Best Book on PID ??

[Jim Thompson]

Recommendations for Best Book on PID ??

Thanks!

...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 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Rich Grise]

On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson wrote:

Recommendations for Best Book on PID ??

Thanks!

I hope I'm not em-bare-ass-ing myself here, but what exactly is "PID" the
acronym for? Somehow or another, I seem to have missed that one. ?:-/

Thanks,
Rich

 

[Terry Given]

Rich Grise wrote:

On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson wrote:


Recommendations for Best Book on PID ??

Thanks!



I hope I'm not em-bare-ass-ing myself here, but what exactly is "PID" the
acronym for? Somehow or another, I seem to have missed that one. ?:-/

Thanks,
Rich

Proportional-Integral-Derivative

Many, many systems can be suitably controlled by using a feedback
controller combining the three terms. Either with an opamp or a DSP (or
for that matter hydraulic or mechanical controllers)

Oh, and Astrom and Wittnemark's "Computer Controlled Systems" has a
pretty good treatment on PID. I have seen a better book, but alas forget
its title - its a chemical process control book.

Cheers
Terry

 

[Tim Wescott]

Rich Grise wrote:

On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson wrote:


Recommendations for Best Book on PID ??

Thanks!



I hope I'm not em-bare-ass-ing myself here, but what exactly is "PID" the
acronym for? Somehow or another, I seem to have missed that one. ?:-/

Thanks,
Rich



"Proportional, Integral, Derivative" I think. It refers to the world's

most common linear controller algorithm.

--

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

 

[sparky]

"Rich Grise" <rich@example.net> wrote in message
newsan.2004.11.23.20.38.10.28968@example.net...

On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson wrote:

Recommendations for Best Book on PID ??

There is a book called PID Primer for sale on the these groups every now
and then. It seems to cover the basics very well.


And for Rich
PID = Proportional Intregral Differential

as applied to tuning instrument control circuits. This
applies equally to both electronic and pnuematic instrumentation.

Thanks!


I hope I'm not em-bare-ass-ing myself here, but what exactly is "PID" the
acronym for? Somehow or another, I seem to have missed that one. ?:-/

Thanks,
Rich

 

[Gregg]

Behold, Jim Thompson signalled from keyed 4-1000A filament:

Recommendations for Best Book on PID ??

Thanks!

...Jim Thompson

PID?

Jim....you really oughtta see a doctor :-/

;-p

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

 

[j.b. miller]

Try www.quanser.com for some GREAT stuff especially the PID controls.

OK, I'm biased, I actually built a lot of his equipment and was impressed
with the precision of the mechanics and the true realtime software in
Windows.

Jay

 

[Terry Given]

Spehro Pefhany wrote:

On Tue, 23 Nov 2004 21:28:09 GMT, the renowned Rich Grise
rich@example.net> wrote:


On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson wrote:


Recommendations for Best Book on PID ??

Thanks!


I hope I'm not em-bare-ass-ing myself here, but what exactly is "PID" the
acronym for? Somehow or another, I seem to have missed that one. ?:-/

Thanks,
Rich


Proportional-Integral-Derivative. It was invented more than 75 years
ago. It refers to feedback control with terms proportional to the
error, the integrated error and the derivative of the error wrt time.
(error being Process Variable (PV) - Setpoint (SP)).

Determining the three proportional terms is "tuning" the controller.
Over 90% of process control loops are PI or PID.

of which 1/3 provide a significant process improvement, 1/3 provide
little or no process improvement and 1/3 make the process worse - due
almost entirely to the inability of users to tune them correctly.

I wonder if autotuning has helped the situation any - probably not much,
I imagine the installed base of non-auto-tuning units isnt going to be
replaced in a hurry.

Cheers
Terry

 

[Spehro Pefhany]

On Tue, 23 Nov 2004 15:59:35 -0800, the renowned John Larkin
<jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote:

There are two aspects of this: the most obvious is the linear loop
dynamics, the classic Laplace-transform closed-loop response. Then
there's the far trickier nonlinear stuff: auto/manual control,
bumpless transfer, overshoot, integrator windup, process slew limits
(just ask a boiler to go from 0 to 100% steam flow in 30 seconds! Or
100 to zero, even worse!), autotuning, noise, feedforward, and
protection from runaway under various conditions. It's the latter
messy stuff that most of the textbooks tend to ignore.

John

You say that like it's a bad thing! ;-)


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

 

[Tim Wescott]

Martin Riddle wrote:

There is PID without tears on Embedded.com (I think), which a simplistic view.

"PID Without a PhD", and that's a "simplified" view, please. Inspired
by the directions given to union millwrights by control engineers who
aren't allowed to touch the equipment in many, if not most, mills.
Written by some schmo named "Wescott". Available through
http://www.wescottdesign.com/articles/pidwophd.html.

It certainly doesn't teach control theory, but it will let you twiddle
the knobs to get a working system most of the time (predicting how well
you'll like the result before you start requires control theory, however).

