3 ms·
Don’t they have voting CPUs? If one goes out of sync discard that result and restart it. And wouldn’t the value end up on the CPU the same if it was hardcoded
by cjbgkagh 2y ago
Don’t they have voting CPUs? If one goes out of sync discard that result and restart it.
And wouldn’t the value end up on the CPU the same if it was hardcoded or not?
Perhaps there could be some verification done with hardcoded loop bounds for making sure things work in real time. I’ll read the article before commenting further. Edit: Yeah, the hardcoded bounds is to give some sort of guarantee as to how long a function will take.
- mr_toad 2y agoI’ve only heard of voting CPUs being used on launchers. I think the level of redundancy on other craft varies.
- fuzztester 2y agoiirc, I read about voting CPUs (like 4 of them) being used on space shuttles or earlier spacecraft. I could be wrong though.
- pauldino 2y agoThat's not the case for JPL missions (the paper originally is from JPL) which generally have 2 separate independent computers where 1 is active at a time. Since they're independent, the 2 computers don't actually have to run the same software, I believe during Mars entry descent and landing the standby compute element runs a different less sophisticated but easier to validate version of the EDL code to take over if any fault is detected while the primary software is running. (I was going to do a quick check on dataverse.jpl.nasa.gov to confirm that but it seems to be down) Also I think a few years ago on the Mars Curiosity rover (2012) there was some corruption in the flash storage on one of the computers that prevents the full flight software from being loaded on to it, so instead it runs a stripped-down version of the code with very limited functionality to function as a lifeboat in case the fully-working computer ever fails. https://ieeexplore.ieee.org/document/9843266 https://ieeexplore.ieee.org/document/9843266