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Beyond Lewis and Clark Gap, Sol 4482- (September 2, 2016-)
algorimancer
post Jun 13 2017, 04:54 PM
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QUOTE (atomoid @ Jun 12 2017, 07:26 PM) *
...almost as if a lake shoreline feeds the channel ...


Nice, the channel is obvious. I'm wondering whether what appears as a lake shoreline is actually the upper portion of the channel wrapping around and heading off to the right. The overhead view hints at something to that effect.
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jvandriel
post Jun 13 2017, 09:33 PM
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The Pancam L2 view on Sol 4737-4744.

Jan van Driel

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marsophile
post Jun 13 2017, 11:41 PM
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Attached Image


We are now close enough to the Winnemucca edge to get good stereo separation in the above parallel eye image. Note the overhanging rock at the edge and the tapered form beneath it. Stalactite?
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fredk
post Jun 14 2017, 01:48 PM
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I don't see any real sign of an overhang, just a shadow - compare with this view:
http://merpublic.s3.amazonaws.com/oss/merb...KPP2596L2M_.JPG
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Sean
post Jun 14 2017, 02:24 PM
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I made my first MERB RGB images from Sol 4759...

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Ipparchus
post Jun 15 2017, 10:57 AM
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QUOTE (fredk @ Jun 11 2017, 05:47 PM) *
The plan was to try to straighten the LF wheel on 4754 but I see no sign of movement in the hazcams...

I think Oppy could still move if she drives backwards and steers the left and right rear wheels to the right(the excact opposite direction than the front wheels).What do you think? pancam.gif wheel.gif wheel.gif wheel.gif


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RoverDriver
post Jun 15 2017, 02:39 PM
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Scott Maxwell and I did some quick testing with the SSTB in 2008 or 2009 with the LF wheel toed-in and it was still driveable going straight. Changing direction reliably, that would be more challenging. *I* haven't give up hope on that actuator tho.

Paolo


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marsophile
post Jun 15 2017, 04:22 PM
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If all else fails, would it be possible to exploit a terrain effect to straighten the wheel?
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Explorer1
post Jun 16 2017, 12:31 AM
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The team would have to find the perfect spot (a rock?), and maneuver against it perfectly... a tricky problem!
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RoverDriver
post Jun 16 2017, 02:08 AM
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QUOTE (marsophile @ Jun 15 2017, 08:22 AM) *
If all else fails, would it be possible to exploit a terrain effect to straighten the wheel?


We have donated all the suitable rocks to our sister Curiosity. We would have needed a formation that would act sort of like a vice, insert the wheel there and rotate the vehicle. We unintentionally ended in a vice situation before with Curiosity and we tried (and succeeded) to avoid getting the wheel stuck there.

Even if we could find a suitable setup nearby, manage the impossible and set the wheel there, would you really send the command to turn the vehicle around? There's a 1500:1 gear ratio on the gearbox. I would be afraid to bend the strut, or at least damaging the drive actuator!

Not trying to be blunt, but we in ops need to be really careful not to make more damage and completely disable the vehicle. This should not discourage anyone to provide suggestions. I will read them all.

Paolo


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marsophile
post Jun 16 2017, 03:33 PM
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This is just a shot in the dark, but is there any way to leverage the mechanism used to deploy the wheels on landing?
Perhaps raise only the left-front wheel slightly so it offers less resistance to movement, if this is possible?

Please pardon my naivete. I don't have a good knowledge of the rover mechanisms.
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Hungry4info
post Jun 16 2017, 03:40 PM
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If that were possible, they would probably have done it for Spirit.


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djellison
post Jun 16 2017, 04:53 PM
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QUOTE (marsophile @ Jun 16 2017, 08:33 AM) *
This is just a shot in the dark, but is there any way to leverage the mechanism used to deploy the wheels on landing?


No - it latched into place, it can't go back.
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hendric
post Jun 16 2017, 07:03 PM
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Could you orient the rover body so that the offending actuator gets maximum heating and cooling throughout a Martian day? Maybe that will loosen up whatever is stuck. Perhaps even try intentionally moving it in and out of the Sun during the day.

Try driving the wheel over a pointy rock, applying pressure on different parts of the wheel so that the actuator get wiggled a little. Not just forwards and backwards, but inboard/outboard edge of the tire too. Rock doesn't have to be tall, just high enough out of the bedrock that different pressure is applied to the wheel/actuator joint. Do it back and forth a few times to try loosening it.

Similar to Marsophiles idea, but instead of locking the wheel in place against two rocks, drag and push it over a pointy rock so that the wheel catches & skitters across the rock. It shouldn't be stuck, per se, but it should be pulling and pushing across the rock so that the treads hold and then release, vibrating the assembly.

How does the distance driven by the test bed compare to the distance on Spirit and Oppy? Has the test bed run into any similar issues with its actuators?


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Phil Stooke
post Jun 16 2017, 07:13 PM
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But how can you know whether those actions will make the situation worse rather than better? They can't be tested very accurately on Earth given limited knowledge of the exact geometry, positioning accuracy of the wheel on the rock, hardness or friability of the rock etc. I would be more inclined to run through the full range of engineering solutions - heaters, varying current applied to the actuator, driving forwards and backwards. Things that can be tested in the Mars Yard.

Phil


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