FPGA Central

So, I've put the finishing touches on my book, and the publisher's
marketing department is asking me questions. Some of them I don't have
good answers to, because (a) I'm on the fringe of my target audience,
and (b) everyone learns differently, and my way is through osmosis and
thinking, which doesn't make it easy to cough up a bunch of specific
information like conferences and magazines.

The book's title is "Applied Control Theory for Embedded Systems", the
subject should be self explanatory. So if you feel that you're in the
target audience, and if you're in a generous mood, here are some
questions I have for you:

What do they call you at work (sorry -- what's your official job title?)

What magazines do you read? Websites you visit regularly?

Do you go to conferences? Which ones? (this is the one that motivated
this posting, by the way -- I only go to the Embedded Systems
Conference; I know there's a circuit-related one in Silicon Valley but I
can't remember the name, nor do I know if there are any ones anywhere else.

Have you had to close a control loop recently? Did you do a web search?
What keywords did you use?

Have you read any related books? Was it just a college text, or was it
specifically directed at closed loop control for the practicing embedded
systems designer? What did you think of it? What was it?

Thanks in advance.

--

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

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

On Fri, 24 Feb 2006 10:39:46 -0800, Tim Wescott wrote:

> Have you had to close a control loop recently? Did you do a web search?
> What keywords did you use?

Isn't that what academicians call "negative feedback"? ;-)

Good Luck!
Rich

"Tim Wescott" <[email protected]> wrote in message
news:[email protected]..
> So, I've put the finishing touches on my book, and the publisher's
> marketing department is asking me questions. Some of them I don't have
> good answers to, because (a) I'm

A self procreating **** up?

> Tim Wescott
> Wescott Design Services
> http://www.wescottdesign.com
>
> Posting from Google? See http://cfaj.freeshell.org/google/

Genome wrote:

> "Tim Wescott" <[email protected]> wrote in message
> news:[email protected]..
>
>>So, I've put the finishing touches on my book, and the publisher's
>>marketing department is asking me questions. Some of them I don't have
>>good answers to, because (a) I'm
>
>
> A self procreating **** up?
>



--

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

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

On Fri, 24 Feb 2006 20:21:10 GMT, "Genome" <[email protected]>
wrote:

>"Tim Wescott" <[email protected]> wrote in message
>news:[email protected]..
>> So, I've put the finishing touches on my book, and the publisher's
>> marketing department is asking me questions. Some of them I don't have
>> good answers to, because (a) I'm
>
>A self procreating **** up?

Hmm. That's the finest definition of life I've heard!

Jon

Hi Tim

> So, I've put the finishing touches on my book, and the publisher's
> marketing department is asking me questions. Some of them I don't have
> good answers to, because (a) I'm on the fringe of my target audience, and
> (b) everyone learns differently, and my way is through osmosis and
> thinking, which doesn't make it easy to cough up a bunch of specific
> information like conferences and magazines.
>
> The book's title is "Applied Control Theory for Embedded Systems", the
> subject should be self explanatory. So if you feel that you're in the
> target audience, and if you're in a generous mood, here are some questions
> I have for you:
>
> What do they call you at work (sorry -- what's your official job title?)

They call me Software Engineer (they call me other names too when they find
bugs in the software, but I doubt you are interested in knowing), but my
business card says Software
Development Manager.


> What magazines do you read?
Nuts and Volt, Servo, Motorcyclist, Computer, IEEE Potentials, Dr. Dobbs


> Websites you visit regularly?
Google news, Orkut, CNN


> Do you go to conferences? Which ones? (this is the one that motivated
> this posting, by the way -- I only go to the Embedded Systems Conference;
> I know there's a circuit-related one in Silicon Valley but I can't
> remember the name, nor do I know if there are any ones anywhere else.

Not so often, I wish I had the money/time to attend to more conferences. The
last one was IC-AI (International Conference on Artificial Intelligence)
which I published and presented a paper.


> Have you had to close a control loop recently? Did you do a web search?
> What keywords did you use?

Yes. Yes. PID control; control theory; fuzzy control


> Have you read any related books? Was it just a college text, or was it
> specifically directed at closed loop control for the practicing embedded
> systems designer? What did you think of it? What was it?

