I am opening this topic to serve as the go-to place for talking about the upcoming 2.9 software release for Trad Helis. I think this will be necessary as 2.9 will have SIGNIFICANT changes in the way that the helis fly, and also in the settings you will use.
Yesterday, I flew 4 packs of "2.9 - rc2" from the downloads section on my 450 heli. The file is located here:
I would be interested in having some other people try some test flying with this. I'll have to walk you through the setup, as it requires a bit of work to get a flying parameter setting using the rate controllers which are now active. You CANNOT fly using the old parameters for Stabilize PID. Don't even try it. Also, the Alt_Hold parameters will have significantly changed.
This is slightly complicated by the fact that we have some new Heli-specific Rate PID parameters called "Rate_Pitch_FF", also for Roll and Yaw. Unfortunately these are only accessible in MP from the Advanced Parameters List. Hopefully I can get that fixed. What I'd like to do is for TradHeli, in MP, remove the Rate_Pitch_D, in the Config PID screen, and replace it with Rate_Pitch_FF. This is because I have found the D-term to be completely unusable anyway. The FF is feed-forward. This was what I found was the key to getting the heli to be able to fly in rate mode. Basically, it is like P-term, but has no error correction. It's sort of like this:
P-output = P-term x (Rate Input - Current Rate)
FF-output = FF-term x Rate Input
then you also have the I-term output. So the total servo command is:
Servo-output = P-output + I-output + FF-output
I have also implemented the FF on the yaw controller, and found that it actually helps to stop the slight "tail wag" that we always had.
There are also some new settings for the collective. These are Stab_Col_Min and Stab_Col_Max. What these are for is sort of like Idle-up pitch curves. You can now set up your swash plate with full negative pitch, maybe a range of -10° to +10°, or +/-12°, but when flying in Stabilize mode, you can set Stab_Col_Min to reduce the amount of negative pitch available to something like -3° or whatever you prefer. This gives a nice soft feel. However, in Acro mode, you will get the full range, and also the auto-pilot modes get the full range. For example, I set my Col_Min and Col_Max to give me +/-10°, and then I set Stab_Col_Min to 40, which is 40%, and this changes the negative pitch to only -2° in Stab mode.
The only thing to know here is that when you change modes between Acro and Stab, the swash-plate will jump up and down, so you have to be ready for it. It's no different than using Idle-up in your Tx.
My test flights yesterday went quite well. The Alt_Hold now works beautifully, and I actually prefer landing in Alt_Hold rather than Stabilize! I also did a few flips with it in Acro mode (very ugly, I'm not good at this) using full negative collective when upsidedown, and it worked well. It didn't seem to get confused. Finally, I tried going into Acro, rolling it over upside-down or sideways, then back to Stabilize, and it flipped right way up which is good.
The only problem I have seen so far is that when flying in Alt_Hold, if you push the cyclic full forward and get up a high speed, the altitude starts to oscillate badly. I suspect this is a classic "phugoid", or pitch/throttle oscillation. We'll have to work on this. However it seems to fly well up to about 1/2 Vmax.
I'll try to post my Parameter file here tonight, but I caution that the settings will be HIGHLY dependent on your servo speed, as well as many other setup differences.
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Hey guys, sorry for all the confusion, but I think there's really no need for you guys to go through all those steps and configuration changes. That was mostly during the early days when this setup wasn't mature anymore. You should not need to worry about compiling with Arduino IDE, nor worrying about Config files or any of that.
You simply install the APM, plug the USB cable in, and load it with 2.9.1 directly from Mission Planner. Then you just need to tune your PIDs. Pretty simple stuff.
Jeff, sorry, I don't know anything about Optical Flow setup.
Bummer, crashed my 600 today. It had been going so well.
I was attempting running waypoints at 25 m/s, and it was generally going well. But, long story short, on one run it didn't, and it way overshot the target landing spot and went over the parking lot. I then mistakenly threw the Thr Hold switch instead of the Stabilized mode switch. And... the rest is history.
Not too bad, I have most of the parts. I did blow 1 servo so that sucks. And of course the main blades. And I lost a collective turn-buckle. Usually one of those things get thrown into a parallel dimension. Boom. Probably the main shaft too. Etc. etc.
Real bummer is Hobby King is pretty much out of 600 blades. I'll have to run some beater blades I have lying around.
Out of curiosity would there ever be a mode that is like rate mode? Basically making the sticks like a arcade mode forward lets say is like 4 meters per second same with left and right. This would be good for any Joe off the street to pick up the controls and fly the helicopter. I would imagine a lot more people would be willing to fly helicopters if they could control it this way.
