US 4,562,529 AGranted

Control of real time industrial processes

AssigneeProgramasyst Limited

InventorAndrew F. Drummond

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Abstract

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 STATE.sub.(N) AND OMI.sub.(N,M) =STATE.sub.(M) where N and M may have any integral value up to P, N does not equal M, STATE.sub.(N), OMI.sub.(N,M), and STATE.sub.(M) are all logical variables, and 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: (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 (ii) initiating any relevant and necessary control action on finding a STATE having the logical value TRUE.

Claims21

Dependent claims

A method of, controlling an industrial process for which a multiplicity of "operating states" of the process are separately identifiable, each said operating state being a combination of all the control conditions instantaneously prevailing throughout the process, which method comprises the steps of:

(a) representing each one of said multiplicity of said operating states in a control apparatus (30) by a corresponding logical variable of a "set" of such variables, in which set the multiplicity of members of the set is equal to at least the said multiplicity of said operating states;
(b) causing the variables of said set to comply in said apparatus with the rules that:
(i) one, and only one, member of the set can have the value TRUE at any one time, all others inherently then having the value FALSE;
(ii) any other member of said set can be required for control of the controlled process be the next succeeding member to take the value TRUE;
and
(iii) no member of said set may take the value FALSE except as a consequence of another member of the set taking the value TRUE;
(c) maintaining a correspondence between said separately identifiable operating states of the process and the logical values of the corresponding members of said set in said control apparatus (30) by detecting from feed back data or otherwise the occurrence of the required conditions appertaining to the change of operating state of the process from one current, operating state to another operating state and accordingly causing the said variable representing the said another operating state to take the value TRUE, the variable representing said one operating state thereupon automatically reverting to the value FALSE;
and
(d) initiating in said control apparatus any necessary and relevant control action consequent upon the setting to the value TRUE of said logical variable representing said another operating state;
and in which method representation of the operation of said process in said control apparatus (30) progresses from the member of said set which is currently TRUE directly to any other member of the set as appropriate upon detecting the occurrence of the required conditions appertaining to the relevant change of operating state of the process.

7 more elements

A control apparatus for which a multiplicity of "operating states" of the process are separately identifiable, each said operating state being a combination of all the control conditions instantaneously prevailing throughout the process for controlling an industrial process, which apparatus comprises:

(a) means for representing (in 56) each one of said multiplicity of said operating states by a corresponding logical variable of a "set" of such variables, in which set the multiplicity of members of the set is equal to at least the said multiplicity of said operating states, said means being constructed and arranged such that the variables of said set comply with the rules that:
(i) one, and only one, member of the set can have the value TRUE at any one time, all others inherently then having the value FALSE;
(ii) any other member of said set can as required for control of the controlled process be the next succeeding member to take the value TRUE;
and
(iii) no member of said set may take the value FALSE except as a consequence of another member of the set taking the value TRUE;
(b) means for maintaining (in 52) a correspondence between said separately identifiable operating states of the process and the logical values of the corresponding members of said set by detecting, from current value data relating to various relevant parameters of the controlled process as provided by respective feedback devices (32, 38;
34, 40;
36, 42)--or otherwise, the occurrence of the required conditions appertaining to the change of operating state of the process from one current operating state to another operating state and accordingly causing the said variable representing the said another operating state in said representing means to take the value TRUE, whereupon the variable representing said one operating state in said representing means automatically reverts to the value FALSE;
and
(c) means (54, 44-60) responsive to a said variable newly taking the value TRUE for providing in response thereto output control signals for initiating any necessary and relevant control action by said control apparatus (30) consequent upon setting to the value TRUE said logical variable representing said another operating state;
and in which apparatus representation of the operation of said process in said representing means progresses from the member of said set which is currently TRUE directly to any other member of the set as appropriate upon detecting the occurrence of the required conditions appertaining to the relevant change of operating state of the process.

8 more elements

Dependencies are inferred from the claim text.