Yes. A couple of books actually.
Got some hints from Schaums for control theory, and two other books that I
borrowed from the university's library.
The problem with all of them is that they go deep on the math of control
theory but are not practical (no relationship between CT and embedded
devices)



Do I get a free book?

Good luck with your publishing... A man has three missions on Earth: Have
kids, plant a tree and write a book. I accomplish the first two... someday
I'll write a book.

Cheers

Padu

"Tim Wescott" <[email protected]> wrote in message
news:[email protected]..
> So, I've put the finishing touches on my book, and the publisher's
> marketing department is asking me questions. Some of them I don't have
> good answers to, because (a) I'm on the fringe of my target audience,
> and (b) everyone learns differently, and my way is through osmosis and
> thinking, which doesn't make it easy to cough up a bunch of specific
> information like conferences and magazines.
>
> The book's title is "Applied Control Theory for Embedded Systems", the
> subject should be self explanatory.

I hopr you have lest out Nyquist diagrasm and Root Locus. Never seen anybody
using them on a real design other than academics.


Tam

On Friday, in article
<[email protected]>
[email protected] "Tim Wescott" wrote:

>So, I've put the finishing touches on my book, and the publisher's
>marketing department is asking me questions. Some of them I don't have
>good answers to, because (a) I'm on the fringe of my target audience,
>and (b) everyone learns differently, and my way is through osmosis and
>thinking, which doesn't make it easy to cough up a bunch of specific
>information like conferences and magazines.

They need what they think they need for standard tick box list of checks.

>The book's title is "Applied Control Theory for Embedded Systems", the
>subject should be self explanatory. So if you feel that you're in the

Sounds like a sensible idea fo a book..

>target audience, and if you're in a generous mood, here are some
>questions I have for you:
>
>What do they call you at work (sorry -- what's your official job title?)

I used to have all sorts of job titles, as often every company has different
meanings for job titles (let alone the made up ones that appear now).

Having spent over 12 years working for myself in a one man company I
have various titles (some legal, some other meanings) depending on what
I am doing at the time and the questioner. Job titles only really have
relevance to questions.

>What magazines do you read? Websites you visit regularly?

Magazines IEE/IEEE periodicals (some), Circuit Cellar..

Websites are not something I spent a lot of regular time on specific ones
as it depends what I am working on or doing, except in bursts for datasheets
or specific issues, it would be Dilbert, Google, Ebay.

>Do you go to conferences? Which ones? (this is the one that motivated
>this posting, by the way -- I only go to the Embedded Systems
>Conference; I know there's a circuit-related one in Silicon Valley but I
>can't remember the name, nor do I know if there are any ones anywhere else.

Never gone to a conference, occasionally seem some of the papers. From
various sources it depends on the hosting country, speakers country,
sometimes who is sponsoring their 'research' and what is deemed patentable
under which jurisdiction as to whether you see enough detail anyway. I know
of cases in many fields where published papers are very 'sanitised' for
varying reasons to make you wonder if the paper is worthwhile.

>Have you had to close a control loop recently? Did you do a web search?
> What keywords did you use?

Mainly revisiting various loop controls/tuning for PID, servo loops and
nuances. Considering some of the project time spans, recent could be two
years (due to many other things).

>Have you read any related books? Was it just a college text, or was it
>specifically directed at closed loop control for the practicing embedded
>systems designer? What did you think of it? What was it?

Most of them I found too abstract or too ideal mathematical models with lots
of assumptions. some of the worst assumptions I have seen is we have a model
for an actutator/motor that applies to all actuators/motors, where as in
real life modeling of the subsystem is quite complex and cannot always be
done theoretically but has to be done at first empirically as the full design
is 'n' stages down the road. In one instance to get the model and even think
of tuning it was complicated by differing response times of sensors to software

Quadrature encoders
position indicators
optical position from line scan processing

Further complicated by temperature, standing or moving before hand or worse
still some of it was effected by different control loops controlling
high voltage light sources and other parts of the system.

That was even before you looked at mechanical interactions, tolerances,
determining fault conditions (mechanical, electrical, optical).

Too often the books forget about fault conditions, that can be directly
determined or have to be determined from other sources.

