Joined Feb 2011
2,980 Posts
Well @Percolator is unquotable and in trouble now but after watching that whole video it seems he is confusing autolevel and basic stability.
I write multicopter software too and mine floats like that but it is most certainly not "autolevel". It you look at videos of copters with "autolevel" the usual test is to disturb the flight, often violently by throwing the copter into the air Warthox style.
If it can level itself, that's autolevel.
The ttcopter video above is what you can expect to achieve with well-zeroed gyros at reasonably high gain, and as kapteinkuk explained, no I-term... oh and NO wind lol.

"Virtual accelerometers" using the kind of gyros we use are famous for quickly generating huge errors. There's even a google tech video from the brightest minds out there on the subject.
Again, this is not what you see in that video.
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Old Jun 29, 2012, 06:21 PM
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United States, MD, Frederick
Joined Aug 2010
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Quote:
Originally Posted by sg1anubis View Post
I find that having autolevel disabled flies best for me. Perhaps it is because I am used to the leveling algorithms of multiwii and arducopter, but it could just be that I haven't tuned it correctly. With higher P values my quad is more controllable but even with the sensor calibrated it levels at a significant angle. With higher I values it becomes unstable very quickly (perhaps conflicting with my gyro PIDs). What PIDs are you using for both gyro and acc? I am trying to tune in autolevel on an 8" quad-x.
My P is 130, limit 100

I is 65, limit 20.

However, I have spent all of about 10 minutes messing with it, so you may have to disregard those.

It flies best for me with autolevel P at 50, P limit at 35, and I have left the I for autolevel at zero for now since there wasnt anything about it in the setup guide.


With these settings, my 450mm quad flies great, and I cant wait to mess with stick scaling to do some aggressive rolls.


I'll share what could be the worlds crappiest flight video, but it's the work of an 8 year old girl with an iphone at 9pm...

Kk2 (1 min 38 sec)
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Old Jun 29, 2012, 10:21 PM
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United States, NY, Wappingers Falls
Joined May 2005
309 Posts
I got my board yesterday and today had the time to install and test fly. Needs adjustment. The motor speed fluctuates at hover causing the quad to climb and descend. I have the esc's motor timing set to high. Not sure if this is the problem. Also, does the screen back light turn off after a certain period automatically?
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Old Jun 29, 2012, 11:26 PM
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Australia, QLD, Brisbane
Joined Nov 2011
949 Posts
I am getting fast wobbles like the P is too high on the Turnigy Micro quad frame.

See my blog for the parts details.

I have the P on roll/pitch down to 40 and it's still happening. One thing is that I have mounted the board on nylon standoffs. Should I try foam in case it's getting vibrations?
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Old Jun 30, 2012, 01:31 AM
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United States, AZ, Scottsdale
Joined Sep 2011
518 Posts
Quote:
Originally Posted by Erknie View Post
I am getting fast wobbles like the P is too high on the Turnigy Micro quad frame.

See my blog for the parts details.

I have the P on roll/pitch down to 40 and it's still happening. One thing is that I have mounted the board on nylon standoffs. Should I try foam in case it's getting vibrations?
I would say it is likely vibration related, but you can try lowering P first. I'm using my board with a home built micro (8"), same parts as the turnigy micro quad. My P is at 30 with a limit of 15, as is my I. I haven't tuned level, it gets out of control. I just finished building my micro fpv V6, it will be interestingly to fly because of the yaw on a v6. I may be able to modify the mix so it doesn't sweep but that will have to wait until tomorrow. I'll put together a build log sometime too.
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Old Jun 30, 2012, 06:10 AM
Registered User
Austin, TX
Joined Jan 2009
817 Posts
P and I limit

been flying multis for a while and havent run across P/I limits....P/I/D yes
and am familiar with tuning the gains....

but what affects do the "limits" have and how do you work those into your tuning?

PS I usually tune P for stability, D as high as I can to minimize overshoot, and I for FF attitude hold....how would the limits play into that?

also, I want to use this in flying wings also..especially the autolevel feature for the roll axis which has NO stability in a flying wing....anybody played with this board in that application yet? if so...tuning insights would be appreciated...

thanks
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Old Jun 30, 2012, 06:13 AM
Out of helis, sanity returning
Tallahassee, FL
Joined Feb 2009
2,097 Posts
Quote:
Originally Posted by jmc67 View Post
I got my board yesterday and today had the time to install and test fly. Needs adjustment. The motor speed fluctuates at hover causing the quad to climb and descend. I have the esc's motor timing set to high. Not sure if this is the problem. Also, does the screen back light turn off after a certain period automatically?
Watch this video:

Hobbyking's KK2: QUICK START TUNING GUIDE (4 min 9 sec)


Sounds like P oscillations. He says that to high on the P can make the quad jump up and down.
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Old Jun 30, 2012, 06:46 AM
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Australia, QLD, Brisbane
Joined Nov 2011
949 Posts
Can the KK2 do PPM SUM? I couldn't see it in the menu unless it's called something else. Would be nice to have only one receiver cable.
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Old Jun 30, 2012, 09:32 AM
not insane; Mom had me tested
hallstudio's Avatar
Marietta Ga.
Joined Apr 2005
820 Posts
Quote:
Originally Posted by jmc67 View Post
I got my board yesterday and today had the time to install and test fly. Needs adjustment. The motor speed fluctuates at hover causing the quad to climb and descend. I have the esc's motor timing set to high. Not sure if this is the problem. Also, does the screen back light turn off after a certain period automatically?
drop your P gains down. i had the same problem.
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