• 1.37K Posts
  • 775 Comments
Joined 3 years ago
Cake day: June 24th, 2023
  • paulhammond5155@lemmy.worldtoNASA's Perseverance Mars Rover@lemmy.world•What are these?English
    3·
    18 days ago

    Thank you all for the great feedback… And those two, bouncing off each other the way they did, a great example of scientific deduction

    I only read the other replies after I posted my answer (some good stuff there :) It’s great when everyone chips in, shows we have an active community :) Mine was a stock answer that I posted to Reddit several years ago (not long after Perseverance landed IIRC).

    It’s a huge pity the team on M2020 have not followed in the footsteps of MSL for posting regular blogs. I’d love to hear that the team had used the Fiducial Markers at some point in the mission. We may even see them in use soon on MSL if the drill checks show any sort of damage to the drill, as the original method of changing a drill bit probably wont work as well as designed / planned. We can see the bit boxes were designed to be used with the drill stabilizers for alignment. Those stabilizers will hardly come into play now (since the feed motor brake failed / locked), so they are going to have to align the arm very carefully to capture a new DBA. The fiducials could really help…

  • paulhammond5155@lemmy.worldtoNASA's Perseverance Mars Rover@lemmy.world•What are these?English
    6·
    22 days ago

    These are Fiducial Markers (or fiducials for short). Fiducials basically allow the rover’s computers to measure itself.

    The markings are a staple of engineering that can serve two parallel purposes, to calibrate cameras and to calibrate various mechanisms on the rover.

    They’re a common feature in high-tech photography and robotics here on Earth, but the use of fiducials on extra-terrestrial robots is relatively new.

    The technique started informally on the Mars Exploration Rover (MER) mission, which landed Spirit and Opportunity on the Red Planet’s surface in 2004.

    JPL engineers noticed that, over time, the accuracy of the MER robotic arm was degrading, and they weren’t really sure why. So some of the JPL engineers came up with an algorithm that would just recognize a circular feature on the end of the arm. Then every day, it could track where that actually was versus where the robotic rovers thought it was. The idea blossomed into more than just an engineering hack with Curiosity. JPL engineers came up with the design for the fiducials for Curiosity, as they needed something that would be easy for either a computer program or a person to accurately pick the center of. Having that intersection in the middle makes it easier for a person, as they can zoom in on the image and click exactly on that intersection, and the design also makes it easy for a computer, because it can compute the center of a circle. From there, basic trigonometry lets engineers piece together the positions and orientations of the various parts of the rover.

    To measure all of the mechanisms on the rover, fiducials are installed all over the turret, on the end of the rover’s arm, as well as on the tops of the steering actuators and on the top deck of the rover.

    They were so useful they are were installed on the Mars Insight lander and the M2020 rover.

    M2020 also uses the smaller ‘April Tags’. They’re fiducial markers for machine vision systems and are “robust to lighting and viewing angle”.

  • paulhammond5155@lemmy.worldOPtoNASA's Curiosity Mars Rover@lemmy.world•Attempt # 1 to free the stuck drill fails (Sol 4879)English
    8·
    24 days ago

    Oh, no! So it basically got its finger stuck in a hole? Can they detach the drill bit if they can’t get it loose?

    Yup it’s stuck.

    There is a documented method where they can detach the Drill Bit Assembly (DBA) See image below of the complete DBA.

    That would leave the DBA and the drill bit in the rock.

    There are two brand new DBAs mounted to the front of the rover that in theory can be used to replace the DBA stuck in the rock.

    However there is an actuator in the drill that is designed to release the DBA and re-engage with a new DBA mounted on the front of the rover in its Bit Box.

    1. At this time we don’t know if that release actuator is still in working order, as since landing in 2012 they have not needed to change a drill bit.

    2. There is a Drill Feed Mechanism on the drill. This has been locked up for many years after its internal locking brake failed. That failure forced the team to establish a new way of drilling sample holes and retaining powdered rock without using the stabilizers on either side of the drill or CHIMRA. This however left the drill in its fully extended position.

    3. I have no idea if unlatching and re-latching a new DBA is still possible with the drill feed mechanism fully extended.

    I’m sure the team have plenty more ideas to attempt to release the bit. They are normally very conservative in these situations and will try the less risky things first, gradually digging deeper into their bag of tricks. Fingers crossed they can release this bit and test it to ensure it is working properly before drilling its next sample hole.

    Here’s a rover selfie that shows the 2 spare DBAs mounted on the front of the rover

    Hopefully this situation will be addressed / explained in a future mission update / blog

    Watch this space…