ArduCopter Traditional Heli (was: "600-size heli")

Rob_Lefebvre September 16, 2012 at 2:36pm

If any of you guys have flybarless and would like to test my Acro mode, we might be able to solve this "too snappy" problem. I've flown it a little bit, and it's OK, and I know how to make it better. But my FBL heli is in pieces at the moment.

Are you proficient flying manually?

Then we can work on it together. Once we have a working "acro" mode, we can try putting the stability controller on top of the rate controller, just as the quads are now. It will make it fly smoother in stab mode.

What do you think?

Christoph September 16, 2012 at 5:56am

Update with more sucess stories:

2nd mission done. Three waypoints, after every waypoint a loiter_time command.

The loiter settings are really strong, because when the heli goes from the waypoint command into the loiter command, it tries to stop quite strongly. It pulled the heli back that I almost wanted to manually interfere. I did not do, so the heli overshoot backwards, but then found a stable loiter position after short oscillation.

I really need to find someone to help, to get a video of that. But my wife is not happy about me playing arducopter all day ;)

I should open another post about the wifes complaining....

Christoph September 15, 2012 at 1:15am

Great news. Loiter is working!!!

I'll prepare the camera to send you the proof. I am using similar parameters as Rob. But here some observations:

- loiter P (Rob used between 6 and 7). I had the value on CH6 and it also worked with smaller values

- stab P: I also used lower values 1.5 and 1.0 because with the high values the heli is really twitchy

- regarding the GPS not found issue. I tried to disconnect/connect power last time on the field maybe 10 times without success. Back home I connected the USB cable so powering up the APM with power from the USB cable. Guess what. The APM did not take long to make red and green light blinking, thus the GPS was found. Back on the field it worked as well with the external power. Is maybe something clogged up and awaiting a signal from the USB? Maybe something is not correctly closed after the log download sequence?

However. Thanks to the programmers!!!

The loiter routine must have been really improved. Loiter is working on trad heli also with the Mtek GPS.

Rob_Lefebvre September 9, 2012 at 4:31pm

I just did it! I successfully loitered for about 2 minutes with no circling! Winds are light, about 10 km/h, but just eliminating the circling is huge! Normally it would circle as soon as you engaged the Loiter, even with no wind.

Two key things. First and probably most important, I've had my Stab P terms too low. 0.7, it flew nice and gentle, but was not responsive enough for the Loiter control. I tuned it up to 2.4 on roll, and 1.4 on pitch, just to give you an idea. I've had to split the pitch/roll, which makes sense if you think about the extreme non-symmetry of a helicopter. When I have pitch at 2.4, I get a good wobble out of it when I do a quasi-step command. Now it's much more snappy on commands.

Then, I thought I would need to use softer settings than the quad for Loiter, but in fact, more aggressive. LoiterP 5 in the quad, 6.5 in the heli. I is .2 in the quad, .1 in the heli. And D is .5 in the quad, .7 in the heli. I think it makes sense that the I term is lower, because is has more mass, and the flybar dulls the responses a bit, so it needs to be slower on the I term. I dunno... I'll keep playing with it. This was literally the last 2 minutes of my 3rd set of packs.

I'll put a quick video shortly. Too bad I don't have any more batteries left!

Here's my param file so you can see where I'm at:

Rob600.param

Christoph September 9, 2012 at 12:14am

Just did a test flight. Stabilize is working. very short alt hold test worked as well. But too short too really judge. What do I need to do to enable the extended logging? Want to know before I start with loiter again.

Rob_Lefebvre September 8, 2012 at 8:06am

Here's some video I shot last night. I wanted to demonstrate the yaw control. This is with no external gyro.

Again, sorry about the Max Headrom effect. One of my computers does this, the other doesn't. I don't get it. This is put together on Windows Movie Maker. i7-2600 processor on this one, so it's got tons of power, but it does this for some reason.

Christoph September 8, 2012 at 5:40am

Ok, I am back. Loaded the latest firmware 2.7.3 from MP.

Everything seems to be fine on the bench. Just the reaction in stabilize with the default settings is much weaker than in former versions. So tilting the heli does only lead to small corrections on the swash. Should be good enough for flying.

Does anyone know why beeing on the flight tab in the MP leads to a very laggy response on the screen. The HUD bearly shows any movements because there seems to be a very strong lack in updating the date?

