-
The Small Frontier: Trends Toward Miniaturization and the Future of Planetary Surface Rovers
-
A Hybrid Flying Robot Utilizing Water Thrust and Aerial Propellers: Modeling and Motion Control System Design
-
Advances in Langevin Piezoelectric Transducer Designs for Broadband Ultrasonic Transmitter Applications
-
A Review of Bio-Inspired Actuators and Their Potential for Adaptive Vehicle Control
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.
- Journal Cluster of Instruments and Instrumentation: Actuators, AI Sensors, Instruments, Micromachines and Sensors.
Impact Factor:
2.3 (2024);
5-Year Impact Factor:
2.4 (2024)
Latest Articles
Lightweight Adaptive Feature Compression and Dynamic Network Fusion for Rotating Machinery Fault Diagnosis Under Extreme Conditions
Actuators 2025, 14(9), 458; https://doi.org/10.3390/act14090458 - 19 Sep 2025
Abstract
Reliable fault diagnosis of rotating machines under extreme conditions—strong speed, load variation, intense noise, and severe class imbalance—remains a critical industrial challenge. We develop an ultra-light yet robust framework to accurately detect weak bearing, and gear faults when less than 5% labels, 10
[...] Read more.
Reliable fault diagnosis of rotating machines under extreme conditions—strong speed, load variation, intense noise, and severe class imbalance—remains a critical industrial challenge. We develop an ultra-light yet robust framework to accurately detect weak bearing, and gear faults when less than 5% labels, 10 dB noise, 100:1 imbalance and plus or minus 20% operating-point drift coexist. Methods: The proposed Adaptive Feature Module–Conditional Dynamic GRU Auto-Encoder (AFM-CDGAE) first compresses 512 d spectra into 32/48 d “feature modules” via K-means while retaining 98.4% fault energy. A workload-adaptive multi-scale convolution with spatial attention and CPU-aware λ-scaling suppresses noise and adapts to edge–device load. A GRU-based auto-encoder, enhanced by self-attention, is trained with balanced-subset sampling and minority-F1-weighted voting to counter extreme imbalance. On Paderborn (5-class) and CWRU (7-class) benchmarks, the 0.87 M-parameter model achieves 99.12% and 98.83% Macro-F1, surpassing five recent baselines by 3.1% under normal and 5.4% under the above extreme conditions, with only 1.5 to 1.8% F1 drop versus 6.7% for baselines. AFM-CDGAE delivers state-of-the-art accuracy, minimal footprint and strong robustness, enabling real-time deployment at the edge.
Full article
(This article belongs to the Section Actuators for Manufacturing Systems)
►
Show Figures
Open AccessArticle
Adaptive Sliding Mode Control for Unmanned Surface Vehicle Trajectory Tracking Based on Event-Driven and Control Input Quantization
by
Zhihui Li, Mengyuan Li, Xinrui Jing, Changfu Yuan and Kai Wang
Actuators 2025, 14(9), 457; https://doi.org/10.3390/act14090457 - 18 Sep 2025
Abstract
This primary study aims to optimize network resource utilization efficiency in marine control systems. A novel event-triggering condition is proposed to significantly reduce communication traffic, where the error norm is squared while the input norm remains linear. To simulate realistic environmental disturbances, bounded
[...] Read more.
This primary study aims to optimize network resource utilization efficiency in marine control systems. A novel event-triggering condition is proposed to significantly reduce communication traffic, where the error norm is squared while the input norm remains linear. To simulate realistic environmental disturbances, bounded unknown parameters are incorporated. Within the networked transmission architecture, input quantization is introduced, enabling the design of a quantized feedback controller without prior knowledge of quantization parameters. By integrating the event-triggering mechanism with sliding mode control, a quantized feedback control system is developed. The closed-loop system’s stability is rigorously proven via Lyapunov theory, with guaranteed boundedness of trajectory tracking errors. Numerical simulations validate the effectiveness of the proposed method for marine vehicle trajectory control under environmental disturbances.
Full article
(This article belongs to the Special Issue Control System of Autonomous Surface Vehicle)
►▼
Show Figures

Figure 1
Open AccessArticle
Motion Control of Gallium-Based Liquid Metal Droplets in Abrasive Suspensions Within a Flow Channel
by
Yapeng Ma, Baoqi Feng, Kaixiang Li and Lei Zhang
Actuators 2025, 14(9), 456; https://doi.org/10.3390/act14090456 - 18 Sep 2025
Abstract
Gallium-based room-temperature liquid metal is a promising multifunctional material for microfluidics and precision machining due to its high mobility and deformability. However, precise motion control of gallium-based liquid metal droplets, especially in abrasive particle-laden fluids, remains challenging. This study presents a hybrid control
[...] Read more.
