Patent ID: 9399245
Filing Date: 2016-07-26
CPC Classification: B21B

Claim Text:
1. A method of providing flatness control for rolling a strip in a mill comprising a plurality of rolls controllable by means of actuators, the method comprising: a) receiving flatness measurement data pertaining to a flatness of the strip from a plurality of sensors, b) determining a flatness error as a difference between a reference flatness of the strip and the flatness measurement data, c) determining an adjusted flatness error based on the flatness error and weights or actuator position combinations which provide a flatness effect below a threshold value and provide constraints to control unit outputs controlling the actuators, and d) controlling the actuators based upon the adjusted flatness error to thereby control the flatness of the strip, wherein step c) comprises using a mill matrix reflecting a steady state flatness response of the mill, decomposing the mill matrix into singular value decomposition form, and by means of the singular value decomposition of the mill matrix, providing costs to the adjusted flatness error and control unit outputs to the actuators in directions corresponding to separate singular values of the mill matrix.