By Bob Rice1 and Doug Cooper Integrating (or non-self regulating) processes display counter-intuitive behaviors that make them surprisingly challenging to control. In particular, they do not naturally settle out to […]
By Bob Rice1 and Doug Cooper As has been discussed elsewhere in this e-book, it is best practice to follow a formal recipe when designing and tuning a PID controller. […]
By Bob Rice1 and Doug Cooper The case studies on this site largely focus on the control of self regulating processes. The principal characteristic that makes a process self regulating […]
When considering the range of control challenges found across the process industries, it becomes apparent that very different controller behaviors can be considered “good” performance. While one process may be […]
A fairly common stumbling block for those new to controller tuning relates to step 2 of the controller design and tuning recipe. Step 2 says to “collect controller output (CO) […]
The controller design and tuning recipe we have used so successfully on this site requires that we bump our process and collect dynamic data as the process responds. For the […]
Ziegler and Nichols first proposed their method in 1942. It is a trial-and-error loop tuning technique that is still widely used today. The automatic mode (closed-loop) procedure is as follows:
The term “plant-wide control” is used here to describe the use of advanced software that sits above (or on top of) the individual PID controllers running a number of process […]
Processes with streams comprised of gases, liquids, powders, slurries and melts tend to exhibit changing (or nonlinear) process behavior as operating level changes. We discussed the nonlinear nature of the […]
There are two sample times, T, used in process controller design and tuning. One is the control loop sample time (step 4 of the design and tuning recipe) that specifies […]