Gallium-based room-temperature liquid metal is a promising multifunctional material for microfluidics and precision machining due to its high mobility and deformability. However, precise motion control of gallium-based liquid metal droplets, especially in abrasive particle-laden fluids, remains challenging. This study presents a hybrid control framework for regulating droplet motion in a one-dimensional PMMA channel filled with NaOH-based SiC abrasive suspensions. A dynamic model incorporating particle size and concentration effects on the damping coefficient was established. The system combines a setpoint controller, high-resolution voltage source, and vision feedback to guide droplets to target positions with high accuracy. Experimental validation and MATLAB simulations confirm that the proposed dynamic damping control strategy ensures stable, rapid, and precise positioning of droplets, minimizing motion fluctuations. This approach offers new insights into the manipulation of gallium-based liquid metal droplets for targeted material removal in micro-manufacturing, with potential applications in microelectronics and high-precision surface finishing.
Full article
(This article belongs to the Section Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Prescribed-Performance-Bound-Based Adaptive Fault-Tolerant Control for Rigid Spacecraft Attitude Systems
by
Zixuan Chen, Teng Cao, Shaohua Yang and Yang Cao
Actuators 2025, 14(9), 455; https://doi.org/10.3390/act14090455 - 17 Sep 2025
Abstract
This paper investigates the attitude control problems of spacecraft subject to external disturbances and compound actuator faults, including both additive and multiplicative components. To address these problems, an improved learning observer (ILO) is proposed. Compared to traditional learning observers (TLOs), the improved learning
[...] Read more.
This paper investigates the attitude control problems of spacecraft subject to external disturbances and compound actuator faults, including both additive and multiplicative components. To address these problems, an improved learning observer (ILO) is proposed. Compared to traditional learning observers (TLOs), the improved learning observer incorporates the previous-step state estimation error as an iterative term. Based on the observer’s outputs, a robust adaptive fault-tolerant attitude control scheme is developed using the backstepping method, under a prescribed performance bound (PPB). This control framework guarantees that the attitude tracking error adheres to prescribed transient performance specifications, such as bounded overshoot and accelerated convergence. Unlike conventional control schemes, the proposed approach ensures that system trajectories remain strictly within the desired bound throughout the transient process. A comprehensive Lyapunov-based analysis rigorously demonstrates the global uniform ultimate boundedness of all closed-loop signals. Numerical simulations substantiate the efficacy of the proposed approach, highlighting the enhanced disturbance estimation capability of the ILO in comparison to the TLO, as well as the superior transient tracking performance of the PPB-based control strategy relative to existing methods.
Full article
(This article belongs to the Section Aerospace Actuators)
►▼
Show Figures

Figure 1
Open AccessArticle
Global-Initialization-Based Model Predictive Control for Mobile Robots Navigating Nonconvex Obstacle Environments
by
Seung-Mok Lee
Actuators 2025, 14(9), 454; https://doi.org/10.3390/act14090454 - 17 Sep 2025
Abstract
This paper proposes a nonlinear model predictive control (MPC) framework initialized using an initial-guess particle swarm optimization (IG-PSO) algorithm for mobile robots navigating in environments with nonconvex obstacles. The proposed method is designed to address the local minimum problem inherent in conventional optimization-based
[...] Read more.
This paper proposes a nonlinear model predictive control (MPC) framework initialized using an initial-guess particle swarm optimization (IG-PSO) algorithm for mobile robots navigating in environments with nonconvex obstacles. The proposed method is designed to address the local minimum problem inherent in conventional optimization-based MPC by incorporating a PSO-based global search method to generate effective initial guesses. In addition, a grid-based representation of the nonconvex obstacles is implemented to systematically define the collision avoidance constraints within the MPC formulation. The proposed method was validated in real-time simulations using the Robot Operating System (ROS) and the Gazebo physics simulator. The results demonstrate that the proposed MPC initialized by IG-PSO generates collision-free trajectories that avoid local minima and track the desired reference trajectory in environments with nonconvex obstacles. Compared with conventional IPOPT-based MPC, the proposed method exhibited improved performance in the tested scenario. The proposed method also maintains real-time control capabilities by selectively activating the IG-PSO algorithm only as required. The findings of this study demonstrate the potential of the proposed framework for robust and efficient trajectory planning in complex, nonconvex obstacle environments.
Full article
(This article belongs to the Section Actuators for Robotics)
►▼
Show Figures

Figure 1
Open AccessArticle
Fast Fourier Transform-Based Activation and Monitoring of Micro-Supercapacitors: Enabling Energy-Autonomous Actuators
by
Negar Heidari, Parviz Norouzi, Alireza Badiei and Ebrahim Ghafar-Zadeh
Actuators 2025, 14(9), 453; https://doi.org/10.3390/act14090453 - 16 Sep 2025
Abstract
This work provides the first demonstration of FFTCCV as a dual-purpose method, serving both as a real-time diagnostic tool and as a phase- and morphology-engineering strategy. By adjusting the scan rate, FFTCCV directs the crystallographic evolution of Ni (OH)2 on Ni foam—stabilizing
[...] Read more.
