QUOTE (Tesheiner @ Apr 24 2009, 01:19 PM)
That was my fault. (English isn't my mother language)
And now looking to the FHAZ images, the "trench" is really minimal. Perhaps we should rename the thread as "(Almost) stuck near Porcupine" or "Pit stop near Porcupine".
Now, going back to the first posts in the thread. At that point in time, with no available data except for the end of drive pictures, I was convinced the "incident" happened during the blind part of the drive. Later on I realized it was during the autonav part. I always thought the latter had "slip-check" (visodom?) enabled so such kind of excessive slippage would be immediately detected. Is that true?
Eduardo, English is not my primary language either, and I did not mean to criticize. It was really meant as a joke.
Slip checks are called typically every 10-20m, not at every step. Each slip check takes 5-12min, that's why we do not do that more often. We have determined that even if we have an embedding event whiel commanding 20m this should result in a situation that we should be able to resolve in a sol or two. This has been determined to be an acceptable risk. We do slip checks both during the blind (both forwards and backwards) and the autonav portion of the drive (forwards only).
This embedding evend does not surprise me. The lee side of the ripples are covered by a soft, cohesionless fine powder, while the opposite side is more compact and results in better traction. Autonav tried to avoid the ripple since it had a slope that was considered too high. The avoidance resulted into an arc that was sufficient to clear the ripple crest, but not the "fluffy stuff" (techincal term that drivers use to call this type of terrain).
So, IMHO, this is something that from time to time will happen, we have means to mitigat the effects and we know how to deal with the consequences.
Paolo