4 ms·

Actually the computing power of Ingenuity surpasses one of the Perseverance rover (and probably by a lot). The rover has a radiation hardened RAD 750 CPU (based

by nuccy 6y ago

Actually the computing power of Ingenuity surpasses one of the Perseverance rover (and probably by a lot). The rover has a radiation hardened RAD 750 CPU (based on PowerPC 750 architecture, which was introduced in 1997 to compete with Intel's Pentium II [1,2]) with 250-150nm technology process operating at 200Mhz[3]. Ingenuity's Snapdragon 801 can reach up to 2.5 GHz and is based on more energy-efficient 28nm modern (released in 2014) ARM architecture [4]. This CPU even has Wi-Fi and GPS, though probably not much of a use on Mars :) 1. https://arstechnica.com/science/2019/11/space-grade-cpus-how-do-you-send-more-computing-power-into-space/ https://arstechnica.com/science/2019/11/space-grade-cpus-how... 2. https://en.wikipedia.org/wiki/RAD750 https://en.wikipedia.org/wiki/RAD750 3. https://mars.nasa.gov/mars2020/spacecraft/rover/brains/ https://mars.nasa.gov/mars2020/spacecraft/rover/brains/ 4. https://www.qualcomm.com/products/snapdragon-processors-801 https://www.qualcomm.com/products/snapdragon-processors-801

donquichotte 6y ago
Do you know why radiation hardening is not needed for the Ingenuity? Is there a mechanical shield? Or is it just the shorter runtime that makes the use of an off-the-shelf processor acceptable?
- jhurliman 6y ago
  I had the opportunity to go down to JPL and speak with team members about this design decision. The space hardened processors are not fast enough to do real time sensor fusion and flight control, so they were forced to move to the faster snapdragon. This processor will have not flips on Mars, possibly up to every few minutes. Their solution is to hold two copies of memory and double check operations as much as possible, and if any difference is detected they simply reboot. Ingenuity will start to fall out of the sky, but it can go through a full reboot and come back online in a few hundred milliseconds to continue flying. In the far future where robots are exploring distant planets, our best tech troubleshooting tool is to turn it off and turn it on again.
  - alfla 6y ago
    Do you have a source for those fast reboots? It's running Linux after all
    - nynx 6y ago
      A few hundred milliseconds seems easily doable with a custom linux distro.
      - yason 6y ago
        Unless your /dev/sda wants a fsck. :-)
    - chasd00 6y ago
      is Ingenuity running Linux? All of the flight controller software i've seen for autonomous drones don't use an operating system.
      - lights0123 6y ago
        Yep, from the article: "This the first time we’ll be flying Linux on Mars. We’re actually running on a Linux operating system. The software framework that we’re using is one that we developed at JPL for cubesats and instruments, and we open-sourced[0] it a few years ago. So, you can get the software framework that’s flying on the Mars helicopter, and use it on your own project. It’s kind of an open-source victory, because we’re flying an open-source operating system and an open-source flight software framework and flying commercial parts that you can buy off the shelf if you wanted to do this yourself someday. This is a new thing for JPL because they tend to like what’s very safe and proven, but a lot of people are very excited about it, and we’re really looking forward to doing it." [0]: https://github.com/nasa/fprime https://github.com/nasa/fprime
  - nynx 6y ago
    I'm a little surprised they didn't go for three separate computers and compare them for every operation, or something like that, but I'm sure they have their reasons.
- mlindner 6y ago
  My entirely uninformed opinion is that radiation hardened silicon is something that comes from government that isn't actually needed for most purposes. It's something you do when cost is no object.
interestica 6y ago
I haven't seen much on the 'sky crane' portion. It seems that it will just use whatever fuel it has left after the landing procedure to just get as far away as possible. It seems like the perfect place to stick some experimental imagery gear: film everything you can all the way down and transmit it back to Perseverance. And there's the possibility that it would survive its crash too with all hardware intact.
mzs 6y ago
There are also two redundant TI MCUs on the copter >TMS570LC43x high-reliability automotive processor operating at 300 MHz, with 512 K RAM, 4 MB flash memory, UART, SPI, GPIO https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_A...

by nuccy 6y ago

donquichotte 6y ago

Do you know why radiation hardening is not needed for the Ingenuity? Is there a mechanical shield? Or is it just the shorter runtime that makes the use of an off-the-shelf processor acceptable?

jhurliman 6y ago
I had the opportunity to go down to JPL and speak with team members about this design decision. The space hardened processors are not fast enough to do real time sensor fusion and flight control, so they were forced to move to the faster snapdragon. This processor will have not flips on Mars, possibly up to every few minutes. Their solution is to hold two copies of memory and double check operations as much as possible, and if any difference is detected they simply reboot. Ingenuity will start to fall out of the sky, but it can go through a full reboot and come back online in a few hundred milliseconds to continue flying. In the far future where robots are exploring distant planets, our best tech troubleshooting tool is to turn it off and turn it on again.
- alfla 6y ago
  Do you have a source for those fast reboots? It's running Linux after all
  - nynx 6y ago
    A few hundred milliseconds seems easily doable with a custom linux distro.
    - yason 6y ago
      Unless your /dev/sda wants a fsck. :-)
  - chasd00 6y ago
    is Ingenuity running Linux? All of the flight controller software i've seen for autonomous drones don't use an operating system.
    - lights0123 6y ago
      Yep, from the article: "This the first time we’ll be flying Linux on Mars. We’re actually running on a Linux operating system. The software framework that we’re using is one that we developed at JPL for cubesats and instruments, and we open-sourced[0] it a few years ago. So, you can get the software framework that’s flying on the Mars helicopter, and use it on your own project. It’s kind of an open-source victory, because we’re flying an open-source operating system and an open-source flight software framework and flying commercial parts that you can buy off the shelf if you wanted to do this yourself someday. This is a new thing for JPL because they tend to like what’s very safe and proven, but a lot of people are very excited about it, and we’re really looking forward to doing it." [0]: https://github.com/nasa/fprime https://github.com/nasa/fprime
- nynx 6y ago
  I'm a little surprised they didn't go for three separate computers and compare them for every operation, or something like that, but I'm sure they have their reasons.
mlindner 6y ago
My entirely uninformed opinion is that radiation hardened silicon is something that comes from government that isn't actually needed for most purposes. It's something you do when cost is no object.

interestica 6y ago

I haven't seen much on the 'sky crane' portion. It seems that it will just use whatever fuel it has left after the landing procedure to just get as far away as possible. It seems like the perfect place to stick some experimental imagery gear: film everything you can all the way down and transmit it back to Perseverance. And there's the possibility that it would survive its crash too with all hardware intact.

mzs 6y ago

There are also two redundant TI MCUs on the copter >TMS570LC43x high-reliability automotive processor operating at 300 MHz, with 512 K RAM, 4 MB flash memory, UART, SPI, GPIO https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_A...