Quadcopter Drone Crash : PX4 Position Mode drift (Sat Count=20) and RC lagging response

PX4 Autopilot
1

Hi,
I am using a Pixhawk-4 flight controller running PX4 FW 1.10.1 on an quad-copter drone custom-built. I done multiple hover test on the same plate form , however yesterday on 8th August 2020 when i takeoff the drone for hovering, it takeoff very well and it hover for 18:50min (drone flight time is 40min)

  1. suddenly after at 18:52 it start drifting in " Position mode " (with satellite count 20) , without RC input as shown in the below picture of 3D Flight review.

Drift by Self withut RC Input.PNG
Drift by Self withut RC Input.PNG878×694 174 KB

  1. When i notice the drift i take the RC and trying to save the drone from trees , but the response of the RC input was lagging and the drone was out of control ( as shown in the below snap of 3D Flight Review) ,so i switch to " Stabilized mode " and trying to land safely but the drone hit a tree and fall down.

No Pitch Response.PNG
No Pitch Response.PNG1723×609 271 KB

I review the log but found nothing , kindly help me to found out the Reasons of the above issues of crash.

Log Flight Review: https://logs.px4.io/plot_app?log=0f91d62f-4871-4d83-8cd7-1b17836d93c3

3D View Flight Review : https://logs.px4.io/3d?log=0f91d62f-4871-4d83-8cd7-1b17836d93c3

PID Flight Review : https://logs.px4.io/plot_app?plots=pid_analysis&log=0f91d62f-4871-4d83-8cd7-1b17836d93c3

Kindly note that problem happened after 18:50min of flight.

2

One thing I’ve noticed is that during that time, the position setpoints of X & Y are missing on the graph (even though you’re still in POSITION flight mode)…
I have no idea what can cause this, maybe some dev will be able to tell…

3

Yes dear you are right all X, Y and Z local position were missed even in the position mode.
image

image
image660×829 39.8 KB

I found another issue is that the Actuator-0 out is not responding ( dead for some time )as shown in below snap

image
image1075×459 58.6 KB

it shows two possibility either the ESC failed or Motor , but on physical check motor is ok , i am doubt full about ESC. There is some glitches in the ESC out to motor may be due to use of long PWM wire or may be mosfet failure in ESC. the ESC start working in stabilized mode again.

from this we can conclude that the Pitch was not responding even the Pitch Radio stick full bottom as shown in the above pictures of 3D flight review.