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Öğe Altı bacaklı bir robotun fpga kontrolü(2016) Demirel, Hüseyin; Erkol, Hüseyın Oktay; Erkal, Bilgehan-Öğe Moving object detection using an adaptive background subtraction method based on block-based structure in dynamic scene(Elsevier Gmbh, 2018) Savas, M. Fatih; Demirel, Huseyin; Erkal, BilgehanToday, determining background which forms the basis of the video surveillance system whose use is increasing in parallel with developing technology, is a complicated process to implement for cases involving dynamic scene. In this study, we proposed a block-based adaptive method which can be adaptable to dynamic environmental conditions. By grouping the pixels in the picture frame as 2 x 2 non-overlapped blocks, we reduced the amount of noise and the time delay caused by processing of pixels. By a simple counter structure, we created an adaptive threshold parameter which can be adapted according to the case in N surrounding. We used this parameter to perform an update of the background model and reduced background model normalization process. So, we reduced the update time of background operably. Our proposed method achieved successful results in levels of grey levels. (C) 2018 Elsevier GmbH. All rights reserved.Öğe On the performance of a fuzzy variable structure satellite attitude controller under sensor and actuator uncertainties(Inderscience Enterprises Ltd, 2020) Erkal, BilgehanControlling the attitude of a satellite with high accuracy and stability under both sensor and actuator delay is a great problem. It is possible to correct for errors, but a robust controller is more preferable. In this study, the attitude of a 3-DoF satellite model incorporating uncertainties (delays in handling both sensors and actuators) is controlled using a suitably designed integral fuzzy variable structure (IFVSC) controller. The attitude control accuracy of the IFVSC is evaluated and compared to other reference controllers (one is a PID controller and the other is a loop shaping controller). IFVSC is found to perform well with T-d = 0.2 s sensor and actuator data delay.Öğe Performance evaluation of a fuzzy variable structure satellite attitude controller under sensor data delay(2014) Erkal, Bilgehan; Demirel, HüseyinOne of the main sources of uncertainties in controlling the attitude of a satellite is the time delays seen in sensor data. Although it is possible to process sensor data to correct the deficiencies caused by delays, it is more suitable to design the controller robust enough to handle uncertainties well. In this study, the attitude of a 3-degrees of freedom satellite model, incorporating uncertainties (both sensor data delay and actuator misplacements), is controlled using a suitably designed fuzzy variable structure controller (FVSC). The performance of the FVSC is evaluated and compared to that of other reference controllers [proportional-derivative (PD), linear-quadratic-Gaussian (LQG), and loop-shaping controllers (LSCs)]. The FVSC performs well in both nondelayed and delayed (T_d = 0.2 s and 0.4 s) cases, while the PD and LQG controllers provide good response only for nondelayed cases (i.e. T_d = 0 s). A robust LSC also performs well in both cases, but its root mean squared error is high compared to the FVSC in the delayed case.Öğe Performance evaluation of a fuzzy variable structure satellite attitude controller under sensor data delay(Tubitak Scientific & Technological Research Council Turkey, 2014) Erkal, Bilgehan; Demirel, HuseyinOne of the main sources of uncertainties in controlling the attitude of a satellite is the time delays seen in sensor data. Although it is possible to process sensor data to correct the deficiencies caused by delays, it is more suitable to design the controller robust enough to handle uncertainties well. In this study, the attitude of a 3-degrees of freedom satellite model, incorporating uncertainties (both sensor data delay and actuator misplacements), is controlled using a suitably designed fuzzy variable structure controller (FVSC). The performance of the FVSC is evaluated and compared to that of other reference controllers [proportional-derivative (PD), linear-quadratic-Gaussian (LQG), and loop-shaping controllers (LSCs)]. The FVSC performs well in both nondelayed and delayed (T-d = 0.2 s and 0.4 s) cases, while the PD and LQG controllers provide good response only for nondelayed cases (i.e. T-d = 0 s). A robust LSC also performs well in both cases, but its root mean squared error is high compared to the FVSC in the delayed case.