This work provides the first demonstration of FFTCCV as a dual-purpose method, serving both as a real-time diagnostic tool and as a phase- and morphology-engineering strategy. By adjusting the scan rate, FFTCCV directs the crystallographic evolution of Ni (OH)2 on Ni foam—stabilizing α-nanoflakes at 0.7 V·s−1 and β-platelets at 0.007 V·s−1—while simultaneously enabling electrode-resolved ΔQ tracking and predictive state-of-health (SoH) monitoring. This approach enabled the precise regulation of electrode morphology and phase composition, yielding high areal capacitance (546.5 mF·cm−2 at 5 mA·cm−2) with ~75% retention after 3000 cycles. These improvements advance the development of high-performance micro-supercapacitors, facilitating their integration into wearable and miniaturized devices where compact and durable energy storage is required. Beyond performance enhancement, FFTCCV also enabled continuous monitoring of capacitance during extended operation (up to 40,000 s). By recording both anodic and cathodic responses, the method provided time-resolved insights into device stability and revealed characteristic signatures of electrode degradation, phase transitions, and morphological changes. Such detection allows recognition of early failure pathways that are not accessible through conventional testing. This monitoring capability functions as an embedded health sensor, offering a pathway for predictive diagnosis of supercapacitor failure. Such functionality is particularly important for energy-driven actuators and smart materials, where uninterrupted operation and preventive maintenance are critical. FFTCCV therefore provides a scalable strategy for developing energy-autonomous microsystems with improved performance and real-time state-of-health monitoring.
Full article
(This article belongs to the Section Miniaturized and Micro Actuators)
►▼
Show Figures

Figure 1
Open AccessArticle
Research on Dual-Motor Redundant Compensation for Unstable Fluid Load of Control Valves
by
Zhisheng Li, Yudong Xie, Jiazhen Han and Yong Wang
Actuators 2025, 14(9), 452; https://doi.org/10.3390/act14090452 - 15 Sep 2025
Abstract
Control valves are widely applied in nuclear power, offshore oil/gas extraction, and chemical engineering, but suffer from issues like pressure oscillation, flow control accuracy degradation, and motor overload due to unstable fluid loads (e.g., nuclear reactions in power plants and complex marine climates).
[...] Read more.
Control valves are widely applied in nuclear power, offshore oil/gas extraction, and chemical engineering, but suffer from issues like pressure oscillation, flow control accuracy degradation, and motor overload due to unstable fluid loads (e.g., nuclear reactions in power plants and complex marine climates). This paper proposes a dual-motor redundant compensation method to address these challenges. The core lies in a control strategy where a single main motor drives the valve under normal conditions, while a redundant motor intervenes when load torque exceeds a preset threshold—calculated via the valve core’s fluid load model. By introducing excess load torque as positive feedback to the current loop, the method coordinates torque output between the two motors. AMESim and Matlab/Simulink joint simulations compare single-motor non-compensation, single-motor compensation, and dual-motor schemes. Results show that under inlet pressure step changes, the dual-motor compensation scheme shortens the stabilization time of the valve’s controlled variable by 40%, reduces overshoot by 65%, and decreases motor torque fluctuation by 50%. This redundant design enhances fault tolerance, providing a novel approach for reliability enhancement of deep-sea oil/gas control valves.
Full article
(This article belongs to the Section Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Fully-Distributed Bipartite Consensus for Linear Multiagent Systems with Dynamic Event-Triggered Mechanism Under Signed Topology Network
by
Han Sun, Xiaogong Lin and Dawei Zhao
Actuators 2025, 14(9), 451; https://doi.org/10.3390/act14090451 - 13 Sep 2025
Abstract
This article investigates the bipartite consensus control problem of general linear multiagent systems over an antagonistic interaction topology using a dynamic event-triggered mechanism. Primarily, for each agent, a distributed dynamic event-triggered control scheme is proposed based on a signed cooperative–competitive communication graph. Controller
[...] Read more.
This article investigates the bipartite consensus control problem of general linear multiagent systems over an antagonistic interaction topology using a dynamic event-triggered mechanism. Primarily, for each agent, a distributed dynamic event-triggered control scheme is proposed based on a signed cooperative–competitive communication graph. Controller updates and triggering condition monitoring are executed only when a specified event is triggered, thereby reducing communication overhead. Subsequently, by integrating the time-varying control gain into the presented control strategy, a fully distributed bipartite controller architecture is defined without using global topology information. As a result, the influence of coupling weights on each agent can be restrained, enabling the realization of bipartite consensus for multiagent systems. Moreover, the proposed dynamic event-triggered control protocol is rigorously proven to exclude Zeno behavior over the entire time horizon. Finally, numerical simulations are presented to demonstrate the effectiveness of the proposed method.