Then there is the text (Astrom) I have which goes from the basics to adaptive controllers etc.
PID controllers Theory ,design tuning. Lotsa good stuff.

I have Astrom's adaptive control book, and I love it. Part of my
admiration is inspired by the fact that he devotes a whole chapter to
alternatives to adaptive control -- anyone who's writes a book about a
pretty new theory then tells you when you don't really need it has
integrity, in my view.

--

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

 

[Rich Webb]

On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson
<thegreatone@example.com> wrote:

Recommendations for Best Book on PID ??

For learning (i.e., some math but not dense page after page of it) look
at "Control System Design Guide," George Ellis, ISBN 0-12-237461-4. I
have (and enjoyed) the 2nd edition of the book; the ISBN is for the 3rd,
published in 2004.

Web site, free companion software: http://www.qxdesign.com/index.htm

--
Rich Webb Norfolk, VA

 

[john jardine]

"John Larkin" <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote in
message news:hod7q01m735p9spgkvtmau7mg3v9uv8eqq@4ax.com...

On Tue, 23 Nov 2004 17:19:04 -0500, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Tue, 23 Nov 2004 21:28:09 GMT, the renowned Rich Grise
rich@example.net> wrote:

On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson wrote:

Recommendations for Best Book on PID ??

Thanks!


I hope I'm not em-bare-ass-ing myself here, but what exactly is "PID"
the
acronym for? Somehow or another, I seem to have missed that one. ?:-/

Thanks,
Rich

Proportional-Integral-Derivative. It was invented more than 75 years
ago. It refers to feedback control with terms proportional to the
error, the integrated error and the derivative of the error wrt time.
(error being Process Variable (PV) - Setpoint (SP)).

Determining the three proportional terms is "tuning" the controller.
Over 90% of process control loops are PI or PID.

There are two aspects of this: the most obvious is the linear loop
dynamics, the classic Laplace-transform closed-loop response. Then
there's the far trickier nonlinear stuff: auto/manual control,
bumpless transfer, overshoot, integrator windup, process slew limits
(just ask a boiler to go from 0 to 100% steam flow in 30 seconds! Or
100 to zero, even worse!), autotuning, noise, feedforward, and
protection from runaway under various conditions. It's the latter
messy stuff that most of the textbooks tend to ignore.

John

True.

Spent early years on petrochemical plant control&instrumentation. Safe
pneumatics, 3-15psi range (Foxboro, Honeywell, Taylor etc). Air driven
analogues of all the elecronic stuff that's about now, such as square root
extractors, multipliers, mass flow computers etc. All process control by
pneumatic PID controllers/recorders. The control courses all offered
numerous pat equations for optimising the plant dynamics. We learnt to our
dismay the equations looked neat in a textbook but useless on real plant.
Most of the control systems ended up proportionally slugged down to near
stupidity, with only the occasional bit of integral to wind down sticky
setups. 'Reset' never had chance to get a look in.
I never did identify one of those mooted ideal systems that could be
classically tuned. The real world stuff had many processes at work in // and
they -all- interacted. Lowest common denominator was the tuning rule.
regards
john

 

[Terry Given]

John Larkin wrote:

On Tue, 23 Nov 2004 17:19:04 -0500, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:


On Tue, 23 Nov 2004 21:28:09 GMT, the renowned Rich Grise
rich@example.net> wrote:


On Tue, 23 Nov 2004 13:45:14 -0700, Jim Thompson wrote:


Recommendations for Best Book on PID ??

Thanks!


I hope I'm not em-bare-ass-ing myself here, but what exactly is "PID" the
acronym for? Somehow or another, I seem to have missed that one. ?:-/

Thanks,
Rich

Proportional-Integral-Derivative. It was invented more than 75 years
ago. It refers to feedback control with terms proportional to the
error, the integrated error and the derivative of the error wrt time.
(error being Process Variable (PV) - Setpoint (SP)).

Determining the three proportional terms is "tuning" the controller.
Over 90% of process control loops are PI or PID.


There are two aspects of this: the most obvious is the linear loop
dynamics, the classic Laplace-transform closed-loop response. Then
there's the far trickier nonlinear stuff: auto/manual control,
bumpless transfer, overshoot, integrator windup, process slew limits
(just ask a boiler to go from 0 to 100% steam flow in 30 seconds! Or
100 to zero, even worse!), autotuning, noise, feedforward, and
protection from runaway under various conditions. It's the latter
messy stuff that most of the textbooks tend to ignore.

John

Oh yes. One of the best papers I have read lately is:
"An Electronic Throttle Control Strategy Including Compensation of
Friction and Limp-Home Effects" Deur, Pavkovic et al,
IEEE industry apps may/june 2004 vol 40 no.3 pp821-834

These guys take the whole shebang into account. Interestingly enough
they optimise the large-signal step response by omitting the setpoint
from the P & D terms (something Astrom et al talk about).

Cheers
Terry

 

[Ron H]

Do you want to understand it or do you just need to tune it?

