Journal Description
Actuators
Actuators
is an international, peer-reviewed, open access journal on the science and technology of actuators and control systems published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within SCIE (Web of Science), Scopus, Inspec, and other databases.
- Journal Rank: JCR - Q2 (Engineering, Mechanical) / CiteScore - Q1 (Control and Optimization)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 19 days after submission; acceptance to publication is undertaken in 1.9 days (median values for papers published in this journal in the first half of 2025).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.3 (2024);
5-Year Impact Factor:
2.4 (2024)
Latest Articles
Disturbance-Resilient Flatness-Based Control for End-Effector Rehabilitation Robotics
Actuators 2025, 14(7), 341; https://doi.org/10.3390/act14070341 - 8 Jul 2025
Abstract
Robotic-assisted therapy is an increasingly vital approach for upper-limb rehabilitation, offering consistent, high-intensity training critical to neuroplastic recovery. However, current control strategies often lack robustness against uncertainties and external disturbances, limiting their efficacy in dynamic, real-world settings. Addressing this gap, this study proposes
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Robotic-assisted therapy is an increasingly vital approach for upper-limb rehabilitation, offering consistent, high-intensity training critical to neuroplastic recovery. However, current control strategies often lack robustness against uncertainties and external disturbances, limiting their efficacy in dynamic, real-world settings. Addressing this gap, this study proposes a novel control framework for the iTbot—a 2-DoF end-effector rehabilitation robot—by integrating differential flatness theory with a derivative-free Kalman filter (DFK). The objective is to achieve accurate and adaptive trajectory tracking in the presence of unmeasured dynamics and human–robot interaction forces. The control design reformulates the nonlinear joint-space dynamics into a 0-flat canonical form, enabling real-time computation of feedforward control laws based solely on flat outputs and their derivatives. Simultaneously, the DFK-based observer estimates external perturbations and unmeasured states without requiring derivative calculations, allowing for online disturbance compensation. Extensive simulations across nominal and disturbed conditions demonstrate that the proposed controller significantly outperforms conventional flatness-based control in tracking accuracy and robustness, as measured by reduced mean absolute error and standard deviation. Experimental validation under both simple and repetitive physiotherapy tasks confirms the system’s ability to maintain sub-millimeter Cartesian accuracy and sub-degree joint errors even amid dynamic perturbations. These results underscore the controller’s effectiveness in enabling compliant, safe, and disturbance-resilient rehabilitation, paving the way for broader deployment of robotic therapy in clinical and home-based environments.
Full article
(This article belongs to the Special Issue Intelligent and Advanced Control for Human-Centric Robotic Actuation and Interaction)
Open AccessArticle
Variable Structure Depth Controller for Energy Savings in an Underwater Device: Proof of Stability
by
João Bravo Pinto, João Falcão Carneiro, Fernando Gomes de Almeida and Nuno A. Cruz
Actuators 2025, 14(7), 340; https://doi.org/10.3390/act14070340 - 8 Jul 2025
Abstract
Underwater exploration is vital for advancing scientific understanding of marine ecosystems, biodiversity, and oceanic processes. Autonomous underwater vehicles and sensor platforms play a crucial role in continuous monitoring, but their operational endurance is often limited by energy constraints. Various control strategies have been
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Underwater exploration is vital for advancing scientific understanding of marine ecosystems, biodiversity, and oceanic processes. Autonomous underwater vehicles and sensor platforms play a crucial role in continuous monitoring, but their operational endurance is often limited by energy constraints. Various control strategies have been proposed to enhance energy efficiency, including robust and optimal controllers, energy-optimal model predictive control, and disturbance-aware strategies. Recent work introduced a variable structure depth controller for a sensor platform with a variable buoyancy module, resulting in a 22% reduction in energy consumption. This paper extends that work by providing a formal stability proof for the proposed switching controller, ensuring safe and reliable operation in dynamic underwater environments. In contrast to the conventional approach used in controller stability proofs for switched systems—which typically relies on the existence of multiple Lyapunov functions—the method developed in this paper adopts a different strategy. Specifically, the stability proof is based on a novel analysis of the system’s trajectory in the net buoyancy force-versus-depth error plane. The findings were applied to a depth-controlled sensor platform previously developed by the authors, using a well-established system model and considering physical constraints. Despite adopting a conservative approach, the results demonstrate that the control law can be implemented while ensuring formal system stability. Moreover, the study highlights how stability regions are affected by different controller parameter choices and mission requirements, namely, by determining how these aspects affect the bounds of the switching control action. The results provide valuable guidance for selecting the appropriate controller parameters for specific mission scenarios.