A lot of theory books are a bit like the old sciences joke

A bookie wanted to know if there was a scientific way to
determine the outcome of any horse race, so he asked the
three scientists.

The chemist said "Too many unknowns and variables"

The biologist said "Too many factors to make it possible"

The Physicist said "Yes"

When the bookie asked how, the physicist said

"For spherical horses in a vacuum"

The worst demo of control software for computer (PC and larger) data
acquistion systems I saw had classic limits and real world is somewhere
else issues. Basically the demo consisted of a model of a simple oven that
was heated and its temperature would rise, until the door was opened. The
longer the door was closed or open the higher or lower the temperature would
go.

Now those here would hopefully know that if the door was opened the lowest
temperature that could be reached was ambient in real life, in a model
should be absolute zero. This model had no limits so the temperature could
go below absolute zero or higher than the sun! So did not show the software
in best light of showing how good the software could be.

Hopefully your book will not be like that.

--
Paul Carpenter | [email protected]
<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

Tim Wescott wrote:
> So, I've put the finishing touches on my book, and the publisher's
> marketing department is asking me questions. Some of them I don't have
> good answers to, because (a) I'm on the fringe of my target audience,
> and (b) everyone learns differently, and my way is through osmosis and
> thinking, which doesn't make it easy to cough up a bunch of specific
> information like conferences and magazines.
>
> The book's title is "Applied Control Theory for Embedded Systems", the
> subject should be self explanatory. So if you feel that you're in the
> target audience, and if you're in a generous mood, here are some
> questions I have for you:
>
> What do they call you at work (sorry -- what's your official job title?)
>
> What magazines do you read? Websites you visit regularly?
>
> Do you go to conferences? Which ones? (this is the one that motivated
> this posting, by the way -- I only go to the Embedded Systems
> Conference; I know there's a circuit-related one in Silicon Valley but I
> can't remember the name, nor do I know if there are any ones anywhere else.
>
> Have you had to close a control loop recently? Did you do a web search?
> What keywords did you use?
>
> Have you read any related books? Was it just a college text, or was it
> specifically directed at closed loop control for the practicing embedded
> systems designer? What did you think of it? What was it?
>
> Thanks in advance.
>

I knew it!
http://books.elsevier.com/us//elsevi...unity=elsevier
The book is too small.

On Fri, 24 Feb 2006 10:39:46 -0800, Tim Wescott <[email protected]>
wrote:
>So, I've put the finishing touches on my book, and the publisher's
>marketing department is asking me questions. Some of them I don't have
>good answers to, because (a) I'm on the fringe of my target audience,
>and (b) everyone learns differently, and my way is through osmosis and
>thinking, which doesn't make it easy to cough up a bunch of specific
>information like conferences and magazines.
>
>The book's title is "Applied Control Theory for Embedded Systems", the
>subject should be self explanatory. So if you feel that you're in the
>target audience, and if you're in a generous mood, here are some
>questions I have for you:

>What do they call you at work (sorry -- what's your official job title?)
Engineer

>What magazines do you read? Websites you visit regularly?
EETimes, Sensors, Medical Devices, Machine Design
IEEE Spectrum, .....for some reason they won't send me ESP
I got ESP back in 1995, but they won't renew my free subscription
CircuitCellar, Nuts and Volts, sometimes Servo.

>Do you go to conferences?
No. Can't justify the cost. Way to expensive considering the
lost time, conference fees and travel costs.

>Have you had to close a control loop recently?
> Did you do a web search? What keywords did you use?
Sure, but what does that have to do with the websearch?

>Have you read any related books? Was it just a college text, or was it
>specifically directed at closed loop control for the practicing embedded
>systems designer? What did you think of it? What was it?

Quantum Programming. I thought it was great!
A good summary of state machines and an alterative ways to use them.

On Time and Under Pressure by Ed Sullivan. An old book. . A great
overview of what makes a great organization tick, particularly the
Version Control and Automated Build processes,

Patent it Yourself, David Pressman. A great step by step process for
submitting a patent.

The Scientist and Engineer's Guide to Digital Signal Processing
Free PDF book. I've been reading chapters. Great stuff.

I don't generally read "controls" books anymore unless they are
product manuals. For anything new, I'll read technical publications,
or the web. For anything old I just refer to my bookshelf.

