This book explores various techniques for tuning controllers to design centralized PI/PID controllers for both stable and unstable systems represented by transfer function matrices. It reviews straightforward tuning methods for decentralized PID controllers in multivariable systems. An overview of techniques such as the design of decentralized PI controllers using the no proportional kick method and analytical methods is provided, along with illustrative examples. Additionally, the book includes simulation studies on designing decentralized PI controllers for the Reactive Ion Etcher (RIE) process. It details several advanced methods for centralized controller design, including the Biggest Log Modulus Tuning (BLT) method, the Synthesis method, and the Modified Internal Model Control (IMC) method, applicable to both stable and unstable systems. For the design of centralized control systems, methods such as the Relative Gain Array (RGA), the Relative Normalized Gain Array (RNGA), and the Effective Transfer Function (ETF) based on the Enhanced RGA (ERGA) are discussed. The book emphasizes that improved performance can be achieved by identifying three parameters of the Critically Damped Second Order Plus Time Delay (CSOPTD) model rather than relying solely on the First Order Plus Time Delay (FOPTD) model. Several simulation examples are provided for designing multivariable control systems, specifically for controlling crude distillation columns in petroleum units, using the method of inequalities and the random search method.

Furthermore, the book presents a method for designing multivariable controllers based on the goal attainment technique, also supported by examples. This textbook is ideal for B.Tech and M.Tech students in Chemical Engineering who specialize in Process Control, Control Engineering, Instrumentation Engineering, and Electrical Engineering. It is also a valuable resource for researchers in Control Engineering.