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Quad crash, Pixhawk 2, AC 3.5.5


(Roman) #1

Hi. My quad crashed today. FC is Pixhawk 2 Cube, motors - T-Motor 4014, 15" props, custom frame.
Please help analyzing the log file for the cause.

After several minutes of flight I started accelerating and cornering, it wobbled and felt to the ground.

https://talizi.com/log.bin

Thank you.
Roman


(Greg Fletcher) #2

I reviewed your log. Found no indications of motor failure. Looks to me like it the PID tuning is not good for your copter. It became unstable and started oscillating and the amplitude increased until it flipped or hit the ground. Try lowering the P & I params for roll and pitch. Try 60 % of what it is now. If you see, and here oscillations fly gently and land. If you can get it to fly safely you can do an auto tune.
http://ardupilot.org/copter/docs/basic-tuning.html


(Greg Fletcher) #3

Hello, My post above was from my analysis from a week ago. I thought it was done, just now I saw your post again and after I logged in my stuff was still there waiting for me to hit the reply button, sorry bout that.:confused:


(Dave) #4

What’s odd though is if you look at Des/actual pitch and roll it looks pretty well tuned.


(Roman) #5

Hi. Thank you for your analysis. I tuned it using autotune and it flies very well. I tested it in heavy winds and with heavy loads, many different PIDs were tested. It looks like oscillations happen when I fly it with no weight attached, when I lower the throttle and descent. I think it was little light and RPMs were not enough to maintain the heading and stabilize. When I do fast left turn while descending it starts wobbling heavily until I raise the throttle.