NASA Mars Perseverance Rover: Digging Into Drill Data
upstart writes:
NASA Mars Perseverance Rover: Digging Into Drill Data:
You probably think that the drill being employed on Perseverance Rover is bound to be special, but do you know just how clever it is? The problem that the drill has to balance is getting maximum life from the drill bit itself while achieving the job of collecting samples of rock and sediment.
One of the first things we look at is how difficult it was for the drill to make progress through the rock. The rover has a rotary percussive drill, which means the drill bit pushes against the rock while spinning and hammering. When we are coring or abrading, an algorithm controls the amount of force and percussion. We call this algorithm "prodapt," short for proprioceptive adaptive, because the drill adjusts its settings by sensing and assessing its own performance in real-time. The goal is to try and maintain a certain rate of progress into the rock that isn't too slow or too fast. The rate we aim for keeps our drill bits healthy and creates high-quality cores and abrasions for the scientists.
The prodapt algorithm can range from level 0 to level 20. Levels 0 through 2 have no percussion at all, which we call rotary only drilling. (We never do rotary only abrading, so these low levels are only used while coring.) Level 3 has light percussion, and the percussion and force increase all the way up to the most force and the most percussion at level 20.
If the drill senses that it is not making fast enough progress through a rock, it will increase the prodapt level. If it senses that it is making progress too quickly, it will decrease the level. One note: although hard rocks often require higher levels, the interaction between the drill and the rock is complex, so prodapt level doesn't always match up with rock strength. A rock might require high drill levels but break easily if a different type of tool was used.
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