Discussion on Problems and Solutions in Wood Drying Computer Control System

In recent years, domestic and foreign furniture, decoration, musical instruments and other industries have flourished. The quality, performance, and competitiveness of various wood products in the domestic and foreign markets depend on the dry quality of the wood to a large extent. Wood processing plants are The requirements for dry quality of wood are getting higher and higher, and the advancement of the process and control technology in the wood drying process is the key to the quality of wood drying.

In the 1980s, developed countries abroad have widely used computer control technology in the process of wood drying production control. Since the early nineties, the use of computerized control of wood drying production processes and other related technologies has developed extremely rapidly. In many countries, the wood dry coal equipment has been fully automated. For example, industrialized countries such as Italy and the former West Germany have made significant progress in this area. The wood drying equipment and control systems they introduced are recognized as the most advanced.

At present, the domestic drying control system in Pu'er uses manual or semi-automatic control methods, and the wood drying process is completely based on the experience and responsibility of the workers. The dry and dense control system can no longer meet the requirements of wood processing for drying capacity and dry quality. Since the 1990s, China has been engaged in timber drying teaching. Experimental and production scholars. Engineers and technicians have made rapid development of wood drying technology by introducing various technologies such as introduction, digestion, absorption, and self-developed techniques. Some of the domestic drying equipment are close to the international level in terms of technology and quality.

Cotton collection period: 200003 2 Problems in the Wood Drying Computer Control System and Its Causes The production status of the automatic or semi-automatic wood drying equipment imported from abroad and developed by China itself is considered, although these equipments are relative to the wood drying equipment in China. It is more advanced, but there are still many problems.

Among them, the main problem is that the reliability and stability of the computer control system of these wood drying equipments are not flawed, and its control ability is less adaptable to various aspects such as the structure, installation direction, geographic location and control actuators.

According to the analysis, we believe that the main reason for sending seeds is that the control method adopted is not advanced enough, and it is difficult to adapt to the requirements of the process control of the special wood drying process with complex and uncertain mathematical models. Whether the classical control theory or the modern control theory is used to design a control system, it is necessary to know in advance the precise mathematical model of the control object or the production process. Then, according to the mathematical model and the given performance index, an appropriate control law is selected to design the control system. However, due to the large number of drying equipments and discrete thermal parameters, there are many influencing factors, and there are crossovers between them, which make the model complex and difficult to solve. It is a non-linear, multi-variable, large-lag and strong-spread. Complex systems, hard to "get a definitive mathematical model. There are many parameters that must be mastered to control the drying process, and these data are often inaccurate. For example, the thickness or length of wood can be measured very accurately, but its moisture content, relative humidity of air medium and other physical quantities are difficult to measure accurately. Especially when using electric moisture meter to measure wood moisture content, its accuracy is very low. For the relative humidity of the air, the value measured with the hygrometer is only within a very narrow range to ensure its tipping. The hygroscopic materials used to determine the equilibrium moisture content all have a constant water resistance, and there is a non-negligible deviation. In addition, when measuring the conditions of the air medium passing through the stack in the drying chamber, the properties of the air medium change, and only average values ​​can be taken during the measurement. The parameters measured on a small laboratory dryer do not represent the actual conditions of large dried honey.

The study did not count the control of the wood drying process as a result of many factors affecting the drying process, such as the temperature and relative humidity in the drying room. Air pressure and speed. As long as these factors are controlled, you can get an ideal. The environment conducive to dry wood. However, these factors have mutual cross-fertilization and it is difficult to obtain a definite mathematical model. The adjustment of factors is often based on experience. Even if there are ready-made drying methods and benchmarks, they should be revised according to the species of wood, the size and orientation of the dryness, etc. Sometimes the magnitude of the correction is very large, and the adjustment value is also different. Therefore, the conventional control method can hardly meet the requirements.

3 wood drying gauge control system reference fuzzy control theory and technology discussion fuzzy automatic control is "fuzzy set theory. The Numeral Control of Computer Based on Fuzzy Linguistic Variables and Fuzzy Logic Embedding .

Fuzzy control is mainly based on artificial experience. For a skilled operator, he does not solve the controlled system from the point of view of precise mathematical expressions. Instead, he uses appropriate practical experience to take appropriate measures. Subtly controls the production process of complex systems. If we sum up and describe the practical experience in the minds of these skilled operators, and express them in words, then it is a qualitative and inaccurate decision rule. Then, using the tool of fuzzy mathematics to quantify it, it is converted into a fuzzy control algorithm. The fuzzy control algorithm imitates human's operation strategy and accepts the person's experience through the fuzzy controller, thereby realizing the machine to replace the person to control the production process automatically.

Fuzzy control is a method that is very suitable for industrial production process and large system control. The huge size of the desiccant passenger equipment and the discreteness of thermal parameters have a lot of influence on the impact, and there are crossovers between them. This makes the model very complex and difficult to solve. In such a complex system with nonlinearity, multivariables, hysteresis, and strong convergence, neither the classical control theory nor the modern control theory is effective, but the use of fuzzy control can achieve surprisingly satisfactory results, and its control system can In the drying process, the fuzzy control room parameters are automatically modified, improved, and adjusted so that the control performance of the wood drying process is continuously replaced and improved.

The application of fuzzy control theory and technology in the control of wood drying process is an innovative pull for the theory and technology of wood drying automatic control. It not only has important academic value for improving the theory and technical level of wood drying control in China, but also can greatly improve the quality of wood products in China and reduce their cost. If it is promoted to food and food processing. Drying devices for pharmaceutical, tanning and other industries. It is of great significance to promote the development of related economic development.

Jump Rope

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