Full article
(This article belongs to the Special Issue Advanced Underwater Robotics)
Open AccessArticle
Distributed Adaptive Angle Rigidity-Based Formation Control of Near-Space Vehicles with Input Constraints
by
Qin Wang, Yuhang Shen, Hanyu Yin, Jianjiang Yu and Yang Yi
Actuators 2025, 14(7), 339; https://doi.org/10.3390/act14070339 - 8 Jul 2025
Abstract
This paper presents a distributed adaptive formation control strategy for a multiple near-space vehicles (NSVs) system operating under unknown input constraints and external disturbances. In challenging near-space environments, the control system must address not only model uncertainties and parameter variations but also accommodate
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This paper presents a distributed adaptive formation control strategy for a multiple near-space vehicles (NSVs) system operating under unknown input constraints and external disturbances. In challenging near-space environments, the control system must address not only model uncertainties and parameter variations but also accommodate the input limitations of actuators. To address these challenges, we design an adaptive distributed formation control strategy for vehicle formation that relies exclusively on relative attitude information. This approach is grounded in the principles of angle rigidity formation theory, which has not previously been applied in the near-space vehicle domain. The aim of the adaptive formation control strategy is to maintain the desired formation shape for the near-space vehicles (NSVs) system with external disturbances, actuator dead zones, and saturation. In addition, neural networks are employed to approximate the inherent nonlinear uncertainties within the NSV models. An adaptive estimation technique is concurrently included to address parameter variations and to alleviate the impact of external disturbances, actuator dead zones, and saturation effects. Finally, a Lyapunov-based analysis is used to rigorously demonstrate the stability of the NSV formation system. The simulation results validate the effectiveness and robustness of the proposed control strategy in uncertain environments.
Full article
(This article belongs to the Section Aerospace Actuators)
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Open AccessArticle
Design and Implementation of Flexible Four-Bar-Mechanism-Based Long-Stroke Micro-Gripper
by
Liangyu Cui, Haonan Zhu, Xiaofan Deng and Yuanyuan Chai
Actuators 2025, 14(7), 338; https://doi.org/10.3390/act14070338 - 7 Jul 2025
Abstract
To meet the demand for submillimeter-level gripping capabilities in micro-grippers, an amplification mechanism based on a flexible four-bar linkage is proposed. The micro-gripper designed using this mechanism features a large gripping stroke in the millimeter range. First, the amplification effect of the flexible
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To meet the demand for submillimeter-level gripping capabilities in micro-grippers, an amplification mechanism based on a flexible four-bar linkage is proposed. The micro-gripper designed using this mechanism features a large gripping stroke in the millimeter range. First, the amplification effect of the flexible four-bar linkage was structurally designed and theoretically analyzed. Through kinematic analysis, a theoretical model was developed, demonstrating that the flexible four-bar linkage can achieve an extremely high amplification factor, thus providing a theoretical foundation for the design of the micro-gripper. Then, kinematic and mechanical simulations of the micro-gripper were conducted and validated using ANSYS 2025 simulation software, confirming the correctness of the theoretical analysis. Finally, an experimental platform was set up to analyze the characteristics of the micro-gripper, including its stroke, resolution, and gripping force. The results show that the displacement amplification factor of the gripper designed based on the flexible four-bar linkage can reach 40, with a displacement resolution of 50 nm and a gripping range of 0–880 μm. By using capacitive displacement sensors and strain sensors, integrated force and displacement control can be realized. The large-stroke micro-gripper based on the flexible four-bar linkage is compact, with a large stroke, and has broad application prospects.
Full article
(This article belongs to the Section Miniaturized and Micro Actuators)
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Open AccessArticle
A Lightweight Soft Exosuit for Elbow Rehabilitation Powered by a Multi-Bundle SMA Actuator
by
Janeth Arias Guadalupe, Alejandro Pereira-Cabral Perez, Dolores Blanco Rojas and Dorin Copaci
Actuators 2025, 14(7), 337; https://doi.org/10.3390/act14070337 - 6 Jul 2025
Abstract
Stroke is one of the leading causes of long-term disability worldwide, often resulting in motor impairments that limit the ability to perform daily activities independently. Conventional rehabilitation exoskeletons, while effective, are typically rigid, bulky, and expensive, limiting their usability outside of clinical settings.
