Method and apparatus for real-time control

Claim 1

Digital processing apparatus for monitoring and controlling an industrial process, the apparatus comprising processing means for processing a set of data signals representative of a corresponding set of periodically sensed process parameter values, and for generating in real-time, in response to said data signals, a set of calculated response values representative of requested process parameter values, said processing means including knowledge base means for providing knowledge relating to the industrial process, to enable said processing means to process said data signals in accordance with said knowledge, said knowledge base means including rule base means for providing a set of rules representative of said knowledge, inference engine means for calculating intermediate data values in response to said data signals and said rules, and for calculating, in real-time, said response values, in response to any of said data signals, said intermediate data values, and said rules, said inference engine means including expression evaluation means for evaluating logical expressions representative of any of said data signals, said intermediate data values, and said rules, each said logical expression including a set of variables corresponding to said data signals, time-stamp means, for determining and assigning a time-stamp value to each said data signal, said time-stamp values being representative of a time at which each said process parameter value is generated, and currency evaluation means, responsive to said time-stamp signals and to user-selected currency range values, for assigning an expiration-time value for each data signal, intermediate data value, and variable, and for discarding data signals having an expiration-time value outside a corresponding user-selected currency range value.