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A cascade fuzzy adaptive based interaction torque control of a pneumatically actuated forearm rehabilitation robot under disturbance effects
(Sage Publications Ltd, 2024) Dagdelen, Mustafa; Sarigecili, Mehmet Ilteris; Ozbek, Necdet Sinan
In this study, an intelligent adaptive interaction torque control for a pneumatically actuated forearm rehabilitation robot has been proposed. The main objective is to provide a haptic environment that ensures stable interaction torque fields at changing levels. To achieve this goal, a cascade fuzzy adaptive controller, that is specifically tailored to handle varying levels of interaction torque and ensure stability throughout the rehabilitation process, has been designed. To improve the efficiency of the controller, non-linear friction torque identification of the pneumatic actuator based on changing operating conditions has been conducted. Parallel to this, a user motion intention detection algorithm has been designed to provide compliant, safe and suitable human-robot interactions. The disturbance cases have been considered to make the system robust to unknown conditions. Stability analysis has been performed, specifically focusing on the boundary-input boundary-output (BIBO) stability conditions. In order to demonstrate the superior performance of the proposed cascade fuzzy adaptive algorithm, a cascade PID algorithm has also been meticulously designed for comparison. Numerous experimental validation tests involving a healthy user were conducted in a Hardware-in-the-Loop environment, focusing on torque trajectory tracking performance. The proposed control technique exhibited improved convergence dynamics compared to the cascade PID algorithm, yielding mean absolute error levels of 0.0218 Nm and 0.099 Nm for target interaction torque under disturbance-free and disturbed conditions, respectively.
A fractional fuzzy PI-PD based modified smith predictor for controlling of FOPDT process
(IEEE Computer Society, 2017) Ozbek, Necdet Sinan; Eker, Ilyas
In this study, a novel fractional fuzzy proportional-integral proportional-derivative (PI-PD) based modified Smith predictor (SP) is presented for controlling of an industrial air heating system with time delay. The performance of the proposed controller is validated with real-time experimental applications. Furthermore, a performance comparison is demonstrated via results of real-time applications through a set of performance indices. © 2016 IEEE.
A Fractional Fuzzy PI-PD Based Modified Smith Predictor for Controlling of FOPDT Process
(IEEE, 2016) Ozbek, Necdet Sinan; Eker, Ilyas
In this study, a novel fractional fuzzy proportional-integral proportional-derivative (PI-PD) based modified Smith predictor (SP) is presented for controlling of an industrial air heating system with time delay. The performance of the proposed controller is validated with real-time experimental applications. Furthermore, a performance comparison is demonstrated via results of real-time applications through a set of performance indices.
A new compressible flow model for pneumatic directional control valves
(Sage Publications Ltd, 2023) Dagdelen, Mustafa; Sarigecili, Mehmet Ilteris; Ozbek, Necdet Sinan
In this study, a new compressible flow model for small orifice openings in pneumatic proportional directional control valves has been proposed. It is crucial to precisely control pneumatic valves over all control ranges; yet, conventional flow models fail around the closed position of the valve. The main deficit of the existing studies in the literature is to assume constant values for the parameters of the flow model over changing operating conditions. It has been demonstrated that these rough assumptions are insufficient in precisely predicting the mass flow rate, particularly for small orifice openings. An enhanced experimental setup has been introduced to improve the effectiveness of the proposed model. The cracking pressure ratio and parameters of the model have been identified with experimental method. In the proposed model, new empirical coefficients have been established after a thorough investigation of the impact of supply pressure on the flow behavior of the valve. Validation studies of the model in both the filling and exhausting states of the valve have been carried out at various supply pressures and orifice openings, yielding rather promising modeling performances. In validation tests, the real pressure and the pressure produced by new model have been compared, and good agreement has been achieved with 0.0039% absolute error. According to the findings, the proposed improved flow model can be selected in precision pneumatic control applications.
A Novel Interactive System Identification and Control Toolbox Dedicated to Real-Time Identification and Model Reference Adaptive Control Experiments
(IEEE, 2015) Ozbek, Necdet Sinan; Eker, Ilyas
This paper proposes a control-oriented identification toolbox with a set of real-time interactive computer-aided experiments to analysis parametric system identification techniques and adaptive control concepts. The proposed experiments are highlighted through a user-friendly graphical user interface (GUI) which is developed in Matlab/Simulink (R) environment. The identification and control methods considered here include; process reaction curve method, off-line and on-line parameter identification and model reference adaptive control technique (MRAC); this aspect of the paper makes it a beneficial guide to a large number of readers.
