Crash in Alt_hold while all was looking okay

Log Analysis -- deprecated Copter Logs -- deprecated
1

Hi !

Here is a log from a F550 clone Hexacopter running 3.1.2.

It was loitering and then alt-holding for a short while, flying perfectly.

Then it suddenly turned over (at approx 40m heigth) and fell down. There was a short moment of decellerating and then it fell again crashing into the ground.

You can see odd things starting at log line 6250.

Could some pro look at this and give me a hint what happened ?

For me it looks like a failure on the right side as roll suddenly started with declining but usually it should still stabilize, right ?

Thank you for looking at the log !!!

Nils

2

Your throttle OUT goes to “zero” before rising sharply and then return to "zero"
I think “know bug Stability” present on 3.1.2.

Ciao - Giuseppe

3

Actually, it is very possible to detect number of cells by voltage, provided that the pack is not very discharged.
I use the code below to set alarm thresholds.

Part of start checklist is to check that reported cell numbers is correct, if you use 4s - you know that you should see ~16V on a full battery.

if ((vbat_A > 100) && (vbat_A < 127)) {
num_cells = 3;
batlow1 = LOW1_3S;
batlow2 = LOW2_3S;
}
if ((vbat_A > 130) && (vbat_A < 169)) {
m2h_num_cells = 4;
batlow1 = LOW1_4S;
batlow2 = LOW2_4S;
}
if ((vbat_A > 170) && (m2h_vbat_A < 220)) {
num_cells = 5;
batlow1 = LOW1_5S;
batlow2 = LOW2_5S;
}