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Stroke is one of the leading causes of long-term disability worldwide, often resulting in motor impairments that limit the ability to perform daily activities independently. Conventional rehabilitation exoskeletons, while effective, are typically rigid, bulky, and expensive, limiting their usability outside of clinical settings. In response to these challenges, this work presents the development and validation of a novel soft exosuit designed for elbow flexion rehabilitation, incorporating a multi-wire Shape Memory Alloy (SMA) actuator capable of both position and force control. The proposed system features a lightweight and ergonomic textile-based design, optimized for user comfort, ease of use, and low manufacturing cost. A sequential activation strategy was implemented to improve the dynamic response of the actuator, particularly during the cooling phase, which is typically a major limitation in SMA-based systems. The performance of the multi-bundle actuator was compared with a single-bundle configuration, demonstrating superior trajectory tracking and reduced thermal accumulation. Surface electromyography tests confirmed a decrease in muscular effort during assisted flexion, validating the device’s assistive capabilities. With a total weight of 0.6 kg and a fabrication cost under EUR 500, the proposed exosuit offers a promising solution for accessible and effective home-based rehabilitation.
Full article
(This article belongs to the Special Issue Shape Memory Alloy (SMA) Actuators and Their Applications)
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Open AccessArticle
Fuzzy PD-Based Control for Excavator Boom Stabilization Using Work Port Pressure Feedback
by
Joseph T. Jose, Gyan Wrat, Santosh Kr. Mishra, Prabhat Ranjan and Jayanta Das
Actuators 2025, 14(7), 336; https://doi.org/10.3390/act14070336 - 4 Jul 2025
Abstract
Hydraulic excavators operate in harsh environments where direct measurement of actuator chamber pressures and boom displacement is often unreliable or infeasible. This study presents a novel control strategy that estimates actuator chamber pressures from work port pressures using differential equations, eliminating the need
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Hydraulic excavators operate in harsh environments where direct measurement of actuator chamber pressures and boom displacement is often unreliable or infeasible. This study presents a novel control strategy that estimates actuator chamber pressures from work port pressures using differential equations, eliminating the need for direct pressure or position sensors. A fuzzy logic-based proportional–derivative (PD) controller is developed to mitigate boom oscillations, particularly under high-inertia load conditions and variable operator inputs. The controller dynamically adjusts gains through fuzzy logic-based gain scheduling, enhancing adaptability across a wide range of operating conditions. The proposed method addresses the limitations of classical PID controllers, which struggle with the nonlinearities, parameter uncertainties, and instability introduced by counterbalance valves and pressure-compensated proportional valves. Experimental data is used to design fuzzy rules and membership functions, ensuring robust performance. Simulation and full-scale experimental validation demonstrate that the fuzzy PD controller significantly reduces pressure overshoot (by 23% during extension and 32% during retraction) and decreases settling time (by 31.23% and 28%, respectively) compared to conventional systems. Frequency-domain stability analysis confirms exponential stability and improved damping characteristics. The proposed control scheme enhances system reliability and safety, making it ideal for excavators operating in remote or rugged terrains where conventional sensor-based systems may fail. This approach is generalizable and does not require modifications to the existing hydraulic circuit, offering a practical and scalable solution for modern hydraulic machinery.
Full article
(This article belongs to the Special Issue Intelligent and Precision Control for Mechatronic/Electro-Hydraulic Systems—Second Edition)
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Open AccessArticle
Composite Perturbation-Rejection Trajectory-Tracking Control for a Quadrotor–Slung Load System
by
Jiao Xu, Defu Lin, Jianchuan Ye and Tao Jiang
Actuators 2025, 14(7), 335; https://doi.org/10.3390/act14070335 - 3 Jul 2025
Abstract
Tracking control of a quadrotor–slung load system is extremely challenging due to its under-actuation property, couple effects, and various uncertainties. This work proposes a composite backstepping control framework combining command filter control and a multivariable finite-time disturbance observer to ensure robust position and
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Tracking control of a quadrotor–slung load system is extremely challenging due to its under-actuation property, couple effects, and various uncertainties. This work proposes a composite backstepping control framework combining command filter control and a multivariable finite-time disturbance observer to ensure robust position and orientation control for aerial payload transportation with high precision. Firstly, the kinematic and dynamic model under perturbations is derived based on Newton’s second law. The thrust control force consists of two orthogonal parts, each dedicated to regulating the position and orientation of the slung load independently. Then, hierarchical backstepping control generates the two parts in the load-translation and the load-orientation subsystems. Command filters are introduced into nonlinear backstepping to smoothen the control signals and overcome the problem of explosion of complexity. Additionally, to counteract the adverse effect of perturbations emerging in the linear velocity and angular velocity loops, multivariable finite-time observers are developed to ensure the estimation errors converge within a finite time horizon. Finally, comparative numerical simulation results validate the efficacy of the developed quadrotor–slung load tracking controller. Simulation results show that the proposed controller achieves smaller position tracking and orientation errors compared to traditional methods, demonstrating robust disturbance rejection and high-precision control.
