I guess it's better to start a new thread on a different topic.
How do you tune the PID for Pitch and Roll? Are the Rate numbers are work like a flybar and the Stab numbers are for self leveling? So, I could zero out the Stab numbers and tune the Rate first?
Could any one share your working heli PID for me to start with?
Replies
HI, which channel of Ardupilot I must connect to 7CH of my receiver?
https://code.google.com/p/arducopter/wiki/AC2_SimpleMode
thanks.
With the Stab going against strong wind, it oscillate like a tope at times. Along with incorrect trim, and drifting tail, it's not present to fly at the moment. At least it is flyable though. That's one of the reasons I tried the Position Hold mode and hoped the heli would stay put at one spot.
Hmm... Just looked at the wiki and there are no such mode called "Position" while the APM Planner has that choice in there. The Loiter mode is just circling. What is OF_LOITER?
I have a Align 450 Pro V2. The tail servo is inside the body, not on the tail like the old one did. The heli was using a Skookum SK720 before and it was tuned perfectly with almost no vibes and all the linkage are at 90% at zero pitch. It's a very well tuned machine.
My current settings:
Stabilize Yaw: P=1.3, I=0, IMAX=6 (default)
Rate Yaw: P=0.193, I=0.1, D=0.001, IMAX =50 (default)
At first, I had Stab Yaw P=1, and used Ch6 to tried to adjust Rate Yaw P from 0.2 to 0.4. The tail was vibrating no matter what I did. So I fixed P as 1.3 (so that at least I have some control on the yaw), and then adjust Rate Yaw P from 0.1 to 0.3. Finally found 0.193 was the highest I could go.
From my last flight trying to adjust the Stab Roll and Pitch, I've noticed that the tail was still wagging at times. So I kept the Stab Yaw at 1.3, and tried to adjust Rate Yaw P between 0.193 to 0.3. But then the tail was not in control at all.
By the way, seems like there are no Ch6 choices to adjust Rate Yaw I. There are only:
CH6_YAW_KP
CH6_YAW_KI
CH6_YAW_RATE_KP
CH6_YAW_RATE_KD
Found a write up by Randy in the 7th page in the monster 600 thread. Thanks again Randy. :)
Randy wrote:
I haven't specifically tested but yes, I think the Rate values must be there for stabilize to work properly.
I think ACRO/RATE as a control method is still possible. People who want to do tricks and are skilled enough to control their heli/quad by specifying the rate of change of the roll and pitch with their radio controls are welcome to use it (i'm not one of these people I'm afraid!).
Stabilize is now dependent upon rate but rate is not dependent upon stabilize.
In stabilize mode, if you let go of the controls, the heli should return to a level position. internally the stabilize pid will compare your radio controls to the heli's attitude and say, 'oh, the heli is leaning to the left by 10 degrees, better roll back to the right at 5 deg per second...hey, Mr Rate control, do that for me". Then the rate controller kicks in and looks at the rate of change of the roll and says, "hmm..we're rolling right by only 2 deg per second, better modify the swash plate to increase the right roll".
In acro/rate mode, if you let go of the controls, the heli will remain in whatever attitude it's currently in. So if it's leaning to the left by 10 degrees, it will keep leaning. the roll controller gets direct instructions from the radio, "don't roll, pitch or yaw" and it would then compare this to the current rate of change of the axis and adjust the swash (or tail) to stop any change.
IMAX allows you to set the maximum I value of the PID controller. "I" is like trim. If your heli isn't level (say leaning to the left more than you're specifying you want with the radio), the I term will slowly climb to counteract this. The IMAX is a safety feature, it stops this I term from getting too big. If it got too big you can imagine that it might completely overpower P and/or D.