From news Fri Apr 21 12:24:09 2000 Path: ditka!news.mv.net!newsfeed.mathworks.com!cyclone.swbell.net!newsfeed.berkeley.edu!cnn.nas.nasa.gov!nadia.dfrc.nasa.gov!not-for-mail From: pkearn@eircom.net (Paul Kearney) Newsgroups: sci.aeronautics,sci.aeronautics.airliners Subject: Re: Inertial Navigation ??? Date: 21 Apr 2000 10:40:51 -0700 Organization: Ireland On-Line Customer Approved: shafer@sci.aeronautics Message-ID: NNTP-Posting-Host: orville.dfrc.nasa.gov X-Trace: news.iol.ie 954601291 193.203.145.15 (Sat, 01 Apr 2000 16:01:31 BST) X-Newsreader: Gnus v5.4.37/XEmacs 19.16 Chris Dahler wrote: ::Hmmm. Actually, the way navigational systems work in Boeing airplanes ::is not by updating the IRS's. As far as I know, once the IRS's are ::aligned on the ground, their position information cannot be updated ::until the aircraft is stationary again. ::Navigation is actually taking place via the Flight Management Computer ::(FMC). The FMC accepts navigational inputs from several sources (GPS, ::DME/DME, VOR/DME, IRS). The FMC chooses which position to accept Ah,,, cant be right all the time. Yes... the FMC is updating the position-info it gets from the IRS... by cross-testing with info from the DME Youre right I'm wrong. From news Fri Apr 21 12:24:09 2000 Path: ditka!news.mv.net!newsfeed.mathworks.com!cyclone.swbell.net!newsfeed.berkeley.edu!cnn.nas.nasa.gov!nadia.dfrc.nasa.gov!not-for-mail From: inet@intellisys.net (brian whatcott) Newsgroups: sci.aeronautics,sci.aeronautics.airliners Subject: Re: Inertial Navigation ??? Date: 21 Apr 2000 10:42:43 -0700 Organization: Teleport Approved: shafer@sci.aeronautics Message-ID: NNTP-Posting-Host: orville.dfrc.nasa.gov X-Newsreader: Gnus v5.4.37/XEmacs 19.16 In article , pkearn@eircom.net says... >..... >Now with GPS - the NAV systems can be updated even when out in the >Atlantic/Pacific where DME may not be available. Which i suppose is >''re-zeroing'' itself. >The B737 Flight Managment Computer uses DME/DME cross-bearings to >confirm its location when it knows that it has 2 DME's to work with. >But... your machine wont have this luxury... >i take it that youre talking 3-D for your own project and therefore >counting stepper-motor pulses on a known diameter wheel to indicate >position change from known-origin would be useless ?? Well, well. This dead reckoning suggestion of Paul's took me back a few years to a visit I made to the Dublin Bus Company. They adopted a very forward looking scheme in the 70's to monitor public transport buses in their system in real time - with a radio link at a control center with traffic displays. Before GPS and the like were a viable choice, they were using bus wheel counters to transmit progressive position reports with lamp post mounted interrogators to keep the drift in bounds. I seem to recall they had a little teething trouble with using an array of minicomputers to process various parts of the task - before deciding that the tasks could well be amallgamated. Fascinating - wonder what became of it? Brian Whatcott Altus OK From news Fri Apr 28 15:31:18 2000 Path: ditka!daver!news.he.net!feed2.onemain.com!feed1.onemain.com!news-out.cwix.com!newsfeed.cwix.com!news.msfc.nasa.gov!cnn.nas.nasa.gov!nadia.dfrc.nasa.gov!not-for-mail From: westin*nospam@graphics.cornell.edu (Stephen H. Westin) Newsgroups: sci.aeronautics,sci.aeronautics.airliners Subject: Re: Inertial Navigation ??? Date: 26 Apr 2000 11:30:47 -0700 Organization: Cornell University Program of Computer Graphics Approved: shafer@sci.aeronautics Message-ID: NNTP-Posting-Host: orville.dfrc.nasa.gov X-Newsreader: Gnus v5.4.37/XEmacs 19.16 inet@intellisys.net (brian whatcott) writes: > Well, well. This dead reckoning suggestion of Paul's took me back a > few years to a visit I made to the Dublin Bus Company. > > They adopted a very forward looking scheme in the 70's to monitor > public transport buses in their system in real time - with a radio > link at a control center with traffic displays. > > Before GPS and the like were a viable choice, they were using bus > wheel counters to transmit progressive position reports with lamp post > mounted interrogators to keep the drift in bounds. I believe Etak was founded on the basis of similar technology: compass and wheel rotation for dead-reckoning automotive navigation. At one point, GM bought a chunk of the company, I think. Apparently they digitized lots of map data, which forms the core of the business today. They are apparently owned by Sony. