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Permalink Reply by Todd Steury on November 1, 2011 at 5:43am

It's the propellers that have to be level. It doesn't matter if the APM, frame, or anything else is level, only the props - after all, it's the props that generate thrust.

There are two ways to set level in the field, which is potentially better than setting level in mission planner, especially if APM is physically plugged into the computer (when you remove the plug, you will inevitably move the APM, which will affects it's relationship with the props).

 

The first way is to hold disarm for 10 seconds (hold yaw all the way to the left). This will just 'reset' the level in APM to the current position of the copter. Obviously, this is only a good way to set level if the propellers are perfectly level.

 

The second way is to hold arm for 20 seconds (hold yaw all the way to the right). This will engage the in-flight leveling procedure, which should last 45 seconds (although on my copter, it only lasts 13). When in-flight leveling is engaged, the roll and pitch stick doesn't just fly the helicopter, but adjusts the level setting based on your stick. Thus, if your copter is drifting forward and to the right, when you pull back and to the left on the stick, the level setting should slowly adjust to account for that movement such that eventually you'll be able to let go of the stick and the copter won't drift. Once the copter is stable, land it, wait out the rest of the 45 seconds (leds blink in a special way when in-flight leveling is engaged), and then disarm the copter (yaw left for 2 seconds) to save the new 'level' to APM. That's it!

 

BTW - very important; don't try to use in-flight leveling except in an absolutely windless environment! Also, fly the copter at least 4 feet off the ground to minimize ground effects.

 

Hope that helps. Let us know if any of that isn't perfectly clear.

 

Hope that helps.

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Permalink Reply by Farooq Niaz on November 1, 2011 at 7:10am

Inflight levelling is not 45 seconds as i saw somewhere in code so need to adjust the code to icrease the adjustment time

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Permalink Reply by Farooq Niaz on November 1, 2011 at 7:11am

But should we do auto level or auto trim first

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Permalink Reply by Todd Steury on November 1, 2011 at 7:24am

Still not sure what the difference is between 'auto level' and 'auto trim' (if any). From the code, it appears these are the same thing.

 

You may be right, however, about the 45 seconds. That's how long in-flight leveling is supposed to last according to the build wiki (http://code.google.com/p/arducopter/wiki/AC2_Flying), but I only get about 13 seconds out of my APM. 

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Permalink Reply by Farooq Niaz on November 1, 2011 at 7:33am

Yes i dont remember exactly where i saw it in code but it was much less than 45 sec and i saw it too while testing

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Permalink Reply by Geir Engebakken on November 1, 2011 at 7:58am

It is about 15 secs for my copter. Anyhow tried it, and all works so much better! I tried it outside in quite a lot of wind after auto leveling,and was a bit sceptic at first when trying to hover with the wind, it just flew ahead quite fast, turning around and hovering against the wind was a much more stable feeling. In fact so stable I opted to go for a loiter test....and it worked! Fantastic to watch it operate all by itself. It had quite a large diameter in the loitering circle though, i would guess about 20 meters, but after slowly aproaching the edge of its circle, it set off to center again. I let it do its business for a couple of minutes! Probably have some PID tuning to do to get it perfect, but what a great experience it was anyhow.

About what should be level i read somewhere that the APM should be level, and that seems natural to me, the propellers are just giving more or less thrust so i guess that is not the primary function for level.

Anyhow, great thing finally having progress, great job folks!

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Permalink Reply by Tommy Larsen on June 18, 2012 at 1:44am

HI

I'm tying the in-flight leveling procedure but i'm not sure if i shall hold the arm for 20 secs from when it's disarmed or armed ?? Shall i arm first and then start the 20 secs ?

 

BR

Tommy

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DistributorPermalink Reply by Dany Thivierge on June 18, 2012 at 8:27am

this is an old thread... this is the way to do it right now: (Thanks again Marco!) 

Steps:

1) assign Autotrim to CH7 with the planner (and to a 2 position switch in your tx) (redo radio config to get it to register! 

2) at the ground switch on/off the autotrim function and see if the led with autotrim enabled start to "rotate" (not the normal led blinking function)

3) takeoff with autotrim off in windless condition, still your quad in the air and switch on autotrim and try to mantain your quad in the same position with a little stick movements,remembering that you have to make the correction and then back to center stick (not the throttle, lol) to see how he is placed in air... when you quad is firm enough switch off the autotrim function, land and disarm the motors

Then you can try loiter, not before...

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