Full article
(This article belongs to the Special Issue Advanced Technologies in Actuators for Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Design and Analysis of a Dual-Screw Propelled Robot for Underwater and Muddy Substrate Operations in Agricultural Ponds
by
Yan Xu, Pengchao Dai, Mingjin Xin, Liyan Wu and Yuqiu Song
Actuators 2025, 14(9), 450; https://doi.org/10.3390/act14090450 - 12 Sep 2025
Abstract
Conventional underwater vehicles, which are typically equipped with oscillating fins or standard propellers, are incapable of effective locomotion within the viscous, high-resistance environment of muddy substrates common in agricultural ponds. To address this operational limitation, this paper presents a compact dual-screw propelled robot
[...] Read more.
Conventional underwater vehicles, which are typically equipped with oscillating fins or standard propellers, are incapable of effective locomotion within the viscous, high-resistance environment of muddy substrates common in agricultural ponds. To address this operational limitation, this paper presents a compact dual-screw propelled robot capable of traversing both the water column and soft substrate layers. The robot’s locomotion is driven by two optimized helical screw propellers, while depth control and roll stability are actively managed by a control fin. A dynamic model of the robot–fluid interaction was developed to optimize the screw configuration that achieves a maximum theoretical thrust of 40 N with a calculated 16% slippage rate in mud. Computational fluid dynamics simulations were employed to determine the optimal angle for the control fin, which was found to be 9°, maximizing the lift-to-drag ratio at 12.09 for efficient depth maneuvering. A cable-free remote control system with a response time of less than 0.5 s governs all operations. Experimental validation in a controlled tank environment confirmed the robot’s performance, demonstrating stable locomotion at 0.4 m/s in water and 0.3 m/s in a simulated mud substrate. This dual-screw propelled robot represents a promising technological solution for comprehensive monitoring and operational tasks in agricultural pond environments.
Full article
(This article belongs to the Special Issue Design and Control of Agricultural Robotics)
►▼
Show Figures

Figure 1
Open AccessArticle
Research on Inertial Force Suppression Control for Hydraulic Cylinder Synchronization of Shield Tunnel Segment Erector Based on Sliding Mode Control
by
Fangao Zhang, Zhaoqiang Wang, Xiaori Zhang, Xiaoqiang Wang and Xiaoxi Hu
Actuators 2025, 14(9), 449; https://doi.org/10.3390/act14090449 - 11 Sep 2025
Abstract
As a critical component in tunnel construction, the segment erector of shield tunneling machines critically influences segment assembly quality and construction efficiency, largely determined by its dual-cylinder synchronization control. Addressing challenges such as dynamic coupling, nonlinear disturbances, and significant inertial force fluctuations inherent
[...] Read more.
As a critical component in tunnel construction, the segment erector of shield tunneling machines critically influences segment assembly quality and construction efficiency, largely determined by its dual-cylinder synchronization control. Addressing challenges such as dynamic coupling, nonlinear disturbances, and significant inertial force fluctuations inherent in hydraulic cylinder synchronization under large-inertia loads and variable working conditions, this study proposes an optimized inertial force suppression strategy utilizing an improved sliding mode control (SMC). Mechanical and hydraulic dynamic models of the dual-cylinder lifting mechanism were established to analyze load distribution and force-arm variation patterns, thereby elucidating the influence of inertial forces on synchronization accuracy. Based on this analysis, an adaptive boundary-layer SMC, incorporating real-time inertial force compensation, was designed. This design effectively suppresses system chattering and enhances robustness. Simulation and experimental results demonstrate that the proposed method achieves synchronization errors within ±0.5 mm during step responses, reduces inertial force peaks by 50%, and exhibits significantly superior anti-interference performance compared to conventional PID control. This research provides theoretical foundations and practical engineering insights for high-precision synchronization control in shield tunneling, demonstrating substantial application value.
Full article
(This article belongs to the Section Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Adaptive Event-Triggered Full-State Constrained Control of Multi-Agent Systems Under Cyber Attacks
by
Jinxia Wu, Pengfei Cui, Juan Wang and Yuanxin Li
Actuators 2025, 14(9), 448; https://doi.org/10.3390/act14090448 - 11 Sep 2025
Abstract
For multi-agent systems under Denial-of-Service (DoS) attacks, a relative threshold strategy for event triggering and a state-constrained control method with prescribed performance are proposed. Within the framework of combining graph theory with the leader–follower approach, coordinate transformation is utilized to decouple the multi-agent
[...] Read more.