Öğe Performance of the Rapid Convergence Time for The Perturb and Observe MPPT Algorithm by Using Harris Hawks Optimization in Photovoltaic Systems(Gazi Univ, 2024) Astaomar, Seraj; Erkal, BilgehanThe efficiency of Maximum Power Point Tracking (MPPT) algorithms is crucial for optimizing the performance of photovoltaic (PV) systems. Traditional methods like the Perturb and Observe (P&O) algorithm are commonly used due to their simplicity, but they often suffer from issues such as slow convergence and oscillations around the maximum power point under changing environmental conditions. This study introduces an enhanced P&O algorithm by integrating it with Harris Hawks Optimization (HHO), a nature-inspired optimization technique known for its robust convergence characteristics. The proposed hybrid P&OHHO algorithm aims to accelerate convergence time and improve the overall tracking performance of the PV system. To maximize power from PV modules at varying sun irradiance levels, Harris-Hawks Optimization (HHO) is offered as a performance improvement method for the conventional Perturb and Observe (P&O) approach in photovoltaic systems. The proposed model encompasses a boost converter for DC-DC power controlled by an MPPT algorithm, a PV panel, and a resistive load. The MPPT algorithm proposed is founded upon the execution of a hybrid technique that combines Harris-Hawks Optimization, a new method inspired by nature, and the conventional P&O approach. The suggested method has been tested through simulation testing utilizing the environment created by MATLAB Simulink. The findings of the simulation illustrate that the HHO-P&O MPPT algorithm, as described, successfully identified the global maximum power point more efficiently. Additionally, it exhibited a rapid convergence speed, superior outcomes in comparison to the standard Perturb and Observe method, and a swift dynamic reaction.Öğe Practical radial distribution feeder for techno economic in ders based on ann and chameleon optimization algorithms(Gazi Univ, 2023) Bojod, Jemaa; Erkal, BilgehanDistributed energy resources (DERs) are a better choice to meet load demand close to load centers. Optimal DER placement and DER ratings lead to power loss reduction, voltage profile improvement, environmental friendliness, dependability, and postponement of system changes. This study uses artificial neural networks and the Chameleon Optimization Algorithm to analyze the best integration of renewable energy sources and electric vehicles in distribution feeders to reduce power loss, regulate voltage levels, and decrease the cost and emissions under unpredictable load demand. In this study, the generated output power of the models is compared to solar photovoltaic generation systems and wind turbine generation systems. As a result, a fitness function with several objectives has been developed to reduce total active power loss while also reducing total cost and emissions generation. The study took into account the influence of EV charging/discharging behavior on the distribution system. The 28-bus rural distribution network in feeders is used to test the suggested methodology. Final analysis of the numerical results showed that the Artificial Neural Network and Chameleon Optimization Algorithms outperformed in terms of power loss (440.94 kw) and average purchase of real power (2224 kw), but these parameters do not favor the other optimization algorithms. This showed that the proposed strategy is both viable and effective.