Model predictive controller for coordinated cross direction and machine direction control

Abstract

A process for coordinated control of machine direction MD and cross direction CD actuators in a sheetmaking machine for manufacturing a sheet of material is disclosed. The process involves measuring a plurality of sheet properties at regular intervals to collect sheet measurement data. The sheet measurement data is manipulated to establish a plurality of sheet property measurement arrays, which are then mapped to a common resolution. The common resolution sheet property measurement arrays are concatenated into one larger one-dimensional common resolution measurement array. The common resolution measurement array and an array of past changes in actuator set point are used as inputs to a paper machine process model state observer to generate the estimated current internal state of the sheet manufacturing process. A plurality of future-sheet property target arrays are concatenated into one target array. The array of the estimated current internal state of the web manufacturing process and the paper machine process model are employed to generate an array of future predictions of sheet properties. The array of future predictions of sheet properties, the target array, object function weights, the last actuator set points, and hard constraints are inputted into an object function which is solved to yield optimal changes in the actuator set points for coordinated MD and CD control of the sheet making process.