Feedforward-Feedback Control of a Cross-Flow Grain Dryer
Tom R. Rumsey
Authors AffiliationsDavid Platt was on leave from RAFAEL, Israel; Ahmet Palazoglu was Associate Professor, Department of Chemical Engineering, University of California, Davis; Tom R. Rumsey was Associate Professor, Department of Agricultural Engineering, University of California, Davis.
Hilgardia 60(1):1-27. DOI:10.3733/hilg.v60n01p027. February 1992.
A feedforward-feedback control of a cross-flow dryer is developed based on a simple mass balance on the dryer, rather than on indirect approaches and empirical relations. The feedforward action is based on a pseudo inlet moisture and adjusts the grain flow to correct for inlet moisture variations. A feedback loop is also added to account for possible process changes and model inaccuracies.
Simulations of a rice dryer show good control of the outlet moisture for variations in the inlet moisture with or without simultaneous disturbances in air flowrate. Effect of the feedforward algorithm on feedback control is also investigated, and the suggested combination of feedforward and feedback controls is tested for variations in the inlet moisture when its measurements are biased.
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