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Abstract

A system for controlling the pressure in a chamber with a computer controlled exhaust throttle valve. A characterization relationship describes the static properties of the valve geometry, valve actuation mechanism and gas flow properties. This characterization relationship can comprise a theoretical or empirical function which associates a sufficient number of valve positions with the corresponding pressure, and may be parameterized by other auxiliary variables such as inlet gas flow values, gas types and compositions. An inverse relationship between the current measurable variables of the process, such as pressure, inlet flows and other auxiliary parameters is defined. A linearization method uses the inverse relationship to modify the effect of the valve positioning on the corresponding value of pressure in such a way that the combined behavior of the process and the linearization method yields a linear relationship between a new control variable and the pressure. A linear feedback control method then controls the modified, linearized system.

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First Claim