One Size Does Not Fit All: Tuning a Controller for Your Specific Process, 2001 Process Control, Electrical & Info. Conference Proceedings

George Buckbee--There are many methods for tuning a PID controller. To choose the proper tuning method and the proper tuning parameters, you must have a good understanding of the process to be tuned. To be more precise, you need to understand the process objectives, the process dynamics, interaction with other loops, and the operating strategy. This paper will demonstrate that even if the process equipment is identical, the proper tuning methods and tuning parameters for two loops could be dramatically different.

Methods of controller tuning include Ziegler-Nichols Ultimate Gain (closed loop), Cohen-Coon reaction curve (open loop), Lambda, and several others. While these methods are well understood academically, there are many practical aspects that must be taken into account. Process issues and operating strategies play a key role in selecting the proper method of tuning.

You must have a solid understanding of the process objectives and controller objectives to select the proper tuning parameters. Choosing tuning parameters blindly, based on the results of an equation, can spell disaster...quite literally!

The paper will discuss the aspects of the process that must be understood, as well as how to collect this information. Then, it will examine controller tuning approaches, and explain how to choose both a tuning method and a set of tuning constants.