Full article
(This article belongs to the Section Aerospace Actuators)
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Open AccessArticle
Multi-Valve Coordinated Disturbance Rejection Control for an Intake Pressure System Using External Penalty Functions
by
Louyue Zhang, Duoqi Shi, Chao Zhai, Zhihong Dan, Hehong Zhang, Xi Wang and Gaoxi Xiao
Actuators 2025, 14(7), 334; https://doi.org/10.3390/act14070334 - 2 Jul 2025
Abstract
Altitude test facilities for aero-engines employ multi-chamber, multi-valve intake systems that require effective decoupling and strong disturbance rejection during transient tests. This paper proposes a coordinated active disturbance rejection control (ADRC) scheme based on external penalty functions. The chamber pressure safety limit is
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Altitude test facilities for aero-engines employ multi-chamber, multi-valve intake systems that require effective decoupling and strong disturbance rejection during transient tests. This paper proposes a coordinated active disturbance rejection control (ADRC) scheme based on external penalty functions. The chamber pressure safety limit is formulated as an inequality-constrained optimization problem, and an exponential penalty together with a gradient based algorithm is designed for dynamic constraint relaxation, with guaranteed global convergence. A coordination term is then integrated into a distributed ADRC framework to yield a multi-valve coordinated ADRC controller, whose asymptotic stability is established via Lyapunov theory. Hardware-in-the-loop simulations using MATLAB/Simulink and a PLC demonstrate that, under ±3 kPa pressure constraints, the maximum engine inlet pressure error is 1.782 kPa (77.1% lower than PID control), and under an 80 kg/s2 flow-rate disturbance, valve oscillations decrease from ±27% to ±5%. These results confirm the superior disturbance rejection and decoupling performance of the proposed method.
Full article
(This article belongs to the Special Issue Actuation and Robust Control Technologies for Aerospace Applications)
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Open AccessArticle
Load and Positional Constraints’ Impact on the Accuracy and Dynamic Performance of an Autonomous Adaptive Electrohydraulic Pump-Controlled Actuator for Mobile Equipment
by
Alexey N. Beskopylny, Evgeniy Ivliev, Vyacheslav Grishchenko and Denis Medvedev
Actuators 2025, 14(7), 333; https://doi.org/10.3390/act14070333 - 2 Jul 2025
Abstract
This study investigates the external load and positional constraints’ impact on the accuracy and performance of an autonomous adaptive electrohydraulic actuator with pump control intended for mobile equipment. An actuator simulation model was developed in the MATLAB/Simulink (version R2021A) environment, and a full-scale
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This study investigates the external load and positional constraints’ impact on the accuracy and performance of an autonomous adaptive electrohydraulic actuator with pump control intended for mobile equipment. An actuator simulation model was developed in the MATLAB/Simulink (version R2021A) environment, and a full-scale experimental setup was constructed to validate this model. Various motion trajectories under different load conditions were analyzed to evaluate discrepancies between simulated and experimental results and to identify key performance characteristics across operational modes. The results demonstrate that the simulation model adequately replicates the actuator’s dynamic behavior, although deviations emerge under high-load conditions. Notably, in the absence of external load, the static positioning error does not exceed 0.025 mm (0.05% of the 50 mm target value), while under the maximum load of 8000 N, the error increases to 0.075 mm (0.15% of the 50 mm target value). These limitations are primarily due to current constraints imposed by the actuator’s power supply capacity (up to 300 W at 24 V), which restrict pressure buildup rates under heavy loads. Nevertheless, the proposed control system exhibits robustness to load variations and ensures positioning accuracy within acceptable limits, demonstrating its practical suitability for mobile machinery applications. The developed simulation model also serves as a valuable tool for control system tuning and testing in the absence of a physical prototype.
Full article
(This article belongs to the Section Control Systems)
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Open AccessArticle
The Systematic Design of Voice Coil Motor Structures for Rapid Zoom Optical Lens
by
Junqiang Gong, Dameng Liu and Jianbin Luo
Actuators 2025, 14(7), 332; https://doi.org/10.3390/act14070332 - 2 Jul 2025
Abstract
In order to solve the zoom delay issue for high-magnification zoom optical systems, a voice coil motor (VCM) is used to achieve rapid zooming. In this paper, the structural design of VCMs is systematically analyzed through magnetic field numerical computations. Firstly, finite element
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In order to solve the zoom delay issue for high-magnification zoom optical systems, a voice coil motor (VCM) is used to achieve rapid zooming. In this paper, the structural design of VCMs is systematically analyzed through magnetic field numerical computations. Firstly, finite element method (FEM) is used to analyze magnetic field of single magnets, and simulations correspond to experimental results. Both FEM and equivalent magnetic charge (EMC) results confirm that increasing magnet thickness while reducing its lateral dimensions will contribute to magnetic enhancement. Furthermore, the influence of structural parameters VCM is analyzed, validating the yoke’s critical role in suppressing edge effects and optimizing magnetic circuit efficiency, and optimal yoke thickness and magnet width range are determined. Moreover, a simple EMC calculation method is proposed for rapid and accurate determination of the magnetic field distribution in the VCM air gap. Optimal structural parameters of VCM are determined for a 40× rapid zoom lens with cost and space limitations. Driving force Fdrive = 5.58 N is about 5 times the demand force Fd = 1.06 N, and the prototype fabrication of the rapid zoom lens is successfully accomplished. Moving group reaches 35.4 mm destination within 0.18 s, and photographs confirm that the rapid zoom system achieves 100-ms-level short/long-focus transition. Rapid zoom lens shows great potential in applications including security surveillance, industrial visual inspection, and intelligent logistics management.