An Adaptive Passivity Based Control of Grid Connected VSC with Integral Action
(Institute of Electrical and Electronics Engineers Inc., 2019) Uslu, Akin; Ozbek, Necdet Sinan; Aydemir, Timur
In this paper, we propose improved passivity based control (PBC) strategy for grid connected voltage source converter (VSC). In order to provide global asymptotical stability of the closed loop control system in the sense of Lyapunov approach, VSC is modelled within port-Hamiltonian framework. Classical PBC techniques are insufficient to achieve zero steady state tracking error. To eliminate this errors caused by constant disturbances, integrator is inserted into to the proposed PBC. Furthermore, designed adaptive observer allows sensorless operation for the proposed method. Simulation results are presented to validate the proposed controller. © 2019 IEEE.
An Evaluation of Model-Free Control Strategies for Quadrotor Type Unmanned Aerial Vehicles
(IEEE, 2019) Ozbek, Necdet Sinan
The present study addresses two representative model-free control strategies namely, model-free intelligent PID (i-PID) and type-2 fuzzy adaptive PID in control of a quadrotor type vertical take-off and landing (VTOL) unmanned aerial vehicle. The objectives of this study are i) to summarize the modeling and flight control methods of quadrotor in some classifications, ii) to investigate merits and demerits of model-free control strategies, iii) to compare the control performance in terms of some quantitative performance criteria. The results illustrate the performance of such methodologies applied to the quadrotor system.
An Experimental Comparative Study of Modified Smith Predictor Based Fractional Order Controller Design Strategies for a Time Delay Process
(IEEE, 2017) Ozbek, Necdet Sinan; Eker, Ilyas
This paper presents real-time applications of various modified Smith Predictor (SP) based fractional order controller design strategies in control a time-delay thermal process. The elaborated methods and tuning strategies are selected carefully. A comprehensive performance evaluation is illustrated through a set of performance metrics. Further, complementary comments are highlighted on the advantages and drawbacks of each control scheme.
An Interactive Computer-Aided Instructional Strategy and Assessment Methods for System Identification and Adaptive Control Laboratory
(IEEE-Inst Electrical Electronics Engineers Inc, 2015) Ozbek, Necdet Sinan; Eker, Ilyas
This study describes a set of real-time interactive experiments that address system identification and model reference adaptive control (MRAC) techniques. In constructing laboratory experiments that contribute to efficient teaching, experimental design and instructional strategy are crucial, but a process for doing this has yet to be defined. This paper is an attempt towards filling this gap. Its contributions are: 1) to describe a sample set of experiments for both senior undergraduate-and graduate-level students, to strengthen their understanding of system identification and control; 2) to help instructors wishing to set up a laboratory with an interactive learning strategy; and 3) to propose a set of assessment criteria for engineering accreditation in system identification and control laboratories. A benefit of this paper for engineering educators is that it provides a roadmap for transferring complex theory problems into prototypes in the laboratory. Furthermore, the instructional strategies proposed can easily be adapted to other engineering courses.
Co-Design Approach and Co-Simulation Tools for Networked Cyber-Physical Control Systems
(Institute of Electrical and Electronics Engineers Inc., 2020) Ozbek, Necdet Sinan
Networked cyber-physical systems, which are formed by the synthesis of computational strategies, communication techniques as well as control theory, have recently received a great deal of attention in the control engineering framework. However, the design, analysis, and synthesis of networked control systems bring a number of challenges due to the network-induced imperfections. With this motivation in mind, the objectives of the current research are twofold. Firstly, an overview of the most important network-induced constraints is provided. Then, the co-design approach and co-simulation tools devoted to networked control system applications are discussed. The problems between the communication medium and the control method are elaborated. From this aspect, the present research provides a practical guide of simulation platforms devoted to networked control system applications. © 2020 IEEE.
