From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: * X-Spam-Status: No, score=1.2 required=5.0 tests=BAYES_00,FROM_WORDY, INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fac41,e01bd86884246855 X-Google-Attributes: gidfac41,public X-Google-Thread: 103376,fb1663c3ca80b502 X-Google-Attributes: gid103376,public From: "Ken Garlington" Subject: Re: Interresting thread in comp.lang.eiffel Date: 2000/07/14 Message-ID: <4CEb5.16334$7%3.1008702@news.flash.net>#1/1 X-Deja-AN: 646314307 References: <8ipvnj$inc$1@wanadoo.fr> <8j67p8$afd$1@nnrp1.deja.com> <395886DA.CCE008D2@deepthought.com.au> <3958B07B.18A5BB8C@acm.com> <395A0ECA.940560D1@acm.com> <8jd4bb$na7$1@toralf.uib.no> <8jfabb$1d8$1@nnrp1.deja.com> <8jhq0m$30u5$1@toralf.uib.no> <8jt4j7$19hpk$1@ID-9852.news.cis.dfn.de> <3963CDDE.3E8FB644@earthlink.net> <8k5alv$1oogm$1@ID-9852.news.cis.dfn.de> <8kl25k$2q7k0$1@ID-9852.news.cis.dfn.de> <396F13B6.9216FFE4@acm.com> X-Priority: 3 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6600 X-Complaints-To: abuse@flash.net X-Trace: news.flash.net 963581440 216.215.75.113 (Fri, 14 Jul 2000 08:30:40 CDT) Organization: FlashNet Communications, http://www.flash.net X-MSMail-Priority: Normal NNTP-Posting-Date: Fri, 14 Jul 2000 08:30:40 CDT Newsgroups: comp.lang.ada,comp.lang.eiffel Date: 2000-07-14T00:00:00+00:00 List-Id: "Marin D. Condic" wrote in message news:396F13B6.9216FFE4@acm.com... > Ken Garlington wrote: > > is: Suppose you're driving your car in rush-hour traffic, and someone > > suddenly throws black paint on the windshield, and all the windows. Putting > > aside such obvious fixes as breaking or rolling down a window (in other > > words, using an alternate sensor), what do you do? You could jam on the > > brakes (which a rocket or airplane can't do, unfortunately), or you could > > take your last known information and try to guess how to turn the wheel so > > that you get to the shoulder safely (what I usually call standby gains). I > > don't know how successful that is with a rocket; it works OK with an > > airplane, but it's a much more benign environment. > > A common FDA strategy for such a situation would be to go fail-fixed. > You hold everything exactly where it is at with the hope that the > sensors will come back on-line before disaster happens. If you're in the > middle of a burn, you keep burning. In the middle of a coast - keep > coasting. If you're in the middle of a transient - you're screwed! Right - it's what a flight control engineer would call "standby" (or fixed) gains. > With rockets, the strategy is quite often to do your very best to > continue to press on with the mission as best you can, because > everything else is a total loss. There's no such thing as having the > pilot limp the vehicle on back to the base and let the maintenance guys > take a look at it. Exactly. However, I assume your chances of mission success are far from assured. A much better strategy is to fix the problem at the source -- in this case, the IRS.