Browsing by Author "Kerestecioğlu, Feza"

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Citation - Scopus: 2
Active Reconfigurable Control of a Submarine With Indirect Adaptive Control
(2003) Demirci, Ufuk; Kerestecioğlu, Feza; Kerestecioğlu, Feza
An indirect adaptive controller is designed for submersibles. The design is developed using a linearized MIMO model of a submarine. Standard recursive least squares estimation method is used to estimate the parameters. Depth and pitch angle of the submarine is controlled by means of the well-known indirect self-tuning method. In case of a system fault estimated parameters of the submarine model have been used to update the controller coefficients.
Citation - WoS: 0
Circular Formations of Non-Communicating Robot Groups Via Local Strategies
(Sage Publications Ltd, 2023) Kerestecioglu, Feza; Kerestecioğlu, Feza; Sen, Uemit; Isikver, Cagri; Goktekin, Ahmet
Local strategies, which are based on cost minimization, to achieve circular formations of autonomous robot groups are presented. It is assumed that the group members have no communication capabilities or any means of interchanging information among themselves, and that they can only rely on their sensors, which provide relative positions of their nearby group members. It is verified on simulations that via appropriately defined cost functions arc, arc-triangle and circle formations are obtained, which can be maintained during navigation.
Citation - Scopus: 0
Circular Formations of Non-Communicating Robot Groups Via Local Strategies
(SAGE Publications Ltd, 2024) Kerestecioğlu,F.; Kerestecioğlu, Feza; Şen,Ü.; Işıkver,Ç.; Göktekin,A.
Local strategies, which are based on cost minimization, to achieve circular formations of autonomous robot groups are presented. It is assumed that the group members have no communication capabilities or any means of interchanging information among themselves, and that they can only rely on their sensors, which provide relative positions of their nearby group members. It is verified on simulations that via appropriately defined cost functions arc, arc-triangle and circle formations are obtained, which can be maintained during navigation. © The Author(s) 2023.
Citation - Scopus: 1
Connected Navigation of Non-Communicating Mobile Agents
(IEEE, 2012) Kerestecioğlu, Feza; Kerestecioğlu, Feza; Cezayirli, Ahmet
This article discusses the connectivity of autonomous mobile robots that do not have communication capabilities. We show that if the group members follow the proposed Local Steering Strategy which utilizes information only about the relative positions of neighbor robots they can sustain their connectivity even in the case of bounded position measurement errors and the occultation of robots by other robots in the group. To reduce the computational burden in the implementation of the proposed methodology we used sub-optimal solutions. © 2012 IEEE.
Citation - WoS: 6
Citation - Scopus: 8
Design and Implementation of a Nano-Scale High-Speed Multiplier for Signal Processing Applications
(Elsevier, 2024) Ahmadpour, Seyed-Sajad; Kerestecioğlu, Feza; Jafari Navimipour, Nima; Ul Ain, Noor; Kerestecioglu, Feza; Yalcin, Senay; Avval, Danial Bakhshayeshi; Hosseinzadeh, Mehdi
Digital signal processing (DSP) is an engineering field involved with increasing the precision and dependability of digital communications and mathematical processes, including equalization, modulation, demodulation, compression, and decompression, which can be used to produce a signal of the highest caliber. To execute vital tasks in DSP, an essential electronic circuit such as a multiplier plays an important role, continually performing tasks such as the multiplication of two binary numbers. Multiplier is a crucial component utilized to implement a wide range of DSP tasks, including convolution, Fourier transform, discrete wavelet transforms (DWT), filtering and dithering, multimedia information processing, and more. A multiplier device includes a clock and reset buttons for more flexible operational control. Each digital signal processor constitutes a multiplier unit. A multiplier unit functions entirely autonomously from the central processing unit (CPU); consequently, the CPU is burdened with a significantly reduced amount of work. Since DSP algorithms must constantly carry out multiplication tasks, the employment of a high-speed multiplier to execute fast-speed filtering processes is vital. The previous multipliers had lots of weaknesses, such as high energy, low speed, and high area, because they implemented this necessary circuit based on traditional technology such as complementary metal-oxide semiconductor (CMOS) and very large-scale integration (VLSI). To solve all previous drawbacks in this necessary circuit, we can use nanotechnology, which directly affects the performance of the multiplier and can overcome all previous issues. One of the alternative nanotechnologies that can be used for designing digital circuits is quantum dot cellular automata, which is high speed, low area, and low power. Therefore, this manuscript suggests a quantum technology-based multiplier for DSP applications. In addition, some vital circuits, such as half adder, full adder, and ripple carry adder (RCA), are suggested for designing a multiplier. Moreover, a systolic array, accumulator, and multiply and accumulate (MAC) unit are proposed based on the quantum technologybased multiplier. Nonetheless, each of the suggested frameworks has a coplanar configuration without rotated cells. The suggested structure is developed and verified utilizing the QCADesigner 2.0.3 tools. The findings showed that all circuits have no complicated configuration, including a higher number of quantum cells, latency, and an optimum area.
