Control of multi-variable processes

A method for enhancing control of operation of a multi-variable process, the method comprising the steps of:

• (a) deriving a multi-dimensional representation of process variables of the process according to individual coordinate axes, the derived multi-dimensional representation of the process variables including representing current values of the individual process variables on respective ones of the coordinate axes;
• (b) defining a feasible region of the process variables, the feasible region being based on sets of values for the process variables accumulated respectively in relation to a multiplicity of previous operations of the process to establish limits for each of the process variables individually;
• (c) defining, for each process variable, a range within which the current value of that process variable is to lie in order for operation of the process to remain within the feasible region, the range defined for each individual process variable being dependent on the values of the others of the process variables;
• (d) detecting, in respect of each of the process variables, whether an alarm condition exists, and an alarm condition existing in respect of that process variable when the current value of that process variable lies outside the range defined for that process variable;
• (e) responding to the existence of the alarm condition in respect of any of the process variables to calculate change of the value of at least one of the process variables required for annulling the alarm condition;
• (f) indicating, in relation to the one process variable, the calculated change of value required for annulling the alarm condition, and the step of indicating the calculated change including a step of providing a visual display of the derived multi-dimensional representation of the process variables, the visual display comprising representation of the coordinate axes, representation of the current values of at least some of the process variables on their respective coordinate axes, and representation of the ranges defined individually for the process variables represented in the display, the calculated change of value required for annulling the alarm condition being represented in the visual display by a displacement of the representation of the current value of at least one of the process variables along a respective coordinate axis of the displayed process variable;
• and
• (g) changing the value of the one process variable in accordance with the calculated change for annulling the alarm condition.