Reply by Rune Allnor July 10, 20072007-07-10
On 10 Jul, 15:34, dspg...@netscape.net wrote:

> You could also try our friends at FMV - The new Visby class has ROV's, > so they may have looked at some of this. Perhaps contact Elias. > > Cheers, > David
Hi David, I talked with Elias on the phone a couple of weeks ago. He clicked onto this immediately; I'll probably use some of my vacation to go visit him some time in September. We are coming up on the Real Deal now; 6 times 120 km of surveying to be performed inside, say six weeks or so. The "make or break" kind of thing. Oh well. I'm a mere 18 hours short on a 4-week trip, the second completed inside of ten weeks. A shore-side vacation will be very, very nice now... Rune
Reply by July 10, 20072007-07-10
On Jul 8, 12:08 am, Rune Allnor <all...@tele.ntnu.no> wrote:
> On 7 Jul, 17:41, John_W_Her...@yahoo.com (John Herman) wrote: > > > So you are designing a system for a specific range and have transponders > > installed and surveyed in so the only remaining question is how accurate does > > the position estimate have to be? It makes a huge difference. > > I amd not designing a system, I am evaluating one. > > The expected accuracy of our surveys is very high. Whenever we > are out of spec we have to do a system evaluation to find out why, > and if there were anything we could or should have done differently. > I know a lot about the acoustcis side of both surveying, comms and > oceanography, and have developed a more or less trustworthy instinct > for how those sorts of factors affect the accuracy of the surveys. > Now > I need to learn as much as possible about the navigation side of > things. > I can't do the required evaluation unless I know in as much detail as > possible how the C&N systems work, what their "intrinsinc" > characeristics are, and how they are affected by oceanography, > platform stability, only occasional access to GPS references, > sparse / dense reference transponder grids, etc. > > Rune > > > In article <1183017060.455598.143...@m36g2000hse.googlegroups.com>, Rune > > > Allnor <all...@tele.ntnu.no> wrote: > > >On 27 Jun, 15:47, SamSvL <sam...@nlr.nl> wrote: > > >> Rune Allnor <all...@tele.ntnu.no> wrote in news:1182749246.005438.80620 > > >> @w5g2000hsg.googlegroups.com: > > > >> > Hi all. > > > >> > I'm working with submerged vehicles; ROVs and AUVs. I need to learn > > >> > about control and navigation systems for these things, and would like > > >> > pointers to literature. > > > >> > Anything, from "N&C for dummies" to the latest IEEE Journal articles, > > >> > is of interest. > > > >> > I appreciate any help. > > > >> > Rune > > > >> Hi Rune, > > > >> No satellite navigation (GPS) when submerged! > > > >I know. > > > >However, the general setup is very similar aeronatics: > > > >When using ROVs, a surface vessel (with GPS nav) serves > > >as a "moving refernce" much the same way GPS satellites > > >do in aeronautics. > > > >A number of refernce transponders have been installed > > >in the area we operate, serving as fixed beacons for > > >both ROV and AUV. > > > >The vehicles have onboard INS systems. > > > >The trick is to make sense / use of all these nav > > >data flowing around the system. > > > >Rune- Skjul sitert tekst - > > > - Vis sitert tekst -
Hi Rune, SAR historically had similar problems blending GPS and INS systems and compensating for Lever Arms. Some of that problem has gone away with the newer technologies. You could check from either DRDC-Ottawa (Mostly Radar) or DRDC-Atlantic (Mostly Sonar). Here's the basic link: http://pubs.drdc-rddc.gc.ca/pubdocs/pcow1_e.html You could also try our friends at FMV - The new Visby class has ROV's, so they may have looked at some of this. Perhaps contact Elias. Cheers, David
Reply by Rune Allnor July 8, 20072007-07-08
On 7 Jul, 17:41, John_W_Her...@yahoo.com (John Herman) wrote:
> So you are designing a system for a specific range and have transponders > installed and surveyed in so the only remaining question is how accurate does > the position estimate have to be? It makes a huge difference.
