Okyay Kaynak

Okyay Kaynak
Bogazici University · Department of Electrical and Electronic Engineering

PH.D.

About

449
Publications
76,153
Reads
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15,277
Citations
Introduction
His current research interests are in the fields of AI, intelligent control and mechatronics. He has authored three books and edited five and authored or co-authored more than 400 papers that have appeared in various journals and conference proceedings. He is a Clarivate Analytics Highly Cited Researcher (2017, 2018 and 2019) and a recipient of Humboldt Research Prize (2016). Dr. Kaynak is a fellow of IEEE. He served as the president of IEEE Industrial Electronics Society during 2002-2003.
Additional affiliations
January 1989 - present
Bogazici University
Position
  • Professor (Full)

Publications

Publications (449)
Article
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The study of artificial intelligence (AI) has been a continuous endeavor of scientists and engineers for over 65 years. The simple contention is that human-created machines can do more than just labor-intensive work; they can develop human-like intelligence. Being aware or not, AI has penetrated into our daily lives, playing novel roles in industry...
Article
Inaccurate model, uncertainties and valve bias are the main challenges for the controller design of high precision electro-hydraulic servo systems. To achieve a satisfactory tracking control performance under such difficulties, a fractional order integral sliding mode controller based on a radial basis function neural network(RBFNN) is proposed and...
Article
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Abstract—Threats of cyber attacks have penetrated from disclosing critical user information to destroying/manipulating industrial control systems. Study on data security during network transmission has raised increasing attention in the systems and control community, which is found very necessary and timely in the context of Industry 4.0. In most e...
Article
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This paper investigates a novel model-free optimal controller for nonlinear autonomous underwater vehicles (AUVs). It is considered that the AUV considered as the case study is subject to multi-asymmetric constrained inputs. To achieve the optimal controller, a performance index function with exponential discounted value term and input hyperbolic f...
Article
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Multi-step time-series prediction is an essential supportive step for decision-makers in several industrial areas. Artificial intelligence techniques, which use a neural network component in various forms, have recently frequently been used to accomplish this step. However, the complexity of the neural network structure still stands up as a critica...
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Deep learning techniques have promoted the rise of artificial intelligence (AI) and performed well in computer vision. Medical image analysis is an important application of deep learning, which is expected to greatly reduce the workload of doctors, contributing to more sustainable health systems. However, most current AI methods for medical image a...
Article
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With the frequent occurrence of safety incidents in cyber–physical systems (CPSs), great significance has been attached to the study of defense schemes against cyber–physical attacks. In this paper, an integrated data-driven defense scheme is proposed, which can sensitively detect data integrity attacks such as false data injection (FDI) attacks, d...
Article
During the last two decades, profound technological changes have taken place around us, supported by disruptive advances, both on the software and hardware sides. An amalgamation of information, communication, and artificial intelligence is taking place, as well as the cross-fertilization of a wide range of concepts, referred to as the digital tran...
Article
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A digital twin (DT) is classically defined as the virtual replica of a real-world product, system, being, communities, even cities that are continuously updated with data from its physical counterpart, as well as its environment. It bridges the virtual cyberspace with the physical entities and, as such, is considered to be the pillar of Industry 4....
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Starting in the second half of the last century, the widespread use of computers has significantly changed the lifestyles of humankind. Since then, with the explosive and perhaps disruptive developments in digital technology, the internet and Internet of Things and artificial intelligence have promoted a growing interaction among humans and machine...
Article
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Symbiotic autonomous systems (SAS) are advanced intelligent and cognitive systems that exhibit autonomous collective intelligence enabled by coherent symbiosis of human–machine interactions in hybrid societies. Basic research in the emerging field of SAS has triggered advanced general-AI technologies that either function without human intervention...
Article
This brief proposes a subspace-aided fault detection approach for the drive systems of strip rolling mills. Considering the impact of the unknown periodic load generated by the strip rolling process, the primary contributions are concluded as follows. First, this brief presents an approach to describe the subspace of the unknown/unmeasurable period...
Chapter
Gradient descentGradient Descent (GD) is a computational optimization method which is based on the first-order Taylor expansion of nonlinear functions. In order to find a local minimum for a nonlinear function, this algorithm uses the initial parameters of the nonlinear function and updates these parameters in the negative direction of the gradient...