For multi-agent systems under Denial-of-Service (DoS) attacks, a relative threshold strategy for event triggering and a state-constrained control method with prescribed performance are proposed. Within the framework of combining graph theory with the leader–follower approach, coordinate transformation is utilized to decouple the multi-agent system. Inspired by the three-way handshake technology of TCP communication, a DoS detection system is designed based on event-triggering. This system is used to detect DoS attacks, prevent the impacts brought by DoS attacks, and reduce the update frequency of the controller. Fuzzy logic systems are employed to approximate the unknown nonlinear functions within the system. By using a first-order filter to approximate the derivative of the virtual controller, the computational complexity issue in the backstepping method is addressed. Furthermore, The Barrier Lyapunov Function (BLF) possesses unique mathematical properties. When the system state approaches the pre-set boundary, it can exhibit a special variation trend, thereby imposing a restrictive effect on the system state. The Prescribed Performance Function (PPF), on the other hand, defines the expected performance standards that the system aims to achieve in the tracking task, covering key indicators such as tracking accuracy and response speed. By organically integrating these two functions, the system can continuously monitor and adjust its own state during operation. When there is a tendency for the tracking error to deviate from the specified range, the combined function mechanism will promptly come into play. Through the reasonable adjustment of the system’s control input, it ensures that the tracking error always remains within the pre-specified range. Finally, through Lyapunov analysis, the proposed control protocol ensures that all closed-loop signals remain bounded under attacks, with the outputs of all followers synchronizing with the leader’s output in the communication graph.
Full article
(This article belongs to the Special Issue Advanced Technologies in Actuators for Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
An Adaptive Estimation Model for the States and Loads in Electro-Hydraulic Actuation Systems
by
Dimitar Dichev, Borislav Georgiev, Iliya Zhelezarov, Tsanko Karadzhov and Hristo Hristov
Actuators 2025, 14(9), 447; https://doi.org/10.3390/act14090447 - 11 Sep 2025
Abstract
In this study, we introduce an advanced framework for state estimation in electro-hydraulic systems, utilizing a structurally adapted Kalman filter. The proposed model was designed to enhance estimation accuracy and robustness under dynamic load variations and evolving measurement conditions. A notable feature of
[...] Read more.
In this study, we introduce an advanced framework for state estimation in electro-hydraulic systems, utilizing a structurally adapted Kalman filter. The proposed model was designed to enhance estimation accuracy and robustness under dynamic load variations and evolving measurement conditions. A notable feature of the approach is the algebraic resolution of one system state during each iteration, enabling the seamless inclusion of variables that are otherwise difficult to measure, without disrupting the model’s linear formulation. In addition, the dynamics of the load torque are empirically characterized through a regression-based model derived from experimental observations. The framework integrates adaptive mechanisms for updating the model and measurement error covariance matrices, facilitating the real-time accommodation of system nonlinearities and environmental changes. Experimental results are presented in different operating modes, reflecting characteristic dynamic movements. They show that the method reduced the root mean square error (RMSE) when estimating angular velocity between five and more than six times, depending on the mode. When evaluating the load torque, even in modes with a sharply changing load, the RMSE value remains stable below 0.05 Nm, which indicates the absence of systematic drift and high stability of the estimates. This confirms the stable operation of the algorithm in dynamic conditions and its applicability in real systems.
Full article
(This article belongs to the Section Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Application-Oriented Analysis of Hexaglide Pose Accuracy in Through-Hole Assembly of Electronic Components
by
Mikhail Polikarpov, Yousuf Mehmood and Jochen Deuse
Actuators 2025, 14(9), 446; https://doi.org/10.3390/act14090446 - 9 Sep 2025
Abstract
Hexaglide parallel manipulators are characterized by high accuracy and dynamic performance, which makes them suitable for industrial high-precision assembly tasks such as placement of electronic THT components on printed circuit boards. In this paper we describe an assembly system that comprises a Hexaglide
[...] Read more.
Hexaglide parallel manipulators are characterized by high accuracy and dynamic performance, which makes them suitable for industrial high-precision assembly tasks such as placement of electronic THT components on printed circuit boards. In this paper we describe an assembly system that comprises a Hexaglide manipulator with vertical ball screws, moving printed circuit boards relative to stationary THT components. We evaluate the effects of the manufacturing tolerances of machine parts, such as bar length tolerance, ball screw axis position uncertainty, and ball screw axis orientation uncertainty, on Hexaglide end-effector pose accuracy using a geometric simulation study based on stochastic tolerance sampling. In the investigated configuration and under standard industrial tolerances, bar length inaccuracy and axis position uncertainty lead to significant position and rotation deviations for the Hexaglide end-effector in the horizontal plane that need to be compensated for by control algorithms to enable THT assembly using the Hexaglide prototype. The geometric simulation method applied in this paper can be used by designers of Hexaglide machines to study and evaluate different machine configurations.
Full article
(This article belongs to the Special Issue Industrial and Biomechanical Applications of Actuators and Robots and Eco-Sustainability)
►▼
Show Figures

Figure 1
Open AccessArticle
Developing an Energy-Efficient Electrostatic-Actuated Micro-Accelerometer for Low-Frequency Sensing Applications
by
Umar Jamil, Muhammad Sohaib Zahid, Nouman Ghafoor, Faisal Nawaz, Jose Raul Montes-Bojorquez and Mehboob Alam
Actuators 2025, 14(9), 445; https://doi.org/10.3390/act14090445 - 8 Sep 2025
Abstract
Micro-accelerometers are in high demand across many due to their compact size, low energy consumption, and excellent precision. Since gravity causes a large movement when the device is positioned vertically, measuring low gravitational acceleration is challenging. This study examines the intrinsic relationship between
[...] Read more.