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. From news Fri Apr 28 15:31:18 2000 Path: ditka!daver!news.he.net!newsfeed.enteract.com!newsfeed.mathworks.com!news.voicenet.com!news2.best.com!cnn.nas.nasa.gov!nadia.dfrc.nasa.gov!not-for-mail From: Doug Holik Newsgroups: sci.aeronautics,sci.aeronautics.airliners Subject: Re: Inertial Navigation ??? Date: 26 Apr 2000 11:46:26 -0700 Organization: Prodigy Internet http://www.prodigy.com Approved: shafer@sci.aeronautics Message-ID: NNTP-Posting-Host: orville.dfrc.nasa.gov X-Trace: newssvr03-int.news.prodigy.com 956669983 4758050 209.156.183.20 (25 Apr 2000 13:39:43 GMT) X-Newsreader: Gnus v5.4.37/XEmacs 19.16 brian whatcott wrote: > In article , pkearn@eircom.net says... > >..... > >Now with GPS - the NAV systems can be updated even when out in the > >Atlantic/Pacific where DME may not be available. Which i suppose is > >''re-zeroing'' itself. > > >The B737 Flight Managment Computer uses DME/DME cross-bearings to > >confirm its location when it knows that it has 2 DME's to work with. GPS alone can not be used to update an INS fix because there is no cross check available, that is the same reason why they are having such a hard time geting GPS certified for low visibility approaches, because of the nature of the system, error checking is impossible without some other navigational aid. You are correct about IRS's updating their position. When an IRS can lock on to 2 vor's it will triangulate its position and update itself. From news Mon May 15 12:25:55 2000 Path: ditka!news.mv.net!newsfeed.mathworks.com!news-hog.berkeley.edu!newsfeed.berkeley.edu!cnn.nas.nasa.gov!nadia.dfrc.nasa.gov!not-for-mail From: "Chuck" Newsgroups: sci.aeronautics,sci.aeronautics.airliners Subject: Re: Inertial Navigation ??? Date: 15 May 2000 11:14:14 -0700 Organization: NASA Dryden Approved: shafer@sci.aeronautics Message-ID: NNTP-Posting-Host: orville.dfrc.nasa.gov X-Newsreader: Gnus v5.4.37/XEmacs 19.16 >> You are correct about IRS's >> updating their position. When an IRS can lock on to 2 vor's it will >> triangulate its position and update itself. > >I have never seen the system you describe, but only UHF DME used to update >the IRS. What aircraft have IRS systems that compute themselves or receive updated position data? The ones I am familar with the IRS position is never updated once the system is put in NAV. INS is another story. Those systems I am familar with do get updated by the FMC. Chuck From news Wed May 17 17:20:45 2000 Path: ditka!news.mv.net!news.shore.net!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newspeer1.nac.net!news.he.net!cnn.nas.nasa.gov!nadia.dfrc.nasa.gov!not-for-mail From: Ron Parsons Newsgroups: sci.aeronautics,sci.aeronautics.airliners Subject: Re: Inertial Navigation ??? Date: 17 May 2000 15:58:24 -0700 Organization: NASA Dryden Approved: shafer@sci.aeronautics Message-ID: References: NNTP-Posting-Host: orville.dfrc.nasa.gov X-Trace: /KtlGUkdb1ydq4X+/QmXRgNoxFHspzJcVRMzQV6uH+b+qlmcSZKSu7mX96Cye54sjqZxAZGbE8Df!Ylz7sgQTuFttkv5QM78gPMh1XT235cfbLwANUc3Clg9RNc+65xHYYHdAni8WegSMUGE6gPaxvWCA X-Newsreader: Gnus v5.4.37/XEmacs 19.16 In article , "Chuck" wrote: >What aircraft have IRS systems that compute themselves or receive >updated position data? The ones I am familar with the IRS position is >never updated once the system is put in NAV. B-757 and 767 both update with DME/DME, VOR/DME or ILS/DME, and later ones use GPS. -- Ron