Chapter
The feedback linearization method can be used to control nonlinear systems without linearizing them around a specific equilibrium point. This controller includes a nonlinear feedback controller to eliminate the nonlinear terms. The mathematical preliminaries to design a feedback linearization controller is established in this chapter. The following...
Chapter
Fuzzy logicFuzzy logic has proved itself as an advanced model-free approach with tremendous impact on control community. Fuzzy logicFuzzy logic has the ability to handle uncertainties, lack of modeling, and operational disturbances in a control system using expert knowledge. In this chapter, rule-based sliding mode fuzzy logic controllers are desig...
Chapter
Optimization is the selectionSelection process of the best elements with respect to some criterion from a feasible set of variables. There may be single or multiple objectives to be considered during optimization. The optimization process generally involves the minimization of a cost or maximization of a profit. Sliding mode controller design probl...
Chapter
Lack of imprecise nonlinear model of real-time systems is inevitable due to several simplifications made, neglected frictions, dead-zones, and saturation. One of the most well-known nonlinear control design tools to deal with uncertainties is sliding-mode control approach. In this method the desired behavior is defined in terms of a sliding manifol...
Chapter
Control of a system—for example, operation of a robot—through a communication link from a distant location is called teleoperationTeleoperation. Remote operations in hazardous and unreachable areas are crucial and inevitable; examples of such areas are complex and challenging tasks in disaster areas, space robotic applications, remotely operated ve...
Chapter
This chapter deals with adaptive design of fuzzy controllers based on sliding-modeSliding mode control law. As it was mentioned earlier, a challenge to design a sliding- modeSliding mode controller is necessity to have the nominal dynamics of the system. This requires a series of modeling prior to the control of the system. Fuzzy logic systems as g...
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Centralized direct digital control systemsDirect digital control systems have several drawbacks, for example, massive wiring requirements, difficult diagnosis, and difficult fault detection procedures. Most of these drawbacks may impose heavy costs on the maintenance of the control system. These disadvantages have given rise to the development of N...
Chapter
The word “fuzzy” means imprecisely defined, confused, and vague. However, fuzzy systems benefit from mathematical formulation to determine their output. This chapter deals with type-1 fuzzy systems as well as interval type-2 fuzzy systems in which different parts of these fuzzy systems are explained.
Article
In this paper, a novel time-domain frequency estimation approach is proposed based on the well-known Subspace Identification Method (SIM). Differing from the Fast Fourier Transformation (FFT) method, the nonlinear identification for frequency estimation is reformulated into the eigenvalue identification problem, which avoids the spectrum peak searc...
Preprint
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Provision of some autonomous functions to an agricultural vehicle would lighten the job of the operator but in doing so, the accuracy should not be lost to still obtain an optimal yield. Autonomous navigation of an agricultural vehicle involves the control of different dynamic subsystems, such as the yaw angle dynamics and the longitudinal speed dy...
Article
The papers in this special section focus on the use of mechatronics in unmanned systems. During the past few decades, unmanned systems have widely been applied in the environs of aerospace, ground, surface, and underwater. It is expected that unmanned systems will have more pervasive applications in industry, military, agriculture, logistics, etc.,...
Article
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Short-term water demand forecasting (StWDF) is the foundation stone in the derivation of an optimal plan for controlling water supply systems. Deep learning (DL) approaches provide the most accurate solutions for this purpose. However, they suffer from complexity problem due to the massive number of parameters, in addition to the high forecasting e...
Preprint
Full-text available
Symbiotic Autonomous Systems (SAS) are advanced intelligent and cognitive systems exhibiting autonomous collective intelligence enabled by coherent symbiosis of human-machine interactions in hybrid societies. Basic research in the emerging field of SAS has triggered advanced general AI technologies functioning without human intervention or hybrid s...
Article
This paper considers the problem of distributed adaptive fuzzy event-based finite-time prescribed performance leader-following tracking control for heterogeneous nonlinear multi-agent systems (NMASs) over a directed topology. Each agent is considered in a non-affine nonstrict-feedback form under input saturation and output constraint which contains...
Article
The Industrial Revolution, which originally involved the change from an agrarian and handicraft economy to a market dominated by factory mechanization during the early 18th century, has profoundly shaped the world. It has progressed through four disruptive phases: Industry 1.0 through Industry 4.0. Industry 1.0 encompassed early automation, while I...
