Actuators

30 pages, 7416 KiB

Open AccessArticle

Neural Network and Generalized Extended State Observer Sliding Mode Control of Hydraulic Cylinder Position in the Independent Metering Control System with Digital Valves

by Xiangfei Tao, Kailei Liu and Jing Yang

Actuators 2025, 14(5), 221; https://doi.org/10.3390/act14050221 - 29 Apr 2025

Abstract

The independent metering control system is renowned for its ability to independently regulate the flow and pressure of various actuators, achieving high efficiency and energy savings in hydraulic systems. The high-speed digital valve is known for its fast response to control signals and [...] Read more.

The independent metering control system is renowned for its ability to independently regulate the flow and pressure of various actuators, achieving high efficiency and energy savings in hydraulic systems. The high-speed digital valve is known for its fast response to control signals and precise fluid control. However, challenges such as jitter in the position control of hydraulic cylinders, unknown dead zone nonlinearity, and time variance in electro-hydraulic proportional systems necessitate further investigation. To address these issues, this study initially establishes an independent metering control system with digital valves. Based on the state space equation and Lyapunov stability judgment conditions, a high-order sliding mode controller is designed. In addition, a radial basis function (RBF) neural network is constructed to approximate uncertainties arising from the modeling process, the accuracy error indicator uses Mean Absolute Error (MAE), and a finite time generalized extended state observer (GESO) is introduced to conduct online disturbance observation for the external disturbances present within the control system. Consequently, a variable structure high-order sliding mode control strategy, augmented by RBF neural networks and finite time generalized extended state observer (RBF-GESO-SMC), is proposed. Finally, simulations and experimental verification are performed, followed by a comprehensive analysis of the experimental results. Compared with the sliding mode control (SMC), the RBF-GESO-SMC diminishes the displacement-tracking control accuracy error by 63.7%. Compared with traditional Proportional-Integral-Derivative (PID) control, it reduces the displacement-tracking control accuracy error by 78.1%. The results indicate that, through the comparison with SMC and PID control, RBF-GESO-SMC exerts significant influence on the improvement of position accuracy, anti-interference ability, transient response performance, and stability. Full article

(This article belongs to the Section Control Systems)

16 pages, 5128 KiB

Open AccessArticle

Enhanced Speed Characteristics of High-Torque-Density BLDC Motor for Robot Applications Using Parallel Open-End Winding Configuration

by Junghwan Park, Handdeut Chang and Chaeeun Hong

Actuators 2025, 14(5), 220; https://doi.org/10.3390/act14050220 - 29 Apr 2025

Abstract

High-torque-density motors are essential in humanoid, wearable, and rehabilitation robots due to their ability to minimize gear ratios, improve back-drivability, and support compact joint design. However, their inherently high back-EMF limits speed performance, and safety regulations often constrain supply voltages to below 50 [...] Read more.

High-torque-density motors are essential in humanoid, wearable, and rehabilitation robots due to their ability to minimize gear ratios, improve back-drivability, and support compact joint design. However, their inherently high back-EMF limits speed performance, and safety regulations often constrain supply voltages to below 50 V in human-interactive environments. To overcome these limitations, this study introduces a novel winding strategy called parallel open-end winding (POEW), which combines the benefits of two individual approaches: Parallel Connected Winding (PCW) and Open-End Winding (OEW). PCW reduces phase resistance and inductance, thereby mitigating voltage drop and back-EMF, while OEW eliminates the neutral point, allowing full-phase voltage utilization. Experimental results show that the POEW configuration achieves a 3.5-fold increase in maximum speed compared to the conventional Series-Connected Winding (SCW), without altering the rotor or stator structure. Torque constant measurements confirm that all proposed configurations maintain torque output with minimal variation. Although the motor constant slightly decreases due to the higher current in parallel paths, the significant speed enhancement under low-voltage conditions demonstrates the practicality and effectiveness of POEW for advanced robotic applications requiring both high torque and speed. Full article