Citation - Scopus: 6
Fault Tolerant Control With Re-Configuring Sliding-Mode Schemes
(2005) Demirci, Ufuk; Kerestecioğlu, Feza; Kerestecioğlu, Feza
In this paper a controller design method for linear MIMO systems is presented which a sliding mode controller is reconfigured in case of system faults. Faults are detected with the residual vector generated from a standard linear observer. Once a fault has been detected the fault distribution matrix can be obtained and used to update the corrective or equivalent control parts of the sliding mode controller. As a result fault tolerant adaptive controllers keep the system performance within acceptable limits or at least avoids the system to wind-up. © TÜBITAK.
Citation - WoS: 0
Citation - Scopus: 1
Fault Tolerant Indoor Positioning Based on Federated Kalman Filter
(Springer, 2024) Ayabakan, Tarik; Kerestecioğlu, Feza; Kerestecioglu, Feza
In this article, multi-sensor indoor positioning, which is based on fusing tri-laterated position data of the target, is considered. A novel method, which is based on federated Kalman filtering and makes use of the fingerprint data, namely, federated Kalman filter with skipped covariance updating (FKF-SCU) is proposed. The data collected on two test beds are used in comparing the performances of the proposed algorithm and that of the regular federated filter. It is shown that the proposed algorithm provides fault tolerance and quick recovery, whenever signal reception from an access point is interrupted, as well as an improvement of 12.57% on the position accuracy.
Citation - WoS: 0
Citation - Scopus: 6
Indoor Positioning Using Federated Kalman Filter
(Institute of Electrical and Electronics Engineers Inc., 2018) Ayabakan, Tarık; Kerestecioğlu, Feza; Kerestecioğlu, Feza
In this paper, the performance of a multi-sensor fusion technique, namely Federated Kalman Filter (FKF) is studied in the context of indoor positioning problem. Kalman filters having centralized and decentralized structures are widely used in outdoor positioning and navigation applications. Global Positioning System (GPS) is the most commonly used system for outdoor positionin/navigation, which cannot be used indoors due to the signal loss. In this study, a decentralized structure for FKF is applied in indoor positioning problem by taking its outdoor navigation performance into consideration. Simulations are performed with distance measurements, which are assumed to be calculated by using Received Signal Strength (RSS). Results gathered via different simulations are evaluated as promising for future studies.
Citation - WoS: 7
Indoor Positioning Using Federated Kalman Filter
(IEEE, 2018) Aybakan, Tarik; Kerestecioğlu, Feza; Kerestecioglu, Feza
In this paper, the performance of a multi-sensor fusion technique, namely Federated Kalman Filter (FKF) is studied in the context of indoor positioning problem. Kalman filters having centralized and decentralized structures are widely used in outdoor positioning and navigation applications. Global Positioning System (GI'S) is the most commonly used system for outdoor positioning/navigation, which cannot be used indoors due to the signal loss. In this study, a decentralized structure for FKF is applied in indoor positioning problem by taking its outdoor navigation performance into consideration. Simulations are perl4med with distance measurements, which are assumed to be calculated by using Received Signal Strength (RSS). Results gathered via different simulations are evaluated as promising for future studies.
