Hey, I got a problem with my octocopter. I start my flight with an automatic takeoff, usually it goes okay, but sometimes drone climbes 1m instead of 5m and then turns on pos hold mode. After takeoff I left drone in position hold mode, it can’t really stay still, it always slowly flies 1-3 meter in random direction (even up and down). Also it can’t hold yaw at all, it always rotates by 5-10 degrees in yaw, sometimes up to 20 by itself. Sometimes it is also difficult to control yaw, it overshoots a lot. All this happens in pos hold when the drone is trying to hold itself without pilot input. Ground effect is not a problem, I tried to check how drone holds itself at 50m and result was the same. But when I’m trying to fly more aggresive everything looks perfectly fine except yaw overshoots, other problems aren’t noticable.
I see quite big vibrations in my log file, but I’m wondering if this could just be caused by vibrations?
Can it also be caused by slow reaction of ESCs? I have regular PWM ESCs.
Some details of my drone: Pix32 V6 flight controller, 16 inch props, Tarot iron man 1000 frame, hobbywing XRotor Pro 40A ESC.
The first log is smooth flight, the second one is very aggresive.
Firstly check the arms and the rotors. Are they aligned properly.
Secondly , did you do a auto tune and land and disarm and saw the PID values saved in the QGC parameter list.
Yes, arms and rotors are perfecly aligned. I have done autotune some time before and parameters was saved succesfully, but I think I need to do that one more time
Hi there,
Imu is the main sensor for stable flight and vibration is the main enemy of the imu. If the vibration is too high attitude estimations will not be quite good. If estimations aren’t good, then controller cannot make the drone stable even if they are tuned properly because their feedback is not proper.
Sometimes, badly tuned pid can make drone vibrate, even if there everything on the drone is mechanically on good shape. (checking your angle and angular setpoint vs estimations they are not aligned, which give insight that you have problem with pid)
However I would firstly be sure that, there is nothing vibrating on the drone, FCU damped etc.
If there is nothing wrong on this first part, and your drone as I understand can fly, make auto tune then check if there is any progress on the log.
You can go for the plot of raw acceleration, x, y and z should be more like a thin line and x,y seperated from z. Check the following link for vibration part Log Analysis using Flight Review | PX4 Guide (main) , it is really clear you will get the idea.
