I am a new user and would like to give thanks to all the contributors as I’ve been lurking for over a year reading up and waiting for a somewhat user friendly implementation. I finally finished building my Trex 470 and have it set up with 3.6 as well as the initial parameters from Chris Olson. It flies wonderfully in stabilize although it creeps forward so I plan to trim that, my first issue is that it is hovering at a little over 3/4 collective, so whenever I switch to loiter mode The helicopter begins climbing until I pull the collective towards the center. My current head speed is 2300 rpm’s And by helicopter is definitely heavier than stock as I have two 3S 5200 batteries in series mounted on it. What are your thoughts on my next step, should I set the H_coll_mid higher, or should I mess with the hover throttle? Here is a link to the documentation I am currently reading about regarding this problem http://ardupilot.org/copter/docs/ac_throttlemid.html#ac-throttlemid
That hover throttle does not apply to helicopters. Helicopters have collective, throttle is for the engine speed.
The settings are IM_STAB_COL_1, 2, 3 and 4. You can set the collective curve and collective lever hover point in Stabilize with those. 1 corresponds to collective at bottom, 2 is about 40% lever, 3 about 60% lever, 4 is collective all the way up. They are set with 0-1000, which is percent times 10 (yeah, we need to make some improvements on the ranges on these settings).
So, for example, if you want 50% collective at 40% lever position, IM_STAB_COL_2 would set to 500.
Much appreciated, I’ll take a look, thanks.
Yeah, you can do different things with those too. Like if you run a lot of negative pitch, but don’t want that in Stabilize, you can set IM_STAB_COL_1 to say 200 (or whatever) and it will limit the negative pitch with the collective at bottom.
Take your full pitch range like say -3 to +11, that’s 14 degrees of pitch range. 50% is 7 degrees, which is 4 degrees positive. If you hover around 5 degrees of pitch, then you’ll want about 4 degrees at IM_STAB_COL_2 and 6 degrees at IM_STAB_COL_3 to have 5 degrees of pitch with the collective centered.
You can also flatten the pitch curve at center collective by making the values of IM_STAB_COL_2 & 3 closer together. That makes the helicopter easier to hover on machines with really touchy collective.
If you try to set IM_STAB_COL_2 to greater than 500 and get a warning from the ground station that this is not allowed, out of range, or dangerous, ignore that and force-save it. I have to fix that because it is none of the above. It is perfectly OK, safe, and not out of range.
Thanks again, I look forward to dialing it in!
Any questions, just ask. I just fixed that GCS error problem with the range on IM_STAB_COL_2 and I’ll PR that fix to master. That was something I was going to do a long time ago and I forgot about it. Thanks for bringing this up to refresh my memory 