CONTROL OF REAL TIME INDUSTRIAL PROCESSES

A control method and apparatus (30) for controlling a real time industrial process of which the operation can be defined by a set of P logical statements of the form EQU STATE.sub.(N) AND OMI.sub.(N,M) =STATE.sub.(M) where PA0 N and M may have any integral value up to P, PA0 N does not equal M, PA0 STATE.sub.(N), OMI.sub.(N,M), and STATE.sub.(M) are all logical variables, and PA0 OMI.sub.(N,M) is the conjunctive OPERATING MODE INCREMENT that is necessary to the progress of the process from STATE.sub.(N) to STATE.sub.(M), and in which set only one such STATE variable at a time can be recognized as having the value TRUE. In the method and apparatus the following steps are performed: PA0 (i) evaluating in turn each successive STATE in at least a group of said STATES in the set on the basis of feedback data relating to current values of various relevant parameters of the process and the current TRUE STATE, by (a) determining the logical value of the preceding STATE or STATES on which said STATE is dependent, (b) determining the logical value of the or each OPERATING MODE INCREMENT on which said STATE is dependent, and (c) evaluating the logical statement defining said STATE, using the logical values just determined for the or each preceding STATE and the associated OPERATING MODE INCREMENT to determine the logical value of said STATE; and PA0 (ii) initiating any relevant and necessary control action on finding a STATE having the logical value TRUE.