Process control systems and methods.
A self-tuning system for controlling a process (10) based on a measured parameter comprises a modular parameter estimator (12) and parameter conversion/controller arrangements (14, 18; 20, 24, 28; 30, 34) which are used in conjunction with the process and which receive as an input the measured parameter. An IMC (internal model controller) arrangement is used for one of the parameter converter/controller arrangements (20, 24, 28) and incorporates a feed forward index which is used for gain scheduling. Regression analysis is also used in conjunction with the conventional gain scheduling to more accurate refine the control action. A limiter is also used in conjunction with the regression analysis to avoid an overly high or overly low correction signal for the controller.