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Turkish Journal of Electrical Engineering and Computer Sciences

Author ORCID Identifier

OQBA ALDREIEI: 0009-0008-3135-0704

CENK ULU: 0000-0002-8588-6247

MERT KURUCU: 0000-0002-5416-7995

MÜJDE GÜZELKAYA: 0000-0002-4150-4278

Abstract

The characteristics of the footprint of uncertainty (FOU) in interval type-2 membership functions (IT2-MFs) are crucial to the performance and robustness of interval type-2 fuzzy controllers (IT2-FCs). However, existing IT2-FC design approaches mostly use fixed FOU structures. This study proposes an online membership function (MF) adjustment mechanism for a single-input interval type-2 fuzzy PID controller (SIT2-FPID)  that adjusts the FOU of the antecedent MFs and weights of the consequent MFs, respectively, to achieve high performance and robustness. The proposed online adjustment mechanism consists of a relative rate observer (RRO), a two-input rule-base adjustment system, and a first-order smoothing filter. The RRO provides the "normalized acceleration (Rv(k))" value, which  provides relative information  on the speed of the system response. The two inputs of the rule-base adjustment system are "error (e(k))" and (Rv(k)). The raw output of the adjustment mechanism, denoted by (γraw(k)), is filtered to generate the effective tuning signal (γ(k)), which is then used as a tuning variable for the FOU of the antecedent IT2-MFs and the weights of the consequent crisp MFs. The SIT2-FPID with a proposed adjustment mechanism is compared with the conventional PID controller and SIT2-FPID with fixed MFs through simulations. Simulation results demonstrate that the proposed SIT2-FPID controller outperforms the conventional PID and SIT2-FPID with fixed MFs controllers in all performance measures and is effective in compensating for input and output disturbances within a short time. These improvements are observed in both linear and nonlinear systems.

DOI

10.55730/1300-0632.4277

Keywords

Online adjustment for MFs, IT2-FPID controller, relative rate observer, footprint of uncertainty

First Page

809

Last Page

832

Publisher

The Scientific and Technological Research Council of Türkiye (TÜBİTAK)

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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