Had a really good tuning session today. I changed the Pitch and Roll Stab P terms to 1, which allowed me to crank the Rate PID gains way up. I was at like RateP =0.2, and now 0.8. It's is much more stable at speed now.
I suggest everybody play around with these numbers.
I'm not done tuning yet, but it's getting really solid. Full speed flying now is much more stable. The Pitch "knife edge" is gone.
Joly, really nice tip! I turned my Stab_Yaw_P term down to 1, and I like the feel much better. In fact, I was able to turn up the P-gain from 2 to about 3. It holds much more solid now. Pretty good feeling. It feels much better.
I suggest everybody try this.
Also, I found that during very high speed flight (up to 126 km/h) the tail would start wagging badly. I put the Yaw Rate P gain on the knob, with high and low set for 0.3 to 0.15. If I turned the knob down at high speed, the tail held nicely without juddering.
Today I managed to fly Alt_Hold at 120 km/h as well. It did really well. The only problem is that pitch is like a knife-edge. You have to be super gentle on the stick or it pops badly.
I plan to try flying waypoints with a speed of 30 m/s tomorrow. That I think will be my ultimate goal in preparation for the Sparkfun Challenge in June.
I'm going to try doing the same thing on the pitch axis. Turning Stab_P down to 1, and then seeing if I can increase the Rate gain. I bet I can. And it will help with the high speed flying I think.
Lastly, I manage to get a full 3D acro mode working. Not done yet, but I can do forward and backwards flips and rolls. And it's well stabilized. It actually is working quite well. I'm pretty happy. Unfortunately I had a little crash on the 450 as a result of this. Don't think I even broke the blades but I stripped some servo gears. :(
The latest acro changes are NOT in my clone yet, so don't pull it!
Maybe someone can help me get a better understanding on this. I flew today with the new APM2.5 with the internal magnetometer. First flight was odd it would loiter great for about 5-10 seconds then do a dramatic forward or side roll. I then took my I term down to zero. Took the helicopter back off and put her right back in loiter mode this time there was no fast dramatic inputs. Loiter worked really well even in 10-15 MPH gust.
The reason I went back to the internal mag was because I really only started having problems when I put an external mag on my helicopter. The mag interference is around 300ish and does not change with the motor on or off.
Was there I term building up and that is why it would make a hard input?
One other thing is the stock config Imax is set at 100 I turned that down to 50 which maybe it's all in my head but it seemed to loiter better with that turned down.
Joly, I'm looking at this bit of code for the DD Tail. And I have a question...
In the case of RSC Mode 1, where we have Ch8 pass-through to the ESC, how do we switch the tail motor on/off? It works nice and simple on a 3-pos switch if you're using RSC Mode 2, but it's not so clear on Mode 1. The only thing I can think of is that in that case, if you are armed, spin the tail motor, otherwise don't.
Did 4 flights with it today. Had a few issues not related to APM. First, I discovered than the "Low Governor" setting in a K-Force/HobbyWing Platinum Pro ESC is basically useless. What is the point of it? Head speed sagged terribly just in a hover. Set it to "High", and that was fine. But the soft-start on it is not soft enough, it cocks the blades back in the grips, and using RSC_Ramp doesn't seem to help. I just live with it. (They swing back out soon enough). If I tighten the grips too much, they don't settle properly and I get a bad wobble.
Did the initial flight with the training gear on, and got the Rate PID's close enough. Went to the airfield, and after a short time, I stripped out the tail drive gear (the one driven by the auto-rotation gear). Ugh. I am not getting enough engagement of that gear. Went back home, and had to disassemble it, and slot all 6 boom mounting holes to slide the whole boom forward to get more mesh. I guess this was just to prove to me how much mechanical tail drives suck. It is by far the most common mechanical problem I have.
Back to the field, got it pretty much dialed in. 2nd flight, Alt_Hold is working. Really really nicely too. It wasn't moving an inch in 20 km/h wind. 3rd flight, starting fast forward flight in Alt_Hold and Stab. Alt_Hold is super solid flying back and forth aggressively.
I also tested Loiter which worked very well, and finally did an RTL which was perfect. Returned home and descended and held at 2m. Exactly what I want.
This heli flies really really nicely. I think it's more stable than my old flybarred 600. Not positive yet, but maybe. The blades also seem to bark more, not sure why. But I was using 2.9.1, instead of my development branch that I use on the 450. I can really feel that it's missing the full I-term. Not nearly enough authority in fast forward flight.
Fired up the new 550/ 600 for the first time, did the blade tracking. At the same time, I did a preliminary vibe check, and this is what I got. I think it looks OK? I bet it will be even lower in the air, as since it was strapped down to a workbench, the vibration is reflected back up through the skids?
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