Dynamic Controller

Frustrated by Conventional Advanced Control Techniques, Charlie Cutler Had to Find a Better Way

By Charlie Cutler

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Running in Manual

Charles Cutler may have been at the helm in the creation of two engineering firms, but his son-in-law Chuck Johnston (left) was right behind him in each case.

Cutler was eventually given management oversight of all the control systems at Shell, optimizing numerous processes and saving the company tons of money. Dynamic matrix control became the standard method of controlling complex processes at Shell during the late 1970s and early '80s.

Even though he already was thinking that he had a commercially viable product on his hands, the lack of computing power kept DMC and Cutler 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," Cutler says. "We had to wait for computers with more horsepower. Now we do matrices of 10,000 x 100,000. We started out with 40 x 40. By the early '80s, we had computers that were reasonably good number crunchers, so I decided we could commercialize." By the time Cutler left, Shell had more than 200 implementations of DMC.

DMC Becomes a Company

Cutler and Chuck Johnston resigned from Shell and founded Dynamic Matrix Control Corp. in June 1984, working out of the Cutler townhouse. The Johnstons moved in next door. It was two years before the first commercial software to configure a multivariable controller became available with the DMC controller software.

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%," he recalls 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.

"This was the first time theory and standard software came together in such a way that all the practical, real-world issues of implementing [multivariable process control] on major process units were dealt with effectively," says Ronald Sorensen, consulting engineer in process control and optimization at Chevron Research & Technology Co., Richmond, Calif.

DMCC was an engineering-driven company built on the philosophy that customers must be satisfied, and the best way to do that was to "continue to work on a project until the customer was convinced we were making them money," Cutler says. Though the financial success of his customers was first in his mind, Cutler remained driven by the need to solve problems.

In 1995, he realized his company's software needed a more user-friendly interface to remain competitive, and he thought of partnering with a simulation company to provide it. In 1996, Houston-based Aspen Technology not only provided the interface but suggested a merger, and Cutler decided to sell.

He worked for Aspen for two years after the sale, then retired,temporarily,to his ranch in west Texas. But his thoughts turned again to control and to solving a problem that he helped create. "One of the problems created by a large DMC controller is the loss of operator skills in operating the process. I thought of ways to use the DMC controller as a training simulator."

So in 2000 he again teamed with Johnston to create Cutler Johnston Corp. Aspen Tech helped create the graphical user interface. Two years of development later, the Universal Process Identification (UPID) resulted. "It permits the creation of an open loop model (all-valve model) that can be used by a training simulator. The software permits a unit to be tested with one PID configuration and later changed to another."

In March, he moved Cutler Johnston from Houston to the west Texas ranch, where Cutler can continue to consult and work with the UPID--as well as enjoy his grandchildren.

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