WARNING to TradHeli users:
Do not attempt to fly AC3.3 until you hear otherwise from me. I have not even bench tested it yet, let alone test flown it. There are quite a lot of changes that have gone in that could be crash-o-matic for helicopters.
AC3.3 release for Tradheli is likely to be delayed.
This post will serve as the official release progress thread for TradHeli.
Warning: DO NOT FLY RC6! It has a critical bug that will likely end in a crash.
Warning for RC5:
RATE_YAW_FILT_HZ param will change defaults from 5Hz to 20Hz to be more suitable for helicopters. If you have never changed this parameter from 5 before, then it will automatically update the value to 20 without warning. This much faster filter will probably require reduction in your P and D terms, and the yaw may oscillate badly. Be prepared to retune these. As a safety measure, probably cut them in half for your first take-off.
Warning #2 for RC5:
I accidentally broke the Landing Detector. It will probably never trigger. You should land in Stabilize mode, or be prepared to shut down the motor as soon as it touches the ground in Alt_Hold, Loiter, Auto, etc.
Replies
Peter, here is the setup video :https://www.youtube.com/watch?v=rAbsZl5hanE
I find the AC3.3 already usable. The default param's very close.
Salut Fred,
Tx for the link! What heli(s) are you flying with 3.3?
A question regarding Pre Arm checks...
More often then not, when I power on my heli and connect via MP I get a Compasses Inconsistent warning and obviously cannot ARM the autopilot. I can see that the headings are good and not drifting. Sometimes a power cycle helps, but most of the time what I have noticed is that if I simply disable the compass pre arm check and then re-enable the check, it goes away. Doing this process I am able to fly and have good flight performance in all flight modes. Is this a bug or is there something else going on here?
The issue is probably that the compass internal to the Pixhawk is being affected by a magnetic field, which is making it point in a different direction to the compass in the GPS puck. This is what is meant by inconsistent. Try setting COMPASS_USE_1 to 0, which means it will completely ignore the internal compass.
Thanks Rob, I'll give it a try.
This did not happen with 3.2 though, at least not every single time... maybe once every 20+ times or so. With 3.3 it happens every time I power up the system...
Could someone explain the Leaky I term to me please? I have not messed with this setting yet and saw that with 3.3 the default should be a value of 300 when actually it is 0. One of the first times I tried flying 3.3 I had one instance where the rotor disc tilted back on its own while spooled up on the ground but nothing since then. The Rate_xxx_I_L_MIN is supposed to prevent this right? Is 300 an appropriate value? What should I expect to see while tuning this?
Thanks
Chris, Leaky I means that the built-up I-term value slowly decays back to zero over time. That means that if the error is zero, it will decay over time. But it also means that if the error is very small, it will not continue to grow. It reaches an equilibrium point, where the decay towards zero, matches the contribution from a small error. This is what prevents helicopters from building up an massive I-term while sitting on the ground and then tipping over as soon as the rotor comes up to speed.
On 3.2, the I-term would leak all the way down to zero. This also meant, that if you had a servo trim error, or a CG off-set, aerodynamic download on the tailboom, etc.... anything, the copter would not be able to fully correct, and would usually hover with a small angle error.
The Leak-Min parameter sets a point below which the I-term will not leak. The number you use should be small enough so as not to allow a ground tip-over, but large enough that the helicopter hovers perfectly level with no angle error.
I added this, because looking at logs, it was apparent that there are a LOT of people not leveling their swash accurately, and CG not being quite right, etc.
Hi Rob,
I've had some success with my Pixhawk vibration dampening mount using some mass. With one RX battery attached underneath, I'm getting lower vibration numbers than before. Is this graph similar to your Gas heli?
Regarding setting up H_COL_MID and mode switching i.e. stabilize to Loiter/Auto
In your setup video, you say to use 0 deg pitch. Would it be better to set this at 4.5deg or hover pitch? Or just set it to 0deg but move IM_STAB_COL_2 and 3 up so that the TX collective stick is mid-stick/central?
Thank you for all your hard work on 3.3 We need to clone you!
Yes, that's is similar to my vibration numbers. Very nice job there.
H_COL_MID should be set to the rotor's minimum torque point, which is typically zero pitch. This is because both the Rotor Speed Control and Collective-Yaw compensation use this number for assumption of lowest torque.
You are correct, to raise STAB_COL_2 and 3 so that it hovers at mid stick.
Great, thank you.
I had the same issue as Chris M in that I could not takeoff in Loiter. In this graph, hover at the start then landed, tried to takeoff in Loiter at 380 then gave up at 385, poor skid's took a hammering going full negative at 100% RRPM. I'm really lucky they didn't let go!
This was the first time I've tried taking off in Loiter 3.3 and believe using an external governor and/ or poor setup of Runup Time may be the cause?
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