Article
This book addresses some of the challenges suffered by the well-known and robust sliding-mode control paradigm. The authors show how the fusion of fuzzy systems with sliding-mode controllers can alleviate some of these problems and promote applicability. Fuzzy systems used as soft switches eliminate high-frequency signal oscillations and can subst...
Article
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Digitization and digitalization have already changed our world significantly. Further disruptions are imminent with the ongoing digital transformation, a major component of which is digital twins. As the big data techniques, Internet of Things, cloud computing, and artificial intelligence algorithms advance, the digital twin technology has entered...
Article
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The intensive research and development efforts directed towards large-scale complex industrial systems in the context of Industry 4.0 indicate that safety and reliability issues pose significant challenges. During online operation, system performance degradation will lead, not only to economic losses, but also potential safety hazards. In the exist...
Article
In recent years, with the rapid growth of rooftop photovoltaic (PV) generation in distribution networks, power system operators call for accurate forecasts of the behind-the-meter (BTM) load and PV generation. However, the existing forecasting methodologies are incapable of quantifying such BTM measurements as the smart meters can merely measure th...
Article
The problem of finite-time path following control for a typical 6-DOF (degree of freedom) autonomous underwater vehicle (AUV) subjected to parametric and modeling uncertainties, disturbances and unknown saturation nonlinearities is studied and discussed in this paper. For the mentioned AUV, finite-time control inputs are designed based on innovativ...
Article
This article investigates the design of an optimal tracking controller for a class of nonlinear continuous-time systems with time-delay, mismatched external disturbances and input constraints. The technique of integral reinforcement learning (IRL) is utilized for determining the control input that optimizes an objective function. To enable the usag...
Article
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Over the past twenty years, numerous research outcomes have been published, related to the design and implementation of soft sensors. In modern industrial processes, various types of soft sensors are used, which play essential roles in process monitoring, control and optimization. Emerging new theories, advanced techniques and the information infra...
Article
In this paper, a real-time three-tank system setup is used for practical investigations. Differing with the virtual simulator of three-tank system, the setup can enable the setting of different types of faults through manual manipulation, users can choose the combinations of different valves and knobs in the setup which is helpful to evaluate and c...
Article
Due to the recent rapid developments in communication and networking technologies as well as computer science, the complexity of automatic control systems has increased significantly. To ensure the safety and the reliability of such systems under continuous operation, real-time supervision and control systems have now to run in parallel. These deve...
Article
This paper considers chaos in a PI control system for the first time and presents an equivalent-input-disturbance (EID)-based control method to suppress a chaotic phenomenon. Since the chaos is caused by two nonlinear terms, two EID estimators are used to separately compensate for them, and thus to suppress any possible chaos. This paper devises a...
Article
A finite-time control method is presented for n-link robots with actuator saturation under time-varying constraints of work space. Barrier Lyapunov functions (BLFs) are designed for ensuring that the robot remains under time-varying constraints of the work space. In order to deal with asymmetric saturation nonlinearity, we transform asymmetric satu...
Article
The fault-tolerant control (FTC) issue is considered in this article for Markovian jump systems (MJSs) in which both nonlinearity and actuator faults exist simultaneously. The existed nonlinearity in the considered MJSs means that there exist limitations to employ the renown sliding mode control (SMC) method directly. In this work, the radial basis...
Article
This paper selected nine novel feature quantities that can reflect control performance in the closed-loop. Combined with support vector machine (SVM) and k-nearest neighbor (KNN), they are used to perform accurate fault diagnosis. Stability margin describes the degree of stability of the transfer function matrix of system, and thus can be used as a...
Article
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In this paper, a data-driven predictive control strategy for nonlinear system is proposed and testified on a continuous stirred tank heater (CSTH) benchmark. A recursive modified partial least square (RMPLS) algorithm is employed to regress the local linear model. The algorithm of locally weighted projection regression (LWPR) is then leveraged to b...
Article
This paper is concerned with a novel data-driven bias-eliminated subspace identification approach for closed-loop systems. Compared with the existing methods, the proposed method firstly proposes to utilize the coprime factorization of the controller to construct an instrumental variable uncorrelated with noise under closed-loop conditions. Further...
Article
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In the conventional approaches to the design of fault diagnosis systems, little effort is usually paid to the selection of the parity vectors. As a result, the systems' performance can be significantly affected. In this work, novel approaches are proposed to derive the parity vectors that construct optimized residual generators for linear and nonli...
