RE: [Paparazzi-devel] crashed

[gisela.noci]

Just a comment on the RF choke on the RX cable.... This is NOT a good idea,
since the RCS received signal will suffer the same attenuation within its
bandpass as would the 'interfering' signals. The signal to noise ratio would
simply remain in the same, but with reduced receiver sensitivity. Any
interfering signals within the receiver bandpass CANNOT be filtered
(choked)out. These signals can only be eliminated at source, such as by
proper system ground design, and probable shielding of the offending noise
generator.

Joe

-----Original Message-----
From: address@hidden
[mailto:address@hidden
] On Behalf Of John Burt
Sent: Sunday, August 09, 2009 7:40 PM
To: address@hidden
Subject: Re: [Paparazzi-devel] crashed

Martin,

I crashed an Easystar just like that during early flight testing. The AP 
(Tiny 2.11) went nonresponsive and dived into the ground, despite my 
having immediately flipped the switch to manual. It would seem that the 
AP processor just locked up - truly a worst case scenario. The cause of 
the behavior was an undervoltage spike condition due to sourcing the 
four servos and RC RX off the 5V supply. In case you haven't already, 
you should always power your hardware off a separate BEC (which begs the 
question of why the AP has a 5V source anyway).

AP generated noise on the ground wire was other cause of bad AP behavior 
that I experienced. This causes glitching and reduced RC range. It has 
been covered ad nauseam in other posts, but I'll repeat it: it's 
especially helpful to put an RF choke on the RC RX cable. Try to wrap 
the wire 4+ times around the choke.

Martin P wrote:
> Hello everyone! 
>
> Last weekend I had a good AUTO1 flight with my Minimag. It reacted to
pitch and roll commands, and I was able to control the throttle. I had an
attitude command in my flightplan which was never left (as I know now).  
>
> Yesterday I tried again, without the attitude statement and without a
holding point block. 
>
> In AUTO1, it killed the throttle. Switched to manual and landed to change
battery because it was not fully charged. 
>
> Took off again. Switched to AUTO1 and it immediately stabilized the plane.
Strangely, this time it did not react to the roll command. I flew around
using the rudder. When I used the elevator stick, the autopilot controlled
the throttle. Good, so far. 
>
> Suddenly the plane dived down vertically from an altitude of roughly 40m.
No reaction, just kept going vertical and slowly spinning around the
longitudinal axis until it crashed. 
>
> There was not as much damage done as I expected. These foamies are
awesome. All RC components including Tiny and Xbee are OK. Except for the
Lipo which is badly bent out of shape and will be replaced for safety
reasons. 
>
> Unfortunately I can't see much from the log as I had lost the link
probably minutes before. I was in stage "HOME" because I had left the
fly-too-far circle before and came back manually.  
>
> The switch was on manual so I probably tried to rescue. The Tiny was
unplugged which can have happened at the crash or before. One aileron was
ripped off and the horizontal IR was missing (I found it in the grass). 
>
> So far, my report. The Minimag is already repaired and I'll keep trying. 
>
> Greetz, Martin 
>
>
>
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>   


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