Nonlinear Model-Based Control: Using First-Principles Models in Process Control has just been made available by ISA. It is the latest book by R. Russell Rhinehart, ISA Fellow, AIChE Fellow and Control magazine Process Automation Hall of Fame inductee. 
First-principles models (engineering models) are used in industry for process design, troubleshooting, training, online analysis, and supervisory optimization. Rhinehart recommends their use for control because they effectively handle nonlinearity, nonstationary behavior, and interacting variables with only one tuning coefficient per controlled variable (CV).
Using optimization, the controller can handle constraints and shape the manipulated variables to achieve desired controlled variable trajectories. This book is his collection of practicable methods. Rhinehart said using first-principles models for control can also enhance the operational staff's understanding of the process, support auxiliary process management, and keep the mathematics at the engineers' comfort level. In addition, unifying all models across diverse process management operations ensures continuity and compatibility. “Most controllers, including model-based controllers, are linear and locally valid.
They are tuned or calibrated for one operating region. But when tank levels or flow rates change, the process gain, time-constant, and dead times all change. This requires retuning or recalibration, which can be expensive and time-consuming. First-principles model-based controllers will work properly throughout the entire operating range. One benefit is that once tuned, they remain tuned until substantial physical changes occur in the process,” Rinehart said.
The book explains four control techniques using first-principles models that have been credibly demonstrated for industrial practice: generic model control, process-model-based control, predictive functional control, and horizon predictive control. It illustrates their applications and discusses the pros and cons of each. To provide a better understanding of first-principles models, the book includes examples of setting up functions for controllers and discusses inherent properties such as ease of tuning, the handling of nonlinearity and interaction, feedforward constraints and the range of operation. With experience in both industry (13 years) and academia (31 years), Rhinehart has made it his mission to bridge the gap between industry and academia.
Rhinehart is professor emeritus in the School of Chemical Engineering at Oklahoma State University and was head of the school for 13 years. He received the 2009 ISA Distinguished Service Award and the 2013 Fray International Sustainability Award. Length: 414 pages. ISBN Print: 978-1-64331-242-2. ISBN ePub: 978-1-64331-243-9.
Kindle: 978-1-64331-244-6 Find this and other technical resources for automation and control professionals. This news item originally appeared in the April 2024 isue of InTech digital magazine.
