[X] My Assistant

[Geert]

Sort of like letting your teenager son drive your car for the first time. ;-)

Somehow I think I'd rather have my teenage daughter drive my car on Mars then on the roads here in Thailand

But my compliments with this great drive and fast pace! I was starting to lose a bit of hope after those RF wheel delays, but this is very good. Once she is past Porcupine the terrain should start to improve quickly and you can release the brake and just let her roll downslope the rest of the way

[SFJCody]

Uh oh.

https://qt.exploratorium.edu/mars/opportuni...W6P1211L0M1.JPG

Time to put it in reverse and floor it!

Edit:

... what happened here?

https://qt.exploratorium.edu/mars/opportuni...W6P1311R0M1.JPG

[djellison]

You can almost hear it..

"Beeep...beeep...'Rover Reversing'...Beeep....beeep."

Attached thumbnail(s)

 

[Geert]

I am still wondering about the steering of those wheels, picture in last message is a good example of this. I'm aware that (with the exception of the stuck RF actuator) she is steering with all wheels, but how is decided which wheel makes which turn?

In above case the forward wheels seem to have made a nice shallow turn, with the center wheels following, however the left aft wheel seems to have made an almost 90 degree very sharp turn. Originally I thought she was slipping sideways but from the current angle it looks more like this was a deliberate turn, so why was the left aft wheel making a much sharper turn then all other wheels? Is this deliberately to compensate for the stuck actuator on the RF wheel, or did she get stuck first and then the left aft wheel slipped sideways as the right wheels kept pushing forward?

I can imagine that if the left forward got stuck with the right side continue pushing forward, the rover starts turning to left, this should be sensed by the IMU as a course deviation, so it starts compensating for this. Which wheels would it turn, or would it add more power to the left wheels? There is no sign that any attempt was made to turn the left forward wheel after it got stuck, and the left aft seems to have 'followed' the turn and not so much countered it.

Is there a system in place that notes that if you get a course deviation without a prior commanded wheel-steering this is a sign of trouble?

In a 'nominal' car, if you make a sharp left turn, the right wheels make significant more rpm then the left wheels, and the whole construction nicely compensates for this I guess MER does the same but in this case with the right side stuck that was counter active (same in a car, with one wheel stuck and the other side more or less up in the air, it's no use applying full throttle..). Is there is system in place to sense that one wheel is getting stuck, or is this only the slip-check every 20 meters?

[djellison]

I'm aware that (with the exception of the stuck RF actuator) she is steering with all wheels,

No - The FL, RL and RR wheels steer. The middle wheels do not.

We've already heard that slip-checks only occur every 20m or so, so it's not hard to imagine the vehicle getting 'stuck', but driving for another 15m, and crabbing sideways as it continued to push against the front wheels which were no longer making progress.