Beer Fermentation Process Fuzzy Control System

This thesis mainly discusses the principle and design of a control and administration system in fermentation of beer. The system applies multilevel and distributed structure. It consists of two levels of microcomputer system and is provided with so many advantages such as simple structure ,low cost and high reliability etc ,that it is one of the best schemes for middle or small scale enterprises to improve their automatic standard of production and administration. Around the subject of improving the reliability and practicalities of the system, the thesis discusses the design ideas ,the structure, the constituents and the realization of the software and hardware of the system in detail. The whole thesis is arranged as follows:The first chapter discusses the current situation of beer production in our country. Considering the development of automation in process of production, the thesis summarizes the current situation and tendency of the computer control technique applied hi the process of production, especially in the fermentation process.The second chapter analyses the beer fermentation process. It also discusses the structure and the functional requirement of the system .In the section of the 'structure of the system' ,the structure of the computer control system ,the structure of the lower computer system, the structure of the control and management software of the higher computer system, the selection of the actuator and the control strategy will be described.The third chapter specifies the hardware design of the lower computer system-a digital temperature controller .In this chapter, the function and constituents of every unit circuits which are used in the lower computer system will be discussed in detail. Many high-performed IC used in the controller improve the performance and the reliability of the lower computer system.The forth chapter narrates the monitoring program of the lower computer system .Modularization method was introduced when we designed the monitoring program. Most of the task in the monitoring program ,such as data acquirement, communication, self-diagnosis ,alarm, display and control signal output ,are triggered by the system real timer.The fifth chapter analyses the fermentation temperature control strategy. In our system ,we select PID arithmetic to control the fermentation temperature and use PWM(Pulse Width Modulation)signal rather than analog signal as output control signal to drive the actuators ,this enables us to use the pneumatic stop valve ,which is cheaper and more reliable ,to take the place of the expensive analog control valve. Considering the slowly time-varying character of the process, we present the PID parameter on-line auto-tuning strategy using fuzzy reasoning method so that the system has high performance in most of situations.