In many publications on process control, the common metric you see is integrated absolute error for a step disturbance on the process output. In many tests for tuning, setpoint changes are made and the most important criteria becomes overshoot of setpoint.
The automation profession suffers from the lack of a common understanding of the terms used and their units. By taking a closer look at key terms for plant dynamics, we can have more intelligent discussions and better recognition of the contributing factors so that we can find what part of...
We conclude our review of nonlinearities with an overview of applications and a detailed list of simple solutions to minimize the adverse effects of this everyday problem in nearly all control loops. It is impressive how setting lambda equal to 3x the largest deadtime value helps to solve most nonlinearity...
Here we use the broader definition of linearity to mean constant dynamics. A linear control loop has a constant total loop dead time, constant primary and secondary time constants, and a constant open loop gain. This perspective reviews the sources of dynamics and causes of nonlinearity.
The speedup of a plant’s response can cause loops to go from a smooth to an oscillatory response. In actual plants, the faster rate of change of a process variable important for product quality such a temperature or composition occurs for various changes in operating conditions.
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...
The use of the term "process dead time" can mislead us in terms of recognizing the many sources of dead time. Also we don't often take into effect the profound effect of the speed and the entry point of a disturbance into the process.
I have dug deep into my memory to add 21 more items to the list of process, mechanical, and piping design mistakes that have made our job as automation engineers more challenging and in some cases impossible. We learn the most by our mistakes.
With a little help from my friends I have come up with a list of process, mechanical, and piping design mistakes that have made our job as automation engineers more challenging and in some cases impossible. We learn the most by our mistakes.
Most process engineers were not taught how process and equipment design affect loop dynamics and performance. Many of the more demanding control applications are the result poor process dynamics. Automation engineers can help bridge the gap and be able to intelligently discuss how plant design is affecting plant performance.