Micro-accelerometers are in high demand across many due to their compact size, low energy consumption, and excellent precision. Since gravity causes a large movement when the device is positioned vertically, measuring low gravitational acceleration is challenging. This study examines the intrinsic relationship between applied voltage levels and displacement in micro-accelerometers. The study introduces a novel design that integrates hybrid flexures, comprising both linear and angular configurations, with an out-of-plane overlap varying (OPOV) electrostatic actuation mechanism. This design aims to measure the micro-accelerometer’s movement and low frequency response. The proposed device with silicon material is designed and simulated using the IntelliSuite® software, considering its small dimensions and 25 µm thickness. The norm value of 28.0916 μN from gravity’s reaction forces on the body, a resonant frequency of 179.668 Hz at the first desired mode, and a maximum stress of 24.7 MPa were obtained through the electro-mechanical analysis. A comparison of the proposed design was conducted with other configurations, measuring a frequency of 179.668 Hz at a minimum downward displacement of 7.69916 µm under the influence of gravity without electrostatic mechanisms. Following this, an electrostatic actuation mechanism was introduced to minimize displacement by applying different voltage levels, including 1 V, 1.5 V, and 3 V. At 3 V, a significant improvement in displacement reduction was observed compared to the other applied voltages. Additionally, dynamic and sensitivity analyses were carried out to validate the performance of the proposed design further.
Full article
(This article belongs to the Special Issue Recent Advances in the Design and Applications for Magnetoelastic and Electroelastic Actuators)
►▼
Show Figures

Figure 1
Open AccessArticle
The Impact of Pump Cavity Gaps on the Flow Characteristics of Helical Mixed-Flow Pumps
by
Wei Han, Yucheng Chen, Tongqing Xue and Pengzheng Lei
Actuators 2025, 14(9), 444; https://doi.org/10.3390/act14090444 - 8 Sep 2025
Abstract
The performance of pump-jet propulsion systems is critically important in defense and marine applications. However, their optimization has encountered bottlenecks due to a lack of theoretical understanding of underlying flow mechanisms. This study investigates the influence of the pump cavity gap on the
[...] Read more.
The performance of pump-jet propulsion systems is critically important in defense and marine applications. However, their optimization has encountered bottlenecks due to a lack of theoretical understanding of underlying flow mechanisms. This study investigates the influence of the pump cavity gap on the flow characteristics and performance of a helical mixed-flow pump using numerical simulations. The gap size is non-dimensionalized as a gap coefficient—defined as the ratio of pump cavity gap to blade thickness—with the inlet ring gap fixed at 0.2 mm. Results demonstrate that the gap coefficient significantly affects internal flow stability and energy loss. A gap coefficient of 0.15 effectively suppresses leakage and vortex formation, improving efficiency (peak efficiency reaches 75%) and head (1.9 m) under low-flow conditions. This configuration also promotes uniform pressure distribution on the impeller shaft surface and reduces turbulent kinetic energy and axial vorticity. In contrast, a smaller gap coefficient (0.125) exacerbates flow separation at high flow rates, while a larger value (0.2) increases leakage losses and degrades performance. The study elucidates correlations between the pump cavity gap and vortex evolution, pressure gradient, and turbulence distribution, providing theoretical support for the optimized design of helical mixed-flow pumps.
Full article
(This article belongs to the Special Issue Advanced Actuators and Magnetic Fluid Systems: Design, Control, and Applications)
►▼
Show Figures

Figure 1
Open AccessArticle
Design and Evaluation of a Torque-Controlled Ankle Exoskeleton Using the Small-Scale Hydrostatic Actuator: miniHydrA
by
Kyrian Staman and Herman van der Kooij
Actuators 2025, 14(9), 443; https://doi.org/10.3390/act14090443 - 8 Sep 2025
Abstract
A small-scale electro-hydrostatic actuator, termed miniHydrA, was developed based on biomechanical requirements for gait and integrated into an ankle exoskeleton. The key advantage of this actuator concept lies in its compact size and the low mass of its output stage, combined with the
[...] Read more.
A small-scale electro-hydrostatic actuator, termed miniHydrA, was developed based on biomechanical requirements for gait and integrated into an ankle exoskeleton. The key advantage of this actuator concept lies in its compact size and the low mass of its output stage, combined with the ability to deliver high support torques, sufficient for full human assistance. During development, hydraulic cylinder leakage and friction were identified as key challenges. To address control requirements, a dedicated control strategy was proposed and implemented. The prototype exoskeleton was evaluated for joint torque tracking performance across a range of torques (0–120 Nm), both in benchtop tests and during treadmill walking trials. In benchtop experiments, zero-torque tracking was achieved with a mean absolute error ranging from 0.03 to 2.26 Nm across frequencies from 0 to 5 Hz. During treadmill walking, torque tracking errors ranged from 0.70 to 0.95 Nm, with no observable deviations in ankle joint kinematics among the three test subjects. These results show the feasibility of the miniHydrA for remote actuation. Compared to Bowden cables, commonly used in exoskeletons and exosuits, the proposed actuator concept offers two key advantages: it is better suited for high-torque applications, and its friction characteristics can be more accurately predicted and modeled, enabling more effective feedforward control.
