Reader Feedback: What Does "Process Control" Mean Anyway?

Dec. 11, 2014
According to This reader, "Process Control" Does Not Have a Sufficiently Universal Meaning

In providing solutions to realize the potentials for improvements in production and manufacturing, I found that the phrase "process control" does not have a sufficiently universal meaning.

Many people by default take it for what is known as "regulatory control," that is, the compensation for disturbances, so that process parameters are close to desired target values—the setpoints. Regulatory control as a function can be optimized, including criteria such as close to target, costs, and constraint requirements, etc. This is, of course, only one aspect of process control.

Another aspect of process control is the adjustment of setpoint values, i.e., giving operating directions to the regulatory control to implement. This engineering job is an aspect of operations management, often implemented through supervisory control. Supervisory control, as a function, can also be optimized, addressing the balance of multitude of objectives, such as product quality, costs, throughput, environmental protection and satisfying constraint requirements, including safety, commitments, availability, capacity, regulations, etc. There are several optimization solutions on the market to achieve these objectives at various levels of thoroughness, which include advanced and intelligent supervisory control.

One way to help resolve the problem mentioned by Paul Studebaker—"Few companies have been able to fully optimize a process, and there remains a great deal of unrealized potential"—I wish would help professionals be well aware of these two areas of control and control optimization.

With that aim in mind, it would be also useful to have an unbiased resource to provide, for each regulatory and supervisory control solution in the market today, a map of what internal and external resources are required to plan, install and maintain each solution. This would include, as conditions and business needs change, the costs of implementation in addition to manpower and fees, the capability scope of each solution, and how quickly improvements are obtained.

Carlos Moreno
Ultramax Corporation

Paul Studebaker responds: Carlos, we start with a broad definition of process control: An engineering discipline that deals with architectures, mechanisms and algorithms for maintaining the output of a specific process within a desired range. Over the years, Control has published and has amassed much of the information you seek, but alas, not in the format you describe. Perhaps others can direct you to an existing organized body of knowledge. Meanwhile, we’ll keep working on it.