Full article
(This article belongs to the Special Issue Actuators in 2025)
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Open AccessArticle
Analysis of Anchoring Muscles for Pipe Crawling Robots
by
Frank Cianciarulo, Jacek Garbulinski, Jonathan Chambers, Thomas Pillsbury, Norman Wereley, Andrew Cross and Deepak Trivedi
Actuators 2025, 14(7), 331; https://doi.org/10.3390/act14070331 - 2 Jul 2025
Abstract
Pneumatic artificial muscles (PAMs) consist of an elastomeric bladder wrapped in a Kevlar braid. When inflated, PAMs expand radially and contract axially, producing large axial forces. PAMs are often utilized for their high specific work and specific power, as well as their ability
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Pneumatic artificial muscles (PAMs) consist of an elastomeric bladder wrapped in a Kevlar braid. When inflated, PAMs expand radially and contract axially, producing large axial forces. PAMs are often utilized for their high specific work and specific power, as well as their ability to produce large axial displacements. Although the axial behavior of PAMs is well studied, the radial behavior has remained underutilized and is poorly understood. Modeling was performed using a force balance approach to capture the effects that bladder strain and applied axial load have on the anchoring force. Radial expansion testing was performed to validate the model. Force due to anchoring was recorded using force transducers attached to sections of aluminum pipe using an MTS servo-hydraulic testing machine. Data from the test were compared to the predicted anchoring force. Radial expansion in large-diameter (over 50.8 mm) PAMs was then used in worm-like robots to create anchoring forces that allow for a peristaltic wave, which creates locomotion through acrylic pipes. By radially expanding, the PAM presses itself into the pipe, creating an anchor point. The previously anchored PAM then deflates, which propels the robot forward. Modeling of the radial expansion forces and anchoring was necessary to determine the pressurization required for proper anchoring before slipping occurs due to the combined robot and payload weight.
Full article
(This article belongs to the Section Actuators for Robotics)
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Open AccessArticle
Global Fixed-Time Fault-Tolerant Control for Tracked Vehicles with Hierarchical Unknown Input Observers
by
Xihao Yan, Dongjie Wang, Aixiang Ma, Weixiong Zheng and Sihai Zhao
Actuators 2025, 14(7), 330; https://doi.org/10.3390/act14070330 - 1 Jul 2025
Abstract
This paper addresses the issues of sensor failures and actuator faults in mining tracked mobile vehicles (TMVs) operating in harsh environments by proposing a global fixed-time fault-tolerant control strategy based on a hierarchical unknown input observer structure. First, a kinematic and dynamic model
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This paper addresses the issues of sensor failures and actuator faults in mining tracked mobile vehicles (TMVs) operating in harsh environments by proposing a global fixed-time fault-tolerant control strategy based on a hierarchical unknown input observer structure. First, a kinematic and dynamic model of the TMV is established considering side slip and track slip, and its linear parameter-varying (LPV) model is constructed through parameter-dependent linearization. Then, a distributed structure consisting of four collaborating low-dimensional observers is designed, including a state observer, a disturbance observer, a position sensor fault observer, and a wheel speed sensor fault observer, and the fixed-time convergence of the closed-loop system is proven. Additionally, by equivalently treating actuator faults as power losses, an observer capable of identifying and compensating for motor efficiency losses is designed. Finally, an adaptive fault-tolerant control law is proposed by combining nominal control, disturbance compensation, and sliding mode switching terms, achieving global fixed-time stability and fault tolerance. Experimental results demonstrate that the proposed control system maintains excellent trajectory tracking performance even in the presence of sensor faults and actuator power losses, with tracking errors less than 0.1 m.
