| Pneumatic systems have been widely used in industrial automation fields, such as chemical industry, textile, micro-electrics and bioengineering, for its advantages of simplicity in structure anti-pollution, high performance to cost, easy maintenance and anti-jamming. However, pneumatic systems have some inherent disadvantages as nonlinearity, low stiffness, low damping ratio and low natural frequency, it is difficult to obtain satisfied control performance, and thus its uses in industry area are limited. In this paper, the study on improving the control precision for the pneumatic system is presented. A high precision electric-pneumatic proportional pressure valve based on parameter self-tuning fuzzy PID control algoritlum is designed.In this paper, the features and development of pneumatic system are summarized, the research and application of intelligent control technology in this domain is expounded. The fuzzy PID controller is presented according to its nonlinear, which makes electric-pneumatic proportional pressure valve achieve good precision.First of all, mathematical modeling method on electric-pneumatic proportional vavle is presented. The method is called mechanism modeling, which contains the establishment of linear mathematical model and nonlinear dynamic model of the system through analyzing the balance of power and pressure-flow characteristics of the electric-pneumatic proportional valve, furthermore, correctness of the modles and validity of the optimization method are verified by a series of experiments and the simulation, which provides a theoretical basis for further study of the system.Secondly, based on the mathematical model of pressure control object, the diffieulties of gas pressure control are analyzed, a kind of gas pressure control strategy based on parameter self-tuning fuzzy PID control method is putforward. The fuzzy PID controller is designed and the simulation of gas pressure control, the result of simulation in the self-adaptively adjusted fuzzy PID controller proves that the controller possess both the precise character of PID controller and the flexible advantage of fuzzy controller, and can guarantee that regulation system has good dynamic and static quality, It has further prospect in engineering application.Last of all, the designing project for the pneumatic proportional valve is presented particularly from two aspects-hardware designing and software designing. In order to facilitate data storage and processing, In addition, a experimental platform is built for testing performance of the pneumatic proportional valve. The pneumatic proportional valve with good control performance are verified by the static characteristic curve, the step response curve, constant pressure control experiments. |
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