Citation - Scopus: 5
Indoor Positioning Using Federated Kalman Filter
(Institute of Electrical and Electronics Engineers Inc., 2018) Ayabakan, T.; Kerestecioğlu, Feza; Kerestecioglu, F.
In this paper, one of the multi sensor fusion techniques, namely Federated Kalman Filter (FKF) performance is studied for Indoor Positioning problem. Kalman Filters having centralized and decentralized structures are widely used for outdoor positioning and navigation applications. Besides them, indoor positioning received large interest in recent years. In this study, decentralized FKF is applied in indoor positioning problem by taking its outdoor navigation performance into consideration. Simulations are done using distance measurements assumed to be priorly calculated. Results gathered via simulations are evaluated to be promising for future studies. © 2018 IEEE.
Citation - WoS: 5
Citation - Scopus: 6
Multi-Sensor Indoor Positioning
(Institute of Electrical and Electronics Engineers Inc., 2019) Kerestecioğlu, Feza; Kerestecioğlu, Feza
In this paper, the performance of three different kinds of Kalman Filter (KF) structure: Single Kalman Filter (SKF)(which filters data of a single sensor), Centralized Kalman Filter (CKF) and Federated Kalman Filter (FKF) are studied considering the indoor positioning problem. Kalman filters are widely used in outdoor positioning and navigation applications providing good results. For multi-sensor applications, KF has centralized and decentralized structures. In this study, multisensor and single-sensor dedicated Kalman filter structures FKF, CKF and SKF are applied in indoor positioning problem by taking its outdoor navigation performance into consideration. Received Signal Strength (RSS) data are generated, from which distance information, a vital part of the simulations, are obtained. Three different noise levels are used to assess performance of filters. Results gathered via different simulations showed that multi-sensor structures provide a better solution than single sensor structures.
Multi-sensor indoor positioning
(Kadir Has Üniversitesi, 2022) AYABAKAN, TARIK; Kerestecioğlu, Feza; Kerestecioglu, Feza
In this study, multi-sensor indoor positioning methods, which fuse the tri-laterated position data of the target are considered. The lateration is based on the dis tances that are obtained using the signal strengths received from different Wi-Fi access points. A new method, which is based on federated Kalman filtering (FKF) and makes use of the fingerprint data, namely, federated Kalman filter with skipped covariance updating (FKF-SCU) is proposed for indoor positioning. After that chal lenging issue of FKF, information sharing coefficient assignment is studied and two online adaptation methods based on received signal strength indication (RSSI) and distance information gathered from APs are proposed. Lastly, FKF-SCU structure is combined with adaptive FKF configuration. The data collected on two different test beds are used to compare the performance of the proposed positioning methods to those of the regular federated and centralized filters. It is shown on the test data that these algorithms improve the position accuracy and provide fault tolerance whenever signal reception is interrupted from an access point.
Citation - WoS: 2
Citation - Scopus: 8
Navigation of Autonomous Mobile Robots in Connected Groups
(IEEE, 2008) Cezayirli, Ahmet; Kerestecioğlu, Feza; Kerestecioğlu, Feza
The navigation of autonomous mobile robots as a group is considered in this paper. Definitions adopted from the graph theory are given to characterize the robot group. A local steering strategy is proposed such that when each robot in the group applies this steering scheme the overall result is that the whole group is displaced without losing its connectivity. This is achieved using only limited-range position sensors and without any communication between the robots.
Citation - WoS: 9
Citation - Scopus: 9
Navigation of Non-Communicating Autonomous Mobile Robots With Guaranteed Connectivity
(Cambridge Univ Press, 2013) Cezayirli, Ahmet; Kerestecioğlu, Feza; Kerestecioğlu, Feza
We consider the connectivity of autonomous mobile robots. The robots navigate using simple local steering rules without requiring explicit communication among themselves. We show that using only position information of neighbors the group connectivity can be sustained even in the case of bounded position measurement errors and the occlusion of robots by other robots in the group. In implementing the proposed scheme sub-optimal solutions are invoked to avoid an excessive computational burden. We also discuss the possibility of deadlock which may bring the group to a standstill and show that the proposed methodology avoids such a scenario in real-life settings.
