Most of the control literature focuses on minimizing the integrated absolute error (IAE) for a step disturbance, often in a linear system. In the process industry, there are many other objectives and complications that require special attention.
The power of the PID largely remains untapped. I have recently documented the extensive capability of the PID but being a realist, I expect MPC is going to take over more and more of the role of the PID.
There are some simple diagnostic checks and rules of thumb on tuning adjustments that can be used to find out if there is a problem with the PID tuning and what is the solution. This guidance in conjunction with good tuning software can reduce process variability introduced or aggravated by...
Before the 1990s relatively few choices in PID structure were offered. There were also various supplier specific rules as to how to set the proportional mode and integral mode tuning settings to get proportional-only and integral-only control. A different model controller may have been needed for a different structure.
Not knowing the implications of the PID Form in an existing control system being migrated or the PID Form learned in a University course can cause gross errors in the tuning parameters and potential instability. The PID Form predominantly used today is not the Form in most of the controllers...
The primary reason why there are so many and so different schools of thought about control algorithms and tuning can be traced back to one parameter in the process response. What PID tuning and what PID structure is pronounced as best and even whether PID control should be used is...
Tuning has a profound effect on the practical limit to control loop performance. While the effect of execution time and filter time is often much less in comparison, these time settings can get the user into trouble depending on tuning and loop dynamics. Here is a perspective, overview, and recommendations.
Fast oscillations are particularly insidious because the best thing a PID controller can do is ignore them. Action taken by PID controller can do more harm than good in terms of resonance, amplification, and perpetuation leading to increased process variability and premature valve failure.
A unified approach to PID Control has been found that enables a common and simplified method for setting PID tuning parameters. Key features can be used to eliminate the need for retuning to deal with different dynamics and objectives.
The PID is by far the most prevalent controller in the process industry. Here we step back for a view of the basics of the proportional, integral, and derivative modes. These PID controller modes have distinct advantages and disadvantages and consequences if one mode dominates.
