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Control charts are graphical plots used in production control to determine whether quality and manufacturing processes are being controlled under stable conditions. (ISO 7870-1) [1] The hourly status is arranged on the graph, and the occurrence of abnormalities is judged based on the presence of data that differs from the conventional trend or deviates from the control limit line.
The international standard IEC 61499, addressing the topic of function blocks for industrial process measurement and control systems, was initially published by the International Electrotechnical Commission (IEC) in 2005. The specification of IEC 61499 defines a generic model for distributed control systems and is based on the IEC 61131 standard.
The resulting plots are analyzed as for other control charts, using the rules that are deemed appropriate for the process and the desired level of control. At the least, any points above either upper control limits or below the lower control limit are marked and considered a signal of changes in the underlying process that are worth further ...
State based control can be thought of as an extension of the unit operation concept in the process industry. [7] Processes are designed with unit operations. With state-based control the control design is divided into units and those units further divided into states, with the proper operating discipline for each state designed in.
Simple example of a process control chart, tracking the etch (removal) rate of Silicon in an ICP Plasma Etcher at a microelectronics waferfab. [1] Time-series data shows the mean value and ±5% bars. A more sophisticated SPC chart may include "control limit" & "spec limit" % lines to indicate whether/what action should be taken.
Examples include business requirements specification or stakeholder requirements specification (StRS). CONOPS is used to communicate the quantitative and qualitative system characteristics to all stakeholders. [2] CONOPS are widely used in the military, governmental services and other fields.
Stateflow (developed by MathWorks) is a control logic tool used to model reactive systems via state machines and flow charts within a Simulink model. Stateflow uses a variant of the finite-state machine notation established by David Harel, enabling the representation of hierarchy, parallelism and history within a state chart.
The state diagram from Figure 2 is an example of an extended state machine, in which the complete condition of the system (called the extended state) is the combination of a qualitative aspect—the state variable—and the quantitative aspects—the extended state variables. The obvious advantage of extended state machines is flexibility.