Full Version: Erebus/victoria Entry & Exploration
Several news articles suggested they would try and straighten the wheels Monday... with nothing happening yet, anyone get the feeling is more serious than JPL are letting on?
From New Scientist
"On Friday, an external review board looked at options for getting the rover off the dune. They were expected to present their final report on Monday. “They generally agreed with the approach that we’re taking,” Erickson says.
If everything continues to goes well, ground controllers will begin developing the first escape commands to send to Opportunity on Monday. The first step will be to straighten rover’s wheels, but getting the rover clear of the dune may take days, possibly even weeks."
http://www.newscientist.com/article.ns?id=dn7356
Lets see: meeting on Monday, at least a day to write and double check the commands, another day to send them, then another day for the commands to be executed and the images to be downlinked.
Maybe we will see some results on Thursday.
"On Friday, an external review board looked at options for getting the rover off the dune. They were expected to present their final report on Monday. “They generally agreed with the approach that we’re taking,” Erickson says.
If everything continues to goes well, ground controllers will begin developing the first escape commands to send to Opportunity on Monday. The first step will be to straighten rover’s wheels, but getting the rover clear of the dune may take days, possibly even weeks."
http://www.newscientist.com/article.ns?id=dn7356
Lets see: meeting on Monday, at least a day to write and double check the commands, another day to send them, then another day for the commands to be executed and the images to be downlinked.
Maybe we will see some results on Thursday.
QUOTE (Sunspot @ May 10 2005, 05:32 PM)
Several news articles suggested they would try and straighten the wheels Monday... with nothing happening yet, anyone get the feeling is more serious than JPL are letting on?
I think they are taking their time, making sure everything is in place, including plenty of available flash for images which they will take a lot of. Possibly straightening the wheels on Wednesday, a few tests, and a drive attempt on Thursday. I doubt Oppy will be out on Thursday though, baby steps first.
QUOTE (kholmar @ May 9 2005, 12:22 AM)
QUOTE (tty @ Apr 29 2005, 12:26 PM)
Incidentally the best way of getting unstuck in both snow and sand if no external help is available is "rocking yourself loose", i e try to drive in the direction you want, then unclutch and let the vehicle slip back. It will go a little way past the equilibrum point and then you cut in traction and go with the rebound. If you repeat the cycle a number of times and time your bursts of power carefully the oscillation will gradually build until you tear yourself loose. It actually works better in sand than snow since you never lose traction completely in sand.
It's hard on the clutch though and I wouldn't like to write software that can do it since it requires quite good timing to work.
tty
It's hard on the clutch though and I wouldn't like to write software that can do it since it requires quite good timing to work.
tty
im not sure you could write software to do this. this technique doesnt just require timing, it requires kinesthetic feedback in real time. (meaning you alter the timing based on what you feel happening)
guess it would be worth a try when the list of options get short.
this is a great forum. this is the ONLY public forum i have ever seen where folks dont argue just to be annoying. very refreshing.
kholmar
The wheels can't free turn. They only turn under power.
QUOTE (dvandorn @ May 10 2005, 09:36 AM)
QUOTE (odave @ May 10 2005, 10:36 AM)
QUOTE (kholmar @ May 9 2005, 03:22 AM)
im not sure you could write software to do this. this technique doesnt just require timing, it requires kinesthetic feedback in real time. (meaning you alter the timing based on what you feel happening)
guess it would be worth a try when the list of options get short.
this is a great forum. this is the ONLY public forum i have ever seen where folks dont argue just to be annoying. very refreshing.
kholmar
You could write software to do it, given the correct sensor suite, which the MERs don't really have. For example, we have robots inserting valves into engine blocks with very tight fit tolerances. The robot's tooling has a multi-axis force/torque sensor that feeds back into the motion software, which adjusts the insertion vector in real time. Special case stuff, certainly, but it can be done. However, I'd assume that a rock-yourself-out system would be hard to mass-justify for launch.
You're right that it would be difficult to get the MERs to do this. I think they'd have to look at the inertial guidance sensors and make adjustments in a very tight loop. It'd be a challenge...
I appreciate the civilized tone of these forums too - before I heard about this place, all I had were the JPL pages and the very few crumbs of value to be found on Usenet.
I like it here a lot
Yeah, I like it here a lot, too. A very welcome change from the signal-to-noise ratio of the Usenet newsgroups. I hardly ever visit the newsgroups anymore, and I think my blood pressure is the better for it...
Back to topic, the other real issue with either MER rocking itself out of a sand trap is that they don't have the horsepower to get the kind of momentum going that would be needed for such a maneuver. Even at a charitable estimate, the MERs creep along the surface more than they motor along. At the speed we can get the wheels moving, you can't push forward and then let gravity pull you back farther than the distance you pushed forward, which is how the rocking maneuver has to work.
