Method of optimal scaling of variables in a multivariable predictive controller utilizing range control

Claim 1

In a process control system having a controller for providing robust control to a process, the process further having at least one manipulated variable and at least one process variable, a method for providing the robust control of a process, comprising the steps of: a) calculating a set of scale factors for the manipulated variables and the process variables; b) initializing the controller with the set of scale factors, the set of scale factors determining a relative importance to the process of the manipulated variables and the process variables; c) initializing the robust control to have predetermined constraints of the manipulated variables and the controlled variables; d) obtaining present values of the manipulated variables and the process variables said process variables corresponding to measurement parameters of the process; e) calculating new values of the process variables for a predetermined number of points in the future in order to have the values of the process variables within the predetermined range to obtain an optimal robustness of the resultant controller, the manipulated variables being within predetermined constraints, and the process variables falling within a predetermined range when controllable; otherwise, keeping process variable constraint violations to a minimum; f) from a plurality of solutions, selecting a most robust solution; and g) controlling the process in accordance with the most robust solution.