>Thanks in advance.
>Tim Wescott
>Wescott Design Services
>http://www.wescottdesign.com

Dougal McDougal of that Elk wrote:

> "Tim Wescott" <[email protected]> wrote in message
> news:[email protected]..
>
>>So, I've put the finishing touches on my book, and the publisher's
>>marketing department is asking me questions. Some of them I don't have
>>good answers to, because (a) I'm on the fringe of my target audience,
>>and (b) everyone learns differently, and my way is through osmosis and
>>thinking, which doesn't make it easy to cough up a bunch of specific
>>information like conferences and magazines.
>>
>>The book's title is "Applied Control Theory for Embedded Systems", the
>>subject should be self explanatory.
>
>
> I hopr you have lest out Nyquist diagrasm and Root Locus. Never seen anybody
> using them on a real design other than academics.
>
>
> Tam
>
>
You should look over my shoulder some time, then.

I use root locus when I'm brainstorming controllers, and I have my
spreadsheet program display top & bottom Nyquist & Bode plots when I'm
tuning from measured frequency responses -- I put a circle of diameter
1/sqrt(2) on the Nyquist plot to indicate the 3dB sensitivity point, and
tune to that.

I _don't_ spend many pages showing how to construct root locus plots --
while you do learn something from it there's a gazillion math
applications that will do it for you.

--

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

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

Fred Bloggs wrote:

>
>
-- snip --

>
> I knew it!
> http://books.elsevier.com/us//elsevi...unity=elsevier

Yes, that's it. Done, thanks be.

>
> The book is too small.
>
That's three years worth of writing! Perhaps I've just managed to
condense the wisdom down, eh?

I'm going to take the first complimentary copy they give me and tape a
red pen to it on a string, to make marginal comments. I expect that if
it lives to a 2nd edition it will grow.

--

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

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

Paul Carpenter wrote:

> On Friday, in article
> <[email protected]>
> [email protected] "Tim Wescott" wrote:
>
-- snip --

>>Have you read any related books? Was it just a college text, or was it
>>specifically directed at closed loop control for the practicing embedded
>>systems designer? What did you think of it? What was it?
>
>
> Most of them I found too abstract or too ideal mathematical models with lots
> of assumptions. some of the worst assumptions I have seen is we have a model
> for an actutator/motor that applies to all actuators/motors, where as in
> real life modeling of the subsystem is quite complex and cannot always be
> done theoretically but has to be done at first empirically as the full design
> is 'n' stages down the road. In one instance to get the model and even think
> of tuning it was complicated by differing response times of sensors to software
>
> Quadrature encoders
> position indicators
> optical position from line scan processing
>
> Further complicated by temperature, standing or moving before hand or worse
> still some of it was effected by different control loops controlling
> high voltage light sources and other parts of the system.
>
> That was even before you looked at mechanical interactions, tolerances,
> determining fault conditions (mechanical, electrical, optical).
>
> Too often the books forget about fault conditions, that can be directly
> determined or have to be determined from other sources.
>
> A lot of theory books are a bit like the old sciences joke
>
> A bookie wanted to know if there was a scientific way to
> determine the outcome of any horse race, so he asked the
> three scientists.
>
> The chemist said "Too many unknowns and variables"
>
> The biologist said "Too many factors to make it possible"
>
> The Physicist said "Yes"
>
> When the bookie asked how, the physicist said
>
> "For spherical horses in a vacuum"
>
> The worst demo of control software for computer (PC and larger) data
> acquistion systems I saw had classic limits and real world is somewhere
> else issues. Basically the demo consisted of a model of a simple oven that
> was heated and its temperature would rise, until the door was opened. The
> longer the door was closed or open the higher or lower the temperature would
> go.
>
> Now those here would hopefully know that if the door was opened the lowest
> temperature that could be reached was ambient in real life, in a model
> should be absolute zero. This model had no limits so the temperature could
> go below absolute zero or higher than the sun! So did not show the software
> in best light of showing how good the software could be.
>
> Hopefully your book will not be like that.
>
I tried to keep it grounded in reality, to live up to the "Applied" in
the title. Most of the examples are simplified, so that I can talk to
the point that I'm trying to make, but I try to keep the other issues
visible.

