Crash

[GoFaster]

Was doing more testing of my OSD today. Made a couple of flights. Then during a mission flight, AQ seemed to die/crash. All motors shut off and the quad plummeted to earth from 14m altitude
Field inspection revealed 3 broken/bent arms, one bent motor mount, broken landing gear, gimbal roll servo and possible damaged gimbal.
Thankfully I got it on video. Analyzing log now. More details later...

- Felix

[kinderkram]

Dammit! Sorry for your loss, Felix.

Any indication why that happend? Sounds like a power loss or failure of the board or other electrical parts causing a shortage or reset. Did the board still run after the crash?

[GoFaster]

AQ v6.6r29 . Conditions: Temp 74F, wind 10-12 mph gusting to 18-20. I was testing changes I made to the MinimOSD code. This was the third flight of the session. I had already flown for about 5 mins in Manual and PosHold modes before activating Mission mode.

The mission was a 5 waypoint mission. All waypoint parameters were 0 relative altitude, 5 m/s max speed, 5 sec loiter, 1 m hit radius. The only differences was absolute POI Heading of 180, 270, 180 ,90 and 0 degrees, respectively.

Screenshot_2012-10-06-12-10-30.png (458.01 KiB) Viewed 11122 times

Sometime ago I moved the FPV cam from the frame to the gimbal, next to the GoPro. Both cams were running as usual but the SD card in the GoPro partially ejected on impact, corrupted the file and lost the juicy part of the flight.

However the FPV cam with the OSD overlay has lots of info on it.
You can see battery pack voltage, throttle position, flight mode, RC channel values, RC signal quality and other things. I've extracted the interesting part from the flight video. The clip starts just before I switch from PosHold to Mission mode and ends when I reach the crash site and unplug the battery. I had already SetHome soon after initial liftoff as part of standard flight procedure.
The C1-C8 values are RC_raw_values sent via MAVLink. C1 is throttle, 2-4 is AER, 5 is OSD control, 6 is Man/PosHold/Mission, 7 is RTH/-/SetHome and 8 is manual gimbal tilt.
When you see the view moving up and down is from me manually slewing the tilt.
http://www.youtube.com/watch?v=yOTdZ3w-ooQ

It appears at the AQ just died in flight. It happened at the second waypoint (WP1). I can't tell if the 5s loiter countdown was completed. Hard to tell whether it's a hardware/power glitch or a software failure/lockup.
I don't think it was a low battery voltage situation unless there was an intermittent connection. I soldered up an octupus silicone wire harness, no Power Distribution Board in use.
The MinimOSD is power via the main battery harness, it never rebooted. If it does not receive any MAVLink heartbeats for >2s, it displays the "Waiting for heartbeats" screen.
When I reached the crash site, I was in such a hurry to unplug the battery that I neglected to look at the AQ's LEDs.
I did notice that the RX LED indicated no reboots or loss of signal. Also the LiPo alarm's display showed each of the 4 cells was at 3.8x volts.

After I got home, removed the SD card and inspected all connections (secure) and possible wiring shorts from the crash (none) - I plugged in a battery. All 4 SimonK ESC's did their normal beeps indicating that all 12 motor phases are intact, and the AQ booted up normally with flashing green LED. It even got GPS lock (indoors) after a bit.
Another indication that AQ did not reboot due to power glitch is because the crash log was the last file on the SD card. If it had rebooted, it would have started another log file.

Here's the flight log. Note that it ends abruptly.
Showing Vin. UKF_Altitude, Motor_Throttle, RC_throttle and RC_Flaps (Man/PosHold/Mission switch)

Zooming into last part of Vin (battery voltage).

[Kisssys]

Hi Felix,

Do the LOG_UKF_Q1 Q2 Q3 Q4 go to zero before the other logging stops?

[GoFaster]

Hi Steve -

Here is the quaternions plot.

Regards,
- Felix

[Kisssys]

Hi Felix,

Looks like that was working OK, you might send the LOG to Bill if you can't narrow down a reason for the failure.

[Teletubbie]

Was this the first time you flew the R29 version?

//Frank

[rwijnhov]

Maybe the minimosd got got and somehow shortcircuit the AQ.

[GoFaster]

[Max]

Sorry to hear about that Felix... My condolences. Have not seen the logs cut off like that even in a couple hard crashes, but once when I was testing some code on the bench and caused a stack overflow. I did notice in the video that the heading indicator ribbon was acting funny, but that's probably irrelevant. I hope the cause of this can be determined!

-Max