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QFT Robust Control
Published in Mario García-Sanz, Robust Control Engineering, 2017
Designing reliable and high-performance control systems is an essential priority of control engineering projects. In practical circumstances, the presence of model uncertainty challenges the design. One robust control approach for these cases is the quantitative feedback theory (QFT). Deeply rooted in the classical frequency domain, QFT provides control solutions that guarantee the achievement of a multi-objective set of performance specifications for every plant within the model uncertainty. It balances the trade-off between the simplicity of the controller structure and the minimization of its activity at each frequency of interest.
Robust fractional-order [proportional integral derivative] controller design with specification constraints: more flat phase idea
Published in International Journal of Control, 2021
Zhenlong Wu, Jairo Viola, Ying Luo, YangQuan Chen, Donghai Li
Quantitative feedback theory (QFT), as a robust control synthesis in frequency domain design approach, has been widely applied in industry (Horowitz, 1982, 2010). A QFT controller is also designed for the controlled plant in this paper, where desired stability margin specification, input disturbance specification, control effort specification are chosen as 1.1, 0.4, 3.5, respectively (Borghesani et al., 1993). One can obtain the QFT controller as which has five parameters and is more than FO[PID]. Its control performance is presented in Figure 17, where the loop gain is also set to be 80%, 100% and 120% of the nominal value. For the QFT controller, the overshoot of the closed-loop system increases slightly with the increasing of the gain which means that the closed-loop system is not sensitive to the variations of the loop gain. However, its overshoots are larger than that of FO[PID]. To compare the sensitivity to the variations of the loop gain quantitatively, Table 3 lists the overshoots and their maximum deviation. It can be learnt that FO[PID] is the least sensitive to the variations of the loop gain. QFT is superior to IOPID and FOPI controllers. Therefore, the effectiveness of the proposed method with the ‘more flat phase’ idea as well as the superiority of the FO[PID] controller can be verified.
Designing the Robust Fuzzy PI and Fuzzy Type-2 PI Controllers by Metaheuristic Optimizing Algorithms for AVR System
Published in IETE Journal of Research, 2022
Mohammadreza Modabbernia, Behnam Alizadeh, Alireza Sahab, Maziar Mirhosseini Moghaddam
For the future works, at first, it may be tried to expand the structure of our proposed Fuzzy and Fuzzy-type2 controllers with the fundamentals introduced in [28–30]. And then, it is going to design some new robust controllers based on mu-synthesis DK iteration, mixed loop-shaping, and quantitative feedback theory (QFT) for extending the introduced AVR robust control strategy.