I think there's a place for simplistic models -- I've done motion
controllers where the emphasis was on getting a mechanism from point A
to point B without toasting any electronics or breaking/jamming the
mechanism, and accuracy was taken care of by other parts of the system.
In those cases a very simple model that ignored such complications
like backlash and friction worked very well -- as long as I remembered
what the limitations of the model were. I tried to keep up a continuing
theme that you need to remember what assumptions you made about your
model, and what those assumptions mean.

--

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

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

Fred Bloggs wrote:
>
>
> Tim Wescott wrote:
>
>> So, I've put the finishing touches on my book, and the publisher's
>> marketing department is asking me questions. Some of them I don't
>> have good answers to, because (a) I'm on the fringe of my target
>> audience, and (b) everyone learns differently, and my way is through
>> osmosis and thinking, which doesn't make it easy to cough up a bunch
>> of specific information like conferences and magazines.
>>
>> The book's title is "Applied Control Theory for Embedded Systems", the
>> subject should be self explanatory. So if you feel that you're in the
>> target audience, and if you're in a generous mood, here are some
>> questions I have for you:
>>
>> What do they call you at work (sorry -- what's your official job title?)
>>
>> What magazines do you read? Websites you visit regularly?
>>
>> Do you go to conferences? Which ones? (this is the one that
>> motivated this posting, by the way -- I only go to the Embedded
>> Systems Conference; I know there's a circuit-related one in Silicon
>> Valley but I can't remember the name, nor do I know if there are any
>> ones anywhere else.
>>
>> Have you had to close a control loop recently? Did you do a web
>> search? What keywords did you use?
>>
>> Have you read any related books? Was it just a college text, or was
>> it specifically directed at closed loop control for the practicing
>> embedded systems designer? What did you think of it? What was it?
>>
>> Thanks in advance.
>>
>
> I knew it!
> http://books.elsevier.com/us//elsevi...unity=elsevier
>
> The book is too small.
>

I love
"Readership: PRIMARY MARKET: ...
SECONDARY MARKET: Engineering students at the *more practical*
engineering and technical schools; ..." emphasis added ;/

Lets out my Alma Mater.

The advanced BS(Physics) students came to Phillips Hall to take our
*REQUIRED* course in quantum mechanics. In the 60's I would have gotten
more hands on "engineering" experience as a BS(Physics) student than I
had a chance of as a 5-yr BSEE candidate. I fault IEEE and other
professional societies for creating that problem with ill thought out
course "standards". But the basic problem predates the various
societies. My father got an ME degree, rather than persuing an EE
degree, because (in the 1920's) the ME candidates received a much
broader background in what would now be considered EE. At that time and
this institution, EE was power plant, power distribution, and AC/DC
machines. Whereas, he had the opportunity to study in an "applicable [
*NOT APPLIED* ] math course" what we routinely use when working with
op-amps.

I'll consider dismounting a major pet peeve hobby horse.

PS. If anyone reading this is member of appropriate IEEE committee on
educational standards, my reply-to is valid and I would be more than
happy to contribute to improving the situation.

Anyone get impression that this is a hot button issue for me ;/

Richard Owlett wrote:
>
.... snip ...
>
> PS. If anyone reading this is member of appropriate IEEE committee
> on educational standards, my reply-to is valid and I would be more
> than happy to contribute to improving the situation.

I was about to mention that no reply-to showed on your article,
when I decided to look at the full headers and discovered it
there. Yet it didn't show up for normal headers on NS 4.75, while
my own reply-to does! Then I realized it was identical to your
'from' address, and concluded that NS had suppressed the non-useful
additional header display.

I still keep finding ways in which NS 4.7x is superior to
Thunderbird 1.5.

--
Some informative links:
news:news.announce.newusers
http://www.geocities.com/nnqweb/
http://www.catb.org/~esr/faqs/smart-questions.html
http://www.caliburn.nl/topposting.html
http://www.netmeister.org/news/learn2quote.html

"Richard Owlett" <[email protected]> wrote in message
news:[email protected]..
>
> PS. If anyone reading this is member of appropriate IEEE committee on
> educational standards, my reply-to is valid and I would be more than happy
> to contribute to improving the situation.
>
> Anyone get impression that this is a hot button issue for me ;/
>
>

It am easy try rowremovethisbitherelett@atandthisbi...scomm.re verseten

See and I have not even have to be member of committeeee to give you
appropriate information to solve your problem plus you am not have pay me
monee for find wrong answer........ Plus I went back and peer reviewed
myselv so iz correct.

