Identification of Intermittent Dryring of Grain and Adaptive Control

1.干燥过程的系统辨识研究：1.研究了干燥过程的系统辨识问题，建立了薄层干燥、厚层干燥为一系列薄层干燥和厚层干燥的状态模型。结果表明，卡尔曼滤波可以通过测量干燥过程中的进风和出风温度来稳定地估计谷物干燥过程中的水分含量。2.定性建模以谷物的成熟度为质量指标，建立了谷物成粒率与谷物初始含水率和温度之间的关系。3.多变量控制系统的设计与估算研究了一种面向规则的自适应控制系统，它控制由质量模型确定的干燥空气温度和由双罐模型确定的谷物在干燥室中的停留时间。在此基础上，提出了一种基于PI反馈的粮食停留时间控制系统，该系统根据粮食的进出风温度和粮食温度来估算粮食在干燥室出口的含水率，并将粮食含水率控制在估计值内。该控制系统对初始含水率和干燥空气温度的变化表现出较好的响应能力，对其他质量指标的建模以扩大控制系统的应用范围和提高估计精度仍是有待解决的问题。作者正在筹划和准备一项发展研究，作为控制系统在实际领域中的应用。

To develop the controlling method which accomplish efficient drying with good quality of dried grain and suppress the influences of variations of initial moisture content of grain and drying air temperature, the followings were investigated :1.System indentification of drying processSpace state models were investigated of thin-layr drying, drying of the thick-layr assumed as series of a thin-layr and thick-layr drying expressed by an approximated drying equation. As a result, moistrure content of grain in drying could be stably estimated by Kalman filter from the measurement of the inlet and outlet air temperature.2.Quality modellingGeminability of grain was adopted as a quality index and the relationship between geminability of grain, initial moisture content and temperature of grain was formulated. With the formulated equation, the allowable temperature of drying air was obtained to maintain a high geminability with a decrease in moisture content of grain.3.Design and estimation of multivariables controlling systemRule oriented adaptive control system was investigated which control drying control drying air temperature determined by the quality model and the residence time of grain in a drying chamber determined by the two-tank model. As a result, the control system of residence time of grain by a PI feedback method was developed in which the moisture content of grain at the outlet of drying chamber is estimated from the inlet and outlet air temperature and the grain temperature, and the moisture content of grain is controlled at the estimated value. The control system shows the good responsibility to the variation of initial moisture content and drying air temperature.As future problems, modelling of other quality indexes to extend application of the control system and the improvement of estimation accuracy remain. The author is planning and preparing a developmental study as the application of the control system to actual fields.