Full article
(This article belongs to the Special Issue Fault Detection and Isolation, Fault Tolerant Control for Autonomous and Transport Vehicles)
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Open AccessArticle
A Computational Intelligence-Based Proposal for Cybersecurity and Health Management with Continuous Learning in Chemical Processes
by
Adrián Rodríguez Ramos, Pedro Juan Rivera Torres and Orestes Llanes-Santiago
Actuators 2025, 14(7), 329; https://doi.org/10.3390/act14070329 - 1 Jul 2025
Abstract
Ensuring cybersecurity and health management is a fundamental requirement in modern chemical industry plants operating under the Industry 4.0 framework. Traditionally, these two concerns have been addressed independently, despite sharing multiple underlying elements which suggest the viability of a unified detection and localization
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Ensuring cybersecurity and health management is a fundamental requirement in modern chemical industry plants operating under the Industry 4.0 framework. Traditionally, these two concerns have been addressed independently, despite sharing multiple underlying elements which suggest the viability of a unified detection and localization solution. This study introduces a computational intelligence framework based on fuzzy techniques, which allows for the early identification and precise localization of both faults and cyberattacks, along with the capability to recognize previously unseen events during runtime. Once new events are identified and classified, the training database is updated, creating a mechanism for continuous learning. This integrated approach simplifies the computational complexity of supervisory systems and enhances collaboration between the Operational Technology and Information Technology teams within chemical plants. The proposed methodology demonstrates strong robustness and reliability, even in complex conditions characterized by noisy measurements and disturbances, achieving outstanding performance due to its excellent discrimination capabilities.
Full article
(This article belongs to the Section Actuators for Manufacturing Systems)
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Open AccessArticle
A Hybrid Control Approach Integrating Model-Predictive Control and Fractional-Order Admittance Control for Automatic Internal Limiting Membrane Peeling Surgery
by
Hongcheng Liu, Xiaodong Zhang, Yachun Wang, Zirui Zhao and Ning Wang
Actuators 2025, 14(7), 328; https://doi.org/10.3390/act14070328 - 1 Jul 2025
Abstract
As the prevalence of related diseases continues to rise, a corresponding increase in the demand for internal limiting membrane (ILM) peeling surgery has been observed. However, significant challenges are encountered in ILM peeling surgery, including limited force feedback, inadequate depth perception, and surgeon
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As the prevalence of related diseases continues to rise, a corresponding increase in the demand for internal limiting membrane (ILM) peeling surgery has been observed. However, significant challenges are encountered in ILM peeling surgery, including limited force feedback, inadequate depth perception, and surgeon hand tremors. Research on fully autonomous ILM peeling surgical robots has been conducted to address the imbalance between medical resource availability and patient demand while enhancing surgical safety. An automatic control framework for break initiation in ILM peeling is proposed in this study, which integrates model-predictive control with fractional-order admittance control. Additionally, a multi-vision task surgical scene perception method is introduced based on target detection, key point recognition, and sparse binocular matching. A surgical trajectory planning strategy for break initiation in ILM peeling aligned with operative specifications is proposed. Finally, validation experiments for automatic break initiation in ILM peeling were performed using eye phantoms. The results indicated that the positional error of the micro-forceps tip remained within 40 μm. At the same time, the contact force overshoot was limited to under 6%, thereby ensuring both the effectiveness and safety of break initiation during ILM peeling.
Full article
(This article belongs to the Special Issue Motion Planning, Trajectory Prediction, and Control for Robotics)
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Open AccessArticle
Investigation of Hysteresis Phenomena and Compensation in Piezoelectric Stacks for Active Rotor
by
Xiancheng Gu, Weidong Yang, Linghua Dong and Jinlong Zhou
Actuators 2025, 14(7), 327; https://doi.org/10.3390/act14070327 - 1 Jul 2025
Abstract
An active rotor with trailing edge flaps (TEFs) is an effective method for helicopter vibration elimination. The nonlinear hysteresis of piezoelectric actuators used to drive TEFs can adversely affect helicopter vibration control performance. In this paper, a hysteresis modeling and compensation study is
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An active rotor with trailing edge flaps (TEFs) is an effective method for helicopter vibration elimination. The nonlinear hysteresis of piezoelectric actuators used to drive TEFs can adversely affect helicopter vibration control performance. In this paper, a hysteresis modeling and compensation study is performed for piezoelectric actuators used in TEFs. Firstly, the hysteresis characteristics of a rhombic frame actuator with input voltages at different frequencies are investigated by bench-top tests. Subsequently, the Bouc–Wen model is adopted to establish the hysteresis model of the piezoelectric actuator, with its parameters identified through the particle swarm optimization (PSO) algorithm. Experimental results demonstrate that the proposed model is capable of accurately capturing the hysteresis phenomenon of the piezoelectric actuator within the frequency range of 10–60 Hz. Finally, a compound control regime is established by integrating inverse Bouc–Wen model control with fuzzy PID feedback control. The experimental results indicate that the developed compound control regime can significantly suppress the piezoelectric actuator hysteresis of TEFs within the frequency bandwidth of 10–60 Hz, which lays the foundation for improving the vibration control performance of the active rotor with TEFs in the future.