DNA

Hi Tim,

Tim Wescott wrote:
> So, I've put the finishing touches on my book, and the publisher's
> marketing department is asking me questions. Some of them I don't have
> good answers to, because (a) I'm on the fringe of my target audience,
> and (b) everyone learns differently, and my way is through osmosis and
> thinking, which doesn't make it easy to cough up a bunch of specific
> information like conferences and magazines.
>
> The book's title is "Applied Control Theory for Embedded Systems", the
> subject should be self explanatory. So if you feel that you're in the
> target audience, and if you're in a generous mood, here are some
> questions I have for you:
>
> What do they call you at work (sorry -- what's your official job title?)
>

dickhead. oops, senior design engineer

> What magazines do you read? Websites you visit regularly?
>

IEEE trans:
industry applications
industrial electronics
power electronics
control systems (although almost entirely useless)

> Do you go to conferences? Which ones? (this is the one that motivated
> this posting, by the way -- I only go to the Embedded Systems
> Conference; I know there's a circuit-related one in Silicon Valley but I
> can't remember the name, nor do I know if there are any ones anywhere else.
>

PCIM, HFPC, APEC

> Have you had to close a control loop recently? Did you do a web search?
> What keywords did you use?

yep. nope. did it all from first principles, using a pen and paper. then
fiddled with resultant parts to optimise both BOM and response.

>
> Have you read any related books? Was it just a college text, or was it
> specifically directed at closed loop control for the practicing embedded
> systems designer? What did you think of it? What was it?
>

a plethora of them. Computer Controller Systems, Astrom & Wittenmark are
right at the top of the list. Slotine & Li, applied nonlinear control is
damn good too, but not for the fainthearted. as is macejowskis
multivariable control. I have a couple of dozen control books, some of
the oldest ones are brilliant - far less use of brute-force techniques,
much more emphasis on understanding. Automatic Control Systems
Enigneering vol. 2, Langill, is fabulous.

> Thanks in advance.
>

Cheers
Terry

On Saturday, in article
<[email protected]>
[email protected] "Tim Wescott" wrote:
>Paul Carpenter wrote:
>> On Friday, in article
>> <[email protected]>
>> [email protected] "Tim Wescott" wrote:
>>
>-- snip --
>
>>>Have you read any related books? Was it just a college text, or was it
>>>specifically directed at closed loop control for the practicing embedded
>>>systems designer? What did you think of it? What was it?
>>
>> Most of them I found too abstract or too ideal mathematical models with lots
>> of assumptions. some of the worst assumptions I have seen is we have a model
>> for an actutator/motor that applies to all actuators/motors, where as in
>> real life modeling of the subsystem is quite complex and cannot always be
>> done theoretically but has to be done at first empirically as the full design
>> is 'n' stages down the road. In one instance to get the model and even think
>> of tuning it was complicated by differing response times of sensors to
>> software

.....

>> That was even before you looked at mechanical interactions, tolerances,
>> determining fault conditions (mechanical, electrical, optical).
>>
>> Too often the books forget about fault conditions, that can be directly
>> determined or have to be determined from other sources.

.......

>> Hopefully your book will not be like that.
>>
>I tried to keep it grounded in reality, to live up to the "Applied" in
>the title. Most of the examples are simplified, so that I can talk to
>the point that I'm trying to make, but I try to keep the other issues
>visible.

I realise that there has to be simplification, but a lot of theory does
not USUALLY cover the applied like what to do when an external sensor
or feedback in the loop says there is a fault and how to make sure the
loop (and the system) return to the correct state (whatever that may be).

An example would be printing shop guillotines that usually require two
spaced out buttons to be pressed at the same time for the whole of the cut
process. On the basis that if both hands are on the buttons then the
operator's hands are not in the machinery! Now dpending on how the system
operates there are basically three safety stop states - stop, move back
a little or return to start position.