However, unlike the dilemma all of us face when we get a car stuck in the snow, Oppy has an advantage -- not only does it have four-wheel-drive, it has *six*-wheel-drive. And four of the six wheels are independently steerable. That really does open up more possibilities than most of us are familiar with from terrestrial driving experience.
-the other Doug
An additional advantage is that MER has six motors. That's positraction. In a car if one of the wheels slips, it drains all the power from the other wheels. With MER if one wheel slips, the other five retain all their power.
QUOTE (Sunspot @ May 10 2005, 05:32 PM)
Several news articles suggested they would try and straighten the wheels Monday... with nothing happening yet, anyone get the feeling is more serious than JPL are letting on?
No, they are straight shooting.
QUOTE (lyford @ May 11 2005, 02:18 AM)
It's a peach! I hope you haven't a copyright for it...
daaa-dada-daaa, dada-daaaa-da 
On Sol453, Panoramic camera was used to take a sequence of "identical" images of Erebus region using L6 filter (blue/green channel). I tried to obtain from them a Super-Resolution image, using method explained by Phil Stooke in another thread:
http://www.unmannedspaceflight.com/index.p...findpost&p=9896
Probably, this was the exact reason to take these images; in fact, when magnified, they seems to show very small pointing differences (at pixel or sub/pixel level - I do not know how them obtained this!). Using a sub-sample of 6 images, I magnified them by 2.5 and then merged. However, due to the lossy compression of original images, first I had to remove major jpeg artifact, introducing a small blur. In fact, final result do not show strong resolution improvement, but quality is improved thanks to the clear signal-to-noise increase, as showed in the comparison below (top portion is a magnified detail of one original image):
In the following "stretched" version, horizon is flat and vertical size is amplified by 4 times; features/rocks on the horizon do not surpass 3 pixel in the original images, and this should correspond to an height of about 40cm at the distance of Erebus rim (500m):
http://www.unmannedspaceflight.com/index.p...findpost&p=9896
Probably, this was the exact reason to take these images; in fact, when magnified, they seems to show very small pointing differences (at pixel or sub/pixel level - I do not know how them obtained this!). Using a sub-sample of 6 images, I magnified them by 2.5 and then merged. However, due to the lossy compression of original images, first I had to remove major jpeg artifact, introducing a small blur. In fact, final result do not show strong resolution improvement, but quality is improved thanks to the clear signal-to-noise increase, as showed in the comparison below (top portion is a magnified detail of one original image):
In the following "stretched" version, horizon is flat and vertical size is amplified by 4 times; features/rocks on the horizon do not surpass 3 pixel in the original images, and this should correspond to an height of about 40cm at the distance of Erebus rim (500m):
Nice work, dilo! The sub-pixel offsets are produced by moving the camera slightly away from the target and back to it again. The pointing is good but not perfect so it never comes back exactly to where it was, not to within, say, a tenth of a pixel which might be truly unnoticeable.
I had an earlier image which showed the view ahead to Erebus with that same type of vertical exaggeration - though there still is not much to see until we get over a small local rise in the ground. But I think the view will soon get a lot more interesting.
Incidentally, Steve Squyres was quoted a few weeks ago as saying that Opportunity is already in the etched terrain. But I think it makes more sense to think of this area with the larger drifts as a transitional terrain. The real etched material is going to look different again, more like one Vostok crater after another on a fairly dramatic scale. Or so I think. I'll eat a Mars Bar if I'm wrong. (and also if I'm right).
Phil
I had an earlier image which showed the view ahead to Erebus with that same type of vertical exaggeration - though there still is not much to see until we get over a small local rise in the ground. But I think the view will soon get a lot more interesting.
Incidentally, Steve Squyres was quoted a few weeks ago as saying that Opportunity is already in the etched terrain. But I think it makes more sense to think of this area with the larger drifts as a transitional terrain. The real etched material is going to look different again, more like one Vostok crater after another on a fairly dramatic scale. Or so I think. I'll eat a Mars Bar if I'm wrong. (and also if I'm right).
Phil
QUOTE (Phil Stooke @ May 12 2005, 10:46 PM)
Incidentally, Steve Squyres was quoted a few weeks ago as saying that Opportunity is already in the etched terrain. But I think it makes more sense to think of this area with the larger drifts as a transitional terrain. The real etched material is going to look different again, more like one Vostok crater after another on a fairly dramatic scale. Or so I think. I'll eat a Mars Bar if I'm wrong. (and also if I'm right).
Phil
Phil
I think you're exactly right, Phil. Though the exposed, eroded evaporite in the actual etched terrain is, I think, not crater-rim excavations but ridges in the ejecta blanket created by the ancient crater cluster of which Erebus and Terra Nova are a part...
-the other Doug
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