I made a new aircraft, the X-UAV Talon Pro is a very simple and easy to control aircraft. Made 2 flights. In the first one, I did Autotune, but the first one, and then the second one, ended in a hard landing, because after takeoff and switching to FBWA mode, the plane did not want to raise the nose at all. I am attaching two telemetry logs. What should I pay attention to, because I don’t understand what to do with it?
Friends, can anyone help me?
The logs files are access restricted.
Thank you. Already fixed it.
did you find the reason of problem…?
No. The problem did not go away. He can’t lift his nose. I checked the center of gravity, even moved it back a bit. Then I set the mixing_gain parameter, it improved the situation but not much. All the same, I don’t want to raise the nose of the plane after Autotune. Now, although it takes a horizontal flight, and it can be landed, but it is still not clear what the reason is. The problem is not solved.
The flight controller was applying full up elevator, but the aircraft did not respond. It seems like there much be some issue with the aircraft setup and/or control throws.
In your second flight after switching to FBWA you have only about 25-30% throttle and airspeed of about 17m/s, that is not enough for level flight or climbing.
Yes, I reduced the throttle, because the plane began to descend rapidly, but did not raise the nose. 17m/s and 30% throttle should be enough for horizontal flight. But that’s not the problem, the problem is that the plane reacts very poorly to the elevator.
Yes, I already increased the mixing_gane from the default of 0.5 to 1. This allowed me to keep the plane horizontal, but it didn’t solve the problem. As soon as you release the throttle, the plane loses altitude.
One tip i would suggest , would be to add one or two camera onboard, to record all movings surface position and check it is all matching ardupilot out channel value in the logs.
Also your could monitor servo power line as an additional battery using analog input.
But in you case Center of gravity is the most important settings to be triple checked.
Stall prevention is working.
See this link.
In FBWA, if the STALL_PREVENTION parameter is set and the throttle falls below TRIM_THROTTLE, the pitch angle is controlled to a negative value. The value depends on STAB_PITCH_DOWN. According to your second flight log, TRIM_THROTTLE=45%, STAB_PITCH_DOWN=2deg, and actual throttle is around 30%, so I guess the target pitch angle value is around -1deg. The actual pitch angle is below -1deg, but there is some movement trying to keep it around 0deg, so it would be considered normal operation.
NavPitch indicates full pitch up, but the output to the elevator servo (RCOU.C2) tends to lower the nose, which also indicates that Stall Prevention is working properly.
When flying in AutoMode, you can see the throttle rises during pitch-up, which is due to TECS. In order to raise the nose of the plane, the speed gained by increasing the throttle must be converted to potential energy by pitch operation. It was a mistake to reduce the throttle to 30% in FBWA mode.