Full article
(This article belongs to the Special Issue Control of Hydraulic Robotic Manipulators)
►▼
Show Figures

Figure 1
Open AccessArticle
Modeling of the Dynamic Characteristics for a High-Load Magnetorheological Fluid-Elastomer Isolator
by
Yu Tao, Wenhao Chen, Feifei Liu and Ruijie Han
Actuators 2025, 14(9), 442; https://doi.org/10.3390/act14090442 - 5 Sep 2025
Abstract
To meet the vibration isolation requirements of engines under diverse operating conditions, this paper proposes a novel magnetorheological fluid-elastomer isolator with high load and tunable parameters. The mechanical and magnetic circuit structures of the isolator were designed and optimized through theoretical calculations and
[...] Read more.
To meet the vibration isolation requirements of engines under diverse operating conditions, this paper proposes a novel magnetorheological fluid-elastomer isolator with high load and tunable parameters. The mechanical and magnetic circuit structures of the isolator were designed and optimized through theoretical calculations and finite element simulations, achieving effective vibration isolation within confined spaces. The dynamic performance of the isolator was experimentally evaluated using a hydraulic testing system under varying excitation amplitudes, frequencies, initial positions, and magnetic fields. Experimental results indicate that the isolator achieves a static stiffness of 3 × 106 N/m and a maximum adjustable compression load range of 105.4%. In light of the asymmetric nonlinear dynamic behavior of the isolator, an improved nine-parameter Bouc–Wen model is proposed. Parameter identification performed via a genetic algorithm demonstrates a model accuracy of 95.0%, with a minimum error reduction of 28.8% compared to the conventional Bouc–Wen model.
Full article
(This article belongs to the Section Precision Actuators)
►▼
Show Figures

Figure 1
Open AccessArticle
Synchronous Leveling Control Method of Crane Vehicle Platform Based on Position–Force Coordination
by
Feixiang Xu, Haichao Hu, Shiyong Feng and Chen Zhou
Actuators 2025, 14(9), 441; https://doi.org/10.3390/act14090441 - 5 Sep 2025
Abstract
Leveling of the crane support platform plays a vital role in operational safety and lifting efficiency; it requires both precise horizontal positioning and the rational distribution of outrigger load. However, the current synchronous leveling methods mainly focus on displacement synchronization leveling while neglecting
[...] Read more.
Leveling of the crane support platform plays a vital role in operational safety and lifting efficiency; it requires both precise horizontal positioning and the rational distribution of outrigger load. However, the current synchronous leveling methods mainly focus on displacement synchronization leveling while neglecting the control of outrigger load, resulting in the problem of individual outrigger overloading. To address this problem, a synchronous leveling control method with variable load constraints (SLCM-VLC) is proposed in this paper based on the framework of model predictive control. Firstly, the proposed method conducts independent outrigger modeling and decoupling of outriggers through adjacent cross-coupling; then a displacement synchronization controller (DSC) is designed to ensure efficient synchronous leveling. Secondly, a collaborative controller of displacement and force (DFCC) under variable load constraints is designed to overcome the limitations of traditional independent optimization. Subsequently, an extended state observer (ESO) is introduced to compensate for environmental disturbances and control deviations. Finally, the effectiveness of the proposed method is verified through a co-simulation using Matlab, Adams, and Solidworks. The results show that, compared with existing leveling control methods, the proposed method can achieve high precision and rapid leveling under smaller peak load, thereby extending the service life of the platform’s electric cylinders.
Full article
(This article belongs to the Section Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Research on Linear Active Disturbance Rejection Control of Electrically Excited Motor for Vehicle Based on ADP Parameter Optimization
by
Heping Ling, Junzhi Zhang and Hua Pan
Actuators 2025, 14(9), 440; https://doi.org/10.3390/act14090440 - 4 Sep 2025
Abstract
In the three-motor hybrid architecture, the auxiliary drive uses electrically excited synchronous motor (EESM), which has the advantages of high torque density, wide speed range and strong anti-demagnetization ability. However, the strong electromagnetic coupling between the field winding and the armature winding leads
[...] Read more.