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(This article belongs to the Section Aerospace Actuators)
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Open AccessArticle
Improving the Regenerative Efficiency of the Automobile Powertrain by Optimizing Combined Loss in the Motor and Inverter
by
Jayakody Shreen and Kyung-min Lee
Actuators 2025, 14(7), 326; https://doi.org/10.3390/act14070326 - 1 Jul 2025
Abstract
This research presents a method for improving the regenerative efficiency of interior permanent magnet synchronous motors (IPMSMs) used in traction applications such as electric vehicles. In conventional powertrain control, the maximum torque per ampere (MTPA) strategy is commonly applied in the constant-torque region.
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This research presents a method for improving the regenerative efficiency of interior permanent magnet synchronous motors (IPMSMs) used in traction applications such as electric vehicles. In conventional powertrain control, the maximum torque per ampere (MTPA) strategy is commonly applied in the constant-torque region. However, this approach does not account for the combined losses of both the motor and inverter. In this study, overall system efficiency is investigated, and an improved current combination is proposed to minimize total losses. The single switching method is employed in the inverter due to its simplicity and its ability to reduce inverter losses. Simulations incorporating both motor and inverter losses were performed for two driving conditions around the MTPA current point. The results show that the optimal current combination slightly deviates from the MTPA point and leads to a slight improvement in efficiency. Experimental results under the two steady-state driving torque and angular velocity conditions confirm that the optimized current combination enhances system efficiency. Furthermore, simulations based on the Urban Dynamometer Driving Schedule predict an increase in recovered energy of approximately 1%. The proposed control strategy is simple, easy to implement, and enables the powertrain to operate with highly efficient current references.
Full article
(This article belongs to the Special Issue Feature Papers in Actuators for Surface Vehicles)
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Open AccessArticle
Research on Active Disturbance Rejection Control of Rigid–Flexible Coupled Constant Force Actuator
by
Chuanxing Jiang, Zhijun Yang, Jun Zheng, Bangshang Fu and Youdun Bai
Actuators 2025, 14(7), 325; https://doi.org/10.3390/act14070325 - 30 Jun 2025
Abstract
This study introduces a rigid–flexible coupled constant force actuator integrated with Active Disturbance Rejection Control (ADRC) to tackle the rigidity–compliance trade-off in precision force-sensitive applications. The actuator utilizes compliant hinges to decrease contact stiffness by three orders of magnitude (
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This study introduces a rigid–flexible coupled constant force actuator integrated with Active Disturbance Rejection Control (ADRC) to tackle the rigidity–compliance trade-off in precision force-sensitive applications. The actuator utilizes compliant hinges to decrease contact stiffness by three orders of magnitude ( ), facilitating effective force management through millimeter-scale placement (0.1∼1 mm) and inherently mitigating high-frequency disturbances. The ADRC framework, augmented by an Extended State Observer (ESO), dynamically assesses and compensates for internal nonlinearities (such as friction hysteresis) and external disturbances without necessitating accurate system models. Experimental results indicate enhanced performance compared to PID control: under dynamic disturbances, force deviations are limited to with a 98.5% reduction in mean absolute error, a 96.3% increase in settling speed, and 99% suppression of oscillations. The co-design of mechanical compliance with model-free control addresses the constraints of traditional high-stiffness systems, providing a scalable solution for industrial robots, compliant material processing, and medical device operations. Validation of the prototype under sinusoidal perturbations demonstrates reliable force regulation (settling time , errors ), underscoring its relevance in dynamic situations. This study integrates theoretical innovation with experimental precision, enhancing intelligent manufacturing systems via adaptive control and structural synergy.
