Winfield Hill wrote:>Guy Macon wrote...Please don't snip out the part where I wrote "a common question is", thus making it look as if I am the one asking asking the question.>> "Why do half the engineers call it Proportional-Integral-Derivative" >> and others call it "Proportional-Integral-Differential?" When I >> did a Google search on "proportional integral differential" I got >> 18,600 hits while "proportional integral differential" only had >> 3,060 hits, but most of the "proportional integral differential" >> hits seem to be by scientists and equipment manufacturers. >> Which is correct?" > > proportional integral derivative - 253,000 hits = correct > proportional integral differential - 315,000 hits = wrongproportional integral derivative - 253,000 hits "proportional integral derivative" - 18,600 hits proportional integral differential - 315,000 hits "proportional integral differential" - 3,060 hits The quotation marks are important in this case. You want to count the times the phrase is used, not the times that all three words are found on different parts of the page. I was taught that "Proportional-Integral-Derivative" is the proper term, but the Google search turns up some disturbing uses. It's in an article published in the Geotechnical Testing Journal on astm.org. It is used by Paul Brinks, who appears to be teaching a class on PID at a state univerity. It's used in a paper titled "A Closed Loop Controller for Electron-Beam Evaporators" published in _Review of Scientific Instruments_. I still think "Proportional-Integral-Differential" is wrong, even a bunch of college boys and one out of six webpages says that it is correct. I just wonder why so many get it wrong. -- Guy Macon <http://www.guymacon.com>

# Shameless Plug

Started by ●November 29, 2004

Reply by ●November 30, 20042004-11-30

Reply by ●November 30, 20042004-11-30

Guy Macon wrote: -- snip --> "Why do some controller boards have an option to reverse the > phase of the D? What is that good for?"OK, I'll bite -- what _is_ it good for? I've never done closed-loop control with prepackaged controllers and I've never seen that done elsewhere. I can certainly see reversing the phase of the whole thing, or reversing the phase of the D term if it's coming from some other feedback source (which would imply a second input) but I _can't_ see the point in intentionally establishing an unstable zero in your control system.>-- snip some more --> > BTW. for what it's worth, I found that relating position servos > and velocity servos to a person controlling a car (speed and > position within the lane) was helpful. I also found it helpful > to show how to use a stopwatch and odometer to derive speed with > no speedometer, a stopwatch and speedometer to derive distance > without an odometer, and a speedometer and odometer to derive > elapsed time with no stopwatch. Your audience is different, > of course - this worked really well with mechanical engineers, > but software engineers are quite different.Many, many software engineers, particularly embedded software engineers are gearheads, and almost all of them drive to work.> > Another gotcha that sometimes trips up software engineers: > non-monotonic ADCs causing a "bad spot" that has positive > feedback. >Yes, this could be _very_ counter-intuitive to my target audience. There isn't room for it in the talk, but I'll have to think about writing a "pitfalls" paper -- unfortunately I've internalized those pitfalls pretty deeply, so it may be hard to remember all of them. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com

Reply by ●November 30, 20042004-11-30

Guy Macon wrote:> I was taught that "Proportional-Integral-Derivative" is the > proper term, but the Google search turns up some disturbing uses. > It's in an article published in the Geotechnical Testing Journal > on astm.org. It is used by Paul Brinks, who appears to be teaching > a class on PID at a state univerity. It's used in a paper titled > "A Closed Loop Controller for Electron-Beam Evaporators" published > in _Review of Scientific Instruments_. > > I still think "Proportional-Integral-Differential" is wrong, > even a bunch of college boys and one out of six webpages says > that it is correct. I just wonder why so many get it wrong. >I fear that my mind was poisoned long ago by a German instructor who pointed out that modern linguistic theory doesn't much recognize a "right way" and a "wrong way" -- it just records prevalent usage, and tries to keep out of the way of the steamroller. When I write something that has two competing terms in use I'll often mention both of them (perhaps in a footnote), and I'll explain why I use the one I do. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com

Reply by ●November 30, 20042004-11-30

"Winfield Hill" <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote in message news:cohse107bd@drn.newsguy.com...> Guy Macon wrote... > > > > "Why do half the engineers call it Proportional-Integral-Derivative" > > and others call it "Proportional-Integral-Differential?" When I > > did a Google search on "proportional integral differential" I got > > 18,600 hits while "proportional integral differential" only had > > 3,060 hits, but most of the "proportional integral differential" > > hits seem to be by scientists and equipment manufacturers. > > Which is correct?" > > proportional integral derivative - 253,000 hits = correct > proportional integral differential - 315,000 hits = wrongBoth are right... Guess what, a 'differential equation', is one including a 'rate of change' (derivative) term... Best Wishes

Reply by ●November 30, 20042004-11-30

On Tue, 30 Nov 2004 12:54:01 -0500, Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote: [snip]> >"proportional intergral derivative" 29 hits >"proportional intergral differential" 18 hits > > > >Best regards, >Spehro Pefhany"intergral" ?:-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.

