PID Equation Deriavation (Automation)

[Ken M]

... and the key thing to remember about Maxwell was where he came from. Just like Kelvin and Watt and Rankine and Black and ...

(... and RMA and kennyb on this site!)

 

[Peter Nachtwey]

More information and no one caught my math error.

http://books.google.com/books?id=1g...X&oi=book_result&resnum=1&ct=result#PPA145,M1

These guys were real engineers back then.
I bet they could put a transfer function or differential equation on the machines they worked on.

I think the PID block and concept of PID has dumbed down what it takes to control a closed loop system. The average PID tuner does not need to do the system identication and the differential equations but I also think this is yet another case where the tool has constrained the thinking of the users.

 

[macs_plc]

There is an Advanced PID Block in I/A Series DCS system..
Its quite Good

See this...

Explanation is ....

The PIDA controller implements continuous PID feedback and additive and multiplicative feedforward control of an analog loop (see Figure 93-1). Its principal inputs, setpoint and measurement,are used to compute its output, the manipulated variable, based on user-set or adaptively tuned values of the tuning parameters – proportional band, integral time, derivative time, delay time, and setpoint relative gain. The feedforward capability can be used to decouple interacting loops, such as a slow level control cascading to a fast flow control, in addition to compensating for measured load upsets.

The combination of the PIDA block, plus FBTUNE and FFTUNE extender blocks provide adaptive control capabilities of the I/A Series patented EXACT MultiVariable control (see the FBTUNE and FFTUNE Block Descriptions in this document). Connections can be made to the FBTUNE and FFTUNE blocks, while the PIDA controller is operating, by configuring the PIDA block’s BLKSTA into the PIDBLK parameter in the FBTUNE and FFTUNE extender blocks. The FBTUNE extender block adaptively tunes the feedback ontroller parameters for controller modes containing proportional and integral terms. The FFTUNE extender block provides dynamic compensation for an absolute multiplicative or additive feedforward input and both static and dynamic compensations for 3 or 4 incremental feedforward inputs and adapts the compensator
parameters. Also an extension connection can be made to a CHARC (characterizer)block, that applies matched functions to setpoint and measurement.

 

[Peter Nachtwey]

There aren't any equations.

What are the equations for the FBTune and FFTune? Why does the set point need a compensator?

 

[macs_plc]

FBTUNE - FeedBack Tunner Block
FFTUNE - FeedForward tunner Block

These are available as two seperate blocks...

Plz go through this pdf file Link for more info..
http://resource.invensys.com/iaseries/pss/21s3/21s3m2b4.pdf

I will post the detailed info in a while.....

 

[macs_plc]

i will post the other pdf in 2 days in detail