Implementation of Failsafe function

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Now in the ArduCopter Alpha 1.0 if you lose a signal from TX, motors will stop.
not having any "Failsafe" on the TX/RX will crash the quad.
Is there any possibility to keep it in the air, at least for now (not talking 
about GPS position hold), just something to prevent it from falling :)

Original issue reported on code.google.com by levine...@gmail.com on 10 Oct 2010 at 10:12

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I dont think allowing the copter to remain in the air will ever be allowable or 
preferable if transmitter signal is lost. In my opinion, a broken quad frame is 
better than losing the entire thing. Ramping down the throttle slowly might be 
an improvement over a hard cutoff though.

Original comment by Miles.R....@gmail.com on 11 Oct 2010 at 1:35

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Yes we have been thinking this same issue. After GPS hold is working properly 
we need to look this thing again. Letting it float in air without any 
possibilities to control is not acceptable as stated. 

Possible solution is to hold 10 seconds or so on current location and then 
slowly start descending if signal is not back. Also if during descending accels 
see "hard" bump we could shutdown engines just in case.  

Original comment by jphelirc on 11 Oct 2010 at 12:31

• Changed state: Started
• Added labels: Type-Enhancement
• Removed labels: Type-Defect

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Slow descending after 10 sec. is a good solution. May be adding same thing for 
low battery ( if the level is VERY low ), stop it on current location and then 
slowly start descending.
And shutting down engines, after ANY "hard" bump, could be a nice feature :) 
it will save many props in some bad landings :)   

Original comment by levine...@gmail.com on 11 Oct 2010 at 1:56

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descending at a fixed position for low battery is not a good idea ;)

i think return to home would be much better (or make it switchable)

Original comment by sebbl.gr...@hotmail.de on 11 Oct 2010 at 2:00

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I think that returning home could be risky, say there is a tree or worse a 
person in the way... perhapse it should retrace the flight path backwords until 
it finds reciever signal again... this possibly may be the safest way to regain 
control... or maybe set it to gain altitute to get above any obstructions and 
then return to home, but it has to be selectible... there isn't a good fix all 
for every situation

Original comment by dirkthe...@gmail.com on 2 Jan 2011 at 10:52

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Original comment by jasonshort on 8 May 2011 at 7:25

• Changed state: WontFix

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most of us, if not all in the future, will have telemetry or FPV video with OSD 
showing last lat and long position of copter to retrieve it. I reckon a simple 
failsafe of setting throttle at a customisable percentage (for differing 
weights, set ups etc) to allow an automatic soft landing would be awesome.... 
unless it's flying above water! Any plans to develop this further guys? I'm 
keen to see what the common thought is.

Original comment by stickite...@yahoo.com on 5 Jul 2011 at 10:38