FBWB Near unresponsive

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1

Okay guys, I have been battling this issue for a long time now.

I currently have programmed manual, stabilize, FBWB, and Autotune.

In stabilize and autotune, the plane limits max bank, and pitch just fine, it also correct and brings it back to level just fine.

In FBWB, I have little throttle control (either max or min, and nothing in between), I have full Yaw control, and no pitch or roll control. As far as I understand it, FBWB should allow full control of pitch and bank, up to their max bank angle, or climb rate.

The max climb rate is set to 7m/s (yes the airframe can handle it), the max bank is set to 55 degrees, and max pitch is set to 45 degrees. Again, all within airframe capabilities.

Auto trim is disabled, yet for some reason If I enter FBWB with no throttle input, I get no throttle control in FBWB. Same If I enter with max throttle. However, If I enter FBWB mode with anything between approximately 25-75% then I get some, very limited throttle control.

I have tried several different parameter files, and even reverted to an earlier version of APM. I am on the next-to-most recent firmware, (I believe 3.1.1 If I am not mistaken). However I have not updated to 3.2 yet…(I will soon, as I intend to use flaperons, and up till now have not because you could not trim the airframe previously)

Currently using a pixhawk, by the way.

Let me know if you guys have any ideas! I am hoping that this has been asked before and I simply can not find any reference. If you do need the parameter file, let me know.

Sincerely,
Justin

2

@Justin_Martin,
Please provide tlogs and/or data flash logs to help troubleshoot your issue.
Regards,
TCIII GM

3

Thanks Thomas.

I attached the most recent Tlog, however my .BIN (dataflash) is too large at 24mb. It only compresses to 12mb, so I can not attach it here… Instead I made just this file public on my google drive.

drive.google.com/folderview?id= … sp=sharing

Should I post any parameters as well?

4

Hi Justin,
I think the primary problem is that the docs explaining how FBWB mode works were not clear enough. I have just rewritten them to be clearer:
plane.ardupilot.com/wiki/flying/ … IRE_B_FBWB
I’d also note that your TRIM_ARSPD_CM is 1200 (ie. 12 m/s) and your ARSPD_FBW_MIN is 11. That doesn’t give much room between “cruise” speed and minimum speed. I’d recommend at least 3m/s difference.
That explains why low throttle didn’t slow the plane very much. In FBWB mode min throttle will fly at ARSPD_FBW_MIN.
Cheers, Tridge