Greg McMillan: The first versions of the proportional-integral-derivative (PID) controller date back almost 100 years, and have evolved into the most powerful and prevalent tool for basic and advanced regulatory control. Starting in the 1960s and over the five following decades, Greg Shinskey detailed the use of the PID for almost every type of application in the process industry, and showed how the PID is the best controller for handling unmeasured process input (load) disturbances.
Shinskey also showed how the PID can handle interactions by relative gain analysis (RGA), decoupling feedforward signals and valve position control. Sigifredo Nino, a Shinskey protégé, has continued his legacy, particularly in using of RGA in refineries. My entire career except for an occasional dabbling in model predictive control has been to make the most out of PID control. My 2015 Momentum Press book Tuning and Control Loop Performance Fourth Edition seeks to build on what I learned from Shinskey, confirming revelations by test cases to show what a PID can do employing often underutilized key features. Sigifredo and I did a tribute to Shinskey in the Control feature article “The greatest source of process control knowledge” that highlights what we learned with a list of Shinskey’s 7 books and 17 of his most influential articles and papers. The fact that all of Shinskey’s books documenting the treasure of his knowledge are out of print is a sad commentary on our publishing system. Fortunately, his last book, Process Control Systems Fourth Edition, is available from the Schneider Electric education department. The depth and extent of knowledge in his books will never be approached and may be lost to future generations. I am trying to keep his legacy alive through my publications and by the automation community via its technical society composing and issuing a comprehensive technical report.
The International Society of Automation (ISA) has done a great job in developing technical reports and standards for many aspects of automation system design and configuration. Back in fall 2019, I decided to form a committee of industry experts on process control to create a technical report titled "PID Algorithms and Performance."
The participation by leading experts has been exceptional. A 137-page ISA 5.9 technical report has been issued for general review and comment by the ISA 5.9 committee. Anyone can join the ISA 5.9 committee by contacting Torry Bailey at ISA headquarters ([email protected]). In this series of columns, we get the views of key ISA 5.9 contributors Yamei Chen, Pat Dixon, Mark Darby, Cheri Haarmeyer, Peter Morgan, Sigifredo Nino, Russ Rhinehart, Michel Ruel, Nick Sands, Jacques Smuts, Hunter Vegas and me.