Reply by ●November 30, 20042004-11-30

On Tue, 30 Nov 2004 16:39:45 +0000, the renowned Guy Macon <http://www.guymacon.com> wrote:> >Winfield Hill wrote: > >>Guy Macon wrote... > >Please don't snip out the part where I wrote "a common question is", >thus making it look as if I am the one asking asking the question. > >>> "Why do half the engineers call it Proportional-Integral-Derivative" >>> and others call it "Proportional-Integral-Differential?" When I >>> did a Google search on "proportional integral differential" I got >>> 18,600 hits while "proportional integral differential" only had >>> 3,060 hits, but most of the "proportional integral differential" >>> hits seem to be by scientists and equipment manufacturers. >>> Which is correct?" >> >> proportional integral derivative - 253,000 hits = correct >> proportional integral differential - 315,000 hits = wrong > >proportional integral derivative - 253,000 hits >"proportional integral derivative" - 18,600 hits >proportional integral differential - 315,000 hits >"proportional integral differential" - 3,060 hits"proportional intergral derivative" 29 hits "proportional intergral differential" 18 hits Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

Reply by ●November 30, 20042004-11-30

Guy Macon wrote:> Winfield Hill wrote: > > >>Guy Macon wrote... > > > Please don't snip out the part where I wrote "a common question is", > thus making it look as if I am the one asking asking the question. > > >>>"Why do half the engineers call it Proportional-Integral-Derivative" >>>and others call it "Proportional-Integral-Differential?" When I >>>did a Google search on "proportional integral differential" I got >>>18,600 hits while "proportional integral differential" only had >>>3,060 hits, but most of the "proportional integral differential" >>>hits seem to be by scientists and equipment manufacturers. >>>Which is correct?" >> >>proportional integral derivative - 253,000 hits = correct >>proportional integral differential - 315,000 hits = wrong > > > proportional integral derivative - 253,000 hits > "proportional integral derivative" - 18,600 hits > proportional integral differential - 315,000 hits > "proportional integral differential" - 3,060 hits > > The quotation marks are important in this case. You want to count > the times the phrase is used, not the times that all three words > are found on different parts of the page. > > I was taught that "Proportional-Integral-Derivative" is the > proper term, but the Google search turns up some disturbing uses. > It's in an article published in the Geotechnical Testing Journal > on astm.org. It is used by Paul Brinks, who appears to be teaching > a class on PID at a state univerity. It's used in a paper titled > "A Closed Loop Controller for Electron-Beam Evaporators" published > in _Review of Scientific Instruments_. > > I still think "Proportional-Integral-Differential" is wrong, > even a bunch of college boys and one out of six webpages says > that it is correct. I just wonder why so many get it wrong.It's simple: the level of literacy, even among "college boys", is appallingly low. Consider how many write "there" when they mean "their" or "they're". "Differential" as an adjective refers to the the difference or the distinction between two quantities or states, as in "differential amplifier" and "differential diagnosis". A PID controller is governed by three terms: one is proportional to error, another is the integral (in the mathematical sense) of something, and the third is the derivative (in the mathematical sense) of (probably) something else. The proportion of people who write "proportional integral differential" is not large considering the proportion of people who say "nucular" and swear it's correct because it derives from "nuculus". I find the reason for that totally uncular. :-D (uncular:nucular::unclear:nuclear) Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������

Reply by ●November 30, 20042004-11-30

Not acording to Sturgeon's Law: 90% of everything is C%&p But that was before the internet - Internet Corollary to Sturgeon's Lwa: 99% of everything is C%&p Bruce Nicholas O. Lindan wrote:>>Why do half the engineers call [PID] "Proportional-Integral-Derivative" >>and others call it "Proportional-Integral-Differential?" > > > In 'Control Speak': > > Differential: the amount of hysteresis in an on/off controller, such > as a home thermostat. > > Derivative: The term D * dPV/dT in a PID controller where: D == derivative > gain; PV = process variable; T == time. Some controllers > use D * dE/dT where E == error. > > Lesson: Half of everything is bunk. >

Reply by ●November 30, 20042004-11-30

Yestedy i culdnt spel "Enginie - Now i are wun. Jim Thompson wrote:> On Tue, 30 Nov 2004 12:54:01 -0500, Spehro Pefhany > <speffSNIP@interlogDOTyou.knowwhat> wrote: > > [snip] > >>"proportional intergral derivative" 29 hits >>"proportional intergral differential" 18 hits >> >> >> >>Best regards, >>Spehro Pefhany > > > "intergral" ?:-) > > ...Jim Thompson

Reply by ●November 30, 20042004-11-30

On Tue, 30 Nov 2004 13:07:37 -0500, Jerry Avins <jya@ieee.org> wrote: [snip]> >It's simple: the level of literacy, even among "college boys", is >appallingly low. Consider how many write "there" when they mean "their" >or "they're". >[snip]>JerryEngineers, as a class, are notoriously bad spellers/grammarians. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.