(This article belongs to the Special Issue Actuation and Sensing of Intelligent Soft Robots)

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16 pages, 5832 KiB

Open AccessArticle

Design and Development of an EMG Upper Limb Controlled Prosthesis: A Preliminary Approach

by Ricardo Rodrigues, Daniel Miranda, Vitor Carvalho and Demétrio Matos

Actuators 2025, 14(5), 219; https://doi.org/10.3390/act14050219 - 29 Apr 2025

Abstract

A multitude of factors, including accidents, chronic illnesses, and conflicts, contribute to rising global amputation rates. The World Health Organization (WHO) estimates that 57.7 million people lived with traumatic limb amputations in 2017, with many lacking access to affordable prostheses. This study presents [...] Read more.

A multitude of factors, including accidents, chronic illnesses, and conflicts, contribute to rising global amputation rates. The World Health Organization (WHO) estimates that 57.7 million people lived with traumatic limb amputations in 2017, with many lacking access to affordable prostheses. This study presents a preliminary framework for a low-cost, electromyography (EMG)-controlled upper limb prosthesis, integrating 3D printing and EMG sensors to enhance accessibility and functionality. Surface electrodes capture bioelectric signals from muscle contractions, processed via an Arduino Uno to actuate a one-degree-of-freedom (1-DoF) prosthetic hand. Preliminary results demonstrate reliable detection of muscle contractions (threshold = 7 ADC units, ~34 mV) and motor actuation with a response time of ~150 ms, offering a cost-effective alternative to commercial systems. While limited to basic movements, this design lays the groundwork for scalable, user-centered prosthetics. Future work will incorporate multi-DoF control, AI-driven signal processing, and wireless connectivity to improve precision and usability, advancing rehabilitation technology for amputees in resource-limited settings. Full article

(This article belongs to the Section Actuators for Robotics)

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19 pages, 14463 KiB

Open AccessArticle

Fault Diagnosis of Rolling Element Bearing Based on BiTCN-Attention and OCSSA Mechanism

by Yuchen Yang, Chunsong Han, Guangtao Ran, Tengyu Ma and Juntao Pan

Actuators 2025, 14(5), 218; https://doi.org/10.3390/act14050218 - 28 Apr 2025

Abstract

This paper proposes a novel fault diagnosis framework that integrates the Osprey–Cauchy–Sparrow Search Algorithm (OCSSA) optimized Variational Mode Decomposition (VMD) with a Bidirectional Temporal Convolutional Network-Attention mechanism (BiTCN-Attention). To address the limitations of empirical parameter selection in VMD, OCSSA adaptively optimizes the decomposition [...] Read more.

This paper proposes a novel fault diagnosis framework that integrates the Osprey–Cauchy–Sparrow Search Algorithm (OCSSA) optimized Variational Mode Decomposition (VMD) with a Bidirectional Temporal Convolutional Network-Attention mechanism (BiTCN-Attention). To address the limitations of empirical parameter selection in VMD, OCSSA adaptively optimizes the decomposition parameters (penalty factor

α

and mode number K) through a hybrid strategy that combines chaotic initialization, Osprey-inspired global search, and Cauchy mutation. Subsequently, the BiTCN captures bidirectional temporal dependencies from vibration signals, while the attention mechanism dynamically filters critical fault features, constructing an end-to-end diagnostic model. Experiments on the CWRU dataset demonstrate that the proposed method achieves an average accuracy of 99.44% across 10 fault categories, outperforming state-of-the-art models (e.g., VMD-TCN: 97.5%, CNN-BiLSTM: 84.72%). Full article

(This article belongs to the Special Issue Intelligent Sensing, Control and Actuation in Networked Systems)

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20 pages, 20736 KiB

Open AccessArticle

Three-Dimensional Modified Cross-Section Hydrofoil Design and Performance Study

by Hongpeng Cao, Yudong Xie and Zilei Ji

Actuators 2025, 14(5), 217; https://doi.org/10.3390/act14050217 - 28 Apr 2025

Abstract

To improve the hydrodynamic performance of hydrofoils, this study combines the shape characteristics of flat and elliptical wings, uses parabolic function to fit the leading and trailing edges of hydrofoils, introduces the cross-section coefficient λ to characterize the cross-sectional size of hydrofoils along [...] Read more.

