Process variable

About: Process variable is a research topic. Over the lifetime, 3983 publications have been published within this topic receiving 43130 citations. The topic is also known as: process parameter.

Method and system for controlling setpoints of manipulated variables for process optimization under constraint of process-limiting variables

Abstract: A system, method, and article of manufacture suitable for determining setpoints of the control variables to optimize the process while taking into account the process-limiting variables in applications where responses are highly non-linear. In a preferred embodiment, the method comprises determining an actual rate of change of a performance limiting process parameter; calculating a predicted rate of change for the performance limiting process parameter for a predetermined future time interval; and adjusting a setpoint for the control variables to optimize the process while taking into account the performance limiting process parameter using the actual rate of change and the predicted rate of change.

Process control method and apparatus

Abstract: A method for controlling changes in the value of a process variable includes the steps of producing electrically a digital number signal representing the desired value of the variable, periodically adding to or subtracting from that number a digital number representing a required change in the variable, to produce an updated desired value signal, and comparing the latter signal or an analogue of it electrically with a signal representing the measured value of the variable to obtain a control signal for regulating the value of the variable. The method is applicable to the control of many industrial processes, for example the control of temperature in a dyebath, temperature cycles in baking ovens, pottery firing ovens and metal treatment furnaces, rates of flow of gases and liquids, tool movements in contour machine tools, and ''''loss of weight'''' feeding systems. Apparatus for carrying out the process is also described, comprising a first shift register for storing a binary number representing a desired value of the variable, a second shift register for storing a binary number representing a change to be made to the desired value in a predetermined time, programme means for receiving programme instructions and periodically transferring numbers to the second shift register, means for periodically combining the numbers in the two registers to produce an updated number and means for transferring periodically updated number signals to a comparator stage for comparison with electric signals representing the measured value of the variable to produce control signals for influencing the variable.

Interfaces from external systems to time dependent process parameters in integrated process and product engineering

Abstract: A method and apparatus for computer modeling the production process is disclosed. An integrated product and process engineering system may be a computer modeling system that models both a generic production process and a specific individual production process. The integrated product and process engineering system may store a time dependent process parameter related to the production process, having uploaded them via an interface. The time dependent process parameters may be retrieve and displayed to the user on a display using a remote function call enabled function module. The time dependent process parameters may be uploaded from an external system or revised using a remote function call enabled function module.

Integration of Process Simulation in Machining Parameter Optimization

Abstract: In recent years, simulation tools have proven valuable for the prediction of machining state variables over a wide range of operating parameters. Such simulation packages, however, are seldom an integral part of machining parameter optimization modules. This paper proposes a methodology for incorporating simulation feedback to fine-tune analytic models during the optimization process. Through a limited number of calls to the computationally expensive simulation tools, process parameters may be generated that satisfy the design constraints within the accuracy of the simulation predictions, while providing an efficient balance among parameters arising from the functional form of the optimization model. The following iterative algorithm is presented: (i) a non-linear programming (NLP) optimization technique is used to select process parameters based on closed-form analytical constraint equations relating to critical design requirements, (ii) the simulation is executed using these process parameters, providing predictions of the critical state variables. (iii) Constraint equation parameters are dynamically adapted using the feedback provided by the simulation predictions. This sequence is repeated until local convergence between the simulation and constraint equation predictions has been achieved. A case study in machining parameter optimization for peripheral finish milling operations is developed in which constraints on the allowable form error,Δ and the peripheral surface roughness, Ra , drive the process parameter selection for a cutting operation intended to maximize the material removal rate. Results from twenty machining scenarios are presented, including five workpiece/tool material combinations at four levels of precision. Achieving agreement (within a 5% deviation tolerance) between the simulation and constraint equation predictions required an average of 5 simulation execution cycles (maximum of 8), demonstrating promise that simulation tools can be efficiently incorporated into parameter optimization processes.