Tim Wescott wrote:
What happened when he needed fish from Gloss-tuh?

--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
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"Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

On Sat, 25 Feb 2006 20:34:04 -0800, Tim Wescott <tim@seemywebsite.com>
wrote:

[snip]
Pronounced just like the sauce ;-)

And sort of like Gloucester.

Then there's Wooster, OH ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

It's what you learn, after you know it all, that counts.

CBFalconer wrote:
Does he slaver it with war-sester-shire saucr?

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Paul Carpenter wrote:

your problem and deal with sensor failures") I'd be delighted to read it.

I haven't really addressed this kind of thing in detail, because I've
mostly worked with loops that lack redundant sensors and which were
inherently mechanically safe. I _do_ have an abhorrence of controllers
with modes, because the mode change always seems to be awkward at best.
I suspect that a modeless controller is going to be inherently better
positioned to deal with sensors coming and going (not perfectly, just
better, often).
models. I think that people are so used to academic problems that they
forget that their models might possibly not be sufficiently accurate.
There's at least a few places in the book where the phrases "if your
model is accurate enough" or "if your linear model applies" appear. I
also made a point in the chapter on dealing with nonlinearities of
showing what happens when you blithely use a linear model to a design a
controller for a nonlinear system (a big scary/embarrassing oscillation,
in the example).

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

On Sun, 26 Feb 2006 09:12:37 -0800, Tim Wescott <tim@seemywebsite.com>
wrote:

Indeed! Though I don't use the material on any regular basis (*), I
had four semesters on non-linear control theory in grad school. Great
fun, the real world!

(*) Though I recently was involved in a laser beam "wobulator"... a
mirror driven by a power amplifier... great fun tuning it up for
stability ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

It's what you learn, after you know it all, that counts.

Tim Wescott wrote:

You should apply for this one next go-round. There might be big bucks in
it for you. The deal is to stabilize the internal mirror pointing system
against acoustic wave interference induced into the turret by platform
motion through the air.
http://www.dodsbir.net/sitis/archive...Bookmark=19430

"Tim Wescott" <tim@seemywebsite.com> wrote in message
news:waCdnbrQguUnspzZRVn-rw@web-ster.com...
When I went to Woopie Tech, it was "guys only". The nearest
"gulls" were at some sort of prep school just down the
street that ran through the center of campus.

And now I have to add my favorite rant: I hope you
discussed at some length the fact that every control loop
needs an auditor, a second, independent measurement device
that is not involved in closing the loop. The reason for
this is that once you have closed the loop, you cannot use
that measurement to know anything about what's really going
on in the process over the long term. If the controller is
functioning properly, the measurement (at the controller)
will be forced to track the setpoint no matter what is
actually happening in the real world. Providing such
auditors used to be standard practice in the process control
industry until about 15 years ago when engineers lost
control of their plants and bean counters started
"cost-reducing" everything. In fact, we used to have RTDs
designed with that in mind: one RTD to control and one to
audit in the same probe.

Also, of course, we had the clever E&I technicians.
Operators would complain that the controller measurements
weren't the same as the auditor measurements, so some dork
with a 12-inch screwdriver would "re-calibrate" the
RTD-to-current-loop converters to make the auditors "read
right."

John E. Hadstate wrote:

If sensors are in the same place, they ought to read the same value.
Audit probes did me the most good when they were located somewhat apart
from the control probe.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

"Jerry Avins" <jya@ieee.org> wrote in message
news:fvudnYRrKteSY5zZnZ2dnUVZ_tydnZ2d@rcn.net...
No!! Between the sensors and the computer is usually a
device ("converter" or "amplifier") to produce a 4-20 mA (or
10-50 mA) signal from whatever the sensor produces
(resistance, millivolts, etc.) Back in the computer room,
there is often another converter to change the 4-20 mA
signal to something like 0-10 Volts or 1-5 Volts. These
devices almost always have "Span" and "Zero" adjustments
accessible to "the dork with the 12-inch screwdriver".
Consequently, without a serious threat to "break fingers",
these converters are often used to make the computer say
whatever the operators want it to say.

