Fail Safe

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Arducoper NG or ACM?
What steps will reproduce the problem?
1. Flying in AUTO- mode, switched transmitter off (TRH_FS_ACTION = 1)
2. Ardupilot switched in "Stabilize"
3. after 20 seconds: "Disarmed"

the copter will normally switch to RTL ?

Version 2.1.17 MAV 1.0 , Copter: 2.81

Use arducopter version 2.8.1 Quad. Copter is at the ground without propellers. 
If I turn the transmitter off, the mode changes to "stabilize". After 20 sec on 
"disarmed". Motors are switched off. The mode "RTL" goes not on active. Have 
tried this out in the flight. The Copter increases slowly under strong wings 
up. What do I make wrong? TRH_FS_ACTION = 1. 
If I read the last contribution should switch the Copter to disarmed after 20 
seconds. Tested it like me without propellers have. It then falls down. Is this 
so good ? (the fail safe was in an earlier version ever OK)
Remark: The text is translated with a translation program. Can one understand 
my question? 

Original issue reported on code.google.com by reinhard...@googlemail.com on 8 Nov 2012 at 9:45

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EDIT:
have in of the planner mode switch is set to Flight Mode 2 as "RTL".
then the output 5 through Poti / mixer to the value that corresponds to the 
mode / RTL, asked. When switching off the transmitter output is 5 then the 
value which corresponds to RTL.
>> This is functional, but certainly not as planned by the APM developers. In 
my opinion it is a deficiency in the APM. Failsafe reacts not only to the 
channel 3, but also on the channel 5 at the moment of turning off the 
transmitter.

Original comment by reinhard...@googlemail.com on 9 Nov 2012 at 8:37

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Hi Reinhard,

I see the same and it is a problem. Even if throttle PWM is below "Throttle 
Failsafe" it's still possible to switch mode.
When I switch my DX8 off the throttle PWM goes below the "Throttle Failsafe" 
trigger level, but because of the receivers failsafe the mode will in my case 
also switch to stabilize.
The result will be that lost radio connection in any mode except from stabilize 
will let the quad fall out of the sky.
I think mode should be ignored if "Throttle Failsafe" is enabled, but until 
this is done it's important that the receivers failsafe is programmed so that 
RTL mode is selected.

Thanks Reinhard

/Benny

Original comment by Benny.Si...@gmail.com on 22 Nov 2012 at 11:08

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Thanks for the report.  Beyond setting THR_FS_ACTION you also need to set 
THR_FAILSAFE to 1 to enable failsafe.  Without this being set the APM's 
failsafe code will never be executed.
I need to warn you though that in 2.8.1 the failsafe can be slightly dangerous. 
 If after landing you turn off your receiver before you disarm your motors, the 
copter will switch into RTL, it's motors will turn on and it will likely 
take-off and then land.  This is obviously not good and it will be fixed in 2.9 
which should be out in a few weeks.

Original comment by rmackay...@gmail.com on 26 Nov 2012 at 11:27

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THR_FAILSAFE is set to 1 and yep I know the "don't turn of the receiver before 
disarm". I learnt that first time I used the APM ;-)

The problem is that the AR8000 receiver have failsafe for all channels (read 
the mode will also change if I loose the connection). For some reason the APM 
still react on mode switch even if the throttle is below THR_FS_VALUE and I 
think thats an error (if we have programmed the APM to RTL when throttle is 
below THR_FS_VALUE it should stay in RTL no matter what we set the mode to).

/Benny

Original comment by Benny.Si...@gmail.com on 27 Nov 2012 at 6:07

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I agree with Reinhard and Benny:
If throttle failsafe is detected (low pwm in throttle), any "mode switch" 
should be ignored and failsafe routine should be executed until throttle exits 
failsafe value or UAV RTL.
IMHO
Regards,
Vitor

Original comment by vitor.ro...@gmail.com on 12 Dec 2012 at 10:26

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This should be fixed in 2.9.  So it ignores the flight mode while you're in 
failsafe.  With the new failsafe in 2.9 you shouldn't set your flight mode 
switch to change to RTL if you lose radio contact.  Better to leave the flight 
mode switch in it's last known position.

Original comment by rmackay...@gmail.com on 1 Jan 2013 at 2:24

• Changed state: Accepted

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Verified that modeswitch is ignored in 2.9 during failsafe

Original comment by Benny.Si...@gmail.com on 19 Jan 2013 at 5:28

• Changed state: Verified