Crash detection in modes other than AUTO?

hi I had a crash recently while in FBWA and because the RC signal is lost shortly before the crash (airplane went behind trees, wall, etc) the plane went into QRTL as I configured. I was hoping that crash detection would disarm the motors, but when I got to the crash site i found the battery completely drained. After looking into the log the battery kept discharging after the crash. I went back and checked the documentation which says the crash detection function only works in auto modes.

I don’t think I can configure failsafe in a way to satisfy in-air loss of signal as well as a crash failsafe. I had to account for the real possibility of momentary RC signal loss and the need to RTL, but this would lead to motor spinning at full power if there is a crash that coincides with loss of RC signal. In this particular case, I was also unable to control the plane in any way via MP or RC, because the signal was completely cut off due to obstacles. I did send a MP command to go into manual, but log shows the plane stayed in QRTL until bat died.

Any ideas here? I think this is a post-crash safety issue.

Hi Ronald,

can you give a link to the logfile ?

hey Rolf sorry I can’t, but the vtol plane behaved just as expected: RC failsafe and QRTL, just the way I set it up, although I didn’t plan for a crash… I am just wondering if there is something I can do so that if crashed, the motors will be disarmed regardless of what mode I was in.

sorry Ronald, you’re right. I wrongly remembered that Crash-detect works in RTL mode as a kind of AUTO also. Then the IMU.x value might have been too low to reach CRASH_ACC_THRESH, especially if the VTOL in QRTL drops vertically. But this speculation is pointless as long as crash detect is implemented only in pure auto modes. But in QRTL mode the question arises why your VTOL did not register the landing and switched off the engine.

well, i’m still working on the log to find out what happened. It was at the end of a transition into fixed-wing mode, and suddenly the drone stopped responding in pitch and went steeply down into the ground. Shortly after I realize there’s a loss of control I switched to Qloiter, the descent continued for two seconds until the RC signal is obscured and failsafe kicks in. There was not enough altitude to recover in quad mode I think.