"John E. Hadstate" <jh113355@hotmail.com> wrote in message
news:zjnMf.31285$Ly6.7326@bignews5.bellsouth.net.. .
coz ov over monkey mistak. ....

Also hav 'honest' backup what no-wun am figur owt. Bonus, am also
iso9005.02.03

Nise Coffeeee plus Doner Kebab...... Easy.

DNA

"Jim Thompson" <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote in
message news:c5h3025qdr8s1i0lc88vcm6jdkeje33i06@4ax.com...
and Warrik (RI) ...

On Sun, 26 Feb 2006 13:38:49 -0800, "Fred Marshall"
<fmarshallx@remove_the_x.acm.org> wrote:

I used to take the New Haven... RR from Boston to DC, then switch to
the C&O on into Huntington. Trying to figure out those conductor
calls was quite a challenge.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

It's what you learn, after you know it all, that counts.

"Genome" <ilike_spam@yahoo.co.uk> wrote in message
news:vLnMf.10240$57.9366@newsfe3-win.ntli.net...
Yep, monkeys with screwdrivers were a big problem in my
plant (as was a raccoon who decided to have a barbecue in
the business area of one of the 230 KV switching substations
;-)

Seriously though, there is a subtlety buried here that
should be brought out. We didn't really become focused on
the problems I described until we started using various Data
Historians in a big way (actually about the same time that
people were getting interesting in things like ISO-9000 and
Statistical Process Control.) After a lot of thinking, a
lot more talking, and several demonstrations where our
historical data showed us that what was happening was not
what we thought was happening, we began to get a handle on
some of the problems.

I can't emphasize enough how important is the collection and
long-term storage of process data to the health of a plant
that has a lot of closed-loop control, but don't rely on the
controller measurements to tell you anything about what's
happening in the process. This principle should be pasted
on every control engineer's forehead: "If a process variable
is important enough that it needs to be automatically
controlled it is important enough that it needs to be
independently audited."

On Sun, 26 Feb 2006 13:38:49 -0800, the renowned "Fred Marshall"
<fmarshallx@remove_the_x.acm.org> wrote:

The train wicket guy in the UK who sold me the ticket to 'Lie-stir'
looked at me funny, but sold the ticket to Leicester nonetheless.



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

John E. Hadstate wrote:
I disn't say they /would/ read the same, but that thay /ought/ to. When
two thermometers in the same stirred pot of soup indicate different
temperatures, at least one of them is wrong. Loop or no loop.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Jim Thompson wrote:
Montreal streetcars (remember them) used to roll along St.
Catherine until they arrived at "GeeGuy". Sometimes
"Laroogeeguy". Those are hard 'g's.

--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

Jerry Avins wrote:
Or you have an unusually busy population of Maxwells demons.

--
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

On Sunday, in article <v5adnZmFqdMffJzZRVn-qA@web-ster.com>
tim@seemywebsite.com "Tim Wescott" wrote:
I don't know if I could really class my thoughts and experiences as an
'article' (so many different meanings to article as in length and depth
of content). I could probably summarise a few of the major ones in a
'War stories' page sometime.

......

Common 'solutions' I hear too often from people (either customers or those
'advising' them) are

"just put a big computer in there that will solve the problem"

or "there are GigaBytes of bandwidth available in the RF spectrum"

or "This will be solved by the promised new version of product X"

If you want I could outline describe in email the worst closed loop complete
system with lots of open loop technology in the way that people were asking
to change things to make it better. I would asked to think about what could
be done with modifications to a company's products to give an answer to the
problem, they did not like my response, and got all three of the above
responses.

--
Paul Carpenter | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/> PC Services
<http://www.gnuh8.org.uk/> GNU H8 & mailing list info
<http://www.badweb.org.uk/> For those web sites you hate

CBFalconer wrote:
I cot confused in Bawston when the MTA dispatcher told me to take the
Pack kah (rhymes with kaka). It took a while to sort that out.

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

"Paul Carpenter" <paul$@pcserviceselectronics.co.uk> wrote in message

I must say that I've had this experience with folks who should have known
better. When asked: "How are you going to do that?" they would say: "well,
there will be a computer inside". They had NO idea what they were going to
do or how they would do it. If the SNR was infinitely low, "well, there
will be a computer inside".

Fred