US 7,459,060 B2Granted

Reverse bump test for closed-loop identification of CD controller alignment

AssigneeHoneywell ASCa Inc.

InventorGregory E. Stewart

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Abstract

A reverse bump test, for identifying the alignment of a sheetmaking system while the system remains in closed-loop control, includes the following steps: (a) leaving the control system in closed-loop, (b) artificially inserting a step signal on top of the measurement (or setpoint) profile from the scanner, (c) recording the data as the control system moves the actuators to remove the perceived disturbance (or setpoint change), and (d) refining or developing a model from the artificial measurement disturbance (or setpoint change) to the actuator profile. The technique supplies the probing/perturbation signal to the scanner measurement, which is equivalent to supplying the probing/perturbation signal to the setpoint target) rather than inserting bumps via the actuator set points as has been practiced traditionally.

Claims27

Dependent claims

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.

5 more elements

Dependencies are inferred from the claim text.