Patent ID: 7820012
Filing Date: 2010-10-26
Classification: D21G

Abstract:
1. A system 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 system comprising: (a) means for determining alignment information from at least two cross-directional positions that includes: (i) means for measuring a profile of the sheet along the cross-direction of the sheet downstream from the plurality of actuators; (ii) means for generating a profile signal that is proportional to a measurement profile; (iii) mean for 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 for adding a perturbative 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 wherein the plurality of actuators is connected to a perturbed profile measurement, a setpoint, or an error, which is the difference between the setpoint and the perturbed profile measurement in the closed-loop through the controller; and (iv) means for 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 (b) means for identifying the changes in alignment of the sheetmaking system, if any, from the alignment shift information from at least two cross-directional positions.