To improve the hydrodynamic performance of hydrofoils, this study combines the shape characteristics of flat and elliptical wings, uses parabolic function to fit the leading and trailing edges of hydrofoils, introduces the cross-section coefficient λ to characterize the cross-sectional size of hydrofoils along the spreading direction, and designs five hydrofoils with different cross-sections. The motion of the hydrofoil is simulated using the finite element analysis software Fluent to obtain the hydrodynamic performance curve of the hydrofoil and analyze the effect of different end face sizes on the performance of the hydrofoil. The results show that compared with the flat wing, the peak drag of the variable section hydrofoil with λ = 0.5 is reduced by 9.3%, the pitching moment is reduced by 23.1%, and the average power is raised by 17.4%. If the appropriate reduction in the cross-section coefficient is too small, it will exacerbate the wing tip vortex shedding, the hydrofoil surface pressure will be too concentrated, and the hydrofoil motion stability will be reduced. The lift coefficient, drag coefficient, and pitching moment coefficient of the hydrofoil are positively correlated with the cross-section coefficient λ, and positively correlated with the motion frequency. Full article

(This article belongs to the Special Issue Control System of Autonomous Surface Vehicle)

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19 pages, 10692 KiB

Open AccessArticle

Design of High-Speed Motor System for EV Based on 1200 V SiC-MOSFET Power Module

by Kun Zhou, Minglei Gu and Yu Zheng

Actuators 2025, 14(5), 216; https://doi.org/10.3390/act14050216 - 26 Apr 2025

Abstract

In this paper, a high-speed motor system for an Electric Vehicle (EV) is designed, of which the rated DC-link voltage is 800 V and peak power can reach 200 kW with a high-efficiency Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor (SiC-MOSFET). With [...] Read more.

In this paper, a high-speed motor system for an Electric Vehicle (EV) is designed, of which the rated DC-link voltage is 800 V and peak power can reach 200 kW with a high-efficiency Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor (SiC-MOSFET). With the help of optimization motor design methods, such as pole–slot combination optimization, process optimization and control optimization, the motor can reach its maximal speed of 25,000 rpm and maximal torque of 240 Nm. Finally, the performance of the high-voltage motor system based on the SiC-MOSFET power module is evaluated by simulation and experiment. Full article

(This article belongs to the Special Issue Power Electronics and Actuators—Second Edition)

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14 pages, 5178 KiB

Open AccessArticle

Non-Singular Fast Sliding Mode Control of Robot Manipulators Based on Integrated Dynamic Compensation

by Xinyi Wang, Xichang Liang, Shunjing Hu and Qianqian Xin

Actuators 2025, 14(5), 215; https://doi.org/10.3390/act14050215 - 26 Apr 2025

Abstract

In order to realize the problem of tracking control of the trajectory of robot manipulators under variable load conditions, this paper proposes a non-singular fast terminal sliding mode tracking control design for robot manipulators based on integrated dynamic compensation. First, in the model, [...] Read more.

