Robust Fuzzy Control Design for Dithered Nonlinear Large-scale Systems with Multiple Time Delays

• Main Authors: Zhao-yu Liu, 劉詔瑜
• Other Authors: none
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/43057747935987327567

碩士 === 國立臺南大學 === 電機工程研究所 === 99 === A robustness design of fuzzy control is proposed to overcome the effect of modeling errors between nonlinear multiple time-delay (NMTD) subsystems and Takagi-Sugeno (T-S) fuzzy models with multiple time delays. In terms of Lyapunov''s direct method, a delay-dependent stability criterion is hence derived to guarantee that the trajectories of NMTD large-scale system under fuzzy control can be steered into a periodic orbit. Based on this criterion and the decentralized control scheme, a set of model-based fuzzy controllers is then synthesized via the technique of parallel distributed compensation (PDC) to stabilize the NMTD large-scale system and the H ∞ control performance is achieved at the same time. If the designed fuzzy controllers cannot stabilize the NMTD large-scale system, a set of dithers (as the auxiliaries of fuzzy controllers) is simultaneously introduced to stabilize the NMTD large-scale system. The injection of high-frequency signals, commonly called dithers, into nonlinear large-scale systems may improve their performance. If the frequencies of dithers are high enough, the outputs of the dithered large-scale system and those of its corresponding mathematical model－the relaxed large-scale system can be made as close as desired. This makes it possible to obtain a rigorous prediction of the stability of the dithered large-scale system by establishing that of the relaxed large-scale system. Finally, a numerical example with simulations is provided to illustrate the concepts discussed throughout this paper.