Determining the Specification of a Control System: An Illustrative Example
Creating the specification of a system by focusing primarily on the detailed properties of the digital controller can lead to complex descriptions that are nearly incoherent. An argument given by Hayes, Jackson, and Jones provides reasons to focus first on the wider environment in which the system will reside. In their approach are two major ideas: pushing out the specification boundaries, and carefully distinguishing between the requirements of the system and the assumptions about the environment. Pushing out the boundaries of the system specification to include the pragmatic intent of the system being specified allows the specification to be understood relative to the environmental context, rather than remaining a mysterious black box in isolation. Clarifying the distinction between assumptions about the environment and requirements that the specification must meet increases the clarity of the specification, and has the potential to seriously reduce the complexity of the final specification. The example of a gas burner is explored in depth to illustrate this approach to system specification.
KeywordsExternal Variable Digital Controller Duration Calculus Oxyacetylene Welding Australian Computer Society
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