Feedback method for controlling non-linear processes

A system for controlling a plant process including manipulated variables comprising input states, and control variables comprising output states, said system comprising;

• sensor means for providing measures of at least said control variables;
• memory means for storing upper and lower limits and a correction time constant for at least one control variable, said upper and lower limits separated by a band of values within which said at least one control variable is considered acceptable, said correction time constant prescribing a rate of return of said one control value to within said band of values;
• processor means coupled to said sensor means and said memory means and including data describing a model of said plant process, said model relating costs of manipulated variables to control variables and, upon solution, further providing predicted values for said at least one said control variable, said processor means further including logic means responsive to a measured value function of said at least one control variable being outside of said band of values, to generate control signals to alter said manipulated variables in a direction to achieve a minimized cost thereof, said manipulated variables being altered at a rate in accordance with said correction time constant and in a direction to cause a predicted value of said at least one control variable to be within said band of values;
• and
• control signal means responsive to said control signals for operating instrumentalities in said plant to control said manipulated variables.