In order to realize the problem of tracking control of the trajectory of robot manipulators under variable load conditions, this paper proposes a non-singular fast terminal sliding mode tracking control design for robot manipulators based on integrated dynamic compensation. First, in the model, the friction torque under the influence of speed is considered while combined with the joint torque estimation for integrated dynamic compensation. Second, a novel non-singular fast terminal sliding mode controller is proposed, which helps to overcome the singularity problem and has been analyzed for stability using the Lyapunov method. Finally, trajectory tracking experiments are conducted on an experimental platform and compared with the PID algorithm, demonstrating the superior control performance of the proposed algorithm. Full article

(This article belongs to the Section Actuators for Robotics)

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20 pages, 5242 KiB

Open AccessArticle

Development of a Force Feedback Controller with a Speed Feedforward Compensator for a Cable-Driven Actuator

by Juan Fang, Michael Haldimann, Bardia Amiryavari and Robert Riener

Actuators 2025, 14(5), 214; https://doi.org/10.3390/act14050214 - 25 Apr 2025

Abstract

Cable-driven actuators (CDAs) are extensively used in the rehabilitation field because of advantages such as low moment of inertia, fast movement response, and intrinsic flexibility. Accurate control of cable force is essential for achieving precise movement control, especially when the movement is generated [...] Read more.

Cable-driven actuators (CDAs) are extensively used in the rehabilitation field because of advantages such as low moment of inertia, fast movement response, and intrinsic flexibility. Accurate control of cable force is essential for achieving precise movement control, especially when the movement is generated by multiple CDAs. However, velocity-induced disturbances pose challenges to accurate force control during dynamic movements. Several strategies for direct force control have been investigated in the literature, but time-consuming tests are often required. The aim of this study was to develop a force feedback controller and a speed feedforward compensator for a CDA with a convenient experiment-based approach. The CDA consisted of a motor with a gearbox, a cable drum, and a force sensor. The transfer function between motor torque and cable force was estimated through an open-loop test. A PI force feedback controller was developed and evaluated in a static test. Subsequently, a dynamic test with a reference force of 100 N was conducted, during which the cable was pulled to move at different speeds. The relationship between the motor speed and the cable force was determined, which facilitated further development of a speed feedforward compensator. The controller and compensator were evaluated in dynamic tests at various speeds. Additionally, the system dynamics were simulated in MATLAB/Simulink. The static test showed that the PI force controller produced a mean force control error of 4.7 N, which was deemed very good force-tracking accuracy. The simulated force output was very similar to the experiment (RMSE error of 4.0 N). During the dynamic test, the PI force controller alone produced a force control error of 9.0 N. Inclusion of the speed feedforward compensator improved the force control accuracy, resulting in a mean error at various speeds of 5.6 N. The combined force feedback controller and speed feedforward compensator produced a satisfactory degree of accuracy in force control during dynamic tests of the CDA across varying speeds. Additionally, the accuracy level was comparable to that reported in the literature. The convenient experiment-based design of the force control strategy exhibits potential as a general control approach for CDAs, laying the solid foundation for precise movement control. Future work will include the integration of the speed compensator into better feedback algorithms for more accurate force control. Full article

(This article belongs to the Special Issue Cable-Driven Parallel Robot Actuators: State-of-the-Art and New Developments)

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17 pages, 16784 KiB

Open AccessArticle

Robust Time-Optimal Kinematic Control of Robotic Manipulators Based on Recurrent Neural Network Against Harmonic Noises

by Yiqun Kuang, Shuai Li and Zhan Li

Actuators 2025, 14(5), 213; https://doi.org/10.3390/act14050213 - 25 Apr 2025

Abstract

Industrial and service manipulators demand implementing time-optimal kinematic control to minimize task duration in a manner of maximizing end-effector velocity during path tracking. However, achieving this objective in the presence of harmonic noise while strictly enforcing joint motion constraints remains a significant challenge. [...] Read more.

