Replies

        • Developer

          Hi Michael,

          You actually have a funny oscillation in your copter like you have a flexible gimbal mounted or something else that can move on your copter.

          Roll looks like you will need Rate P of 0.15 and Rate D of 0.004.

          Pitch Rate D of 0.0117, Rate P of 0.353 and Stab P of 7

          Yaw Rate P can start off at 0.7

          It also looks like you were having to adjust your copter pretty regularly so you may want to try again when you have better conditions.

          What values did you come up with in your manual tune?

          • Thanks a lot!

              I fought those funny oscillations and they don't happen only with very low D. Now thanks to you I suspect that this is just because bad mounted weight (gimbal simulation).

              My current settings are Pitch/Roll P 0.13, D 0.015,  Yaw P 0.23 D 0.01

              What could be possible values for I? I'd like to set safe range on Ch6 to adjust in flight.

            Best regards,

            Michael

            • I and P always get the same value when you do autotune.  Not sure why but that's how it is written.

              Also You want everything on your copter to be stiff - nothing that can wobble.  So never hang something on a string below the copter.  I learned this the hard way with a battery that was secure but very loosely mounted and could slide around a few inches.  Also it was far from center of gravity (towards the back to counter the weight of the camera).

              • Developer

                Hi George,

                Roll and Pitch get I = P, Yaw gets I = 0.1 x P.

            • Developer

              Hi Michael,

              Don't add Rate_Yaw_D, leave it set to zero. The physics of copters doesn't want it. The main parameters you want to use are:

              RATE_YAW_FILT_HZ,5 (2 to 5) for manual tuning I would set to 2 and increase P
              RATE_YAW_P,   increase until oscillation
              RATE_YAW_I,   RATE_YAW_P x 0.1

              • OK, but MissionPlanner does not allow Yaw D be less than 0.01 (or 0.001, don't remember exactly). So I will set it to the possible minimum.

                RATE_PITCH_I = RATE_PITCH_P x 0.1 as well as a start point?

                • Developer

                  Hi Michael,

                  Go to the parameter list and set it to zero. If Yaw D isn't zero then your tune is bad before you begin.

                  When ever you change Yaw rate P set Yaw rate I to 0.1 x P. As long as your I term is less than 0.1 x P you won't see anything that causes any trouble.

    • I'm flying F550-kit based hexa with gimbal, 2400g total with 4 Ah 4s battery.

      Weitght center is pretty low, could this be a reason?

  • Got 2 days ago a new problem in my new autotune attempt ( new battery from 8000mAh to 10000mAh)

    Never experencied this type of problem, and because i can't clearly highlight what happend in the log files, hope anyone had a clue .

    So in the autotune process the copter suddenly lost altitude in a semi-rapid descent and approach dangerously the ground, I've then directly engaged the loiter switch and put full throttle without success, the copter have slowly hit the ground without any damage

    I can clearly see than my ch3 throttle goes to 0 , but on my transmitter I was fully throttle ....

    3702021072?profile=original

    Here are the share link of the log file : 05-06-2015 log

    Any help would be really appreciated

    Thanks

    Log Browser - 2015-06-05 10-43-54.log.jpg

    2015-06-05 10-43-54.log
    • Developer

      Hi Alex,

      This same issue actually happens 4 times immediately before the copter came all the way down.

      You have two problems with your copter. The first is you are hovering at 70% to 80% throttle. This leaves very little room for your copter to use for stabilization before it starts to loose altitude.

      The second issue is it looks like one of your arms may be twisted. I can see this because you have a yaw imbalance based on the motor outputs. This could also be caused by a problem prop/esc/motor or calibration of your esc's.

      The end result of these two problems is you only have 14% throttle range before your copter needs to start reducing throttle to maintain roll and pitch. This is what caused your decent.

      Your D terms are very large. I would suggest going back to default pids and attempting an autotune from there. I would also suggest doing your autotune from the beginning of the battery to ensure you have as much power as possible to stay flying during the tune.

This reply was deleted.

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