Day-ahead electricity price forecasting using artificial intelligence-based algorithms
(Institute of Electrical and Electronics Engineers Inc., 2023) Yorat, Emre; Ozbek, Necdet Sinan; Zor, Kasim; Saribulut, Lutfu
Deregulation and privatization of electricity markets has brought greater attention to electricity price forecasting (EPF) problem in day-ahead and intraday markets since a reliable forecast ensures market participants develop bidding strategies that aim to maximize their profit. Nonlinear and non-stationary characteristics of electricity prices ensemble a barrier in front of an accurate forecast and have required researchers to analyze the effects of exogenous variables such as economic metrics and neighboring countries' prices. In this paper, three different artificial intelligence-based algorithms namely multiple linear regression (MLR), autoregressive integrated moving average (ARIMA) with exogenous variables, and extreme gradient boosting decision trees (XGBoost) are applied to forecast day-ahead electricity prices of the Turkish electricity market by considering the aforementioned exogenous variables. Test results have shown that the XGBoost model has superior results in the error metrics than the other employed methods. Substantial error decrease in symmetric mean absolute percentage error, normalized root mean square error, normalized mean absolute error, and mean absolute scaled error metrics by 19.256%, 19.834%, 23.060%, and 23.016% is observed with respect to the closest performing MLR method on the test set. © 2023 IEEE.
Design and analysis of a novel adaptive learning control scheme for performance promotion of grid-connected PV systems
(Elsevier, 2022) Ozbek, Necdet Sinan; Celik, Ozgur
This paper addresses a hybrid adaptive iterative learning control strategy for controlling power converters that are used in photovoltaic systems to enhance maximum power point tracking capability in the presence of variable atmospheric conditions. The adaptation of the controller to the fast-changing environmental conditions is provided by a fractional-order proportional-integral type learning control mechanism. The developed control scheme is integrated into a grid-connected current-source flyback inverter to highlight the improvements in performance criteria such as convergence speed during transients, tracking accuracy, steady-state oscillations, and robustness. The performance analyses are carried out under various scenarios. The obtained results reveal that the dynamic response of the system is considerably increased under erratic atmospheric conditions while steady-state oscillations are decreased for stable operation conditions. The maximum absolute error that indicates the robustness of the proposed controller is decreased from 2.3704 to 2.1920. In addition, the error deviations of the proposed control algorithm are below 10%. The variance of the error, which shows steady-state stability, is reduced from 2.5123 to 1.6152. Also, the proposed controller reduces the amount of control energy by 20% when compared to the PI controller. Furthermore, the values of IAE and ISE are reported 10% lower in the proposed controller.
Design and real-time implementation of a robust fractional second-order sliding mode control for an electromechanical system comprising uncertainties and disturbances
(Elsevier - Division Reed Elsevier India Pvt Ltd, 2022) Ozbek, Necdet Sinan
The present article evaluates the design, analysis, and implementation of a novel fractional second-order sliding mode control scheme for an uncertain second-order system. The developed controller comprises a fractional-order proportional integral derivative sliding surface. The closed-loop stability analysis is per -formed by using the Lyapunov theorem. The proposed equivalent and switching control signals have been mathematically evaluated at various scenarios comprising uncertainties and disturbances. Several simulations are investigated by including model uncertainties, measurement noises, and disturbances. In addition, various real-time experiments are conducted with different operating conditions. To this end, a real-time reduced-order approximated model of an electromechanical system is constructed. The controller performance has been compared with a number of control techniques to illustrate the promising features of the proposed fractional-order controller. It can be reported that the transient response of the system, control signals applicability, and disturbance rejection capability are quite satis-factory when compared to recently presented control schemes. As a consequence, it is evident that the control scheme has the ability to reduce the chattering phenomenon and increase the system's robustness.(c) 2022 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Design of an optimal fractional fuzzy gain-scheduled Smith Predictor for a time-delay process with experimental application
(Elsevier Science Inc, 2020) Ozbek, Necdet Sinan; Eker, Ilyas
This study addresses an experimental investigation of a novel modified Smith Predictor (SP) based fractional fuzzy gain-scheduled control scheme in control of a time-delayed thermal process. The control strategy employees a fuzzy algorithm to adjust convenient controller parameters based on the system's operating conditions. Performance enhancement of the closed-loop system enables more robust behavior in the presence of disturbance while reducing energy consumption by producing a smooth control signal in comparison with the traditional integer order SP structures. The proposed controller comprises self-tuning capabilities at runtime which makes it adaptive in nature. The motivation of the present paper is in both points of theory and experimental application. The theoretical contribution is to propose a new Smith Predictor based fractional order fuzzy dead-time compensation scheme that can handle uncertainties, parameter variations, and internal external disturbances. The practical contribution is to apply the proposed control scheme to a real-time air-heating process. The performances of the elaborated control strategies are investigated in both computer simulation and experimental application under different operating conditions. The proposed fractional fuzzy control scheme is found superior to the classical PI-PD SP and integer fuzzy controllers for temperature profile tracking tasks. Moreover, complementary comments are highlighted on the advantages and drawbacks of each controller. (C) 2019 ISA. Published by Elsevier Ltd. All rights reserved.
