Development of $$ H_{\infty } $$ H ∞ -Robust Control Strategy for Drying Process in Fluidized Food Bed Dryers

Abstract

Moisture control of food products is of great importance in drying processes. Improving the dryer control system results in consistent production and reduction in energy consumption. In this paper, a state observer is used to estimate the moisture content and other state variables online. Estimated states are used in a control system including the regulator for disturbance rejection and robust controller for tracking objective. Since the bed dryer mechanism is a multivariable complex system associated with various uncertainties, a realistic uncertain model is considered. Moisture content and temperature of tea leaves (or other food products) are controlled at desired set points by manipulating heating rate and food feed rate. Modeling the uncertainties and developing a code based on \( \mu \)-synthesis with DK-iteration, an optimal robust controller is designed. It is observed that controller guarantees robust stability and performance of the system in tracking of desired set points, in the presence of model uncertainties.