The Optimization Research To The Parameters Of Time-delay Filtering System

Time delay is retarded as the lagging of signal transmission. It is a widespread phenomenon in the nature. Because of the existence of time delay in control system, the controlled variable can not timely reflect the disturbance to the system, which brings about obvious overshooting, bad stability and longer regulating time of the system. All these may result in great difficulty to the system analysis and controller design, so how to improve the system performance by restraining the inherent time delay remains an important topic in the field of control theory research.Time-delay filtration is to introduce time-delay link into control system consciously, and the shaping command formed by the pulse sequence and the reference command convolution is taken as the control signals. It is a control technology which can reduce flexible systems residual vibration. But if the time delay introduced is not proper, the system could become unstable instead of the former relative-table system. So it is necessary and important to optimize the parameters of time-delay system for further perfecting time-delay filtration technology.This thesis makes use of the global optimization characteristic of genetic algorithm to set the parameters of the time-delayed filter and develops an improved self-adapted genetic algorithm to solve the disadvantages of simple genetic algorithms and adaptive genetic algorithms based on the principle of the adaptive genetic algorithms, which leads to a better optimization of the parameters of the time-delayed filter.In order to make the system more quickly to reach a steady state, the fractional-order PID is introduced to try to further improve the system performance. By doing this, not only the controlled object can be controlled more flexibly which bring about a perfect control effect, but also the dynamic response of the real system can be accurately described.Based on the thought, this thesis first introduced the development of time-delay system, the background, the significance and the present domestic and foreign research situation of time-delayed filter technology, followed illustrates the background, the research goal and the anticipated results of this issue. Then it explains the idea of time-delayed filtering, the basic principle of time-delayed filter and its design methods. Further more, in this paper we also give a brief introduction to the knowledge of several popular genetic algorithms and use the simple genetic algorithm(SGA), the improved simple genetic algorithm(ISGA) and the improved self-adapted genetic algorithm to optimize the parameters of the system respectively. Finally, the fractional-order PID is introduced, and the five parameters of the PID are set on the basis of genetic algorithms.The simulation results show that the system can more quickly reach a steady state by making use of GA to set the parameters of time-delayed filter system and proposing the fractional-order PID.