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Publication Date: 2025
Iranian Conference on Electrical Engineering, ICEE (26429527)pp. 326-331
This paper presents the design of a bilateral robotic system that integrates advanced control strategies to enhance the teleoperation performance. The system employs these strategies to enable smooth bidirectional communication of motion between the master and slave robots. The estimation of environmental interaction and human force eliminates the need for force sensors on both sides. Impedance-based control is utilized to ensure system stability and improve interaction accuracy. The proposed approach demonstrates effective human-environment interaction and precise teleoperation, as validated through simulation re-sults, showcasing its ability to maintain precise synchronization between the master and slave robots while dynamically adapting the estimation parameters. © 2025 IEEE.
Publication Date: 2025
International Journal of Systems Science (00207721)
This study presents the design, comprehensive analysis, and implementation of a nonlinear bilateral telerobotic system operating in a master-slave configuration. It focuses on the critical importance of transparency, which is essential for achieving realistic force feedback in bilateral teleoperation. While some prior research has investigated the concept of transparency in nonlinear systems, this work represents the first attempt to implement variable impedance control, along with real-time parameter estimation through adaptive rules, to achieve transparency in a nonlinear bilateral teleoperation system. The suggested approach combines robust position control with impedance-based force regulation, while an Extended Kalman Filter (EKF) estimates environmental stiffness and damping parameters online. This synthesis enables the system to adapt to variable interaction conditions and maintain stable and high-fidelity force reflection. In addition, the presented stability analysis using the Lyapunov-based approach guarantees the theoretical robustness of the system under various operating conditions. Extensive simulation studies are presented to confirm the potential of the proposed approach, and the implementation results also validate its practical reliability and effectiveness. This makes the system well-suited for advanced teleoperation, haptic interfaces, and other domains requiring precise control and accurate force reflection capabilities. © 2025 Informa UK Limited, trading as Taylor & Francis Group.
Publication Date: 2025
Aut Journal Of Mechanical Engineering (25882937)9(4)pp. 357-372
This paper presents an improved framework for deep reinforcement learning algorithms integrating online system identification, based on the Dyna-Q architecture. The proposed framework is designed to tackle the challenges of both Multi-Input Multi-Output and Multi-Input Single-Output systems in complex, industry-relevant environments, thereby significantly enhancing adaptability and reliability in industrial control systems. It should be noted that in the suggested novel framework, the system identification and model control processes run in parallel with the control process, ensuring a reliable backup in case of faults or disruptions. To verify the efficiency of the aforementioned approach, comparative evaluations in the presence of three of the most common deep reinforcement learning algorithms, i.e. Deep Q Network, Deep Deterministic Policy Gradient, and Twin Delayed Deep Deterministic Policy Gradient, are conducted on industry-relevant environments simulations available in OpenAI Gym, including the Cart Pole, Pendulum, and Bipedal Walker, each chosen to reflect specific aspects of the novel framework. Results demonstrate that the proposed method for leveraging both real and simulated experiences in this framework improves sample efficiency, stability, and robustness. © 2025, Amirkabir University of Technology. All rights reserved.
Publication Date: 2023
International Journal of Systems Science (00207721)54(6)pp. 1344-1359
Diffusion processes, as fundamental mechanisms for particle movement in systems with different concentrations, are used to describe many real-world physical, chemical, biological, engineering, economic and social phenomena. A diffusion process can be modelled via a fractional-order transfer function with time-delay, where its parameters may be affected by circumstance. Hereupon, this study proposes a pioneer robustness indicator to achieve the phase margin invariance regardless of concurrent uncertainty on different parameters of a diffusion process. Afterwards, an analytical procedure is suggested to tune a Fractional-Order Proportional-Integral-Derivative (FO-PID) controller for a diffusion process, to favourably regulate the values of gain crossover frequency and phase margin, such that the proposed robustness criterion is met. Moreover, the solvability of the problem is analytically investigated. Finally, a numerical simulation on robust temperature control during magnetic local hyperthermia, i.e. a common method to treat cancerous tumours, is presented to validate the efficiency of the paper achievements. © 2023 Informa UK Limited, trading as Taylor & Francis Group.
Publication Date: 2020
IEEE Transactions on Industrial Electronics (02780046)67(3)pp. 2176-2185
Analytical data-driven tuning procedures with the aim of adjusting the values of frequency-domain specifications, e.g., gain margin, phase margin, and corresponding crossover frequencies, are among the most popular control techniques in industrial control. But, the multiplicity of crossover frequencies, as an Achilles' heel in these procedures, may cause that the obtained control system does not meet the intended frequency-domain objectives. Motivated by this fact, this paper improves a newly proposed data-driven tuning procedure for arbitrarily setting the values of gain and phase margins and crossover frequencies, in the viewpoint of guaranteeing the uniqueness of crossover frequencies. This improvement is done by analytically deriving some sufficient conditions for ensuring the uniqueness of gain and phase crossover frequencies in the under-study control system. The hardware-in-the-loop experimental results are presented to validate the importance and efficiency of the improved tuning procedure. © 1982-2012 IEEE.
