PJ2,
Originally Posted by PJ2
You reference "5" sensors
I did? Deary me! Not any more.
Somehow I was thinking (3 x n) +1 = 5 when n =2. Maybe it was when I wrote it, but it's not any longer. It's 7, as Kevin said.
It makes the point stronger.
infrequentflyer789 saw how to rescue me (very gracious!) but truth is it was a cognitive slip. Yes, Leslie points out that you can use digital signatures to reduce the number, but no one trying to build Byzantine-failure-tolerant devices is trying to do that.
The issue being batted around here is more or less as follows. Trying to be completely fault-tolerant (of Byzantine faults as well as others) is currently not on. There are a couple of busses which are being designed to tolerate special classes of Byzantine faults, but they are at the research level. So the question is: what kinds of fault can be tolerated using existing methods?
And here the danger is that one collects a list of phenomena, and says: we can tolerate
this one like this, and
this on like this, and ....... and here are two AoA sensors which are frozen, and we can tolerate this situation like this, and ..... and one ends up with a list without rhyme or much reason. It is possible to do each one after the other. But one is continually shutting the door after the horse has bolted, and the next door will not be where they have already been shut. That is no way to design fault-detecting or fault-tolerant systems.
What is needed is a description of a class of phenomena and how they are to be tolerated. Or many classes, and their mitigations. And I don't see that yet arising out of this discussion.
PBL