Drone loses control on liftoff

ArduCopter Copter 4.0
1

Hi guys,

So I crashed my drone a couple months ago and have now rebuilt it with new parts that were damaged. However, upon liftoff, drone started swaying to the left and crashed again. Upon looking at the bin file, I have a feeling it’s something to do with the motors, can someone please advice what’s going on here?

Specs:
550mm wheelbase
Motor: 5010 750kV
Prop: 1347
ESC: T-motor Air 40A
Battery: 4s Lipo
All up weight: ~2.5kg

Thanks guys

With 1447 Props
2023-08-25 13-40-53.bin

With 1347 props
2023-08-25 16-17-36.bin

2

Try putting in all these adjustments. The ATC_ ones should help with stability, and the others are gathering data for tuning and next flights

ATC_ACCEL_P_MAX,92000
ATC_ACCEL_R_MAX,92000
ATC_ANG_PIT_P,6.5
ATC_ANG_RLL_P,6.5
ATC_RAT_PIT_D,0.004
ATC_RAT_PIT_I,0.12
ATC_RAT_PIT_P,0.12
ATC_RAT_RLL_D,0.004
ATC_RAT_RLL_I,0.12
ATC_RAT_RLL_P,0.12
ATC_RAT_YAW_I,0.05
ATC_RAT_YAW_P,0.5
INS_ACCEL_FILTER,10
INS_HNTCH_ENABLE,1
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,4
LOG_BITMASK,180222
MOT_THST_EXPO,0.65
PSC_ACCZ_I,0.4
PSC_ACCZ_P,0.2

What you can do to avoid mistakes is copy/paste all those into notepad and save as a file with extension “.param” like “some_adjustments.param”
Then in MissionPlanner full paramater list you select Load from File at the far right side, and select that file you just created. Reboot the flight controller after those are successfully applied.

Next run this semi-automatic ESC Calibration:
https://ardupilot.org/copter/docs/esc-calibration.html#semi-automatic-esc-by-esc-calibration

Now go back to MissionPlanner motor test and find the lowest possible percentage of throttle that allows the motors to start reliably and smoothly.
Set that as MOT_SPIN_ARM
Set MOT_SPIN_MIN as that value plus 0.03

The reason I ask for that calibration and MOT_SPIN_ procedure is those values are currently a bit on the high side, so we want to make sure they are correct.

Next try a takeoff in ALTHOLD mode, not Loiter. You will also have to get used to using Stabilise mode since it is the emergency go-to mode when anything goes wrong. It can be difficult to use while the copter is not tuned.
Just mainly hover, and do some gentle pitch and roll movements.

Let’s see that .bin log.

3

Hey Shawn,

I’ve tried introducing the changes you recommended, but it still crashed, and I broke the last 13" props that I have. Here’s one .bin log with 1447 props, and actions taken:
Deleted and uploaded new firmware
Calibrated the ESCs
Make changes according to initial tune parameters

Observed: Drone sways to the left upon takeoff and crashes.

Video: 20230828_055739000_iOS.mov
log: 2023-08-28 15-42-12.bin

Thank you in advance

4

Sorry to hear about that, it’s never nice or funny to have crashed.

Vibrations increase linearly with throttle, indicating there is quite a prop balance issue.
The vibrations will affect nearly all aspects of stability and position control.

I’m also suspecting there might be a motor order issue. Usually when this is wrong the quads flip over backwards, but sideways is also possible.
I checked the RC inputs compared to desired pitch and roll - they closely align and operate as expected, but the actual (or achieved) pitch and roll just do their own thing
Can you go to MissionPlanner motor test and verify that when you click on “test all in sequence” they operate in this A, B, C, D order as pictured:

image

Then also check that the props spin in their correct directions.

You can still put in ALL parameters I previously specified except the top two ACCEL ones.
Set MOT_THST_EXPO,0.65 too please.
All those params wont “make or break” what you have now, but should be quite OK. And it gives us more data if you can get this quad airborne.

For the next test, start in Stabilise (or maybe AltHold mode) and do not spend so long on the ground with props spinning - arm and increase throttle, get clear of the ground sooner and let the flight controller do it’s job.

5

Just did the motor test, order is correct as well as directions and numbering.

Will test the parameters again when the weather allows.

I also noticed that motor 4’s output in RCOU keeps dropping to the minimum spin level, is this normal at all? The reason I did not take off after arming the drone was because motor 4 (B) was not spinning as fast as the other motors, not sure if you can see it from the video I attached. It was twitching until I gave throttle.

Btw, thank you for your response, appreciate it.

6

Did you do the sem-automatic ESC calibration?

7

Yes I did. Also calibrated the ESCs using T-Motor’s recommended steps.

8

Upon further bench tests, we suspect it’s an ESC issue. Would anyone be able to confirm this?
Attached log is stabilise mode without propellers and two motors (1 & 2) keeps dropping to the minimum spin level.

2023-08-29 18-45-07.bin