I amd not designing a system, I am evaluating one. The expected accuracy of our surveys is very high. Whenever we are out of spec we have to do a system evaluation to find out why, and if there were anything we could or should have done differently. I know a lot about the acoustcis side of both surveying, comms and oceanography, and have developed a more or less trustworthy instinct for how those sorts of factors affect the accuracy of the surveys. Now I need to learn as much as possible about the navigation side of things. I can't do the required evaluation unless I know in as much detail as possible how the C&N systems work, what their "intrinsinc" characeristics are, and how they are affected by oceanography, platform stability, only occasional access to GPS references, sparse / dense reference transponder grids, etc. Rune
> In article <1183017060.455598.143...@m36g2000hse.googlegroups.com>, Rune > > > > Allnor <all...@tele.ntnu.no> wrote: > >On 27 Jun, 15:47, SamSvL <sam...@nlr.nl> wrote: > >> Rune Allnor <all...@tele.ntnu.no> wrote in news:1182749246.005438.80620 > >> @w5g2000hsg.googlegroups.com: > > >> > Hi all. > > >> > I'm working with submerged vehicles; ROVs and AUVs. I need to learn > >> > about control and navigation systems for these things, and would like > >> > pointers to literature. > > >> > Anything, from "N&C for dummies" to the latest IEEE Journal articles, > >> > is of interest. > > >> > I appreciate any help. > > >> > Rune > > >> Hi Rune, > > >> No satellite navigation (GPS) when submerged! > > >I know. > > >However, the general setup is very similar aeronatics: > > >When using ROVs, a surface vessel (with GPS nav) serves > >as a "moving refernce" much the same way GPS satellites > >do in aeronautics. > > >A number of refernce transponders have been installed > >in the area we operate, serving as fixed beacons for > >both ROV and AUV. > > >The vehicles have onboard INS systems. > > >The trick is to make sense / use of all these nav > >data flowing around the system. > > >Rune- Skjul sitert tekst - > > - Vis sitert tekst -
Reply by John Herman July 7, 20072007-07-07
So you are designing a system for a specific range and have transponders 
installed and surveyed in so the only remaining question is how accurate does 
the position estimate have to be?  It makes a huge difference.

In article <1183017060.455598.143300@m36g2000hse.googlegroups.com>, Rune 
Allnor <allnor@tele.ntnu.no> wrote:
>On 27 Jun, 15:47, SamSvL <sam...@nlr.nl> wrote: >> Rune Allnor <all...@tele.ntnu.no> wrote in news:1182749246.005438.80620 >> @w5g2000hsg.googlegroups.com: >> >> > Hi all. >> >> > I'm working with submerged vehicles; ROVs and AUVs. I need to learn >> > about control and navigation systems for these things, and would like >> > pointers to literature. >> >> > Anything, from "N&C for dummies" to the latest IEEE Journal articles, >> > is of interest. >> >> > I appreciate any help. >> >> > Rune >> >> Hi Rune, >> >> No satellite navigation (GPS) when submerged! > >I know. > >However, the general setup is very similar aeronatics: > >When using ROVs, a surface vessel (with GPS nav) serves >as a "moving refernce" much the same way GPS satellites >do in aeronautics. > >A number of refernce transponders have been installed >in the area we operate, serving as fixed beacons for >both ROV and AUV. > >The vehicles have onboard INS systems. > >The trick is to make sense / use of all these nav >data flowing around the system. > >Rune >
Reply by Ned Forrester June 28, 20072007-06-28
Rune Allnor wrote:
> On 27 Jun, 15:47, SamSvL <sam...@nlr.nl> wrote: >> Rune Allnor <all...@tele.ntnu.no> wrote in news:1182749246.005438.80620 >> @w5g2000hsg.googlegroups.com: >> >>> Hi all. >>> I'm working with submerged vehicles; ROVs and AUVs. I need to learn >>> about control and navigation systems for these things, and would like >>> pointers to literature. >>> Anything, from "N&C for dummies" to the latest IEEE Journal articles, >>> is of interest. >>> I appreciate any help. >>> Rune >> Hi Rune, >> >> No satellite navigation (GPS) when submerged! > > I know. > > However, the general setup is very similar aeronatics: > > When using ROVs, a surface vessel (with GPS nav) serves > as a "moving refernce" much the same way GPS satellites > do in aeronautics. > > A number of refernce transponders have been installed > in the area we operate, serving as fixed beacons for > both ROV and AUV. > > The vehicles have onboard INS systems. > > The trick is to make sense / use of all these nav > data flowing around the system. >
I guess that depends on which part of the problem you really want to solve yourself. The Kearfott T-16 and T-24 units that we put on our AUVs take in the ADCP and GPS data directly, along with our acoustic fixes, and does the sensor fusion itself. The output is its best estimate of position, based on its own filter. After we manage to convince it of the correct starting point, it does very well as long as ADCP bottom lock is maintained; I think about 0.2% of range, but don't quote me on that. -- NOTE: to reply, remove all punctuation from email name field Ned Forrester n_f_orrester@whoi.edu 508-289-2226 Applied Ocean Physics and Engineering Dept. Oceanographic Systems Lab http://adcp.whoi.edu/ Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
Reply by Rune Allnor June 28, 20072007-06-28
On 27 Jun, 17:38, Tim Wescott <t...@seemywebsite.com> wrote:
> On Wed, 27 Jun 2007 15:47:03 +0200, SamSvL wrote: > > Rune Allnor <all...@tele.ntnu.no> wrote in news:1182749246.005438.80620 > > @w5g2000hsg.googlegroups.com: > > >> Hi all. > > >> I'm working with submerged vehicles; ROVs and AUVs. I need to learn > >> about control and navigation systems for these things, and would like > >> pointers to literature. > > >> Anything, from "N&C for dummies" to the latest IEEE Journal articles, > >> is of interest. > > >> I appreciate any help. > > >> Rune > > > Hi Rune, > > > No satellite navigation (GPS) when submerged! > > > Sam > > No, but if you can surface & stick an antenna up you can get a fix, and > use it to calibrate your inertial sensors. > > You'd be able to get LORAN down a few meters at least -- I'm not sure how > far it'd penetrate the water, but if they can use 30kHz to communicate > with subs 100kHz should get down some.
