SYSTEM AND METHOD FOR PROCESS MONITORING AND CONTROL

摘要

The system for process monitoring and control integrates statistical process control (SPC) with automatic process control (APC) through the use of a fuzzy logic (FZL) controller, In order to relate the inputs to the output, fuzzy inference rules are applied. The fuzzy rules are based on the use of the APC controller during normal situations, deviating to;SPC as soon as abnormalities are detected. When the output error is negligible and the change in the output quality characteristic is almost zero, the fuzzy logic controller (FZLC) provides a utilization factor parallel for applying the APC controller. The FZLC has two inputs: the output error ert and the rate of change of the output quality characteristic dyt. The FZLC has a single output: the controller utilization factor wt. When ert is large and dyt is maximum, the controller utilization factor wt will utilize the application of the SPC controller.

主权项

1. A method for process monitoring and control in an automated system having an automatic process controller, a statistical process controller, and a fuzzy logic controller, the method comprising the steps of:
feeding back an output error ert of the process as a first input to the fuzzy logic controller; feeding back a rate of change of an output quality characteristic dyt of the process as a second input to the fuzzy logic controller; applying a set of fuzzy inference rules in the fuzzy logic controller to produce a controller utilization factor wt as a fuzzy logic controller output; inputting the controller utilization factor wt to the automatic process controller when the output error ert is below a fuzzy output error threshold and the rate of change of the output quality characteristic dyt is below a fuzzy output quality characteristic threshold so that process monitoring and control of the monitored process is controlled by the automatic process controller; and inputting the controller utilization factor wt to the statistical process controller so that process monitoring and control of the monitored process is controlled by the statistical process controller when the output error ert is not below a fuzzy output error threshold or the rate of change of the output quality characteristic dyt is not below a fuzzy output quality characteristic threshold.