I have seen some control systems really screwed by an 'abort' function
that need complete restarts or worse after that, basically because the
control loop hardware/software could not effectively reset correctly.

>I think there's a place for simplistic models -- I've done motion
>controllers where the emphasis was on getting a mechanism from point A
>to point B without toasting any electronics or breaking/jamming the
>mechanism, and accuracy was taken care of by other parts of the system.
> In those cases a very simple model that ignored such complications
>like backlash and friction worked very well -- as long as I remembered
>what the limitations of the model were. I tried to keep up a continuing
>theme that you need to remember what assumptions you made about your
>model, and what those assumptions mean.

Quite often I have seen customers who do not understand the limitations
and assumptions in their systems let alone any model they think they have
created.

Some of the major control loop problems I have seen is applying open loop
blocks to an overall system that is closed loop. Mainly because they
did not understand the limits of the blocks they were using, most
notably delays, determinicity and sampling restraints.

--
Paul Carpenter | [email protected]
<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

Richard Owlett wrote:
> Fred Bloggs wrote:
>
>>
>>
>> Tim Wescott wrote:
>>
>>> So, I've put the finishing touches on my book, and the publisher's
>>> marketing department is asking me questions. Some of them I don't
>>> have good answers to, because (a) I'm on the fringe of my target
>>> audience, and (b) everyone learns differently, and my way is through
>>> osmosis and thinking, which doesn't make it easy to cough up a bunch
>>> of specific information like conferences and magazines.
>>>
>>> The book's title is "Applied Control Theory for Embedded Systems",
>>> the subject should be self explanatory. So if you feel that you're
>>> in the target audience, and if you're in a generous mood, here are
>>> some questions I have for you:
>>>
>>> What do they call you at work (sorry -- what's your official job title?)
>>>
>>> What magazines do you read? Websites you visit regularly?
>>>
>>> Do you go to conferences? Which ones? (this is the one that
>>> motivated this posting, by the way -- I only go to the Embedded
>>> Systems Conference; I know there's a circuit-related one in Silicon
>>> Valley but I can't remember the name, nor do I know if there are any
>>> ones anywhere else.
>>>
>>> Have you had to close a control loop recently? Did you do a web
>>> search? What keywords did you use?
>>>
>>> Have you read any related books? Was it just a college text, or was
>>> it specifically directed at closed loop control for the practicing
>>> embedded systems designer? What did you think of it? What was it?
>>>
>>> Thanks in advance.
>>>
>>
>> I knew it!
>> http://books.elsevier.com/us//elsevi...unity=elsevier
>>
>> The book is too small.
>>
>
> I love
> "Readership: PRIMARY MARKET: ...
> SECONDARY MARKET: Engineering students at the *more practical*
> engineering and technical schools; ..." emphasis added ;/
>
> Lets out my Alma Mater.

TW must be talking about WPI http://www.wpi.edu/ , pronounced Wuss-duh
in those parts.


>
> The advanced BS(Physics) students came to Phillips Hall to take our
> *REQUIRED* course in quantum mechanics. In the 60's I would have gotten
> more hands on "engineering" experience as a BS(Physics) student than I
> had a chance of as a 5-yr BSEE candidate. I fault IEEE and other
> professional societies for creating that problem with ill thought out
> course "standards". But the basic problem predates the various
> societies. My father got an ME degree, rather than persuing an EE
> degree, because (in the 1920's) the ME candidates received a much
> broader background in what would now be considered EE. At that time and
> this institution, EE was power plant, power distribution, and AC/DC
> machines. Whereas, he had the opportunity to study in an "applicable [
> *NOT APPLIED* ] math course" what we routinely use when working with
> op-amps.
>
> I'll consider dismounting a major pet peeve hobby horse.
>
> PS. If anyone reading this is member of appropriate IEEE committee on
> educational standards, my reply-to is valid and I would be more than
> happy to contribute to improving the situation.
>
> Anyone get impression that this is a hot button issue for me ;/
>
>

Wes

Fred Bloggs wrote:

-snip-

>> I love
>> "Readership: PRIMARY MARKET: ...
>> SECONDARY MARKET: Engineering students at the *more practical*
>> engineering and technical schools; ..." emphasis added ;/
>>
>> Lets out my Alma Mater.
>
>
> TW must be talking about WPI http://www.wpi.edu/ , pronounced Wuss-duh
> in those parts.
>
If it was me it was supposed to be off the record.

