300km

Short and Long Failsafe Action Occurs Regardless of Setting

Posted by moglos on March 24, 2013 at 2:36am

Hi group

If I set THR_FAILSAFE to 1 and switch off my transmitter, then the APM goes to CIRCLE mode after 1.5 s and to RTL mode after 20s. It does that if short and long FS are enabled. But it also does that if they are both disabled.

Perhaps more worrying is that on some tests it switched to MANUAL instead of CIRCLE. With THR_FAILSAFE=1 and GCS, Short and Long FS all =0 I did 10 tests starting each time from AUTO mode. 7 times it switched to CIRCLE but 3 times it switched to MANUAL. (The HUD displayed the word FAILSAFE in red all caps each time whether it switched to CIRCLE or MANUAL. So it recognized that a Tx/throttle failsafe had occurred and still switched to MANUAL mode on some occasions).

With the same settings I did 5 tests starting from MANUAL mode, and 3 from STABILIZE mode and they all went to CIRCLE mode.

With settings THR_FAILSAFE, short and long FS all =1 and GCS=0 I did 4 tests starting in STABILIZE mode and they all went to CIRCLE. And I did 25 tests starting in AUTO, most of the time it went to CIRCLE as it should but 6 times it went to MANUAL mode (including 1 where it went to MANUAL for an instant then to CIRCLE mode). The word FAILSAFE appeared on the HUD each time. 

I'm pretty sure I've understood the APM manual properly. And I'm pretty sure I need to be able to turn off the THR_FAILSAFE so that I can fly out of Tx range on an AUTO mission right?

I can think of one workaround, and that is to have the Rx failsafe set with a mode value corresponding to AUTO (and/or the throttle value to 900, it probably won't matter.) I don't know if this is dodgy, there is probably a reason that APM has it's own failsafe system rather than relying on this method?

Any ideas?

I'm using APM2.5 and I've had this problem with firmware version 2.69 (and 2.7 HIL simulation firmware).

2013-03-24 17-00-32.tlog

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Replies

  • James masterman March 24, 2013 at 4:35am
    First thing to do is check what your Rx is doing when it fail safes. In particular what happens to the mode channel. Look at ch8in on the mission planner when you switch off the Tx. That may be the source of the strange mode switching behaviour.

    If you want to fly out of Tx range on an auto mission and complete the mission without RTLing then the Rx needs to set Auto on the mode channel on fail safe and the THR_FAILSAFE should be off.
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