Öğe Prediction of the brain temperature from other body temperatures in hypothermia induced rats by using artificial neural networks(Pergamon-Elsevier Science Ltd, 2012) Demirel, Huseyin; Goktas, H. Haldun; Erkal, Bilgehan; Ciylan, BunyaminIn this study, a microcontroller based temperature controlled hypothermia induction system is realized. The novelty of the experimental system is in using a thermoelectric Peltier cooler to bring the body temperature to hypothermic levels. The right and left ear, rectum, and brain temperatures of a rat are measured with this system. Then, an artificial neural network (ANN) is trained using temperature data to predict brain temperature from other body temperatures. It is shown that the system has the capability to predict the brain temperature with low error from rectum temperature measurements. The results from this empirical prototype also show that it is possible to use the system on humans to induce local hypothermia safely, where an interior temperature probe in the scalp is eliminated. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Uydu yöneliminin bulanık değişken yapılı kontrolcü ile denetimi(Karabük Üniversitesi, 2013) Erkal, Bilgehan; Demirel, HüseyinBu tez çalışmasında, çeşitli uyduların yönelim kontrolünü yüksek belirsizlikler altında kararlı bir biçimde gerçekleştirebilecek gürbüz bir kontrolcü, yapay zeka tekniklerine dayalı olarak tasarlanmıştır. Sensör sisteminde yüksek gecikmeler içeren sistemlerin kontrolü güç bir iştir. Literatürde, bu probleme önerilen çeşitli çözümlerden birisi kontrolcüyü en baştan yüksek bir gürbüzlük seviyesine sahip olarak tasarlamaktır. Tez çalışmasında da bu yaklaşım benimsenmiştir. Çözüm olarak önerilen kontrolcü, melez Bulanık Değişken Yapılı Kontrolcüdür (BDYK). Çalışmada, BDYK parametreleri optimal değerlere ayarlanmıştır. Önerilen kontrolcünün gürbüz karakterini ortaya koymak maksadıyla tasarlanan benzetim ortamı 3 serbestlik derecesine sahip gövde modeline dayalı bir uydu modeli içermektedir. Gövde modeli etrafında eyleyici ve sensör modelleri bulunmaktadır. Eyleyici modeli montaj hatalarından kaynaklanan belirsizlikler içermektedir. Sensör modeli ise çalışmanın farklı aşamalarında değişen oranlarda gecikme ve jitter gürültüsü içermektedir. Benzetim ortamında sistem performansı MATLAB/Simulink altında kaydedilmiş ve yönelim hataları bir grafik haline getirilmiştir. Ayrıca bu grafiklerdeki verilerden elde edilen rms yönelim hataları farklı kontrolcülerin gösterdiği performansları karşılaştırmak maksadıyla hesaplanmıştır. Kontrolcünün gürbüz karakterini ortaya koymak için 3 farklı deney tasarlanmıştır. Her bir deneyde kullanılan uydu modelleri, yönelim komutları ve belirsizlik seviyeleri farklıdır. Böylece kontrolcünün karakteri farklı açılardan ele alınmaya çalışılmıştır. Ayrıca çalışmada karşılaştırma maksadıyla PD, LQG ve LS kontrolcüler gibi farklı kontrolcüler tasarlanmıştır. 1 nolu deneyde ayrıca BDYK?nın integral bir terim içeren başka bir versiyonu (İBDYK) da mevcuttur. İleriki deneylerde BDYK parametrelerini uygun değerlere ayarlamakla bir integral terime ihtiyaç olmadığı gösterilmiştir. Çalışmada, en yüksek belirsizlik seviyeleri 3 nolu deneyde uygulanmıştır. Ayrıca, 3 nolu deneyde kontrolcü performansları değişken gecikmeler ve jitter gürültüsü kullanılarak daha ayrıntılı bir biçimde irdelenmiştir. Sonuç olarak her 3 deneyde BDYK?nın yüksek belirsizlikler altında kararlılığını koruyabilen gürbüz bir karakterde olduğu görülmüştür. Diğer kontrolcülerden, PD ve LQG kontrolcülerin yeterince gürbüz karakterde olmadığı anlaşılmıştır. LS kontrolcünün, BDYK?ya performans olarak en yakın olduğu bulunmuştur. Çalışma sonuçlarına göre BDYK gürbüz bir kontrolcüdür ve başta algılayıcı verisindeki gecikmeler olmak üzere yüksek belirsizlikler ve jitter gürültüsü altında uydu yönelimini kontrol edebilme kabiliyetine sahiptir. Çalışmanın getirdiği en önemli yenilik, başta yüksek gecikmeler olmak üzere çeşitli belirsizliklerle BDYK gibi bir gürbüz kontrolcünün tek başına üstesinden gelebileceğini göstermiş olmasıdır.
