Abstract: A control system regulates a controlled process. A first controller receives at least a first input variable and a second input variable and produces at least a first control variable and a second control variable. A delay unifier associated with the first controller introduces a first delay to one of the first and second control variables, the first delay being determined as a function of a second delay associated with another of the first and second control variables, and outputs first and second control variables with unified delay. A processor models effects of the controlled process. The processor receives the delayed first and second control variables output by the first controller and produces estimated process output variables. A second controller processes a difference between measured process output variables and the estimated process output variables to correct for disturbances.

Abstract: In a scanner used in a paper-making process to measure basis weight and other parameters of the fabricated paper sheet, variations in the separation of an opposed pair of sensing heads due to temperature induced deflections of upper and lower beams on which the heads are movably mounted as well as deflections and/or expansions of other portions of the support structure for the sensor are dynamically measured and compensated for. Temperature sensors mounted on carriages for the sensing heads measure the temperatures at different locations within the sensor support structure so that temperature differentials can be determined. The temperature differentials, which provide a measure of beam deflection at any given position of the head carrying carriage, are applied in accordance with a linearizing algorithm to correct the values provided by the sensing heads.

Abstract: An apparatus and method for controlling mass flow in an extrusion die provides cross-directional measurements of at least one property of an extrusion produced by the extrusion die, such measurements being made at a plurality of cross-directional locations that successively span the extrusion. The measurements are assembled to provide cross-directional profiles of the extrusion. A spatial-frequency splitter operates upon the cross directional profiles to separate selected spatial frequency component profiles from each cross-directional profile. A reference profile is provided for representing desired spatial frequency profiles. An error signal generator generates error signals representing the difference between the spatial frequency component profiles and the desired spatial frequency profiles and actuators control mass flow components of the extrusion die in response to the error signals.

Abstract: A distributed intelligence control system for controlling a cross direction profile characteristic of a traveling sheet, such as paper, during production, includes a scanner for measuring a property of the sheet at a plurality of cross direction locations and producing output signals indicative of the cross direction profile characteristic. A host controller system coupled to receive the output signals from the scanner produces signals representing desired profile information, based on the output signals from the scanner. The system further includes a plurality of actuators, each actuator being operatively associated with a corresponding intelligent actuator controller.

Abstract: A two-dimensional position detector, in combination with dynamic z and/or flutter sensors, provides dynamic misalignment detection and correction of a measuring head, thereby allowing accurate determinations to be made of properties of a sheet material, such as basis weight.

Abstract: Apparatus for distributing a heating medium, such as steam or hot air, to a paper web or calendar roll in sheet making machinery includes a removable profile screen to permit easy cleaning and maintenance. The apparatus comprises an elongated chamber to receive steam or hot air from a supply source with a front wall adapted to receive a removable screen. The removable screen is flexible and defines at least a portion of the front wall conforming generally to the shape of the adjacent surface to be heated. The screen member has a plurality of apertures through which the heating medium is forced to heat the surface. The screen is removably mounted to the apparatus by clip members.

Abstract: A method for determining the cross-machine shrinkage or expansion profile of a travelling sheet produced in a sheetmaking machine between an upstream location and a downstream location. The method involves marking the sheet at the upstream location with an array of marks at measured, predetermined intervals in the cross-machine direction. The sheet is inspected in the cross-machine direction at the downstream location to measure the spacing of the array of marks. A shrinkage or expansion profile of the travelling sheet is developed based on the changes in the spacing between the array of marks at the downstream location. Apparatus for carrying out the method is also disclosed. The method and apparatus of the present invention permit rapid and precise determination of the sheet shrinkage or expansion profile to allow for better control of property variation across the sheet.

Abstract: An on-line laser triangulation position sensing system provides measurements of the surface features of a moving sheet such as paper. The measurements are correlatable with measurements made with standard laboratory surface smoothness testers and provide predictions of the printability of paper during its fabrication. The sensing system includes a segmented balance detector having a high frequency response. The sensing system further includes signal processing circuitry comprising a plurality of channels, each channel including a filter. The various filters have different cutoff frequencies for passing different frequency spectra representing ranges of surface feature scale sizes. The cutoff frequency of each filter is varied in response to variations in sheet speed. The sheet sensing system further includes a sheet stabilizer to minimize flutter in the measurement region and a standardizing member permitting performance verification of the sensor system at at least one scale size spectrum.

Abstract: Disclosed is an apparatus for measuring on-line the color and color-related properties of a moving sheet. Contrast ratio reflectance measurements are made for providing opacity corrections substantially in real time for a full color spectrum. An optical color sensor in accordance with the invention includes a pair of synchronized spectrometers, the first spectrometer being aligned to view a region of the sheet backed with a highly reflective ("white") material and the second spectrometer being aligned to view a region of the sheet backed with a highly absorptive ("black") material. The use of two spectrometers permits substantially simultaneous "black" and "white" measurements for a full color spectrum. The optical color sensing system further includes two light sources, a flashlamp and a continuously energized tungsten filament lamp. Light beams from the two sources are combined to form a sheet-illuminating third beam approximating the D65 standard source.

