Showing papers on "Process variable published in 1971"

Adaptive controller having optimal filtering

Abstract: A self-adaptive controller for use in a control process for providing ordered changes in a manipulated process variable in response to measured changes in a controlled process variable having means for using measured and predicted values of the controlled variable to obtain an estimated value of the controlled variable which estimated value is used via a self-adaptive controller to determine the change in manipulated variable. The controller is described with reference to a paper manufacturing process for controlling the basis weight and moisture content of a continuous web of paper.

Pattern evaluation method and apparatus for adaptive control

Abstract: A method is provided for automatic adaptation of process controller parameters according to the requirements of a non-linear process in order to achieve optimum control action. This method evaluates the response of a measured process variable to upset in the form of a change in set point or load. The upset initiates the adaptation procedure, which determines evaluation intervals related to process dead time and lag characteristics as evidenced by the response of the measured variable over predetermined portions of said upset; the deviation in the measured variable from set point or related demand reference is examined over the evaluation intervals and preferably integrated, the integrated error result being indicative of a required proportional gain change in the case of one type of evaluation interval and indicative of a required reset gain change in another type of evaluation interval. Proportional and reset gains are altered in accordance with this procedure until the gains are optimized as evidenced by maximum conformity to the demand references of the measured variable response to upsets generally.

Hybrid process controller operable in the automatic and manual

Abstract: An electronic controller forming a part of a process control system in which a signal representative of a process variable is compared with a set point signal to produce an output signal to operate a final control element. The controller includes a hybrid digital-analog configuration which permits bumpless transfer between automatic and manual modes, in an arrangement which is drift-free in the manual mode and does not require a long resistor-capacitor time constant.

Process control method and apparatus for regulating temperature

Abstract: A process control method comprises the steps of generating a first electrical signal representing a measured value of a process variable, generating a second electrical signal representing a desired value of said process variable, generating a third electrical signal, which changes at a prechosen rate corresponding to a desired rate of change of said measured value of said process variable, comparing said second electrical signal with said third electrical signal to generate a fourth electrical signal, applying said fourth electrical signal to cause said third electrical signal to tend towards equality with said second electrical signal, and comparing said first electrical signal with said third electrical signal to produce a process control signal therefrom. Apparatus for carrying out the method is also described as well as the application of the method to the control of the temperature of dyebath liquor.