3 ms·

A GPS-driven cutoff seems like an obvious thing to have in this situation, no?

nradov 1y ago
GPS (or GNSS in general) is hardly sufficient for anything safety critical. The signals are very weak and can easily be spoofed or jammed. Even overhead obstructions like trees and buildings nearby can cause significant offsets due to multipath reflection issues.
- zdragnar 1y ago
  RTK driven tractors are not using just standard GPS. They have positional accuracy down to one inch.
- immibis 1y ago
  Simple solution for that. If you jam GPS and it makes an autonomous tractor run over a school, you're liable for the manslaughter of the school kids. Trains can be derailed, but they're still allowed to operate and we just put the derailer in prison. And knives can be used to stab people. And someone can even grab your arm and force you to stab someone with the knife, and the law understands this.
  - nradov 1y ago
    What a stupid "solution". It is almost never possible to catch GNSS jammer users after the fact. GPS alone can never be sufficient, regardless of the legal issues. There are automated technical solutions to this problem involving sensor fusion and/or ground beacons.
    - pfdietz 1y ago
      Simply jamming the GPS would cause the vehicle to stop. What would be needed would be spoofing the GPS to make the vehicle think it was still operating normally, in the field it was supposed to be in, without any detectable quirks, a much harder task.
      - nradov 1y ago
        Jamming or not isn't a binary condition, nor is there a clear line between jamming versus spoofing. Certain types of signal interference will still allow for a position fix but with greatly degraded accuracy. There are algorithms to detect signal quality, but again that alone isn't considered adequate for anything safety critical. Commercial aircraft aren't legally allowed to fly with only GPS for navigation, and for good reason.
        immibis 1y ago
        Right - commercial aircraft are required to use navigation methods that are orders of magnitude easier to spoof than GPS is - such as radio beacons that transmit certain three-letter Morse code IDs on certain frequencies, and the plane just flies directly towards the strongest signal source. That particular one is considered outdated but still used in some areas. Automatic landing is done by tuning into a certain frequency, and two angled transmitters are used so that a plane too far to the left receives a certain pattern and a plane too far to the right receives a different one. A similar system is used for vertical guidance. How easy is it to transmit a short repeating pattern at an aircraft to make it think it's too far to the left? And these are allowed to fly, and refrigerators are legal too even though filling one with propane and a spark source may cause it to explode.

GPS (or GNSS in general) is hardly sufficient for anything safety critical. The signals are very weak and can easily be spoofed or jammed. Even overhead obstructions like trees and buildings nearby can cause significant offsets due to multipath reflection issues.

zdragnar 1y ago
RTK driven tractors are not using just standard GPS. They have positional accuracy down to one inch.
immibis 1y ago
Simple solution for that. If you jam GPS and it makes an autonomous tractor run over a school, you're liable for the manslaughter of the school kids. Trains can be derailed, but they're still allowed to operate and we just put the derailer in prison. And knives can be used to stab people. And someone can even grab your arm and force you to stab someone with the knife, and the law understands this.
- nradov 1y ago
  What a stupid "solution". It is almost never possible to catch GNSS jammer users after the fact. GPS alone can never be sufficient, regardless of the legal issues. There are automated technical solutions to this problem involving sensor fusion and/or ground beacons.
  - pfdietz 1y ago
    Simply jamming the GPS would cause the vehicle to stop. What would be needed would be spoofing the GPS to make the vehicle think it was still operating normally, in the field it was supposed to be in, without any detectable quirks, a much harder task.
    - nradov 1y ago
      Jamming or not isn't a binary condition, nor is there a clear line between jamming versus spoofing. Certain types of signal interference will still allow for a position fix but with greatly degraded accuracy. There are algorithms to detect signal quality, but again that alone isn't considered adequate for anything safety critical. Commercial aircraft aren't legally allowed to fly with only GPS for navigation, and for good reason.
      - immibis 1y ago
        Right - commercial aircraft are required to use navigation methods that are orders of magnitude easier to spoof than GPS is - such as radio beacons that transmit certain three-letter Morse code IDs on certain frequencies, and the plane just flies directly towards the strongest signal source. That particular one is considered outdated but still used in some areas. Automatic landing is done by tuning into a certain frequency, and two angled transmitters are used so that a plane too far to the left receives a certain pattern and a plane too far to the right receives a different one. A similar system is used for vertical guidance. How easy is it to transmit a short repeating pattern at an aircraft to make it think it's too far to the left? And these are allowed to fly, and refrigerators are legal too even though filling one with propane and a spark source may cause it to explode.