Study On Intelligent PID Controller Based On Knowledge

Along with the complication of modern industrial process, and the increase of nonlinearity, uncertainty and complexity during the practical production processes, the conventional PID controller can no longer meet our requirement, therefore, some advanced intelligent control methods developed in recent years have been applied in the PID control field.Fuzzy control has become the most active and fruitful field in the study of Intelligent Automatic Control ,in which Fuzzy PID control not only plays a very important role, but also will be one of main technology in future research and applications. Multiple compound fuzzy PID control employs widely in the process among fuzzy PID, such as Fuzzy-PID control, P-Fuzzy-PID control etc. Multiple compound control, refer to switch from one regulator to another in the different range of error value to realize compound control. By combining the advantages of Fuzzy logic control(FLC) and conventional linear PID controller, the response of multiple compound control is speed and stable in the dynamic state and the conventional linear PID controller guarantees zero-error in the steady state, so they achieved good–control performance.Common multiple compound control is switched automatically by program based on predeterminate error value. Therefore, how to select suitable error value and disturbance during switching are unavoidable defects. However, a new fuzzy switching based on fuzzy rules knowledge proposed in this thesis can dodge those shortages. This algorithm is simple, and control performances, i.e., robustness, the capacity of the anti-interference, tracking, are better than common multiple compound control.All of the simulation results mentioned in this thesis have been derived by Matlab7.01 under the Microsoft Windows XP Professional 2002. Results obtained from simulation using Matlab indicate that the proposed method based on fuzzy rules switching has good-quality controlling ability.