Industrial and service manipulators demand implementing time-optimal kinematic control to minimize task duration in a manner of maximizing end-effector velocity during path tracking. However, achieving this objective in the presence of harmonic noise while strictly enforcing joint motion constraints remains a significant challenge. This paper introduces a novel approach that leverages dynamic recurrent neural networks (RNNs) within a constrained optimization framework to deliver robust, time-optimal kinematic control even under harmonic disturbances. We provide a thorough theoretical analysis of the RNN-based control solver, establishing its convergence and optimality. Importantly, our method maximizes end-effector speed without violating any joint velocity limits, thereby enhancing the path-tracking speed compared to previous schemes. Simulation results and physical experiments further demonstrate the effectiveness and superiority of the proposed approach. Full article

(This article belongs to the Special Issue Motion Planning, Trajectory Prediction, and Control for Robotics)

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15 pages, 7430 KiB

Open AccessArticle

High-Precision Transdermal Drug Delivery Device with Piezoelectric Mechanism

by Shengyu Liu, Junming Liu, Conghui Wang and Yang Zhan

Actuators 2025, 14(5), 212; https://doi.org/10.3390/act14050212 - 25 Apr 2025

Abstract

Piezoelectric (PE) micropumps are distinguished by their high precision, absence of electromagnetic radiation, and straightforward construction principles, making them vital in biomedicine and drug delivery. Integrating PE micropumps with microneedles creates a stable, accurate transdermal drug delivery device capable of finely tuning dosage, [...] Read more.

Piezoelectric (PE) micropumps are distinguished by their high precision, absence of electromagnetic radiation, and straightforward construction principles, making them vital in biomedicine and drug delivery. Integrating PE micropumps with microneedles creates a stable, accurate transdermal drug delivery device capable of finely tuning dosage, rate, and targeting. This paper proposes such a device, combining a PE micropump with a microneedle array. Initially, the internal flow dynamics of the PE micropump and the microneedle forces were analyzed through simulations. Subsequently, the optimal size for the PE micropump was established via parameter optimization experiments. Comprehensive tests were conducted to assess the device’s output performance, including frequency response, voltage characteristics, and flow resistance properties. Key performance indicators evaluated were output flow, pressure, and resolution. Experimental findings revealed that with a constant driving voltage, the PE micropump’s output flow and pressure initially increase and then decrease as the operating frequency rises. Conversely, with a fixed operating frequency, output flow and pressure positively correlate with the driving voltage, showing a near-linear relationship. Under stable working conditions, output pressure and flow are inversely proportional. The PE micropump achieves an output flow of 4.0 mL/min and a pressure of 35.7 kPa at 70 V and 80 Hz. The output flow rate and pressure of the device with the integrated microneedle array are 3.5 mL/min and 30 kPa, the minimum flow resolution is 0.28 μL, exemplifying the potential applications of PE micropumps and microneedles in the field of biomedicine. Full article

(This article belongs to the Section Precision Actuators)

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20 pages, 3969 KiB

Open AccessArticle

Fast Dynamic P-RRT*-Based UAV Path Planning and Trajectory Tracking Control Under Dense Obstacles

by Xiangyu Zhu, Yufeng Gao, Yanyan Li and Bo Li

Actuators 2025, 14(5), 211; https://doi.org/10.3390/act14050211 - 25 Apr 2025

Abstract

This work develops an improved integrated planning and control framework for an unmanned aerial vehicle (UAV) in complex environments with dense obstacles to achieve fast and accurate path planning, trajectory generation, and tracking control. Utilizing the potential function-based rapid-exploration random tree star (P-RRT*), [...] Read more.

This work develops an improved integrated planning and control framework for an unmanned aerial vehicle (UAV) in complex environments with dense obstacles to achieve fast and accurate path planning, trajectory generation, and tracking control. Utilizing the potential function-based rapid-exploration random tree star (P-RRT*), a bidirectional dynamic informed P-RRT* (BDIP-RRT*) algorithm is first introduced to enhance sampling efficiency, facilitating swift path generation. To further optimize the initial path, a greedy algorithm is employed to minimize redundant segments within the generated path. Subsequently, trajectory control points are assigned based on the original path points using an adaptive distance interpolation strategy. A hybrid optimized trajectory generator considering jerk and snap is built to obtain a reference trajectory for the UAV. Moreover, two prescribed-time control laws are designed to ensure fast and accurate UAV position and attitude control. Finally, simulation results are performed to illustrate the effectiveness and superior performances of the developed path planning and control scheme. Full article

