Identification And Controller Design Of Fractional Order Systems In Frequency Domain Under Networked Environment

The accuracy of a system model and the quality of a controller have significant effects on the stability and control performance of a system. Because of the limitations of the traditional integral order models and the PID tuning methods, complex systems cannot be described and controlled effectively. Fractional system identification and controller design method has gradually become a hot research for its high accuracy in system modeling and effective control.This paper studied the modeling of fractional systems and the fractional order PID controller design method based on network environment. According to the analysis of Fractional calculus, the complexity and limitations of the fractional system based on time-domain method were pointed out. And analysis methods of fractional order systems based on the frequency domain were applied to model and control the fractional systems.The main work of this paper comprises the followings:In fractional system identification, identification algorithm based on frequency domain was used to do the research of identification of fractional system. For single-input single-output fractional system transfer function model with time delay, via using the improved identification method of order-scanning frequency domain, the more accurate Mathematical model of fractional order systems was obtained. For multi-input multi-output state space model with time delay, identification method on frequency domain which can effectively identify the parameters, the order and the delay of the system was studied.In terms of the fractional controller design, after analyzing the characteristics of the fractional order PID controller and its impact on the system performance, the design method based on frequency-domain was used to get the effective tuning method of the fractional Order PID controller of fractional system for fractional order systems with delay.In terms of the simulation of fractional order systems, fractional system simulation platform under the network environment was built with the truetime toolbox in Matlab/Simulink. And the impact of network-induced delay and packet loss rate on the fractional system was simulated and analyzed.