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Remembering digital pioneer Charles R. Cutler

May 8, 2020
Cutler conceived of and implemented dynamic matrix control

During the month of March, I had the unqualified pleasure of interviewing and profiling the four uniquely qualified individuals inducted this year into the Control Process Automation Hall of Fame. The ranks of that elite fraternity have climbed to nearly 60 since it was first created in 2001, and while I always expect the inductees to be sharp as tacks (and on that count, I’m always right), it’s often the grace, humor and humility of the individuals leading our industry that impress me the most.

But just as the April issue of Control was about to go to press, I learned of the passing of Charles R. Cutler, one of the earliest inductees into the hall for his pioneering work in multivariable control—as well as a humble, approachable man who always asked to be called “Charlie.”

Characteristically, Charlie began recounting his achievements in his 2003 Hall of Fame profile interview with "I was in the right place at the right time." That place was Shell Oil Co. and the year was 1961.

The Lamar University graduate on football scholarship had decided to pursue a career in chemical engineering after breaking his leg twice on the gridiron. He had been the leading ground gainer in his conference, and passed up an offer to try out for the Green Bay Packers.

Right place, right time

"I was only at Shell a year when they decided to try out computerized process control,” Charlie said. “We would take a linear process, perturb it, take the derivative, and repeat the whole process, using a successive linear process."

So began the experiments that would lead Charlie to conceive and implement the concept of a dynamic matrix control (DMC) algorithm. He was eventually given management oversight of all the control systems at Shell, and DMC became the standard method of controlling complex processes at Shell during the late 1970s and early '80s—and saved the company a ton of money, too.

Even though he already was thinking that he had a commercially viable product on his hands, the lack of computing power kept DMC—and Charlie—captive to Shell. Each implementation was a hand-built, separate controller. "My goal was to make a generic controller that could be configured for each application. It would be easier to install and maintain.

"But the computers of the time wouldn't let us solve real multivariable problems," Charlie said. "We had to wait for computers with more horsepower. By the early '80s, we had computers that were reasonably good number crunchers, so I decided we could commercialize." By the time he left, Shell had more than 200 implementations of DMC.

In June 1984, Charlie and colleague Chuck Johnston resigned from Shell and founded Dynamic Matrix Control Corp. (DMCC), working out of the Cutler townhouse. In 1986, a DMC controller was installed on a Sunoco hydrocracker.

"The first time the controller was turned on, the optimizer reduced the energy usage 15%," Charlie recalled with obvious pride. Soon, every petroleum company had to have DMC. Texaco engineers once said in a technical presentation that DMC was saving $15,000-25,000 a day at the Port Arthur, Texas, refinery alone. After a successful decade of solving complex problems for customers, DMCC was sold to AspenTech in 1996 and Charlie retired in 1998.

“At AspenTech, we're very proud of our association with Charlie, and there's no question we benefited enormously from his unrivaled understanding of control technology and customer implementations,” wrote Antonio Petri, president and CEO of AspenTech, in a tribute recently posted on the company’s website. “On behalf of AspenTech, I extend to Charlie’s family and friends our sincere and heartfelt sympathies. It was a pleasure to know him, and his spirit of ingenuity will be missed.”

It will indeed. 

About the author: Keith Larson
About the Author

Keith Larson | Group Publisher

Keith Larson is group publisher responsible for Endeavor Business Media's Industrial Processing group, including Automation World, Chemical Processing, Control, Control Design, Food Processing, Pharma Manufacturing, Plastics Machinery & Manufacturing, Processing and The Journal.

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