My Thesis advisor once told me that the first time he visited WPI he
spent about an hour on the interstate -- he was looking for Wu'sta. He
passed by Wor-ches-ter several times before it sunk in...

--

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

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

Tim Wescott wrote:
> Fred Bloggs wrote:
>
.... snip ...
>>
>> TW must be talking about WPI http://www.wpi.edu/ , pronounced
>> Wuss-duh in those parts.
>>
> If it was me it was supposed to be off the record.
>
> My Thesis advisor once told me that the first time he visited WPI
> he spent about an hour on the interstate -- he was looking for
> Wu'sta. He passed by Wor-ches-ter several times before it sunk in...

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
"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 Sat, 25 Feb 2006 20:34:04 -0800, Tim Wescott <[email protected]>
wrote:

[snip]
>
>My Thesis advisor once told me that the first time he visited WPI he
>spent about an hour on the interstate -- he was looking for Wu'sta. He
>passed by Wor-ches-ter several times before it sunk in...

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:
> Tim Wescott wrote:
>
>>Fred Bloggs wrote:
>>
>
> ... snip ...
>
>>>TW must be talking about WPI http://www.wpi.edu/ , pronounced
>>>Wuss-duh in those parts.
>>>
>>
>>If it was me it was supposed to be off the record.
>>
>>My Thesis advisor once told me that the first time he visited WPI
>>he spent about an hour on the interstate -- he was looking for
>>Wu'sta. He passed by Wor-ches-ter several times before it sunk in...
>
>
> What happened when he needed fish from Gloss-tuh?

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:
> On Saturday, in article
> <[email protected]>
> [email protected] "Tim Wescott" wrote:
>
--snip--

>>>Hopefully your book will not be like that.
>>>
>>
>>I tried to keep it grounded in reality, to live up to the "Applied" in
>>the title. Most of the examples are simplified, so that I can talk to
>>the point that I'm trying to make, but I try to keep the other issues
>>visible.
>
>
> I realise that there has to be simplification, but a lot of theory does
> not USUALLY cover the applied like what to do when an external sensor
> or feedback in the loop says there is a fault and how to make sure the
> loop (and the system) return to the correct state (whatever that may be).
>
> An example would be printing shop guillotines that usually require two
> spaced out buttons to be pressed at the same time for the whole of the cut
> process. On the basis that if both hands are on the buttons then the
> operator's hands are not in the machinery! Now dpending on how the system
> operates there are basically three safety stop states - stop, move back
> a little or return to start position.
>
> I have seen some control systems really screwed by an 'abort' function
> that need complete restarts or worse after that, basically because the
> control loop hardware/software could not effectively reset correctly.
>
If you were to write an article about this (beyond "think hard about
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).
>
>>I think there's a place for simplistic models -- I've done motion
>>controllers where the emphasis was on getting a mechanism from point A
>>to point B without toasting any electronics or breaking/jamming the
>>mechanism, and accuracy was taken care of by other parts of the system.
>> In those cases a very simple model that ignored such complications
>>like backlash and friction worked very well -- as long as I remembered
>>what the limitations of the model were. I tried to keep up a continuing
>>theme that you need to remember what assumptions you made about your
>>model, and what those assumptions mean.
>
>
> Quite often I have seen customers who do not understand the limitations
> and assumptions in their systems let alone any model they think they have
> created.
>
> Some of the major control loop problems I have seen is applying open loop
> blocks to an overall system that is closed loop. Mainly because they
> did not understand the limits of the blocks they were using, most
> notably delays, determinicity and sampling restraints.
>
I don't think it's just that people don't understand the limits of their
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 <[email protected]>
wrote:

>Paul Carpenter wrote:
[snip]
>>
>> Some of the major control loop problems I have seen is applying open loop
>> blocks to an overall system that is closed loop. Mainly because they
>> did not understand the limits of the blocks they were using, most
>> notably delays, determinicity and sampling restraints.
>>
>I don't think it's just that people don't understand the limits of their
>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).

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.