In former versions it was smooth like hell.

Kranston Kincaid September 7, 2012 at 7:11pm

Well after last weekend I was bound and determined not to let a stupid helicopter and Ardupilot board get the best of me! So I went to my local hobby store and bought another Raptor so I knew everything would be brand spanking new. After a week of building I am back on the circuit and I have not given up, as a matter of fact I have made progress. No more stupid "leans" or "wobbles" or shattered windows. I, my friends have gotten the APM 2.5 to stabilize my Nitro Raptor. I have been thinking about how to do this all week as I was having a hard time believing the APM couldn't handle the vibes. I came up with a variation of the mounting plate I used last week and changed the settings dramatically.

Here I used G-10 plate and mounted the APM to it with foam ear plugs with a open cell foam in the center. Then I used 2 pieces of black dense foam and stuck them to the bottom of the G-10 plate.

Not pictured... I also used rubber washers between my motor to the motor mount and also between the motor mount and the frame.

Huge vibration difference

Unfortunately that still wasn't enough to keep this thing in check. I had to change the setting in the Mission Planner. I am using .37 on the Stab Control P value and 4.0 on yaw. I know that might sound high but that is the only way I could have the same authority over the tail as I once had before the APM. I also changed the AHRS RP_P to .15. I will start to increase those values slowly until I get even more response but I will say anything over .5 on the Stab P, I couldn't even get it up to half throttle without issues. With these values APM works about as well as the KDS Flymentor in Stabilize mode. (I figured since I can already fly a heli pretty good I would start with the APM in the least amount of control as possible and go up from there instead of the other way around.)

I also leveled the heli on the bench and noticed that it would still move forward a little in the air it appeared about 3 degrees off so I used wire to suspend the heli in the air and then leveled it. WOW what a difference 3 degrees makes.

Hung the heli from main rotor until it stop moving and voila, completely level as it would be in air.

So I say all of this just to help someone who may want to try the nitro heli. I know you guys know most of this stuff but thought I'd share. Here's the video just for you! Oh the sudden movements in the beginning are just me showing that it was in stabilize mode not just good piloting

http://youtu.be/f3c-iszxeOM

http://youtu.be/jmxWVExAmKc

Rob_Lefebvre September 7, 2012 at 5:39pm

I just had a great 3 flights with the 600 after changing the bearings on the tail drive shafts. I didn't do anything else, balance anything, dampen anything or change any gears, just changed those little 4mm bearings, and it's good as gold! The yaw control is simply awesome with the built in gyro and the new yaw controller! I can yaw it quick and simply <snaps> to a stop with no overshoot or bounce.

Goes to show how easy it is to throw off the DCM. The bearings weren't even that bad, just a little crunchy.

Overall, it's rock-solid. I put it in manual acro mode and spooled it up, watching the HUD, it really doesn't even move when passing through the spool-up wobbles. It seems it's just the high frequency vibration that really hurts it.

Unfortunately my flying club apparently is closed for 2 weeks because the land owner is hunting geese on it. So I'm really limited in what I can do. I just flew in my back yard to drain the packs and test it out. All I can really do is hover. I tried a bit of Loiter, but it didn't go well. I think my Stab P is way too low, so that wouldn't help. After giving up on loitering in a small space, I started tuning up the Stab. I've already doubled it and it's getting better.

The thing with the flybar is, this can way too low and it doesn't matter, because it's self stabilizing. It makes the controls soft, but it's really not a problem. But I imagine it doesn't help Loiter.

I do wonder what sort of effect it has, the fact that the APM is actually hanging under the disk. The disk is what actually moves and creates thrust, which isn't exactly related to the angle the frame currently takes. How will that affect the auto piloting modes?

Christoph September 5, 2012 at 11:10am

Hi all,what is going on with the trad heli guys? Following this discussion I read more and more about "lean" problems.

As said before, I luckily never experienced any issues due to vibration.

Stopped experimenting with version 2.3 or 2.4 I think, but never got really good loiter results. I am still keen on going to get loiter working with my 450. Is it safe to load the latest firmware supplied by MP or should I rather continue with the old version? Or with an even older? E.g. Malcom proposed to go back to 2.0.4xxx something. I am not having the latest board with the GPS directly attached, but the version before that. Is that an issue regarding the firmware?

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ArduCopter Traditional Heli (was: "600-size heli")

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