Abstract: Disclosed is an apparatus for measuring on-line the color and color-related properties of a moving sheet. Contrast ratio reflectance measurements are made for providing opacity corrections substantially in real time for a full color spectrum. An optical color sensor in accordance with the invention includes a pair of synchronized spectrometers, the first spectrometer being aligned to view a region of the sheet backed with a highly reflective ("white") material and the second spectrometer being aligned to view a region of the sheet backed with a highly absorptive ("black") material. The use of two spectrometers permits substantially simultaneous "black" and "white" measurements for a full color spectrum. The optical color sensing system further includes two light sources, a flashlamp and a continuously energized tungsten filament lamp. The color sensor further includes a sheet backing system including a rotatable standard wheel carrying a white standard tile.

Abstract: A process for transforming a plurality of data points n defining a high resolution profile for a parameter of a sheet material being manufactured into a low resolution profile for control of the parameter is disclosed. The process involves filtering the data points of the high resolution profile using an anti-aliasing filter function to create an intermediate profile and reducing the number of datapoints of the intermediate profile by an integer factor to create the low resolution profile to be used to control the parameter.

Abstract: An actuator converts rotational movement to linear movement and at the same time transmits a limited linear force without requiring slip clutches or the like. The actuator has an electric motor in a fixed housing with a drive shaft on a longitudinal axis. A drive gear, substantially free of backlash, is connected to the drive shaft and has an output connection to drive a drive nut with an internal screw thread on the rotary axis. An output shaft has an external screw thread engaging with the internal screw thread of the drive nut and moves linearly when the drive nut is rotated. A voltage control system allows the voltage to the motor to be set so that for a set voltage there is a predetermined longitudinal force on the output shaft.

Abstract: A caliper profile control system for a paper machine provides reduced start up times after sheet breaks to bring the caliper profile across the sheet to within the desired limits. The method comprises the steps of scanning at predetermined intervals across the width of the paper sheet to monitor thickness error of the sheet from predetermined limits and change in the thickness error between the intervals, in each of a plurality of zones across the sheet. A control change signal is determined for each of the zones based on the error and the change in error using an exponential function of the magnitude of the error to maximize the change in the error and reduce integral action when the error is large. The control signal is used to reduce the error in each zone and the integral action is increased as the error decreases until the predetermined limits are met.

Abstract: In a continuous sheetmaking process, a synthetic measurement is constructed having a higher signal-to-noise ratio than that of each original measurement in situations where more than one (redundant) measurements are available. The input-output dynamic characteristics of each measurement are assumed to be identical except for a gain factor. Using the synthetic measurement, system parameters can be identified in less time with fewer input disturbances. The invention is especially advantageous for application to processes that are expensive to disturb and in which the noise amplitude is high compared to the permissible amplitude of the put disturbance. The signal-to-noise enhanced time-series response measurement may be produced by selecting a time series response measurement that exhibits a greatest magnitude. Alternatively, it may be produced by averaging in the cross-direction a plurality of time series response measurements.

Abstract: An apparatus and method for monitoring and regulating the amount of multiple coating materials containing different compositions applied to a substrate, such as paperboard. The coating measurement is insensitive to changes in both the amount of substrate as well as in the amount of an interfering component associated with the substrate.

Abstract: A nuclear gauge (7) for making measurements of traveling webs (11) in continuous sheet-making processes includes an enclosure (20), an encapsulated nuclear source (28), and a wheel-like member (10) mounted in the enclosure means for carrying the encapsulated nuclear source between two angularly-displaced positions. The first of the angularly-displaced positions is the position whereat the encapsulated nuclear source makes measurements of a web that travels past the gauge, and the second position is the location whereat the encapsulated nuclear source faces a sidewall of the enclosure means at a location remote from the first position. The nuclear gauge also has an aperture (16) which is formed through the enclosure for providing a window through which the encapsuled nuclear source, when located in the first position, can emit radiation onto a web that travels past the window.

Abstract: A method and apparatus for controlling a multiple-input, multiple-output (MIMO) system, such as a sheetmaking system, including identifying a decoupling gain matrix by comparing an actuator control vector against a measured output vector and processing an error vector to update the decoupling gain matrix. The dynamic components of one dynamic mode in the system are separated from that of other dynamic modes such that the input-output characteristic of the process may be treated as independent channels.

Abstract: A system for aligning control zones with measurement zones in a sheetmaking system having a plurality of actuators arranged in the cross-direction, comprising the steps of: a) bumping at least one of the actuators; b) measuring a profile of the sheet at a substantial distance from the bumped actuators; and c) determining a location of the effect of each of the bumped actuators on the sheet.

Abstract: A non-contact thickness measuring sensor is disclosed which determines the thickness of an overlying material on a substrate. The sensor includes two non-contact separation distance measuring devices which may be utilized to measure the distance from the first device to a portion of the interface between the substrate and the overlying material, while the second device determines the distance from the second device to a portion of the surface of the overlying layer. The difference in the measured distances is related to the thickness of the overlying material. In one embodiment, two lasers are used to measure the separation distances. In another embodiment, the two measured distances are coincident. Because of the coincident geometry of these two measurements, the thickness measuring sensor of this embodiment is substantially insensitive to misalignment of the sensor from the normal to the surface of the overlying layer being measured.

Abstract: The present invention relates to apparatuses and methods for measuring and controlling the amount of multiple coating materials applied to a substrate, and in particular to an apparatus and method for monitoring and regulating the amount of multiple coating materials containing different compositions applied to a substrate, such as paperboard. The coating measurement is insensitive to changes in both the amount of substrate as well as in the amount of an interfering component associated with the substrate.