IPB

Welcome Guest ( Log In | Register )

6 Pages V  « < 3 4 5 6 >  
Reply to this topicStart new topic
First 2009 MSL Landing Site Workshop
edstrick
post Apr 25 2006, 05:22 AM
Post #61


Senior Member
****

Group: Members
Posts: 1869
Joined: 20-February 05
Member No.: 174



Hypothetically, you could have inflatable wheels that would be filled with a quick-setting spongy foam during inflation. That way, maintaining pressure during a long mission life wouldn't be critical.

You might have problems maintaining wheel temperature at a reasonable level during foam curing, or coming up with a foam that would cure at suitably low temperatures.
Go to the top of the page
 
+Quote Post
dvandorn
post Apr 25 2006, 05:33 AM
Post #62


Senior Member
****

Group: Members
Posts: 3254
Joined: 9-February 04
From: Minneapolis, MN, USA
Member No.: 15



QUOTE (MaxSt @ Apr 24 2006, 11:26 PM) *
Pathfinder's site was quite rocky...

So is the Viking 1 site -- a rather larger overall rock population than at Gusev, and the dominant rock size is larger. The Viking 2 site is rockier still -- in fact, I would say that the Viking 2 site is non-navigable by a rover the size of the MER, and the Viking 1 and Pathfinder sites are semi-navigable.

The one thing I noticed right off was that Gusev isn't as rocky as any of the previous three landing sites. Of course, Meridiani is something quite different from anything we have ever seen on Mars before.

I think the Viking 1 and Pathfinder sites are rocky primarily because they are located in outflow channels, where massive floods deposited a whole lot of rocks as they rolled through. I've never heard a good geological discussion as to why the Viking 2 site is so densely rock-strewn, though -- it's a rather high-latitude northern site, so perhaps the "type 2" plains deposits have simply been broken into a fairly well-sorted carpet of large fragments by frost heaving?

-the other Doug


--------------------
“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
Go to the top of the page
 
+Quote Post
MaxSt
post Apr 25 2006, 05:54 AM
Post #63


XYL Code Genius
***

Group: Members
Posts: 138
Joined: 23-November 05
Member No.: 566



QUOTE (Jeff7 @ Apr 23 2006, 04:27 PM) *
Having a computer then figure out the "best" route to get somewhere requires a whole new level of complex programming. Having it find multiple routes yet, and evaluate multiple factors, such as traversability and distance travelled, and then choose, that too is difficult.


Actually, pathfinding is quite common in modern computer games (shooters). Computer-controlled opponents have to navigate in 3D maps, to "get" you as fast as possible.
Go to the top of the page
 
+Quote Post
J.J.
post Apr 25 2006, 05:59 AM
Post #64


Junior Member
**

Group: Members
Posts: 85
Joined: 22-March 06
Member No.: 722



QUOTE (dvandorn @ Apr 25 2006, 12:33 AM) *
So is the Viking 1 site -- a rather larger overall rock population than at Gusev, and the dominant rock size is larger. The Viking 2 site is rockier still -- in fact, I would say that the Viking 2 site is non-navigable by a rover the size of the MER, and the Viking 1 and Pathfinder sites are semi-navigable.


Ditto. Every time I see a picture of the Viking 2 site, I think "Pathfinder and the MERs would have
been S.O.L. here..."

The dunes at the Viking 1 site also might have been a rude surprise for a less-cautious or experienced rover team, if driven into. The ones nearest the lander seem to have been much larger than any Opportunity has seen yet, though scale is difficult to determine.


--------------------
Mayor: Er, Master Betty, what is the Evil Council's plan?

Master Betty: Nyah. Haha. It is EVIL, it is so EVIL. It is a bad, bad plan, which will hurt many... people... who are good. I think it's great that it's so bad.

-Kung Pow: Enter the Fist
Go to the top of the page
 
+Quote Post
Cugel
post Apr 25 2006, 08:15 AM
Post #65


Member
***

Group: Members
Posts: 153
Joined: 11-December 04
Member No.: 120



Just some last remarks on the 4 versus 6 wheels: both MER rovers benefitted from their 6 wheel design for at least one time: when they left the lander. The lander was absolutely the single most biggest obstacle both rovers have ever rolled over. MSL doesn't need to roll of a lander, it IS a lander. I'm afraid the guys at JPL are so fond of their 6 wheels, which has become the hallmark of the rovers (they even patented it), we will never get rid of it.

Another small point: a double rocker-bogie system will give you (slightly) better reduced tilt values when crossing obstacles compared to a single system, it's something that can quite easily be computed. However, I think that rocks that really require all 6 wheels are actually so large the EDL team will never allow you to land in their vicinity. They are at least visible (HIRISE) from orbit, so one can simply navigate around them.
Go to the top of the page
 
+Quote Post
edstrick
post Apr 25 2006, 10:38 AM
Post #66


Senior Member
****

Group: Members
Posts: 1869
Joined: 20-February 05
Member No.: 174



dvandorn: ..."I've never heard a good geological discussion as to why the Viking 2 site is so densely rock-strewn, ..."

