[From Rick Marken (931110.1530)]
Bill Powers (931110.1115 MST) to Hans:
This clarifies something in my mind if not yours. You and Martin
Taylor have both been insisting that in some circumstances,
environments are predictable enough that open-loop systems could
operate properly. But what is your evidence that the systems you
observe are actually operating open-loop?
That's what I've been trying to say for the last several posts!!!
Unfortunately, I been using the term "feedforward" where it might
have been clearer to use "open-loop").
To prove that you're talking about an open-loop system,
you would have to show that a disturbance would NOT be resisted.
YES!!!!
And if you DO see that disturbances are resisted, it's really not
acceptable to say, "Oh, it WAS an open-loop system before we
tested it, but as soon as the disturbance was applied it turned
into a control system."
To paraphrase one of America's great presidents and moral
philosophers:
"They COULD say that, but that wouldn't be right".
Best
Tricky Ricky