(96b) Loop Tuning Basics

There are many methods to tune PID controllers. This presentation provides a tutorial on tuning PID process controllers using Internal Model Control (IMC) concepts. This tuning methodology allows the user to ?coordinate? the response of related controllers to optimize the process performance rather than simply focusing on individual ?optimized controller tuning?. For example, is the process optimized by controlling the process variable (PV) close to the set point by aggressive moves of the controller output or, is it optimized by allowing the PV to vary from the set point with less movement of the controller output? Either objective can be easily met with this tuning methodology. Another application is the coordination of cascade loops. How do you know the tuning results in primary controller response being at least 5 -10 times faster than the secondary controller response? These questions are easily answered using the IMC based tuning method. Tuning calculations will be explained and plant examples will be used to illustrate the concepts and results.