Browsing by Author "Kerestecioğlu, Feza"

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Citation Count: 2
Active reconfigurable control of a submarine with indirect adaptive control
(2003) 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 Count: 0
Circular formations of non-communicating robot groups via local strategies
(Sage Publications Ltd, 2023) 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 Count: 1
Connected navigation of non-communicating mobile agents
(IEEE, 2012) 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 Count: 6
Fault tolerant control with re-configuring sliding-mode schemes
(2005) 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 Count: 0
Fault Tolerant Indoor Positioning Based on Federated Kalman Filter
(Springer, 2024) 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 Count: 6
Indoor Positioning Using Federated Kalman Filter
(IEEE, 2018) 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 Count: 0
Indoor Positioning Using Federated Kalman Filter
(Institute of Electrical and Electronics Engineers Inc., 2018) 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 Count: 3
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 Count: 2
Navigation of autonomous mobile robots in connected groups
(IEEE, 2008) 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 Count: 9
Navigation of non-communicating autonomous mobile robots with guaranteed connectivity
(Cambridge Univ Press, 2013) 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 Count: 1
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 Count: 1
A non-communicating multi-robot system with switchable formations
(2013) 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 Count: 2
Nonuniform sampling for detection of abrupt changes
(Birkhauser Boston Inc, 2003) 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 Count: 1
On preserving connectivity of autonomous mobile robots
(IEEE, 2009) 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 Count: 12
Optimal input design for the detection of changes towards unknown hypotheses
(Taylor & Francis Ltd, 2004) 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 Count: 15
A re-configuring sliding-mode controller with a ustable robustness
(Pergamon-Elsevier Science Ltd, 2004) Kerestecioğlu, Feza; Kerestecioğlu, Feza
In this paper a controller design method for underwater vehicles is presented which is based on re-configuration of a sliding-mode controller in case of disturbances caused by shallow water conditions. The disturbance distribution information can be obtained and used to update the corrective gain vector of the sliding-mode controller. This increases the robustness of the controller and hence keeps the system performance within acceptable limits. Proposed method is validated with simulations on a submarine model. (C) 2003 Published by Elsevier Ltd.
Citation Count: 4
RSSI-Based Indoor Positioning via Adaptive Federated Kalman Filter
(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Kerestecioğlu, Feza; Kerestecioglu, Feza
In this paper, federated Kalman filter (FKF) is applied for indoor positioning. Position information that is multi-laterated from the distance information obtained using the received signal strengths collected from several access points are processed in a FKF to estimate the position of the target. Two approaches are presented to adjust the information-sharing coefficients of FKF using online measurements. The data collected on a test bed composed of four access points are used to assess and compare the performances of the proposed algorithms. It is shown that the estimation error can be improved considerably by adjusting the information-sharing coefficients online.
Citation Count: 0
Sliding mode controller solution for the shallow submerged operation ok a submarine
(IFAC Secretariat, 2003) Kerestecioğlu, Feza; Kerestecioğlu, Feza
In this paper a submarine controller is presented which can accommodate the sea wave effects on a submarine a(shallow water operation. Sliding mode method is implemented in a way that the robustness of the controller increased with respect to disturbance distribution vector in order to perform the depth control of a shallow submerged submarine under sea wave disturbances. Designed controller kept the submarine performance within acceptable limits. Copyright © 2003 IFAC.
Citation Count: 5
Zero-crossing based demodulation of minimum shift keying
(2003) Kerestecioğlu, Feza; Kerestecioğlu, Feza
Minimum shift keying (MSK) modulation has features such as constant envelope compact spectrum and good error performance which are all desirable in many digital applications including mobile radio. Numerous receiver structures to demodulate MSK have been suggested such as correlation receivers differential detectors and frequency discriminators MSK is a form of biphase keying and can be detected by a zero-crossing based phase demodulator which gives near optimum performance. In this paper the bit error performance of a zero-crossing based coherent MSK demodulator is theoretically investigated and a closed-form expression for the bit error rate is derived. The results indicate that the demodulator performs within 0.8-1 dB of the theoratical optimum for MSK. Towards the goal of deriving probability of bit error it is also shown that under additive white Gaussian noise (AWGN) zero-crossing locations of MSK signals are Gaussian distributed except at very low signal-to-noise ratios.