In the three-motor hybrid architecture, the auxiliary drive uses electrically excited synchronous motor (EESM), which has the advantages of high torque density, wide speed range and strong anti-demagnetization ability. However, the strong electromagnetic coupling between the field winding and the armature winding leads to the difficulty of current control, and the traditional PID has limitations in dynamic response and immunity. In order to solve this problem, a linear active disturbance rejection control (LADRC) method for the rotor of EESM is proposed in this paper, linear extended state observer (LESO) is used to estimate and compensate the system internal and external disturbances (such as winding coupling and parameter perturbation) in real time. The method only uses the input and output of the system and does not depend on any mechanical parameters, so that the torque response is improved by 50%, and the steady-state fluctuation is reduced by 10.2%. In addition, an adaptive dynamic programming (ADP) parameter optimization strategy is proposed to solve the bandwidth parameter tuning problem of LADRC algorithm in complex operating conditions, and the related mathematical analysis of optimality properties is given. Finally, the proposed method is compared with the traditional PI controller in several operating conditions of EESM, and the effectiveness of the proposed method is validated by the corresponding results.
Full article
(This article belongs to the Section Control Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Simulation-Based Testing of Autonomous Robotic Systems for Surgical Applications
by
Jun Lin, Tiantian Sun, Rihui Song, Di Zhu, Lan Liu, Jiewu Leng, Kai Huang and Rongjie Yan
Actuators 2025, 14(9), 439; https://doi.org/10.3390/act14090439 - 4 Sep 2025
Abstract
Autonomous surgery involves surgical tasks performed by a robot with minimal or no human involvement. Thanks to its precise automation, surgical robotics offers significant benefits in enhancing the consistency, safety, and quality of procedures, driving its growing popularity. However, ensuring the safety of
[...] Read more.
Autonomous surgery involves surgical tasks performed by a robot with minimal or no human involvement. Thanks to its precise automation, surgical robotics offers significant benefits in enhancing the consistency, safety, and quality of procedures, driving its growing popularity. However, ensuring the safety of autonomous surgical robotic systems remains a significant challenge. To address this, we propose a simulation-based validation method to detect potential safety issues in the software of surgical robotic systems, complemented by a digital twin to estimate the gap between simulation and reality. The validation framework consists of a test case generator and a monitor for validating properties and evaluating the performance of the robotic system during test execution. Using a robotic arm for needle insertion as a case study, we present a systematic test case generation method that ensures effective coverage measurement for a three-dimensional, irregular model. Since no simulation can perfectly replicate reality due to differences in sensing and actuation, the digital twin bridges the gap between simulation and the physical robotic arm. This integration enables us to assess the discrepancy between virtual simulations and real-world operations by verifying whether the data from the simulation accurately predicts real-world outcomes. Through extensive experimentation, we identified several flaws in the robotic software. Co-simulation within the digital twin framework has highlighted these discrepancies that should be considered.
Full article
(This article belongs to the Section Actuators for Robotics)
►▼
Show Figures

Figure 1

Journal Menu
► ▼ Journal Menu-
- Actuators Home
- Aims & Scope
- Editorial Board
- Reviewer Board
- Topical Advisory Panel
- Instructions for Authors
- Special Issues
- Topics
- Sections
- Article Processing Charge
- Indexing & Archiving
- Editor’s Choice Articles
- Most Cited & Viewed
- Journal Statistics
- Journal History
- Journal Awards
- Conferences
- Editorial Office
Journal Browser
► ▼ Journal BrowserHighly Accessed Articles
Latest Books
E-Mail Alert
News
Topics
Topic in
Actuators, Algorithms, BDCC, Future Internet, JMMP, Machines, Robotics, Systems
Smart Product Design and Manufacturing on Industrial Internet
Topic Editors: Pingyu Jiang, Jihong Liu, Ying Liu, Jihong YanDeadline: 31 December 2025
Topic in
Actuators, Automation, Electronics, Machines, Robotics, Eng, Technologies
New Trends in Robotics: Automation and Autonomous Systems
Topic Editors: Maki Habib, Fusaomi NagataDeadline: 31 January 2026
Topic in
Actuators, Gels, JFB, Polymers, MCA, Materials
Recent Advances in Smart Soft Materials: From Theory to Practice
Topic Editors: Lorenzo Bonetti, Giulia Scalet, Silvia Farè, Nicola FerroDeadline: 31 December 2026

Conferences
Special Issues
Special Issue in
Actuators
Analysis and Design of Linear/Nonlinear Control System
Guest Editor: Chao-Chung PengDeadline: 22 September 2025
Special Issue in
Actuators
Design, Modeling, and Control of UAV Systems
Guest Editors: Lihui Wang, Bailing Tian, Hongyang BaiDeadline: 25 September 2025
Special Issue in
Actuators
Editorial Board Members’ Collection Series: Nonlinear Control and Dynamics for MEMS
Guest Editors: Najib Kacem, Raffaele ArditoDeadline: 30 September 2025
Special Issue in
Actuators
Actuator Technology for Active Noise and Vibration Control
Guest Editors: Bilong Liu, Qianqian WuDeadline: 30 September 2025