It used to be a standard excercise in the course in underwater acoustics to compute the attenuation of EM waves in salt water. If I remember correctly, EM waves are attenuated by some 50 to 60 dB per wavelength. Given a frequency and signal strength at the surface, one can compute how far down a given system can recieve a useful signal. This is a reason why subs communicate in the ELF range. Rune
Reply by Rune Allnor June 28, 20072007-06-28
On 27 Jun, 15:47, SamSvL <sam...@nlr.nl> wrote:
> Rune Allnor <all...@tele.ntnu.no> wrote in news:1182749246.005438.80620 > @w5g2000hsg.googlegroups.com: > > > Hi all. > > > I'm working with submerged vehicles; ROVs and AUVs. I need to learn > > about control and navigation systems for these things, and would like > > pointers to literature. > > > Anything, from "N&C for dummies" to the latest IEEE Journal articles, > > is of interest. > > > I appreciate any help. > > > Rune > > Hi Rune, > > No satellite navigation (GPS) when submerged!
I know. However, the general setup is very similar aeronatics: When using ROVs, a surface vessel (with GPS nav) serves as a "moving refernce" much the same way GPS satellites do in aeronautics. A number of refernce transponders have been installed in the area we operate, serving as fixed beacons for both ROV and AUV. The vehicles have onboard INS systems. The trick is to make sense / use of all these nav data flowing around the system. Rune
Reply by Happy Trails June 27, 20072007-06-27
On Wed, 27 Jun 2007 10:47:48 -0500, Tim Wescott <tim@seemywebsite.com>
wrote:
>Come to think of it, a GPS receiver on a tether may work, also, if you are >working that close to the surface.
Is that technology not used to track the movements of some marine animals, like whales?
Reply by Tim Wescott June 27, 20072007-06-27
On Wed, 27 Jun 2007 10:42:09 -0500, BobF wrote:

> "Tim Wescott" <tim@seemywebsite.com> wrote in message > news:d7SdnQtp4pLsGR_bnZ2dnUVZ_tXinZ2d@web-ster.com... >> On Wed, 27 Jun 2007 15:47:03 +0200, SamSvL wrote: >> >>> Rune Allnor <allnor@tele.ntnu.no> wrote in news:1182749246.005438.80620 >>> @w5g2000hsg.googlegroups.com: >>> >>>> Hi all. >>>> >>>> I'm working with submerged vehicles; ROVs and AUVs. I need to learn >>>> about control and navigation systems for these things, and would like >>>> pointers to literature. >>>> >>>> Anything, from "N&C for dummies" to the latest IEEE Journal articles, >>>> is of interest. >>>> >>>> I appreciate any help. >>>> >>>> Rune >>>> >>> >>> Hi Rune, >>> >>> No satellite navigation (GPS) when submerged! >>> >>> Sam >> >> No, but if you can surface & stick an antenna up you can get a fix, and >> use it to calibrate your inertial sensors. >> >> You'd be able to get LORAN down a few meters at least -- I'm not sure how >> far it'd penetrate the water, but if they can use 30kHz to communicate >> with subs 100kHz should get down some. > > subs use a floating antenna for LORAN
Well, there's nothing like practical knowledge to blow theory all to hell. Come to think of it, a GPS receiver on a tether may work, also, if you are working that close to the surface. It adds some interesting twists to your "Kalman" filter, to be sure, but it may work. -- Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
Reply by BobF June 27, 20072007-06-27
"Tim Wescott" <tim@seemywebsite.com> wrote in message 
news:d7SdnQtp4pLsGR_bnZ2dnUVZ_tXinZ2d@web-ster.com...
> On Wed, 27 Jun 2007 15:47:03 +0200, SamSvL wrote: > >> Rune Allnor <allnor@tele.ntnu.no> wrote in news:1182749246.005438.80620 >> @w5g2000hsg.googlegroups.com: >> >>> Hi all. >>> >>> I'm working with submerged vehicles; ROVs and AUVs. I need to learn >>> about control and navigation systems for these things, and would like >>> pointers to literature. >>> >>> Anything, from "N&C for dummies" to the latest IEEE Journal articles, >>> is of interest. >>> >>> I appreciate any help. >>> >>> Rune >>> >> >> Hi Rune, >> >> No satellite navigation (GPS) when submerged! >> >> Sam > > No, but if you can surface & stick an antenna up you can get a fix, and > use it to calibrate your inertial sensors. > > You'd be able to get LORAN down a few meters at least -- I'm not sure how > far it'd penetrate the water, but if they can use 30kHz to communicate > with subs 100kHz should get down some.
subs use a floating antenna for LORAN