Citation - Scopus: 7
A New Nano-Design of an Efficient Synchronous Full-Adder/Subtractor Based on Quantum-Dots
(ISRES Publishing, 2023) Kerestecioğlu, Feza; Navimipour,N.J.; Kerestecioglu,F.
Quantum-dot cellular automata (QCA), known as one of the alternative technologies of CMOS technology, promises to design digital circuits with extra low-power, extremely dense, and high-speed structures. Moreover, the next generation of digital systems will be used QCA as desired technology. In designing arithmetic circuits, efficient designs such as full-adder and full-subtractor can play a significant role. In addition, they are considering the most used structures in digital operations. Furthermore, full-adder and fullsubtractor are always effective parts of all complex and well-known circuits such as Arithmetic Logic Unit (ALU), Microprocessors, etc. This paper proposes low complexity and high-speed QCA coplanar synchronous full-adder/subtractor structures by applying formulations based on the Exclusive-OR gate to decrease energy consumption. The proposed design is simulated using QCADesigner 2.0.3. The simulation results confirm the efficiency of the proposed circuit. Moreover, comparative investigation indicates the superiority of proposed designs compared to state-of-the-art designs. Finally, the suggested QCA coplanar synchronous fulladder/subtractor shows 5.88% and 7.69% improvement in consumed cells relative to the best full adder and full subtractor, respectively. © 2023 Published by ISRES.
Citation - Scopus: 1
A Non-Communicating Multi-Robot System With Switchable Formations
(2013) Cezayirli, Ahmet; Kerestecioğlu, Feza; Kerestecioğlu, Feza
We consider connected navigation of autonomous mobile robots with transitions in the group formation. The robots navigate using simple local steering rules without requiring explicit communication among themselves. The formations are achieved by designing proper cost functions and formation transitions are succeeded by switching among these cost functions. The resulting system is proven to be deadlock-free under certain conditions. © 2013 IEEE.
Citation - WoS: 2
Nonuniform Sampling for Detection of Abrupt Changes
(Birkhauser Boston Inc, 2003) Kerestecioğlu, Feza; Kerestecioğlu, Feza; Tokat, Sezai
In this work detection of abrupt changes in continuous-time linear stochastic systems and selection of the sampling interval to improve the detection performance are considered. Cost functions are proposed to optimize both uniform and nonuniform sampling intervals for the well-known cumulative sum algorithm. Some iterative techniques are presented to make online optimization computationally feasible. It is shown that considerable improvement in the detection performance can be obtained by using nonuniform sampling intervals.
Citation - WoS: 1
Citation - Scopus: 6
On Preserving Connectivity of Autonomous Mobile Robots
(IEEE, 2009) Cezayirli, Ahmet; Kerestecioğlu, Feza; Kerestecioğlu, Feza
The connectivity of the autonomous mobile robots is considered in this paper. The group navigation is provided using simple local steering rules and without any explicit communication. Sub-optimal solutions are invoked to avoid computational cost. We show that the connectivity of the group is preserved during the whole motion in spite of bounded measurement errors on angles and distances. Some special cases of group topology are also discussed.
Citation - WoS: 12
Citation - Scopus: 14
Optimal Input Design for the Detection of Changes Towards Unknown Hypotheses
(Taylor & Francis Ltd, 2004) Kerestecioğlu, Feza; Kerestecioğlu, Feza; Cetin, I
The effects of auxiliary input signals on detecting changes in ARMAX processes via statistical tests are discussed. Two extensions to the Cumulative Sum Test are considered. The first is applicable when the direction of the change in the parameter space is known but its magnitude is unknown. The second is applicable when neither is known. The performance criteria for the design of stationary stochastic inputs are based on the asymptotic properties of the tests. It is shown that power-constrained optimal inputs have discrete spectra and a suitably chosen input can greatly improve the detection performance.
Citation - Scopus: 5
Problematizing Emi Programs in Turkish Higher Education: Voices From Stakeholders
(Bloomsbury Publishing Plc., 2021) I˙nal,D.; Kerestecioğlu, Feza; Bayyurt,Y.; Keresteci˙oğlu,F.
[No abstract available]