I found H_LAND_COL_MIN = 550 it is not enough?
I changed all my helis to Pixhawk + FBL-unit because of this. If I try to launch a Pixhawk only setup on rough terrain I get in trouble, while any standard FBL-unit doesn’t present the slightest problem in the same situation, because the swash is neutral.
Probably needs to be much lower. What matters is the actual blade pitch as I specified in the test above.
What sort of terrain are you launching from? I’ve never had an issue. Are you launching from Stabilize or Acro? Stabilize will always push the swashplate over, I can’t stop that while still having it stabilize. Have you ever tried to take off on rough terrain with an FBL in self-level mode, and how does it behave? If you are taking off from rough terrain in Acro mode, when you arm it, it should accept ‘whatever angle it’s currently at’ as the neutral point and won’t try to pull it level.
Most of my helis are tail-draggers, and I’ve not had an issue. So just trying to get a full understanding here.
Hi Rob,
I am flying in the mountains after hiking up above the treeline to get to the area of interest. The launch and landing ‘area’ is usually a very small spot with lots of gradient and there is no hard and even space for the skids. This means the heli will rock no matter how smooth the rpm goes up. Because of the swash inclination I am forced to do a little bit of countersteering with the sticks and the whole launch process is getting ‘very interesting’. ‘Ofcourse’ I can launch and land only in Acro mode, using ACRO_TRAINER = 0 in this terrain. Launching / landing at the local club I have no problem to use the higher modes, but on the slopes Acro is king (PosHold, RTL and Auto for flying missions).
Using a VBar or whatever else in the same situation I do the stick movement test, check the reaction of the FBL, walk back, start the motor, look more or less relaxed how strong the heli rocks and lift off. For the same reason I am on ACRO_TRAINER = 0 I do not use any self leveling mode with VBar for launch and landing. Any kind of self-level mode would yield to another one bites the dust (actually rocks) as the blades would strike on the hill side.
The heli code is way more sensitive on the PID settings than any FBL-unit I have and - sorry to say - it doesn’t feel as good for me and some others.
I am willing to help as much as I can (but my spare time is limited).
I don’t know what the situation is for ultrafuge, but we also use FBL in conjunction with Pixhawk, mostly because our heli pilots are used to FBL (I personally like helis with good old stabilizers, but that’s another topic) and it’s much easier and quicker to set up and get it in the air. FBL also seem to be able to handle harsh vibrations without much care given to isolation/dampening or tuning. Another reason is that we have a switching system as a failsafe so we can bypass the FC completely if anything goes horribly wrong and still be able to fly the heli manually using FBL.
Anyways, in our setup, we needed to reset the FBL’s swash control everytime before taking off so that the swash returns to neutral, especially when the surface is neither perfectly level nor smooth, which we expect most of our use case to be.
We are using Futaba CGY750, and when we initially tried to use Futaba’s AVCS mode which has almost no I-term leakage, the heli would tilt and drag it’s feet and tips over or fly off in random direction when taking off. The situation is worse for experienced pilots as they unconsciously react and move the stick around and tilt the swash even more. The way to reset the swash (and rudder gyro) on CGY750 with AVCS mode engaged is to give full right and full left repeatedly within one second so that’s what we did right before taking off.
Now we only use “Normal” gyro mode on CGY750 and it seems to be working fine.
Just my 2 cents.
Nice to see your return here Rob.
Just checked my H_LAND_COL_MIN and it is zero, seems that was the default when upping to 3.3.3
With that I have about -7°
But I don’t understand the point of adjusting (upwards in my case) this if I set LAND_SPEED appropriately?
OK, but it sounds like you have your solution, to take off in Acro mode? That is the only solution I can think of. Trying to take off in Stabilize or Loiter when the helicopter is very un-level and moving around while spooling up is never going to work. You can’t have the swashplate “relax” back to level in Stabilize mode if the helicopter is on uneven ground. It’s going to try to level the copter. Same with Loiter. Am I missing something here?
Goro seems to be indicating that Futaba’s AVCS system does the same thing. The problem is largely to do with the control system not really knowing when the copter is on the ground or flying.
Yes, thank you, my solution is using a GT5.1 or a GT5.2 or a minVBar or a VBar Neo in Acro mode (ACRO_TRAINER = 0).
