Online Resources: Loop Control Systems

Feb. 26, 2015
This month, the editors of Control browse the web to get you the latest online resources on loop control. Here's how you can stay in the loop!

This System Is Closed

This is a basic tutorial on closed-loop control systems. It covers the basic definitions and descriptions of how closed-loop systems work, a discussion of closed-loop summing points and how to use them, transfer functions, multi-loop closed-loop systems and closed-loop motor control. The direct link is
Electronics Tutorials

PID Control

VeriCal in-situ calibration verification This is a basic discussion, with illustrations, of the principles of Proportional, Integral, Derivative (PID) and how it is used with controllers. It also covers tuning rules and starting settingf for common control loops. The direct link is at
Metso ExperTune

Cascading Control

A brief blog post by Jacques Smuts, author of Process Control for Practitioners covering cascade control basics: what it is; how to manage it; its advantages and disadvantages; when you should use it, and when you shouldn’t. The direct link is at

Big Book of Control Loops

Control Loop Foundation for Batch & Continuous Processes by Terry Blevins and Mark Nixon is a guide for engineers, managers, technicians and others that are new to process control or experienced control engineers who are unfamiliar with multi-loop control techniques. After the traditional single-loop and multi-loop techniques that are most often used in industry are covered, a brief introduction to advanced control techniques is provided. A free 163-page PDF provides a Power Point outline of the same material at The book itself is available from the ISA website in both hard-copy and ebook form in both English and Chinese.

Zen and the art of Loop Control

Process Hall of Famer F. Greg Shinskey meditates on disturbance dynamics, the three classes of disturbances: setpoint changes, load variations and noise. Other meditation subjects include internal model control, feedback, load response, identifying load components, dynamic difference, effects on controller tuning, accommodating setpoint changes, and more. Read “Meditating on Disturbance Dynamics” at

A Seven-Step Program

The performance of industrial control loops directly affects company profitability and operability in several ways. It affects the stability, robustness and safety of the process. In addition, it plays a role in the cost, efficiency and maximum rate of production and influences the quality of the product. This white paper outlines a systematic, seven-step approach for improving control system performance and describes the key points to follow for ensuring each step is implemented successfully. The paper is free, but registration is required. The direct link is at

Process Control for the Real World

Practical Process Control is a free online ebook with contributions by multiple authors. Subject covered include fundamentals, the components of control loops, graphical modeling, PID controller design and modeling,  tuning concepts, controller tuning using closed-;oop data, evaluating controller performance, the control of integrating processes, advanced classical control architectures, cascade control, feedforward and three-element control. The direct link is at
The Control Guru

Tune-Up Time

This free guide offers a best-practices approach to PID controller tuning. It shares a simplified and repeatable procedure for analyzing the dynamics of a process and for determining appropriate model and tuning parameters. Included are basic terminology, steps for analyzing process dynamics, methods for determining model parameters, and other valuable insights. The direct link is at
Yokogawa Corporation of America


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