Linear Quadratic Gaussian control system design

5 Linear Quadratic Gaussian control system design 

An existing eontrol arrangement uses a PID eontroller to eontrol the temperature of the proeess air (measured by thermoeouples) and the dry elay moisture eontent measured by samples taken by the works laboratory. If this is out of speeifieation, then the proeess air temperature is raised or lowered. The dry elay moisture eontent ean be measured by an infrared absorption analyser, but on its own, this is eonsid-ered to be too noisy and unreliable. 

A proposed control scheme by Drew and Burns (1992) uses an LQG design, whereby the three process parameters are controlled in an optimal manner, their values (particularly the moisture control) being estimated. 

System model The dynamic characteristics of the dryer were measured experimentally. This yielded the following transfer functions 

Diserete system model The diserete system model (without disturbanees) is given by 

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Atlians, M. (1971) The Role and Use of the Stochastic Linear-Quadratic-Gaussian Problem in Control System Design, IEEE Trans, on Automatic Control AC-16, 6, pp. 529-551. 

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