# Shameless Plug

Started by November 29, 2004
```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.

--
Guy Macon <http://www.guymacon.com>

```
```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:
> 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
```
```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
```
```"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 = wrong
Both are right...
Guess what, a 'differential equation', is one including a 'rate of change'
(derivative) term...

Best Wishes

```
```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/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.
```
```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
```
```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.
&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
```
```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.
>

```
```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

```
```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]
>Jerry

Engineers, as a class, are notoriously bad spellers/grammarians.

...Jim Thompson
--
|  James E.Thompson, P.E.                           |    mens     |