I don’t want a “relaxing” swashplate in any stabilized mode !
I would like to have in Acro mode (ACRO_TRAINER = 0) the same behaviour as ALL (6 different units from 4 different manufacturers) FBL-units that I own, namely the neutralizing of the swash plate either after stick input or by external disturbance, because it makes things a lot easier.
Sorry, I cannot comment on the Futaba CGY750 as I don’t own one and nobody else in my area that I know of.
Could you please be so kind and check this:
I have problems using the helicopter code for a FBL-unit. Using a Futaba I need to get out the usual Futaba range 1094-1514-1934 via SBUS to feed the FBL-unit.
Settings are:
ACRO_TRAINER = 0
H_FLYBAR_MODE = 1
H_SWASH_TYPE = 1
H_TAIL_TYPE = 1
H_SV1_POS = 90 (aileron)
H_SV2_POS = 0 (elevator)
H_SV3_POS = 180 (collective pitch)
Don’t know if this is the correct way to set it up, if it is, then it doesn’t work flawless.
H_SV4_MIN = 1094, H_SV4_TRIM = 1514, H_SV4_MAX = 1934 works perfect for the tail
H_SV3_MIN = 1000, H_SV3_TRIM = 1503, H_SV3_MAX = 2000, H_COL_MIN = 1094, H_COL_MAX = 1934 works for collective. The only mistake is 1503 instead of 1514, why ?
H_SV[1,2]MIN = 1000, HSV[1,2]TRIM = 1514, HSV[1,2]MAX = 2000 _TRIM works, _MIN and _MAX do not limit the output(I know they are fixed at 1000, 2000), HCYC_MAX = 4150 results in 1087 and 1917.
If I reverse a channel it is 1486 (= 1500 - 14) instead of 1514. The FBL-units need the _TRIM in the correct setting, otherwise they take it as stick input.
1087 - 1514 = -427 and 1917 - 1514 = 403 which is about 6% difference. The FBL-units want to have +/- 100% to do their scaling correct.
Please check.
Thank You
p.s.: Does Autotune work now for helicopters or is it still not a good idea to use Autotune ?
I encountered the same situation and @ultrafuge , in the use of Pixhawk + FBL system debugging process, the channel 4 can be adjusted to the perfect range, but the channel 1,2,3 not.
Ah, now I understand you. You want the target angle to leak back to the current angle in Acro mode. Ok, yes I have thought the same thing.
When transitioning from Ver 3.3.3 to V 3.4.4, is it ok to take over the parameters?
Or is it necessary to set the parameters from the default?
Probably best to reset them to default, and then carefully bring over the ones that are applicable to carry over. I don’t have a detailed list yet.
Mr. Rob
Thanks for your advice.
Reset and enter the parameters…
Thank you very much.
Hi Rob,
I usually had my controller installed on a carbon plate under the heli. It was almost under the main rod. In loiter mode when I gave Yaw input it seemed to turn in place. Recently I had to move it to the tail. Now yaw input causes it to make a small circle. I think this is because the X/Y controller tries to keep the controller at the same spot resulting in a circle. In that case can we have offset X/Y/Z params. This can be used to store the offset of the controller from the CG, preventing this situation.
Offset for GPS and FC comes with 3.5
Hi Robert, as you are working on a pixracer for a heli which i am doing at the same time will you be changing the RSC output to a lower channel number?
For the moment i will just use a normal servo out on my RX but maybe in the future it would be nice to use the pixracer channel Number 6.
malcolm
I can’t find it in the docs, but I’m pretty sure I saw a RC_FUNCTION option in Mission planner to move the RSC output to any channel.
Edit, not RC_FUNCTION, but SERVO#_FUNCTION:
http://ardupilot.org/copter/docs/parameters.html#servo6-function-servo-output-function
Need to set it to 31.
Thanks Jacob
I’ll have a look at the code on my fork and may well change it to suit my needs.
malc
WARNING:
If you are disarmed in Acro mode, and you push the roll stick such that it stores a large error (the swashplate will move, and hold) (when the swashplate flips from one side to another is 180 degrees). The swashplate never relaxes.
If you then arm, and start the motor, the swash never resets. The rotor will spin up, and when it has sufficient speed, it will flip the heli over on the ground.
At this point, I would advise people not to take off in Acro. It’s unsafe.
See this thread for more details.