If the later, search on "Ziegler-Nichols". It's a technique that will get
your loop tuned and running smooth in short order. If the former, there is
no end to the options but before you spend money, search on "PID Controller"
and you'll find plenty of info.


73
K3PID
Ron H.





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[Jim Thompson]

On Tue, 23 Nov 2004 19:45:14 -0600, "Ron H" <rnharsh@attbi.com> wrote:

Do you want to understand it or do you just need to tune it?

If the later, search on "Ziegler-Nichols". It's a technique that will get
your loop tuned and running smooth in short order. If the former, there is
no end to the options but before you spend money, search on "PID Controller"
and you'll find plenty of info.


73
K3PID
Ron H.

Aha!! The perfect pointer! Thanks!

And what do you know, old "Nichols Chart" himself... last used one
about 40 years ago ;-)

...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 |

I love to cook with wine. Sometimes I even put it in the food.

 

[John Larkin]

On Tue, 23 Nov 2004 21:12:33 -0500, John Popelish <jpopelish@rica.net>
wrote:

John Larkin wrote:

Right. I've rarely seen derivative do much to a real-world process but
make it go nuts, the main exception being fast motion control servos.
(snip)
This controller includes a
setpoint slew limiter that creeps even slower when we're within 5
degrees of the setpoint, to guarantee no overshoot; a few degrees over
and we can poach an enzyme that a thousand rabbits died to make.

Eliminating that overshoot is one of the uses of properly applied
derivative.

I never could get derivative to work in this particular application.
The thermocouple is in a dewar maybe a foot downstream of the heater,
and the gas flow isn't fully mixed when it hits the t/c. The heater
emits four little jets of hot air, sort of like Stripe toothpaste. So
the temperature is literally noisy, and derivative goes sort of crazy
if set to any useful-to-the-dynamics level. That's a common problem in
flow systems. I designed all sorts of cute flow stirring devices (a
simple spring isn't bad) but couldn't get anybody interested in poking
them into the dewar.

Customers are the other big control problem.

John

 

[Spehro Pefhany]

On Tue, 23 Nov 2004 21:12:33 -0500, the renowned John Popelish
<jpopelish@rica.net> wrote:

John Larkin wrote:

Right. I've rarely seen derivative do much to a real-world process but
make it go nuts, the main exception being fast motion control servos.
(snip)
This controller includes a
setpoint slew limiter that creeps even slower when we're within 5
degrees of the setpoint, to guarantee no overshoot; a few degrees over
and we can poach an enzyme that a thousand rabbits died to make.

Eliminating that overshoot is one of the uses of properly applied
derivative.

Part of the problem is that numbskull implementations don't properly
LPF the signal before taking the derivative so that ordinary process
and quantization noise makes the D term useless at the proper setting.

You didn't see that with analog controllers, because analog engineers
understand stuff like that. And it doesn't generally appear in the
textbooks.


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

 

[Spehro Pefhany]

On Tue, 23 Nov 2004 19:17:14 -0700, the renowned Jim Thompson
<thegreatone@example.com> wrote:

On Tue, 23 Nov 2004 19:45:14 -0600, "Ron H" <rnharsh@attbi.com> wrote:

Do you want to understand it or do you just need to tune it?

If the later, search on "Ziegler-Nichols". It's a technique that will get
your loop tuned and running smooth in short order. If the former, there is
no end to the options but before you spend money, search on "PID Controller"
and you'll find plenty of info.


73
K3PID
Ron H.


Aha!! The perfect pointer! Thanks!

Z-N tuning is an experimental controller tuning method. It tends to be
a bit aggressive for real systems (so, increase the P. band). I've got
a copy of the original 1942 paper around somewhere if you can't find
it online (shouldn't be that hard).

And what do you know, old "Nichols Chart" himself... last used one
about 40 years ago ;-)

...Jim Thompson

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

 

[Clifford Heath]

John Larkin wrote:

It's the latter
messy stuff that most of the textbooks tend to ignore.

Has anyone here made use of fractional calculus (differentiation
& integration) in control loops?

But perhaps the math is too new for the applications to have been
tested...? There was also a time when roots and powers were always
integral, as differentiation/integration is even now to most folk
.

I'm interested to know what kinds of systems benefit from it, and
how you implemented it - pure curiosity of course.

Clifford Heath.

 

[Spehro Pefhany]

On Tue, 23 Nov 2004 21:44:26 -0500, the renowned John Popelish
<jpopelish@rica.net> wrote:

Spehro Pefhany wrote:

Z-N tuning is an experimental controller tuning method. It tends to be
a bit aggressive for real systems (so, increase the P. band). I've got
a copy of the original 1942 paper around somewhere if you can't find
it online (shouldn't be that hard).

Walter Driedger has posted a PDF copy of the world famous Z-N paper on
his web site:
http://www.driedger.ca/
http://www.driedger.ca/Z-N/Z-N.html

Okay, that's a nice HTML version. I've got a 5M PDF scan version of
the ASME paper here:

http://members.rogers.com/speff/Ziegler-Nichols.pdf


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