Good progress on quadplane testing but can someone check out my logs please?

ArduPlane
1

I’ve made some good progress on getting my Observer/Ranger-Ex Quadplane dialed in. I’ve done 4 transition flights and about 20 hover tests and, whilst it is much better after adjusting some of the parameters, I’m still wondering if it could be a little better in VTOL flight modes? I would really appreciate if some could take a look at my attached flight log, which is from a test flight using all 3 VTOL modes on a calm day:

Whilst I am very familiar with APM Plane, I had to get my head around APM Copter tuning to better understand the VTOL behavior of the aircraft. I think the most noticeable change came when I lowered Q_A_RAT_PIT_I and Q_A_RAT_RLL_I. With the default settings I found the aircraft very sluggish and there was a tendency to nose over on take-off. I have also pushed the Q_A_RAT_PIT_P and Q_A_RAT_RLL_P gains all the way up to 0.3 (I think that’s the max, but there is no oscillation so I think it’s fine). One of my major issues from the outset was very sluggish yaw authority (to pilot input) and that was fixed by pushing Q_A_RAT_YAW_P up to 0.4.

My only concern at this stage is the huge difference in sensitivity (to pilot input) between flight modes. Q_Stabilize and Q_Hover are very sensitive, but Q_Loiter has a much softer feel which I prefer. I doubt I will use Q_Stabilize going forward but I am concerned the difference in sensitivity between Q_Hover and Q_Loiter will bite me one day when manouevering near to the ground. I have lowered Q_ANGLE_MAX to 2,500 which makes things a little tamer but in Q_Hover and Q_Stabilize modes the aircraft rotates to that max angle in flash with minimal stick inout. I did try lowering Q_A_ANG_PIT_P and Q_A_ANG_RLL_P but that felt a bit too sloppy (in all 3 flight modes). Any thoughts on how I can tame Q_Hover and Q_Stabilize so that it’s not so sensitive to pilot input?

Here are my latest settings (which were used for the flight as per the attached logs):
Q_A_RAT_PIT_P: 0.3
Q_A_RAT_RLL_P: 0.3
Q_A_RAT_YAW_P: 0.4
Q_A_RAT_PIT_I: 0.15
Q_A_RAT_RLL_I: 0.15
Q_A_RAT_YAW_I: 0.018 (default)
Q_A_RAT_PIT_D: 0.0036 (default)
Q_A_RAT_RLL_D: 0.0036 (default)
Q_A_RAT_YAW_D: 0.01
Q_ANGLE_MAX: 2500

Thanks,
Jacques

2

@tridge - any chance you could help please? Jacques and I are both facing some challenges with the tuning of our QuadPlane.

Do I understand correctly that since this is a Plane firmware, I should do a regular Plane tuning for the fixed-wing part, and manually tune Q_A_* parameters for the VTOL part (in other words no Copter autotune or Copter PID parameters)? I couldn’t find any autotune for the VTOL, only this Plane doc that may apply for the QuadPlane? http://ardupilot.org/plane/docs/common-transmitter-tuning.html

This post mentions some sensitivity issues. While my QSTABILIZE/QHOVER seem pretty OK, whenever I switch to AUTO or QRTL I see some pretty steep banking/rolling on my plane, probably 45 degrees, which seems also sensitivity related. And then in the case of QRTL the descent is painful to watch, with bumps and significant losses in altitude followed by corrections from the AP until it is basically forced into the ground. QLAND is the complete opposite of that, the smoothest landing. Can this be due to my still using default PID Q_A_* params? I should note I made some big changes to the PID settings I see on the “Config/tuning > Basic Tuning” tab in MP, but I’m guessing they only apply to fixed-wing and therefore should be irrelevant for VTOL?

Thanks!