fuzzy approximation
در نشریات گروه فنی و مهندسی-
Journal of Electrical and Computer Engineering Innovations, Volume:13 Issue: 1, Winter-Spring 2025, PP 13 -26Background and ObjectivesThe two-axis inertially stabilized platforms (ISPs) face various challenges such as system nonlinearity, parameter fluctuations, and disturbances which makes the design process more complex. To address these challenges effectively, the main objective of this paper is to realize the stabilization of ISPs by presenting a new robust model-free control scheme.MethodsIn this study, a robust adaptive fuzzy control approach is proposed for two-axis ISPs. The proposed approach leverages the backstepping method as its foundational design mechanism, employing fuzzy systems to approximate unknown terms within the control framework. Furthermore, the control architecture incorporates a model-free disturbance observer, enhancing the system's robustness and performance. Additionally, novel adaptive rules are devised, and the uniform ultimate boundedness stability of the closed-loop system is rigorously validated using the Lyapunov theorem.ResultsUsing MATLAB/Simulink software, simulation results are obtained for the proposed control system and its performance is assessed in comparison with related research works across two scenarios. In the first scenario, where both the desired and initial attitude angles are set to zero, the proposed method demonstrates a substantial mean squared error (MSE) reduction: 96.2% for pitch and 86.7% for yaw compared to the backstepping method, and reductions of 75% for pitch and 33.3% for yaw compared to the backstepping sliding mode control. In the second scenario, which involves a 10-degree step input, similar improvements are observed alongside superior performance in terms of reduced overshoot and settling time. Specifically, the proposed method achieves a settling time for the pitch gimbal 56.6% faster than the backstepping method and 58% faster for the yaw gimbal. Moreover, the overshoot for the pitch angle is reduced by 53.5% compared to backstepping and 35.5% compared to backstepping sliding mode control, while for the yaw angle, reductions of 43.6% and 37.6% are achieved, respectively.ConclusionThrough comprehensive simulation studies, the efficacy of the proposed algorithm is demonstrated, showcasing its superior performance compared to conventional control methods. Specifically, the proposed method exhibits notable improvements in reducing maximum deviation from desired angles, mean squared errors, settling time, and overshoot, outperforming both backstepping and backstepping sliding mode control methods.Keywords: Inertially Stabilized Platform, Backstepping Control, Disturbance Observer, Fuzzy Approximation, Model-Free Control
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International Journal of Research in Industrial Engineering, Volume:8 Issue: 3, Summer 2019, PP 254 -261
Matrix and its determinant are two basic tools, which are important in financial, accounting, and economic affairs. Therefore, in this paper, a simple and effective method is proposed to obtain the determinant of fuzzy matrices. First, using arithmetic operations based on Transmission Average (TA),the second order fuzzy determinant is calculated.Then,Sarrus rule is defined to calculate third order fuzzy determinant. Finally, by defining minor of fuzzy matrix and ijth adjugate of the fuzzy matrix, nth order fuzzy determinant is calculated. The effectiveness and applicability of the proposed method are verified by solving some numerical examples.
Keywords: Arithmetic operations, fuzzy approximation, Fuzzy determinant -
This paper presents a new controller for speed control problem of the BLDC motors. The nonlinear model of the motor is approximated by implementation of fuzzy rules. The uncertainties are considered in the fuzzy system. Using this model and linear matrix inequality (LMI) optimization, a robust controller for purpose of speed control of the motor has been designed and applied to it. The effectiveness of the designed controls demonstrated through simulation results.Keywords: BLDC Motor, Fuzzy Approximation, Robust Controller
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در این مطالعه، مساله موقعیت و ردیابی برای شناور زیر سطحی خودگردان در صفحه افقی، در شرایط حضور جریان های دریایی به عنوان اغتشاش مورد بحث قرار می گیرد. در این تحقیق، اثر تغییرات و نامعینی در پارامترها مد نظر قرار می گیرد. عملکرد مطلوب کنترل کننده تطبیقی با بهره ثابت با خطی سازی فیدبک و همچنین با روش کنترل تطبیقی با بهره فازی مقایسه شده است. روش کنترلی ارائه شده در شبیه سازی ها مورد آزمایش و بررسی قرار گرفته است. همچنین، کارآیی روش کنترلی ارائه شده با روش های کنترلی دیگر در برخی از تحقیقات مقایسه شده اند. کران دار بودن و آنالیز مشخصات همگرایی مجانبی الگوریتم کنترلی و پایداری آن با استفاده از تئوری پایداری لیاپانوف و به کمک لم باربالات اثبات و ارائه شده است.
