Best Book on PID ??

[Jim Thompson]

Recommendations for Best Book on PID ??

Thanks!

...Jim Thompson

 

[Rich Grise]

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]

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

 

[sparky]

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.

 

[Spehro Pefhany]

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

I've got one by Astrom, also the ISA book "Tuning and Control Loop
Performance", and Liptak's Process Control Handbook.

 

[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

 

[Spehro Pefhany]

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.

 

[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]

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

 

[Chuck Harris]

Best book? It all comes down to some nasty math.

"Servo Mechanism Analysis", by Thaler and Brown, is probably
as good a book as any... It's probably even on your bookshelf,
as it is a good 50 years old.

There is no easy way out of these problems, either you
characterize the open loop system, and design a proper
PID equation to control it, or you fudge things and
hope for the best. Computer based servo loops have made
fudging things much easier than it used to be... but I am
pretty sure, based on your relationship with computers,
that you aren't planning to do a computer based PID.

-Chuck Harris

 

[Rich Webb]

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

 

[Spehro Pefhany]

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

 

[john jardine]

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]

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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[john jardine]

[clip]

I did manage to fry a few hundred k$ worth of NMR probes a while back.
The main system control software (a c++ horror) would occasionally ask
my box to go to +3000 centigrade, so I dutifully turned the heater
power to max and waited for null. We had to add a battery-backed
serial-protocol blackbox recorder to our uP code to catch them in the
act. Then added a max_temp variable that can *only* be manually set
from the front panel of our controller. 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.

John

Well done. What's a few hundred k$ here and there. Would hope the C++
programmers were terminated with maximum predjuduce.
Best I've done is poisoning (ISTR) 10 tons of Platinum oxide catalyst. Was
told the stuff is biblically expensive but they never brought up its value.
At the time there was an explosion and fire and I'd been called out to
overide some auto ESD trips allowing isolation of a plant segment.
regards
john

 

[John Popelish]

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.

 

[Jim Thompson]

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

 

[John Larkin]

message On Tue, 23 Nov 2004 17:19:04 -0500, Spehro Pefhany

On Tue, 23 Nov 2004 21:28:09 GMT, the renowned Rich Grise

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

Recommendations for Best Book on PID ??

Thanks!

[clip]

I did manage to fry a few hundred k$ worth of NMR probes a while back.
The main system control software (a c++ horror) would occasionally ask
my box to go to +3000 centigrade, so I dutifully turned the heater
power to max and waited for null. We had to add a battery-backed
serial-protocol blackbox recorder to our uP code to catch them in the
act. Then added a max_temp variable that can *only* be manually set
from the front panel of our controller. 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.

John

Well done. What's a few hundred k$ here and there. Would hope the C++
programmers were terminated with maximum predjuduce.
Best I've done is poisoning (ISTR) 10 tons of Platinum oxide catalyst.

Damn, topped again!

I did do some interesting things on a supertanker that earned me the
nickname "Lights-Out Larkin."

John

 

[John Popelish]

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).

I am frustrated with industrial PID controllers that force me to
choose between having the P & D terms based entirely on error or
entirely on the process measurement only. What I often need is a
separate gain and derivative term for the process measurement and
setpoint inputs to the controller. This is almost always superior the
gain and/or derivative based entirely on error (setpoint - process
measurement) or base entirely just on the process measurement and lets
me optimize (after I define that word for the particular loop) the
process disturbance response and setpoint change response,
individually. For critical tuning, I have to use the feed forward
connection and external math to to get all the factors I need. Why
must I choose chocolate or vanilla when I really want a swirl.