Patent ID: 7459060

Claim:
A method for alignment of a sheetmaking system having a plurality of actuators arranged in the cross-direction wherein the system includes a controller for adjusting output to the plurality of actuators in response to sheet profile measurements that are made downstream from the plurality of actuators, the method comprising the steps of: (a) determining alignment information from at least two cross-directional positions by: (i) operating the system and measuring a profile of the sheet along the cross-direction of the sheet downstream from the plurality of actuators and generating a profile signal that is proportional to a measurement profile; (ii) adding a perturbative signal to the profile signal to generate a first modified profile signal that simulates a disturbance at a position along the measurement profile or adding a pertubative signal to a setpoint target profile to generate a second modified profile signal that simulates a setpoint change at a position along the measurement profile; (iii) determining alignment shift information based on a closed-loop steady-state response of an actuator profile to the first or second modified profile signal; and (iv) repeating steps (i) through (iii) thereby obtaining alignment shift information from the least two cross-directional positions; and (b) identifying the changes in alignment of the sheetmaking system, if any, from the alignment shift information from at least two cross-directional positions.