Lost throttle response leading to crash

Log Analysis -- deprecated Copter Logs -- deprecated
1

apm 2.6 v 3.1
Bring quad down from approx 25m in stabalize mode, I began to lose throttle response and quad began to lose altitude faster then desired. Throttled up to 100% and quad still continued to lose altitude leading to a crash.

Read 5 most common problems affecting APM:Copter on wikki and performed following troubleshooting.

  1. Graphed Rollin Vs Roll and Pitchin vs Pitch
    Pitchin vs Pitch - begins to diverge right before I lose throttle response
    Rollin vs Roll - Roll flat lines briefly before I lose throttle response
    Neither of these should affect throttle so not sure if I have found a different problem or if it relates to my throttle issue.
    Makes me think there could be a mechanical problem or voltage drop in the Apm leading to brown out. I am using a 3Dr power module.

  2. Check possible brown out I graphed Vcc (first problem, I can’t figure out what the y axis units are for this)
    Fluctuates between 5100-5000, assuming y axis is volts *1000, only thing that makes sense in my head.
    If my assumption about volts *1000 is correct then the power to the board is ok.

  3. Filtered for error messages but there were none.

Attached the rollin v roll and pitchin vs pitch images. Throttle problem began around 4200 on x-axis.
Dataflash log attached

Run out of ideas, need help!!

2

Finally Solved my problem this afternoon. Hooked up the data downlink to the quad and went out for a few flights today. After a few minutes the same problem occurred. Immediately looked at the computer and noticed a failsafe had kicked in. I let go of the controls and the quad calmly landed itself; failsafe worked perfectly but why did it kick in? After a quick inspection I realized I had the battery failsafe set too high. Lowered it the appropriate settings and everything worked perfect. The quad was never really crashing in the first place I was just trying to fly it while it was trying to land itself and never put two and two together.

Don’t know how to put a SOLVED tag on this subject but don’t want to waste peoples time trying to figure this problem out. If someone can let me know or do it themselves that would be awesome.

Thanks