Search results
Results from the WOW.Com Content Network
Model predictive control is a multivariable control algorithm that uses: an internal dynamic model of the process; a cost function J over the receding horizon; an optimization algorithm minimizing the cost function J using the control input u; An example of a quadratic cost function for optimization is given by:
S88 provides a consistent set of standards and terminology for batch control and defines the physical model, procedures, and recipes. The standard sought to address the following problems: lack of a universal model for batch control, difficulty in communicating user requirement, integration among batch automation suppliers, and difficulty in ...
If analysis of the control chart indicates that the process is currently under control (i.e., is stable, with variation only coming from sources common to the process), then no corrections or changes to process control parameters are needed or desired. In addition, data from the process can be used to predict the future performance of the process.
The main advantage of distribution-free control charts is its in-control robustness, in the sense that, irrespective of the nature of the underlying process distributions, the properties of these control charts remain the same when the process is smoothly operating without presence of any assignable cause.
The above eight rules apply to a chart of a variable value. A second chart, the moving range chart, can also be used but only with rules 1, 2, 3 and 4. Such a chart plots a graph of the maximum value - minimum value of N adjacent points against the time sample of the range.
This can be done by improving the control of the process to minimize the effect of disturbances on the process. The efficiency is improved in a two step method of narrowing the variance and shifting the target. [11] Margins can be narrowed through various process upgrades (i.e. equipment upgrades, enhanced control methods, etc.).
A more sophisticated SPC chart may include "control limit" & "spec limit" % lines to indicate whether/what action should be taken. Statistical process control (SPC) or statistical quality control (SQC) is the application of statistical methods to monitor and control the quality of a production process. This helps to ensure that the process ...
Similarly, runs of points on one side of the average line should also be interpreted as a signal of some change in the process. When such signals exist, action should be taken to identify and eliminate them. When no such signals are present, no changes to the process control variables (i.e. "tampering") are necessary or desirable. [3]: 125