There will suddenly be a large change in attitude, and the motor output value becomes constant

ArduCopter Copter 4.0
1

This is a Octo Quad H copter. During the execution of automatic tasks, there will suddenly be a large change in attitude, and the motor output value becomes constant…
This only occurs for a few seconds, but otherwise the posture is maintained well.

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The log file:https://drive.google.com/file/d/1DM9EivyDXsCaKLabA0iB1NDQmxyimOBP/view?usp=sharing
Thanks for any help.

2

I think your motors are too powerful for this frame: the Arducopter often reaches the limit (MOT_SPIN_MIN = 0.15 ~ PWM = 1185) in any flight mode, not just automatic. You can slightly increase the weight for testing.

3

Thank you for your help.It is true that this design has more motor dynamic redundancy.Can I increase my range of control by turning the MOT_SPIN_MIN down?

4

It depends on your system. Check https://ardupilot.org/copter/docs/set-motor-range.html
But I’m not sure if this is a good idea. You can get stability problems when descending / landing with such low % of thrust.
IMHO it is safer to attach a wooden block.

5

Thank you,It helped me a lot.

6

You might be able to get away with keeping everything as-is and fixing a slight motor twist. Like for example the gold line, motor 2, is usually lower than the yellow line motor 3. The avg us does appear to be different enough between the motors that it might be worth looking if they can be improved. That might move the motor output commands on the problem motors up away from the lower limit