(This article belongs to the Section Aerospace Actuators)

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17 pages, 447 KiB

Open AccessArticle

Multi-Level Graph Attention Network-Based Anomaly Detection in Industrial Control System

by Longxin Lin, Anyang Gu, Feiyan Min and Shan Zhou

Actuators 2025, 14(5), 210; https://doi.org/10.3390/act14050210 - 25 Apr 2025

Abstract

Industrial control systems (ICSs) are vital to critical infrastructure in energy, manufacturing, and other industries. As ICSs become increasingly interconnected, their complexity grows, making them more vulnerable to cyber attacks and system failures. This growing complexity underscores the critical need for advanced anomaly [...] Read more.

Industrial control systems (ICSs) are vital to critical infrastructure in energy, manufacturing, and other industries. As ICSs become increasingly interconnected, their complexity grows, making them more vulnerable to cyber attacks and system failures. This growing complexity underscores the critical need for advanced anomaly detection techniques to ensure the safe and reliable operation of ICSs. To address this need, we propose a novel method, the physical process and controller graph attention network (PCGAT), which constructs multi-level graphs based on physical process and controller information. Experiments on two real-world ICS datasets demonstrate that PCGAT achieves superior performance and enables the localization of anomalies within specific physical processes. Moreover, by leveraging graph attention networks (GATs), PCGAT enhances interpretability in anomaly detection. Full article

(This article belongs to the Section Control Systems)

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15 pages, 6446 KiB

Open AccessArticle

Speed Sensorless Motion Control Scheme for a Robotic Manipulator Under External Forces and Payload Changes

by Jorge Pacheco, David Cortés-Vega and Hussain Alazki

Actuators 2025, 14(5), 209; https://doi.org/10.3390/act14050209 - 24 Apr 2025

Abstract

This paper proposes the design of a speed sensorless robust discontinuous controller for the trajectory tracking problem of a 5-DOF robotic manipulator under payload changes and torque disturbances in the joints. The developed observer-based controller is capable of performing trajectory tracking, ensuring stability, [...] Read more.

This paper proposes the design of a speed sensorless robust discontinuous controller for the trajectory tracking problem of a 5-DOF robotic manipulator under payload changes and torque disturbances in the joints. The developed observer-based controller is capable of performing trajectory tracking, ensuring stability, fast error convergence and speed sensorless operation. In order to avoid joint speed measurement, an estimation scheme based on a differentiation algorithm is implemented to estimate it. Simulation tests developed in MATLAB/Simulink are presented to show the high performance of the proposed scheme for two different trajectories with the model of the CRS Catalyst-5 by Thermo Electron^®, Burlington, ON, Canada. Full article

(This article belongs to the Section Control Systems)

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20 pages, 7020 KiB

Open AccessArticle

A Spatiotemporal Domain-Coupled Clustering Method for Performance Prediction of Cluster Systems

by Yirui Zhang, Wei Cai, Jianxin Zhang, Ming Zhu and He Wang

Actuators 2025, 14(5), 208; https://doi.org/10.3390/act14050208 - 24 Apr 2025

Abstract

The performance prediction of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) project represents one of the primary challenges faced by the system. To address the performance prediction issues of the FAST hydraulic actuator cluster system, a spatiotemporal domain-coupled clustering performance prediction method is [...] Read more.

