ISA automation week was a success in terms of technical content. The renewed emphasis on technical presentations particularly in automation and control rejuvenated my interest in the International Society of Automation. I moderated a panel discussion on loop tuning. Harold Wade setup the ISA simulator for the following cases that were designed by me to include some typical application problems.
In the tuning panel discussion, James Beall, Brian Hrankowsky, Michel Ruel, and Hunter Vegas showed how diverse tuning methods and tools can yield similar results. Here are the presentations that summarize the results of the tuning by the panelists:
I also presented a paper on loop performance metrics “How to Get the Most out of Your PID” in the technical program for engineers. The presentation showed simple equations for loop metrics and controller tuning for the self-regulating, deadtime dominant, near-integrating, true integrating, and runaway processes. The relationships offer considerable insight in the maze of tuning methods. The Handbook of PI and PID Controller Tuning Rules – 2nd edition has 500 pages of equations and tables. I found a unifying concept where the major tuning methods such as Lambda, Simplified Internal Model Control (SIMC), Ziegler Nichols Ultimate Oscillation, and Ziegler Nichols Reaction Curve, yield the same expressions for controller gain for maximum disturbance rejection. The key parameter is loop deadtime as noted by Michel Ruel. Both Michel and I have used the deadtime and the maximum ramp rate with the near-integrator approximation to dramatically reduce the tuning time for slow processes. The peak error for a disturbance and rise time for a setpoint change is minimized as the controller gain is maximized. The minimum overshoot requires a balance between the controller gain and reset time settings. The minimum integrated error is achieved for the minimum ratio of the reset time to gain settings.
At the award’s banquet on Monday evening Oct 4, 2008 president Kim Miller-Dunn, director of Rosemount Liquid Analytical customer support and the 2010 ISA president Nelsen Ninin, president of Yokogawa South America, presented me with the ISA Achievement Award. The last person to receive this award was Greg Shinskey.
I had just 2 minutes for my acceptance speech and had prepared some notes, which is not typical for me. Fortunately, after 4 glasses of wine, I decided to wing it. I thanked ISA for such an incredible event to celebrate my wedding anniversary but was concerned what my wife would expect next year.
After this comic relief, I first thanked in particular Dr James R. Fair, Energy Chair Emeritus at the University of Texas, who created and directed Engineering Technology (ET). I then acknowledged Vernon Trevathan, my first supervisor in ET and developer of the ISA Certification of Automation Professionals (CAP) program, who handed off his expertise to me in compressor control, loop performance, and pH control. Vernon like Greg Shinskey got to the heart of the key concepts and first principles. Sadly, we lost Vernon Trevathan last year and Dr Fair last Monday.
In ET we were given the support and inspiration by Dr Fair to find, develop, and publish our expertise. The result was an incredible group of world leaders in their particular fields of expertise who shared their results through publications. It resulted in me writing a dozen technical books and a ½ dozen humorous books, most of which would not have been encouraged by chemical companies or permitted by most patent and public relation departments. I concluded with noting that in my post retirement career as a part time consultant for Emerson, Rosemount Liquid Analytical, Experitec, and Mynah Simulation Technologies, I was benefiting from the expertise of Mark Nixon in DeltaV R&D and Jim Gray in Rosemount Liquid Analytical.