Two Degrees Of Freedom Fuzzy Internal Model Control Based On PAC For Time-delay Systems

The time-delay system is very common in the industrial production process, and it is also difficult to control, especially for the process with long delay time. Because of it's simple design method, well-targeted, IMC (Internal model control) has a wide range of applications in industrial process with time-delay. As a new programmable automatic controller, PAC has a more open architecture, more excellent interoperability, and flexibility than PAC, and it also has a higher stability and better real time than PC. There is important significance to put the combination of IMC and PAC into practical industrial process.In this paper, the background of the PAC and the feature of the process with time-delay and the controlling means of it are introduced firstly. There are mainly three kinds of controlling means: the classical control methods, the advanced control methods, and the intelligent control methods, and the pros and cons of the control methods are discussed. Then the details of the fuzzy control and internal model control are introduced, and the corresponding design of them is given at the same time.Second, the limits of one degree of freedom internal model control is pointed out, that it should compromise between the robust performance and robust stability. Therefore, this paper proposed the method of two degrees of freedom internal model control.Third, considered the strengths and weaknesses of the internal model control and the fuzzy control, the combination of the internal model control and fuzzy control is proposed. Further more based on the combination of two degrees of freedom internal model control and fuzzy control, Fuzzy-IMC with two degrees of freedom are proposed.Last, two first-order processes with time-delay and two second-order processes with time-delay are simulated in the case of model mismatching with the methods of one degree of freedom internal model control, two degrees of freedom internal model control, and two degrees of fuzzy internal model control. The result shows that the performance of two degrees of fuzzy internal model control is superior to the two others. Two degrees of freedom fuzzy internal model control can get not only greater steady, but also the system response speed is improved.