کلید واژگان: شناور زیر سطحی خودگردان، کنترل تطبیقی، کنترل غیر خطی، تقریب زن فازیIn this paper، the problem of the position and attitude tracking of an autonomous underwater vehicle (AUV) in the horizontal plane، under the presence of ocean current disturbances is discussed. The effect of the gradual variation of the parameters is taken into account. The effectiveness of the adaptive controller is compared with a feedback linearization method and fuzzy gain control approach. The proposed strategy has been tested through simulations. Also، the performance of the propos-ed method is compared with other strategies given in some other studies. The boundedness and asymptotic converge-nce properties of the control algorithm and its semi-global stability are analytically proven using Lyapunov stability theory and Barbalat’s lemma.Keywords: Autonomous underwater vehicles, adaptive control, nonlinear control, fuzzy approximation -
مجله آب و فاضلاب، پیاپی 85 (بهار 1392)، صص 82 -93روش های ارزیابی کیفیت منابع آب زیرزمینی و تشخیص موقعیتهای مناسب برداشت برای شرب و استفاده کشاورزی، از مسائلی است که به لحاظ کاربردی بودن، استفاده فراوانی دارد. ارائه یک روش پهنه بندی کیفی جدید با تعیین حدود و شاخص کیفی مناسب از اهم اهداف تحقیق حاضر بود. در این مطالعه پس از ارزیابی متغیر های کیفی آب در هر چاه پایش، روشی کارا به منظور استنتاج شاخص کلی کیفیت آب با به کارگیری ساختار تشخیص و ارزیابی فازی به کار برده شد. در ادامه، اطلاعات 217 چاه برداشت آب در دشت قزوین که شامل 12 پارامتر شیمیایی کیفیت آب بود، به منظور ارزیابی شاخص کیفی پیشنهادی مورد استفاده قرار گرفت. در نهایت، شاخص کیفی فازی جدید با استفاده از یکی از جدیدترین رویکردهای تخمین مکانی بهینه شده توسط الگوریتم ژنتیک به کل منطقه دشت قزوین تعمیم یافت. نتایج نشان دهنده کارایی روش پیشنهادی در پهنه بندی کیفی آب زیرزمینی بود. یکی از نقاط قوت روش پیشنهادی، پرهیز از تجمیع قطعیت گرایانه کیفیت و ارائه شاخصی پیوسته به منظور ارزیابی کیفی آب زیرزمینی بود.
کلید واژگان: آب زیرزمینی، شاخص کیفی آب، پهنه بندی، رویکرد ارزیابی فازیMethods for evaluatingthe quality of groundwater resources and recognition of appropriate locations for urban and agricultural water demand has been known as an important item in water resources planning. The main focus of this paper has been addressed a new water quality mapping based on coupling of fuzzy approximation and water quality indexing. In this paper, after indexing water quality in each monitoring well, based on fuzzy reasoning a new global fuzzy indexing has been presented. In this regard, 12 water quality parameters for 217 monitoring wells in the province of Ghazvin in the north have been used. In the final step, map of fuzzy evaluation over the area of interest has been provided based on an optimized new spatial approximation via Genetic Algorithm (GA). The results showed the capability of the proposed methodology for groundwater quality mapping. The most important contribution of this paper is successful combination of fuzzy reasoning and water quality indexing as a continuous function for evaluating groundwater quality mapping.Keywords: Groundwater, Water Quality Index, Water Quality Zoning, Fuzzy Approximation
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