Viking 2's site has been thought to be on a lobe of ejecta flow from the large impact crater "Mie" to the east. The lobate flow patterns seem to extend west to the landing site, but fine details of the surface in Viking or Global Surveyor / Odyssey images don't seem to show much difference between ejecta lobes and areas to the west. HiRISE and the spectral mapper may clear this up. I have no idea what THEMIS thermal data indicate about rock abundance in and outside the ejecta lobe zone.
Go to the top of the page
 
+Quote Post
Guest_Richard Trigaux_*
post Apr 25 2006, 10:49 AM
Post #67





Guests






Most martian rocks are basalt, and, when cooling, basalt fractures itself into blocks, size of them is relatively constant. of course from a flow to another, the average sizes varies, but remains in the tens of centemetres. We cannot expect to find larger blocks like 10m wide granite blocks. The only exception to date seems some tuffs seen by Spirit when coming down of Husband Hill.
Go to the top of the page
 
+Quote Post
odave
post Apr 25 2006, 02:34 PM
Post #68


Member
***

Group: Members
Posts: 510
Joined: 17-March 05
From: Southeast Michigan
Member No.: 209



QUOTE (MaxSt @ Apr 25 2006, 01:54 AM) *
Actually, pathfinding is quite common in modern computer games (shooters).


Very true, and the pathfinding in some games is quite sophisticated, but that problem is much more constrained than the one facing a rover on another planet. A game has 3D models and other factors affecting motion like water or ice, and these are all well defined per the rules laid out in the software. The pathfinding can be optimized for all of those rules. The rover's problems are not so well defined. It needs to construct its own 3D models on-the-fly from its vision sensors (cameras and lasers and the like), and motion factors like slippage are not constant. There's also realtime feedback to be processed from the motors etc. as the move is happening. And the rover's CPU isn't as beefy as today's average gaming machine, so it's harder to chunk through all of that code.

Having said that, I agree that the pathfinding algorithms developed for the gaming industry could certainly be considered in a rover.


--------------------
--O'Dave
Go to the top of the page
 
+Quote Post
RNeuhaus
post Apr 25 2006, 03:21 PM
Post #69


Senior Member
****

Group: Members
Posts: 1636
Joined: 9-May 05
From: Lima, Peru
Member No.: 385



QUOTE (edstrick @ Apr 25 2006, 12:22 AM) *
Hypothetically, you could have inflatable wheels that would be filled with a quick-setting spongy foam during inflation. That way, maintaining pressure during a long mission life wouldn't be critical.

You might have problems maintaining wheel temperature at a reasonable level during foam curing, or coming up with a foam that would cure at suitably low temperatures.

I don't invite a foam to expand the wheel size, I would prefer the elasticity of a metal due to the reactivity of Martian surface and the large swings of temperature that will shorten the foam life (I think it so unless I am wrong if there is a new technology that overcomes these problems).

Rodolfo
Go to the top of the page
 
+Quote Post
Bob Shaw
post Apr 25 2006, 03:29 PM
Post #70


Senior Member
****

Group: Members
Posts: 2488
Joined: 17-April 05
From: Glasgow, Scotland, UK
Member No.: 239



QUOTE (odave @ Apr 25 2006, 03:34 PM) *
...I agree that the pathfinding algorithms developed for the gaming industry could certainly be considered in a rover.


oDave:

That could be a problem, what with MSL's sample laser - not only have we declared war on a defenceless comet, but presumably the G&N software will be written by iD (and the blaster, oops laser, gets built by UAC!)...

...so they'll never find anything alive, all the beasties will have run away!

Bob Shaw


--------------------
Remember: Time Flies like the wind - but Fruit Flies like bananas!
Go to the top of the page
 
+Quote Post
odave
post Apr 25 2006, 03:38 PM
Post #71


Member
***

Group: Members
Posts: 510
Joined: 17-March 05
From: Southeast Michigan
Member No.: 209



I always preferred the BFG9000 myself biggrin.gif

The possibilities are endless!


--------------------
--O'Dave
Go to the top of the page
 
+Quote Post
ljk4-1
post Apr 25 2006, 03:46 PM
Post #72


Senior Member
****

Group: Members
Posts: 2454
Joined: 8-July 05
From: NGC 5907
Member No.: 430



[quote name= quote in reply -removed
[/quote]

FWIW -

The film version of Doom does take place on a future Mars base:

http://en.wikipedia.org/wiki/Doom_%28film%29


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

Go to the top of the page
 
+Quote Post
MaxSt
post Apr 25 2006, 05:11 PM
Post #73


XYL Code Genius
***

Group: Members
Posts: 138
Joined: 23-November 05
Member No.: 566



QUOTE (odave @ Apr 25 2006, 10:34 AM) *
And the rover's CPU isn't as beefy as today's average gaming machine, so it's harder to chunk through all of that code.


That's correct. But if the rover's goal is 100m per day, that's plenty of time to "stop and think" every 2-3m. Using a lot of RAM should help too. MRO has 20 Gb of memory, so I guess it shouldn't be a problem.
Go to the top of the page
 
+Quote Post
RNeuhaus
post Apr 25 2006, 08:16 PM
Post #74


Senior Member
****

Group: Members
Posts: 1636
Joined: 9-May 05
From: Lima, Peru
Member No.: 385



[quote name= quote in reply -removed
[/quote]
However, the facility of detect and hazard avoidance would need an adequate programming software to manage it. Since the MSL CPU is based of RAD 750 which only runs the Operating System VxWorks which, I don't know much about its goodness to hold a software for Artificial Intelligence purposes, is very well suited for real time operations due to its reliability, adaptability, multitasking and versatiblity to work with its peripheral dispositives and also of its diagnosticability (easy debugging).

Rodolfo
Go to the top of the page
 
+Quote Post
MaxSt
post Apr 26 2006, 06:40 AM
Post #75


XYL Code Genius
***

Group: Members
Posts: 138
Joined: 23-November 05
Member No.: 566



Well, even MERs have some hazard avoidance software, and it runs on VxWorks too.

Not much RAM, though...
Go to the top of the page
 
+Quote Post

6 Pages V  « < 3 4 5 6 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 27th November 2014 - 02:40 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.