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(This article belongs to the Section Control Systems)
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Open AccessArticle
Similarity Analysis of Upper Extremity’s Trajectories in Activities of Daily Living for Use in an Intelligent Control System of a Rehabilitation Exoskeleton
by
Piotr Falkowski, Maciej Pikuliński, Tomasz Osiak, Kajetan Jeznach, Krzysztof Zawalski, Piotr Kołodziejski, Andrzej Zakręcki, Jan Oleksiuk, Daniel Śliż and Natalia Osiak
Actuators 2025, 14(7), 324; https://doi.org/10.3390/act14070324 - 30 Jun 2025
Abstract
Rehabilitation robotic systems have been developed to perform therapy with minimal supervision from a specialist. Hence, they require algorithms to assess and support patients’ motions. Artificial intelligence brings an opportunity to implement new exercises based on previously modelled ones. This study focuses on
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Rehabilitation robotic systems have been developed to perform therapy with minimal supervision from a specialist. Hence, they require algorithms to assess and support patients’ motions. Artificial intelligence brings an opportunity to implement new exercises based on previously modelled ones. This study focuses on analysing the similarities in upper extremity movements during activities of daily living (ADLs). This research aimed to model ADLs by registering and segmenting real-life movements and dividing them into sub-tasks based on joint motions. The investigation used IMU sensors placed on the body to capture upper extremity motion. Angular measurements were converted into joint variables using Matlab computations. Then, these were divided into segments assigned to the sub-functionalities of the tasks. Further analysis involved calculating mathematical measures to evaluate the similarity between the different movements. This approach allows the system to distinguish between similar motions, which is critical for assessing rehabilitation scenarios and anatomical correctness. Twenty-two ADLs were recorded, and their segments were analysed to build a database of typical motion patterns. The results include a discussion on the ranges of motion for different ADLs and gender-related differences. Moreover, the similarities and general trends for different motions are presented. The system’s control algorithm will use these results to improve the effectiveness of robotic-assisted physiotherapy.
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(This article belongs to the Special Issue Intelligent Systems, Robots and Devices for Healthcare and Rehabilitation)
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Open AccessArticle
Learning-Based Variable Admittance Control Combined with NMPC for Contact Force Tracking in Unknown Environments
by
Yikun Zhang, Jianjun Yao and Chen Qian
Actuators 2025, 14(7), 323; https://doi.org/10.3390/act14070323 - 30 Jun 2025
Abstract
With the development of robotics, robots are playing an increasingly critical role in complex tasks such as flexible manufacturing, physical human–robot interaction, and intelligent assembly. These tasks place higher demands on the force control performance of robots, particularly in scenarios where the environment
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With the development of robotics, robots are playing an increasingly critical role in complex tasks such as flexible manufacturing, physical human–robot interaction, and intelligent assembly. These tasks place higher demands on the force control performance of robots, particularly in scenarios where the environment is unknown, making constant force control challenging. This study first analyzes the robot and its interaction model with the environment, highlighting the limitations of traditional force control methods in addressing unknown environmental stiffness. Based on this analysis, a variable admittance control strategy is proposed using the deep deterministic policy gradient algorithm, enabling the online tuning of admittance parameters through reinforcement learning. Furthermore, this strategy is integrated with a quaternion-based nonlinear model predictive control scheme, ensuring coordination between pose tracking and constant-force control and enhancing overall control performances. The experimental results demonstrate that the proposed method improves constant force control accuracy and task execution stability, validating the feasibility of the proposed approach.
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(This article belongs to the Special Issue Motion Planning, Trajectory Prediction, and Control for Robotics)
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Open AccessArticle
High-Order Model-Based Robust Control of a Dual-Motor Steer-by-Wire System with Disturbance Rejection
by
Minhyung Kim, Insu Chung, Junghyun Choi and Kanghyun Nam
Actuators 2025, 14(7), 322; https://doi.org/10.3390/act14070322 - 30 Jun 2025
Abstract
This paper presents a high-order model-based robust control strategy for a dual-motor road wheel actuating system in a steer-by-wire (SbW) architecture. The system consists of a belt-driven and a pinion-driven motor collaboratively actuating the road wheels through mechanically coupled dynamics. To accurately capture
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This paper presents a high-order model-based robust control strategy for a dual-motor road wheel actuating system in a steer-by-wire (SbW) architecture. The system consists of a belt-driven and a pinion-driven motor collaboratively actuating the road wheels through mechanically coupled dynamics. To accurately capture the interaction between actuators, structural compliance, and road disturbances, a four-degree-of-freedom (4DOF) lumped-parameter model is developed. Leveraging this high-order dynamic model, a composite control framework is proposed, integrating feedforward model inversion, pole-zero feedback compensation, and a disturbance observer (DOB) to ensure precise trajectory tracking and disturbance rejection. High-fidelity co-simulations in MATLAB/Simulink and Siemens Amesim validate the effectiveness of the proposed control under various steering scenarios, including step and sine-sweep inputs. Compared to conventional low-order control methods, the proposed approach significantly reduces tracking error and demonstrates enhanced robustness and disturbance attenuation. These results highlight the critical role of high-order modeling in the precision control of dual-motor SbW systems and suggest its applicability in real-time, safety-critical vehicle steering applications.
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(This article belongs to the Special Issue Modeling and Control for Chassis Devices in Electric Vehicles—2nd Edition)
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