Industrial & Engineering Chemistry Research, Vol.51, No.13, 4968-4981, 2012
Tuning a Soft Sensor's Bias Update Term. 2. The Closed-Loop Case
The difficulty in measuring certain types of process variables rapidly has encouraged the use of soft sensors, which can determine the values of difficult to measure process variables based on easily available secondary process variables. A bias update term that allows the system to take into consideration disturbances in the system is often included in such soft sensor systems. In the second part of this two-part series, an investigation of the bias update term in closed-loop operation in the presence of a drifting (integrating) disturbance for the ideal case, the case where there is measurement delay, the case with multirate sampling, and the case where there is a combination of measurement delay and multirate sampling is considered. Proposed tuning rules are provided for all cases in order to obtain optimal closed-loop tracking of the controller. Simulation and experimental validation of the results is also presented.