From: KK6GM <mjsilva@scriptoriumdesigns.com>
Subject: Re: How would Ariane 5 have behaved if overflow checking were notturned off?
Date: Wed, 16 Mar 2011 14:02:47 -0700 (PDT)
Date: 2011-03-16T14:02:47-07:00 [thread overview]
Message-ID: <6ae10c4a-0333-40fb-8243-91a08ec7af0e@fx23g2000vbb.googlegroups.com> (raw)
In-Reply-To: 4d81231d$0$4966$a8266bb1@postbox2.readnews.com
On Mar 16, 1:52 pm, Hyman Rosen <hyro...@mail.com> wrote:
> On 3/16/2011 3:40 PM, KK6GM wrote:
>
> > Here's the alternative, for the Ariane situation. A float value gets
> > converted to a 16-bit integer. The float value is too big to fit
> > (let's say it's 33000). What 16-bit int will that get converted to?
> > -31000? Some random value? How does continuing along with bogus data
> > make the situation better? Will the control loops really work OK with
> > bogus feedback data?
>
> Why are we converting floats to 16-bit integers? It's hard to tell
> from the report, but was this a result of using an Ada fixed type?
> Or the result of similar scaling based on knowing the range?
I have no idea why they were doing that.
>
> > If you have determined via thorough analysis that the variable in
> > question can only _ever_ have a valid range of e.g. -20000 to 20000,
> > and it goes to 33000, what _is_ the right action?
>
> <http://web.archive.org/web/20000815230639/www.esrin.esa.it/htdocs/tid...>
> Recommendation R3 says "Do not allow any sensor, such as the inertial
> reference system, to stop sending best effort data." So if your sensor
> can report data over a certain range, you should probably not use a
> restrictive subtype that represents what you believe the possible
> observed range will be. Otherwise, when Scotty is trying to nudge a
> fraction more warp factor out of the engines, the Enterprise is going
> to shut down and doom the Federation.
You're still not seeing the issue. You may have a 0-200psi
transducer, but if you have _proven_ that the actual pressure can
never be over 70psi, what are you supposed to _do_ with a reading of
150psi? Is it a true reading? If so, your control algorithm will
almost certainly choke on it. Is it a hardware error? Then do what
you would do in the event of a hardware error. Which is what Ariane
did.
next prev parent reply other threads:[~2011-03-16 21:02 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-14 15:49 How would Ariane 5 have behaved if overflow checking were not turned off? Elias Salomão Helou Neto
2011-03-14 16:17 ` KK6GM
2011-03-14 19:25 ` Yannick Duchêne (Hibou57)
2011-03-14 19:28 ` Vinzent Hoefler
2011-03-14 20:28 ` KK6GM
2011-03-15 4:02 ` Yannick Duchêne (Hibou57)
2011-03-15 4:53 ` Shark8
2011-03-14 18:29 ` Vinzent Hoefler
2011-03-16 10:41 ` How would Ariane 5 have behaved if overflow checking were notturned off? robin
2011-03-16 15:16 ` Simon Wright
2011-03-17 11:48 ` robin
2011-03-16 16:58 ` Martin Krischik
2011-03-16 23:39 ` How would Ariane 5 have behaved if overflow checking werenotturned off? robin
2011-03-17 18:48 ` Vinzent Hoefler
2011-03-18 12:06 ` Alex R. Mosteo
2011-03-18 21:15 ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-20 10:42 ` Vinzent Hoefler
2011-03-20 17:06 ` How would Ariane 5 have behaved if overflow checking werenotturned off? Martin Krischik
2011-03-20 17:11 ` Martin Krischik
2011-03-20 18:10 ` Dmitry A. Kazakov
2011-03-21 13:24 ` Leif Roar Moldskred
2011-03-20 13:07 ` How would Ariane 5 have behaved if overflow checking were notturned off? Florian Weimer
2011-03-20 17:00 ` Martin Krischik
2011-03-20 20:17 ` Florian Weimer
2011-03-20 20:37 ` Vinzent Hoefler
2011-03-20 20:14 ` Vinzent Hoefler
2011-03-16 18:20 ` Vinzent Hoefler
2011-03-16 18:29 ` Hyman Rosen
2011-03-16 18:55 ` Vinzent Hoefler
2011-03-16 19:40 ` KK6GM
2011-03-16 20:52 ` Hyman Rosen
2011-03-16 21:02 ` KK6GM [this message]
2011-03-16 21:09 ` Shark8
2011-03-16 21:13 ` Hyman Rosen
2011-03-16 21:35 ` Shark8
2011-03-16 22:27 ` Vinzent Hoefler
2011-03-16 21:04 ` Shark8
2011-03-16 21:10 ` Hyman Rosen
2011-03-16 21:27 ` KK6GM
2011-03-16 21:31 ` Shark8
2011-03-16 22:32 ` Vinzent Hoefler
2011-03-18 21:14 ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-16 23:46 ` How would Ariane 5 have behaved if overflow checking werenotturned off? robin
2011-03-17 0:26 ` Simon Wright
2011-03-17 11:01 ` Georg Bauhaus
2011-03-17 11:04 ` robin
2011-03-17 13:36 ` Niklas Holsti
2011-03-18 21:13 ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-19 10:12 ` Niklas Holsti
2011-03-17 22:51 ` How would Ariane 5 have behaved if overflow checking werenotturned off? Vinzent Hoefler
2011-03-18 21:13 ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-20 10:42 ` Vinzent Hoefler
2011-03-15 6:28 ` Stephen Leake
2011-03-15 17:32 ` Keith Thompson
2011-03-15 17:40 ` KK6GM
2011-03-15 19:44 ` Robert A Duff
2011-03-15 19:12 ` Florian Weimer
2011-03-15 19:45 ` KK6GM
2011-03-15 19:57 ` Vinzent Hoefler
2011-03-20 13:00 ` Florian Weimer
2011-03-20 20:13 ` Vinzent Hoefler
2011-03-15 19:42 ` John B. Matthews
2011-03-17 11:44 ` robin
2011-03-17 18:37 ` Vinzent Hoefler
2011-03-17 23:04 ` How would Ariane 5 have behaved if overflow checking were notturned off? robin
2011-03-18 15:55 ` Vinzent Hoefler
2011-03-17 21:37 ` How would Ariane 5 have behaved if overflow checking were not turned off? Vinzent Hoefler
2011-03-16 10:33 ` robin
2011-03-16 15:08 ` Simon Wright
2011-03-17 12:39 ` robin
2011-03-17 13:41 ` Georg Bauhaus
2011-03-17 23:34 ` How would Ariane 5 have behaved if overflow checking were notturned off? robin
2011-03-18 12:57 ` Hyman Rosen
2011-03-18 16:49 ` KK6GM
2011-03-18 17:18 ` Dmitry A. Kazakov
2011-03-19 17:55 ` Keith Thompson
2011-03-20 18:39 ` Robert A Duff
2011-03-17 18:43 ` How would Ariane 5 have behaved if overflow checking were not turned off? Vinzent Hoefler
2011-03-17 20:58 ` Simon Wright
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