A new two-dimensional (2D) variation modeling and control technique for a machine producing a web of material, such as paper, uses functional transformation with basis functions which are wavelets, preferably wavelets derived from and closely resembling the responses generated by actuation of cross direction (CD) actuators of the machine. By using the disclosed functional transformation together with carefully selected basis functions, memory and real-time processing requirements are substantially reduced so that practical controls can be readily implemented. In addition, the functional transformation technique of the present application expands conventional CD correction to also correct for a portion of the residual variations which, until now, have remained uncorrected. The new 2D profile is treated as the superposition of two main components: a pure machine direction (MD) variation component and a two-dimensional sheet variation component. The pure MD variation is identical to the conventional MD variation; however, the two-dimensional sheet variation represents the evolution of a sheet property being measured in both a temporal direction (TD) and a spatial direction (SD), i.e. it includes both the traditional pure CD profile and a portion of the residual variation. The TD is aligned with the MD and the SD is perpendicular to the TD or is aligned with the CD. The new 2D variation is controlled by a new 2D control arrangement which includes an optimal predictive SD controller and a model based TD controller to quickly achieve 2D web uniformity.

Two-dimensional web property variation modeling and control

The thickness of a cut length of a continuously extruded elastomer is controlled by sampling the weight of a section of the continuous extrusion at a running-weigh-scale each second; computing and storing one-minute averages of the running-weigh-scale samples; sampling the weight of a cut length of the extrusion at a check-weigh-scale; comparing the check-weigh-scale value to the oldest stored running-weigh-scale one-minute average to obtain a targeted average; comparing the targeted running-weigh-scale average to the newest stored running-weigh-scale one-minute average to obtain a deviation from the targeted value if one exists; and converting the deviation from the targeted running-weigh-scale value to a control signal for increasing or decreasing the speed of a take-away belt positioned at the extruder exit orifice to vary the thickness of the extrusion in accordance with the deviation control signal and the speed of the belt.

Method and apparatus for controlling the thickness of extruded stock

A procedure and apparatus for locating faults in the machine elements of a paper machine and in their functioning, wherein variations in the paper characteristics are continuously observed, the periodicity of the variations is recorded and the periodicity of the variations in the paper characteristics is compared with the periodicity in the functioning of the paper machine's machine elements. The apparatus comprises observation members (1-11) for observing the variations occurring in the paper characteristics; synchronizing pick-ups (43-53) disposed on machine elements (13-22) of the paper machine for observing the periodicity of the functioning of said machine elements; a recording means (40) for recording the periodicity of the variations in paper characteristics and the periodicity in the functioning of the machine elements; and a data processing unit (41) for comparing the periodicity of the variations in paper characteristics and that in the functioning of the machine elements.

Procedure and apparatus for fault location in the functioning of machine elements of a paper machine

A method and a device for tuning and control of industrial processes having varying material flow rate. An adder is configured to add excitation signals to the controller output signal. A measurement system is configured to measure a property in response to the excitation signals. A model based tuning unit is adapted to estimate the value of at least one parameter with unknown value of a process model structure describing the effect of varying material flow rate, based on the measurements of the property and the output signal from the controller, and to calculate a model that describes the dynamics from controller output to controller input based on the estimated value of the parameter, and to perform model based tuning of the controller based on the model that describes the dynamics from controller output to controller input.

Method and device for tuning and control

A system for controlling a processor having at least one sampling port connected to a stage of the processor in order to sample a reactant product from the processor. The system includes a controller configured to control a processing parameter of the processor based on measurements of at least one property of the reactant product such that changes to the processing parameter maintain a target value for the at least one property of the reactant product. The system further includes a dead time compensator. The dead time compensator is configured, based upon a prescribed dead time related to a time before at least one effect of at least one change to the processing parameter is fully realized, to evaluate the reactant product to determine if the effect has been realized at a plurality of sequential times offset from the dead time.

System and method for controlling a processor including a digester utilizing time-based assessments

A controller for a machine or process having a transportation lag is responsive to a signal sampled at time intervals less than the time required for the transportation lag. The sampled signal is fed to a controller which drives the machine prior to completion of the time required for the transportation lag. A negative feedback loop around the controller includes a transfer function indicative of the d.c., steady state response of the machine being controlled and a positive feedback loop indicative of the total transfer function of the machine being controlled, including the transportation lag thereof. A further negative feedback loop is provided between the machine output and the controller input. In a specifically disclosed embodiment, full corrections to errors of moisture and fiber content of a fibrous sheet are made within a transportation lag between a slurry input point of a headbox and scanning gauges located downstream of a dryer.

J Rice

Papers

Control system and method for machine or process having dead time