Southward from San Antonio to the Next Waypoint |
Southward from San Antonio to the Next Waypoint |
Apr 24 2010, 03:42 PM
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#136
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
A stall would result in a dramatic change in the current signature on the motor would it not? Something that would almost certainly flag up a drive fault.
Have we ever heard of a motor stalling, but the drive continuing regardless? I know that Spirit was using a cautious automatic system to recover from stalls within a sol, but for a drive motor to stall on Opportunity and yet the rover carry on driving would be highly unusual.# I think we're just seing something of an NPE (Near Purgatory Event) Note, in FredK's image - the 100% perfect track's just outside the churned material. The Front and Rear wheels have similar track width, but the middle wheels are slightly inboard of that. That clear track mark infers the FL wheel turning normally at that time. |
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Guest_Sunspot_* |
Apr 24 2010, 03:48 PM
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#137
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Guests |
Maybe its some soil properties experiment??
But then the latest update does say the right middle wheel has elevated current. |
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Apr 24 2010, 05:05 PM
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#138
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
QUOTE Note, in FredK's image - the 100% perfect track's just outside the churned material. Agreed. And a Navcam from Sol 2220 suggests that the right Front and Rear wheels were turning and tracking normally and the right Middle wheel started to drag. The right Front wheel then began to churn and veer off to one side, as shown on the attached annotated NavCam. Nothing on Scott Maxwell's blog yet. --Bill -------------------- |
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Apr 24 2010, 05:06 PM
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#139
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Senior Member Group: Members Posts: 4246 Joined: 17-January 05 Member No.: 152 |
It's pretty clear what's happened when you look at this navcam frame:
http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol2220 As Doug said, the middle wheel tracks are normally inwards of the front and rear, as at the top of that navcam frame. Then presumably about a third of the way from the bottom of that frame, the RM wheel started to dig in (stall?), forming a trench (edit - dashed blue in Bill's pic). Then the RF wheel slipped into that trench, so it's track moved inwards a bit to line up with the RM track (dashed yellow in Bill's pic). Then the RR (not FL as Doug said) track was visible outwards of the trench (red in Bill's pic). The more I think about this the more I lean on the side of a regular embedding event. As I pointed out above, the RM trench isn't perfectly smooth. But also, if the RM stalled outright, I might've expected Oppy to yaw around counterclockwise as her right side was slowed by the dead wheel. But there's no sign of that. Also, I might've expected furrows of soil piled up along either side of the RM track, like with Spirit's RF. Again, no clear sign of that. We'll find out soon enough... Edit - thanks for the nice illustration, Bill! |
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Apr 24 2010, 05:48 PM
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#140
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Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
-------------------- If Occam had heard my theory, things would be very different now.
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Apr 24 2010, 06:57 PM
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#141
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
New images down:
http://qt.exploratorium.edu/mars/opportuni...00P1214R0M1.JPG There's clearly some degree of sinking on the right side as well, so it does look more like a soil composition change rather than a wheel problem on the left side--good news if true! (Naughty Nprev. Inline image turned into link - ADMIN) EDIT: Oops, sorry! (Now I finally understand exactly how that works...) -------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Apr 24 2010, 07:12 PM
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#142
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Senior Member Group: Moderator Posts: 4279 Joined: 19-April 05 From: .br at .es Member No.: 253 |
Have we ever heard of a motor stalling, but the drive continuing regardless? IIRC, when Spirit's RF wheel failed on the way to McCool hill (sol 781) the drive didn't finished immediately but continued enough time to make a long trench. Now waiting for some official (or "leaked" ) news. |
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Apr 24 2010, 07:24 PM
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#143
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Senior Member Group: Members Posts: 1887 Joined: 20-November 04 From: Iowa Member No.: 110 |
Spirit's right front wheel failed on sol 779, the trench was created following tests to determine the nature of the fault.
QUOTE Sol 779: Spirit drove about 29 meters (95 feet) and acquired post-drive images. A fault in the right front wheel drive actuator terminated the drive. Sol 781: Spirit completed diagnostic tests and drove 3.9 meters (13 feet) using only five wheels. Diagnostic tests showed that the right-front-wheel problem involved the drive actuator, not the steering. http://marsrovers.jpl.nasa.gov/mission/sta...006.html#sol778 I see what appear to be two cleat marks in the image fredk posted, the one nearest the wheel partially buried by soil dropped by the right rear wheel. |
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Apr 25 2010, 02:38 PM
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#144
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The Poet Dude Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60 |
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Apr 25 2010, 03:29 PM
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#145
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
Soil mechanics experiment to combine with the previous study of driving cross-ripple that they did. That's my guess.
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Apr 25 2010, 03:51 PM
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#146
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Solar System Cartographer Group: Members Posts: 10153 Joined: 5-April 05 From: Canada Member No.: 227 |
You do the Hokey Cokey...
-------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Apr 25 2010, 03:55 PM
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#147
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The Poet Dude Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60 |
Yep, Phil, that's what it's all about...
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Apr 25 2010, 04:04 PM
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#148
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Senior Member Group: Members Posts: 4246 Joined: 17-January 05 Member No.: 152 |
Discuss... What are you guys referring to? If you mean the little wiggle in the tracks about 1/3 down from the horizon in that navcam image, that's just the small turn in place at the end of the sol 2218 drive: http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol2218 |
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Apr 25 2010, 07:38 PM
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#149
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Member Group: Members Posts: 399 Joined: 28-August 07 From: San Francisco Member No.: 3511 |
Was this a new trouble free drive then? How far Algernon?
-------------------- 'She drove until the wheels fell off...'
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Apr 25 2010, 07:56 PM
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#150
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Senior Member Group: Moderator Posts: 4279 Joined: 19-April 05 From: .br at .es Member No.: 253 |
No, just a picture looking backwards taken from the current site.
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