Preprint
p>During the last two decades, profound technological changes have taken place around us, supported by disruptive advances, both on software and hardware sides. An amalgamation of information, communication and AI is taking place, as well as the cross-fertilization of a wide range of concepts, referred to as the digital transformation. As a re...
Preprint
p>During the last two decades, profound technological changes have taken place around us, supported by disruptive advances, both on software and hardware sides. An amalgamation of information, communication and AI is taking place, as well as the cross-fertilization of a wide range of concepts, referred to as the digital transformation. As a re...
Article
Full-text available
This paper describes a novel approach for the control of underwater robots that can handle uncertainties and disturbance problems, which are commonly met in underwater environments. The considered system is an underwater manipulator with n-degrees of freedom. The approximation capability of an adaptive neural network is exploited to estimate uncert...
Preprint
Full-text available
Traffic flow characteristics are one of the most critical decision-making and traffic policing factors in a region. Awareness of the predicted status of the traffic flow has prime importance in traffic management and traffic information divisions. The purpose of this research is to suggest a forecasting model for traffic flow by using deep learning...
Article
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Filters are the fastest among the different types of feature selection methods. They employ metrics from information theory, such as mutual information (MI), Joint-MI (JMI), and minimal redundancy and maximal relevance (mRMR). The determination of the optimal feature selection set is an NP-hard problem. This work proposes the engineering of the Gen...
Article
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It is well known that cyber-physical systems (CPSs) commonly exist in both industrial manufacturing and people’s daily lives. As a hot topic within Industry 4.0, CPSs have attracted interest from both academia and industry. Typical examples of CPSs include autonomous vehicles, smart grid, process control systems, and industrial robotics systems. Th...
Article
In most of industrial applications, the dynamics of the system in hand are perturbed by a number of operational conditions. Also the outputs of the sensors always include noise. To alleviate these common problems, this paper presents a novel fuzzy control approach based on the immersion and invariance (I&I) approach under the conditions of unknown...
Article
In this paper, a fractional order model of pneumatic servo system is introduced by replacing the integer order dynamic equation with the corresponding fractional order one. Then, a Fractional order Proportional-Integer-Differential (FPID) controller is optimized for the servo system using an online multi-variable multi-objective genetic algorithm (...
Article
In this paper, the complex problems of internal forces and position control are studied simultaneously and a disturbance observer-based radial basis function neural network (RBFNN) control scheme is proposed to: 1) estimate the unknown parameters accurately; 2) approximate the disturbance experienced by the system due to input saturation; and 3) si...
Article
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In this paper, a novel robust predictive control strategy is proposed for the synchronization of fractional-order time-delay chaotic systems. A recurrent non-singleton type-2 fuzzy neural network (RNT2FNN) is used for the estimation of the unknown functions. Additionally, another RNT2FNN is used for the modeling of the tracking error. A nonlinear m...
Article
Robust and accurate control of a flapping-wing aerial vehicle (FWAV) system is a challenging problem due to the existence of backlash-like hysteresis nonlinearity. This paper proposes uncertainty and disturbance estimator (UDE)-based control with output feedback for FWAV systems. The approach enables the acquisition of the approximate plant model w...
Article
Gas flow has fractional order dynamics; therefore, it is reasonable to assume that the pneumatic systems with a proportional valve to regulate gas flow have fractional order dynamics as well. There is a hypothesis that the fractional order control has better control performance for this inherent fractional order system, although the model used for...
Article
Full-text available
The performance of the pneumatic elements and the micro-controller steadily increases as the price of them decreases. This trend promotes the high performance tracking control research on pneumatic servo systems. However, it is very difficult to obtain exact model parameters, which is one of main obstacles to design a high performance controller. M...
Article
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In this paper, a robust adaptive control scheme is proposed for the leader following control of a class of fractional-order multi-agent systems (FMAS). The asymptotic stability is shown by a linear matrix inequality (LMI) approach. The nonlinear dynamics of the agents are assumed to be unknown. Moreover, the communication topology among the agents...
Article
Full-text available
Industrial cyber-physical systems (ICPSs) are the backbones of Industry 4.0 and as such, have become a core transdisciplinary area of research, both in industry and academia. New challenges brought about by the growing scale and complexity of systems, insufficient information exchange and the exploitation of knowledge available have started threate...