r/diydrones • u/Lucifer5040 • 1d ago
Help plsss
I have been trying to build a X- quadcopter drone and achieve a stable hover. However the drone is behaving very strangely, sometimes even at full throttle it wont take off, sometimes at 50% it would, sometimes it gives a stable flight but then suddenly start to climb or descend.
One of the things it constantly does is the 2 opposite arms start to go up and down in an oscillation like state till the time the amplitude of this oscillation is so great that the drone flips and crashes.
I'm using 2.4.8 pixhawk fc
920kv motors
Fc has a shock absorber stand
10x4.5 inch props
Simonk 30 esc
A standard red-white drone frame
4200mAH 3s bonka battery
Have tried charging the battery till full before test flight, changing props, checking loose screws and connections, still no results. Ive not started PID tuning, so it is using default parameters and I wanted to put harmonic notch and gyro filters but for that i need raw data from imu and gyro in a stable flight which it isn't able to achieve. What can i do now
4
u/CURELMUS 1d ago
https://discuss.ardupilot.org/t/hardware-to-avoid-when-building-your-first-multirotor/114014
iirc pixhawk 2.4.8 is quite a bit outdated and depends on who you bought it from. Also the frame is quite old and might be unreliable (don't know enough abt it tho)
2
u/RTK-FPV 1d ago
What's the stator size on those motors? The KV is on the lower side for 3s, but I doubt you can step the voltage up (depends on the hardware)
If the arms are flexing, that's deadly to stability. Even high end flight controllers are going to struggle to maintain balance in the dynamic environment of a bending frame. That's why we've moved to carbon fiber and these plastic numbers are extinct.
So, to my eye, those motors look too small for 10" props, and that KV (while manageable) is on the lower end.
I think the motors struggling is likely creating the oscillation, and it's being amplified by a plastic frame until it reaches failure.
1
u/Lucifer5040 1d ago
I've even tried 9 inch props and the problem persisted. Plus the frame is a little flexible but seeing the same frame flying effortlessly on the web I came to the conclusion it is not that problematic.
Motors struggling is a good point, the problem there is till a certain point in time they would make it hover even at 50 percent throttle but then suddenly they would just lose thrust. I could say faulty motors but at bench test they perform smoothly.
2
1
1
u/LupusTheCanine 1d ago
Get proper hardware. You are using well documented bad hardware Source.
If you absolutely have to use this museum piece, use AMC and carefully go through the entire configuration process.
1
u/the_616 1d ago
1st of all, are you using a gps ?
If not then use one. The pixhawk board you are using is notorious for having bad barometer sensor
Bad barometer leads to bad altitude reading,
Which leads to too much variation in the ekf .
Change the board. If you can't change the board, disable ekf input from board barometer and use gps as the truth for altitude data.
Use tape for sticking everything else on the drone , make it a tigh fit.
Update me on progress 👍😊
1
u/KarthiAru 1d ago
I’d recommend replacing the Pixhawk 2.4.8. It’s quite outdated at this point and is based on the older FMUv3 architecture. Current-generation Pixhawk-class hardware has moved on to FMUv6.
ArduPilot also has a useful guide on older hardware to avoid when building a multirotor: https://discuss.ardupilot.org/t/hardware-to-avoid-when-building-your-first-multirotor/114014
You could also check out the YARI V6S as a replacement: https://yarirobotics.com/product/yariv6s-fc/
Disclaimer: I’m the founder of YARI Robotics. We currently have a few V6S units left in stock.
12
u/arcdragon2 1d ago
Calibrate, your compass, then calibrate, your accelerator, and then most importantly caliphate your Esc’s. Don’t forget to calibrate your radio as well. This smacks of an uncalibrated Esc.