Hey Paul, I really appreciate your detailed responses. Now when I sort threw the raw images I know what they are for!!! This makes it fun as I can now stop and try to determine how far off the rover is. Looks like it was fairly close on 1942 and 1944 if I’m reading them right, a little high?

Just a little off, not bad when you consider that as well as understanding the estimated location, they have to take into consideration, the yaw of the rover, as well as the roll and the pitch. When they have drifted by whatever limits they set themselves, they reset the rover’s ‘frame’ these are known as sites (you can see them on the drive reports that are shared here.

Depending on the terrain, they reset the site number when required, this happens on average about every 13 to 15 drives, but in challenging terrain it can happen more frequently. They just reset the site number to 91 at the end of the last drive (sol 1947). Which is not bad considering that they have only driven 546 times since landing, so their internal navigation, which is based on the motion sensors are pretty accurate.

At the end of the last drive (Sol 1947) they adjusted the drive distance by just 16cm having driven 1212 meters since the last reset, so I think that shows that the motion sensors are very accurate :)

I’d post more drive images, but Lemmy times out when I am trying to upload. I’ll try again later.