3 ms·
I'd imagine a combination of inertial and GPS, combined with a Kalman filter. Inertial handles short term estimation; GPS correcting drift in the inertial syst
by pfdietz 2y ago
I'd imagine a combination of inertial and GPS, combined with a Kalman filter. Inertial handles short term estimation; GPS correcting drift in the inertial system. But they could roll in other information sources at the end.
- imglorp 2y agoFor the centimeterish precision needed to hover into the chopsticks, they also have the opportunity to use signals from the tower area for final alignment. I'm thinking riding a beam like aviation ILS. Just speculating but it would be easy to implement. Optical/camera alignment is probably out of the question due to fire and smoke.
- pfdietz 2y agoThe arms themselves could have sensors on them. Inductive loops sensing the presence of the stainless steel structure? Also, I doubt centimeter scale precision would be needed; the arms have some compliance in them, I'm sure, as well as the ability to control how far in they swing.
- imglorp 2y agoYeah really - it's half centimeter nav according to BG. Ctrl-f for centimeter: https://arstechnica.com/space/2024/10/spacex-catches-returning-rocket-in-mid-air-turning-a-fanciful-idea-into-reality https://arstechnica.com/space/2024/10/spacex-catches-returni... Surveying GPS can do that with WAAS and a bunch of integration time and extra receivers, but not in real time: https://www.gps.gov/systems/gps/performance/accuracy https://www.gps.gov/systems/gps/performance/accuracy So that's why I think they need to have a high resolution, close range, 3d positioning method for the final seconds.