[time-nuts] D term (was no subject)

Lee Mushel herbert3 at centurytel.net
Mon Jan 26 13:27:24 EST 2015

I'm fairly sure that Jim is right.   I never had to worry about PID machine 
control before the late sixties and by the mid-seventies the concepts were 
firmly in place and in use.   It certainly was the appearance of solid state 
industrial controls which made it all possible.   And those ideas have made 
possible some system performance that I recall as being impossible only a 
few years earlier.

Lee Mushel
----- Original Message ----- 
From: "Jim Lux" <jimlux at earthlink.net>
To: "Poul-Henning Kamp" <phk at phk.freebsd.dk>; "Discussion of precise time 
and frequency measurement" <time-nuts at febo.com>
Sent: Monday, January 26, 2015 8:21 AM
Subject: Re: [time-nuts] D term (was no subject)

> On 1/26/15 5:55 AM, Poul-Henning Kamp wrote:
>> --------
>> In message <54C5A270.7090007 at earthlink.net>, Jim Lux writes:
>>> And there's decades, if not centuries, of experience with P, PI and PID
>>> controllers in a practical sense.
>> Not quite a century I belive:  Only the advent of electronics formalized
>> the theory and developed the practice.
>> Almost all mechanical "governors" er pure P.
> Maxwell strikes again
> http://upload.wikimedia.org/wikipedia/commons/b/b1/On_Governors.pdf
> definitely more than P controllers..
> cups with liquid (Siemens governor), nonlinear mechanisms, etc.
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