Large quadcopter wobbling and shows unpredictable behaviour everytime

ArduCopter Copter 4.3
1

I have a 18kg quadcopter having the following specification:
pixhawk cube orange, here3 gps
MN8014 100KV MOTORS
FLAME 80A ESC
22000maH , 12S
R9X RECEIVER
when in auto mission, it just takeoff nicely but gong for waypoint with a speed of 3 m/s, it just become very instable . it almost flipped due to this instabilty, such that we have taken manual control in althold mode to make it stable.

what could be the possible reason for such kind of behaviour?
1.is it because of the high wind blowing , drag or something.?
2.is it because of inappropriate PID values?

2

for further flight analysis post a log file from the flight controller. its awfully hard to help with just a description.

3

here is the link for the log file,
https://drive.google.com/drive/folders/1Qaflu1NkzMVTpE1-3xH9UxCiH2xBnxiZ?usp=sharing

thanks,
jatin

4

I would reduce these parameters to a half, the check with Loiter mode before going to Auto

PSC_VELXY_D
PSC_VELXY_I
PSC_VELXY_P

Have to flown successfully in AltHold?

5

I cant load that log, there’s something wrong with it.
I would say update to latest stable firmware.
Set up the Harmonic Notch Filter.
Check logs, move towards running Autotune.

Dont use Auto or Guided modes until tuning is completed in Stabilise, AltHold and Loiter (in that order)

6

Have you find the reason of crash? I wonder…

7

I was able to load that log.

  • MOT_THST_EXPO,0.85 is definitely way too high
  • The PWM range for those ESCs is wrong
  • Vibrations are too high

Definitely see if you can reduce vibrations before flying more - check in the doco and search through other discussions on how to reduce physical vibrations. This is very important.

I recommend setting all these. I’ve looked over your existing settings and the log file to come up with these. You can copy/paste them into notepad and save as a .param file. Then use MissionPlanner or QGC to load and write the new .param file - this avoids typing errors.

ARMING_CHECK,1
ATC_ANG_YAW_P,4.5
ATC_INPUT_TC,0.2
ATC_RAT_YAW_I,0.08
ATC_RAT_YAW_P,0.80
AUTOTUNE_AGGR,0.1
BATT_ARM_VOLT,44.30
BATT_CRT_VOLT,42.00
BATT_FS_CRT_ACT,1
BATT_FS_LOW_ACT,2
BATT_LOW_VOLT,43.20
GPS_GNSS_MODE,65
GPS_GNSS_MODE2,65
INS_HNTCH_ENABLE,1
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,4
LOG_BITMASK,180222
LOG_DISARMED,0
LOG_REPLAY,0
MOT_BAT_VOLT_MAX,50.40
MOT_BAT_VOLT_MIN,39.60
MOT_PWM_MAX,1940
MOT_PWM_MIN,1100
MOT_THST_EXPO,0.4
PSC_ACCZ_I,0.4
PSC_ACCZ_P,0.2

Use MissionPlanner motor test to check these are still appropriate:

  • The MOT_SPIN_ARM value has to be for the lowest possible value that allows to motors to start up reliably and smoothly
  • Then add 0.03 onto that value for MOT_SPIN_MIN

Now provided you’ve been able to improve the vibration issue, do a test flight just in AltHold - hover for a while and do some gentle movements and ascents and descents.

Let’s see that .bin log file.

EDIT:
I meant to also say I’ve specified reducing some YAW values so yaw will not interfere with pitch and roll at this early stage.

1 Like
8

thanks for your help. the issue is solved