Publication Date: 2020
European Journal of Control (09473580)52pp. 67-77
Local hyperthermia is one of the most common methods to treat cancerous tumors, near the skin surface or natural body orifices. In order to study the problem of temperature control during local hyperthermia, firstly the heat conduction process during this therapy is analytically modeled by a time-delayed fractional-order transfer function, parametrized with respect to the body temperature. Since the body temperature may vary under the influence of patient physiological reaction and heat source, a robustness criterion is proposed to achieve the phase margin invariance despite of the temperature variations. Afterwards, an analytical method is proposed to tune stabilizing FO-PI/PD controllers for desirably adjusting the values of phase margin and gain crossover frequency, where the suggested robustness feature is satisfied in temperature control during the treatment. Finally, to validate the effectiveness of the paper achievements, by using practical parameters numerical simulation results are presented. © 2019 European Control Association
Publication Date: 2018
IET Control Theory and Applications (17518644)12(15)pp. 2022-2030
Different real-world processes can be described by a linear model parameterised with respect to the processoperating point, as an uncertain parameter. The family of transport processes with long memory is a kind of these processeswhich are characterised by the parameterised time-fractional diffusion equations. This study proposes a generalised isodamping feature for achieving the phase margin invariance regardless of the uncertain parameter variations in control of timefractional diffusion processes. Also, the study suggests an analytical method to tune stabilising fractional-order proportional-integral/proportional-derivative controllers for adjusting a desired value for the phase margin at a desired gain crossoverfrequency, while the proposed robustness criterion is satisfied in control of time-fractional diffusion processes. Furthermore,conditions for solvability of the problem and stability of the obtained control system are analytically derived. Finally, an exampleon robust temperature control of the cutting edge in alpha silicon carbide cutting tools is presented to confirm the effectivenessof the obtained achievements. © 2018 The Institution of Engineering and Technology.
Publication Date: 2018
IEEE Transactions on Control Systems Technology (10636536)26(3)pp. 797-812
This paper deals with robust frequency compensation in control of fractional-order plants with an uncertain fractional pole/zero (or specially in control of integer-order plants with an uncertain pole/zero). The specifications yielding a robust compensation are introduced, and fractional-order compensators are proposed for satisfying these specifications in the set-point tracking control of the above-mentioned plants. Also, the infinite ranges for the uncertain parameter of the plant, in which satisfying robust compensation specifications is possible by the obtained compensators, are exactly specified. Furthermore, the stability of the obtained control system is analytically analyzed. Moreover, it is shown that in the special cases, the proposed compensators result in control systems having invariant phase/gain margin regardless of the variations of the uncertain parameter of the plant. Numerical simulation and experimental results are presented to verify the effectiveness of the obtained compensators. © 2017 IEEE.
Publication Date: 2017
IEEE Transactions on Industrial Informatics (15513203)13(5)pp. 2311-2321
This paper presents an analytical method to tune a fixed-structure fractional-order compensator for satisfying desired phase and gain margins with adjustable crossover frequencies. The proposed method is based on the measured frequency data of the plant. Since no analytical model for the plant is needed in the compensator tuning procedure, the resulted compensator does not depend on the order and complexity of the plant. Also, sufficient conditions for the existence of a compensator with no zero and pole in the right half-plane for satisfying the aforementioned objectives are analytically derived. Furthermore, different hardware-in-the-loop experimental results are presented to show the efficiency of the proposed tuning method. © 2005-2012 IEEE.
Publication Date: 2016
JVC/Journal of Vibration and Control (10775463)22(19)pp. 4074-4086
Nowadays, design and tuning of controllers with predefined structures are among the most popular topics in control system theory. During the last decade, many studies have focused on designing fixed-structure fractional-order compensators. This paper presents a generalized version of fractional-order compensators to achieve the required magnitudes and phases at two given frequencies (for example, to achieve desired phase and gain margins with adjustable cross frequencies). In this generalization, at first some basic analysis of the phase behaviour of this introduced type of fractional-order compensators is presented. Also, exact formulas are found for designing this family of compensators in order to provide the aforementioned control objective. Finally, a numerical example is presented to confirm the effectiveness of the proposed design method in control systems. © The Author(s) 2015.