Design, Analysis and Experimental Application of a Fractional Sliding Mode Control for a Benchmark Process
(IEEE, 2019) Ozbek, Necdet Sinan; Eker, Ilyas
This study investigates the design and real-time application of fractional order sliding mode control (FOSMC) for an industrial air heating process. The closed-loop stability of the system is analysed with Lyapunov theorem. The compensation results of the modelled system are investigated under a sinusoidal tracking reference temperature profile. The physical limitations of the real system are taken into account through experimental applications. Further, the performance evaluation is tabulated with a number of quantitative measures.
Event-Based Control Strategies for HVAC Systems
(Institute of Electrical and Electronics Engineers Inc., 2019) Ozbek, Necdet Sinan; Uslu, Akin
Recent developments in hardware and software enable us to develop resource-aware and computationally efficient optimal control strategies, which are important for efficiently usage of energy resources. Event-based control is one of the energy-efficient methods especially for distributed and complex control systems. The prominent feature of the event-based control is the idea of removing unnecessary updating of control input when the system state stays in desired bounds. This paper focuses on the central idea of event-triggered and time-triggered control strategies for Heating, Ventilating, and Air Conditioning (HVAC) applications. Furthermore, recent techniques on HVAC are classified concerning some prominent features. Thus, the present research provides an in-depth guide for designers who investigate the HVAC control application. © 2019 IEEE.
Experimental evaluation of various modified Smith predictor-based fractional order control design strategies in control of a thermal process with time delay
(Inderscience Enterprises Ltd, 2019) Ozbek, Necdet Sinan; Eker, Ilyas
In this study, a number of modified Smith predictor (SP)-based fractional order control strategies are investigated experimentally on a thermal process. Controller design methods and tuning strategies are elaborated step by step. Further, control strategies are discussed in relation to design specifications, control cost, implementation issues, and operating modes encountered in practice. Performance comparison is presented via several illustrations and numerical measures. Particular attention is paid to the tracking precision, quality of the control signal, robustness against disturbances and energy efficiency. Complementary comments are addressed based on merits and demerits of the each control technique.
Feedback control strategies for quadrotor-type aerial robots: a survey
(Sage Publications Ltd, 2016) Ozbek, Necdet Sinan; Onkol, Mert; Efe, Mehmet Onder
Control of aerial robots is a popular research field as applications with different payloads lead to a variety of flight missions. Quadrotor-type unmanned systems are one such example considered in this paper. The performance in any flight experiment depends strictly on the chosen feedback control scheme, which is the core issue addressed in the paper. A number of approaches have been reported in the literature and this paper presents a survey of these schemes with an in-depth discussion of recent research outcomes. A detailed performance evaluation of the controllers, namely proportional-integral-derivative control, sliding mode control, backstepping control, feedback linearization-based control and fuzzy control schemes, are presented. Due to the popularity of the quadrotor-type aerial vehicles, the contribution of the current work is to provide an in-depth guide to the autopilot designers of quadrotor-type unmanned aerial vehicles.
Investigation of Time-Delayed Controller Design Strategies for an Electromechanical System
(IEEE, 2017) Ozbek, Necdet Sinan; Eker, Ilyas
This paper presents a set of time-delayed controller techniques for an electromechanical system. The design specifications and analytical tuning methods of the controller are highlighted with related literature review. Furthermore, applications and performance evaluation of controllers are presented.
Optimized PID-Sliding Mode Controller Based Predictor Design
(Institute of Electrical and Electronics Engineers Inc., 2021) Ozbek, Necdet Sinan
In this paper, a robust control scheme of a time-delayed process has been elaborated through a predictor structure. The control technique is constructed based on an optimized proportional-integral-derivative first-order sliding mode control (SMC) technique combined with Smith-Predictor. The optimization of the control parameters is addressed with genetic algorithms (GA). The results are investigated with various scenarios. The control performances are evaluated in terms of tracking precision, transient response, and disturbance rejection capability. © 2021 IEEE.

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