Modeling and control of sheet weight and moisture for paper machine transition

A method for modeling and controlling headbox transient responses for weight and moisture of a web of paper being manufactured by a paper making machine, said method comprising the steps of:

• determining fast mode weight and moisture responses due to headbox changes by performing the steps of:
• determining weight and moisture responses resulting from a step change applied to said headbox;
• setting a time delay for said fast mode weight and moisture responses equal to a first time period extending from said step change applied to said headbox to a time of first weight and moisture responses;
• measuring a first rate of change for said weight and moisture responses from an initial value to a peak value;
• and
• setting a time constant and process gains for said fast mode weight and moisture responses to correspond to said first rate of change for said weight and moisture responses,
• determining slow mode weight and moisture responses due to headbox changes;
• forming headbox weight and moisture transient models for headbox changes as a combination of said fast mode weight and moisture responses and said slow mode weight and moisture responses;
• determining a stock weight and moisture response model for operation of stock flow of said paper making machine;
• and
• controlling said stock flow in accordance with said stock weight and moisture response models and said headbox weight and moisture transient models to compensate for weight and moisture changes in said web of paper resulting from headbox changes.