The performance prediction of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) project represents one of the primary challenges faced by the system. To address the performance prediction issues of the FAST hydraulic actuator cluster system, a spatiotemporal domain-coupled clustering performance prediction method is proposed. By preprocessing data from the FAST health monitoring system, virtual samples constructed from temporal-domain data are integrated with spatial-domain data, thereby resolving the small-sample and even zero-sample issues caused by missing fault data in the FAST hydraulic actuator cluster system. The effectiveness of the spatiotemporal domain-coupled clustering is validated through performance prediction of the hydraulic actuator cluster system. Subsequent optimization of the prediction protocol based on experimental outcomes demonstrated exceptional performance, with 96.8% of actuators achieving prediction accuracies exceeding 99%. This advancement establishes a robust technical foundation for accurate performance prediction in the FAST hydraulic actuator cluster system, thereby enhancing operational reliability and maintenance efficiency. Full article

(This article belongs to the Section Control Systems)

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22 pages, 4126 KiB

Open AccessArticle

Enhancing Obstacle Avoidance in Dynamic Window Approach via Dynamic Obstacle Behavior Prediction

by Bongsu Hahn

Actuators 2025, 14(5), 207; https://doi.org/10.3390/act14050207 - 24 Apr 2025

Abstract

This paper proposes an enhanced local path planning method based on the Dynamic Window Approach (DWA), enabling a mobile robot to safely avoid obstacles and efficiently reach its destination. To overcome the limitations of the conventional DWA in handling dynamic obstacles and to [...] Read more.

This paper proposes an enhanced local path planning method based on the Dynamic Window Approach (DWA), enabling a mobile robot to safely avoid obstacles and efficiently reach its destination. To overcome the limitations of the conventional DWA in handling dynamic obstacles and to improve goal reachability, the velocity term—originally evaluated solely by speed—was redefined as the distance difference between the robot’s predicted future position and the target destination. This modification allows the robot to more effectively anticipate its short-term position while simultaneously considering potential obstacle locations. In particular, a linear prediction model for dynamic obstacle behavior was introduced, which estimates the future positions of obstacles based on their current position, velocity, and heading direction. Under the assumption that obstacles maintain constant speed and direction over short intervals, this model enables the robot to proactively plan avoidance maneuvers before a collision risk arises. Furthermore, a novel risk assessment strategy was incorporated to enhance collision prevention. This approach categorizes obstacles in front of the robot according to both distance and angle, evaluates obstacle density in various directions, and guides the robot toward safer paths with fewer surrounding obstacles. The effectiveness of the proposed method was validated through extensive simulations, comparing the conventional DWA, a modified DWA with the new velocity term, and the proposed DWA with dynamic obstacle behavior prediction. The results demonstrated that the proposed approach significantly reduced the number of collisions and overall travel time, thereby confirming its superiority in highly dynamic and uncertain environments. Full article

(This article belongs to the Section Control Systems)

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17 pages, 4203 KiB

Open AccessArticle

Nonlinear Backstepping Fault-Tolerant Controllers with Extended State Observers for Aircraft Wing Failures

by Yansheng Geng, Bo Wang and Xiaoxiong Liu

Actuators 2025, 14(5), 206; https://doi.org/10.3390/act14050206 - 24 Apr 2025

Abstract

To effectively overcome changes in aircraft aerodynamic and control characteristics caused by wing surface damage, this paper proposes a fault-tolerant control method based on an extended state observer (ESO) to ensure flight mission requirements under wing surface and control surface failures. First, considering [...] Read more.

To effectively overcome changes in aircraft aerodynamic and control characteristics caused by wing surface damage, this paper proposes a fault-tolerant control method based on an extended state observer (ESO) to ensure flight mission requirements under wing surface and control surface failures. First, considering the characteristics and requirements of backstepping control in addressing nonlinear problems, an extended observer is designed to estimate disturbances and uncertainties induced by wing surface failures, and its stability is analyzed by using the Lyapunov method. Next, a backstepping control law for the airflow angle loop is designed based on the extended observer. The serial-chain method is introduced as an allocation algorithm for fault-tolerant flight control in order to compensate for the changes in control efficiency caused by wing surface faults. And stability analysis is conducted by integrating the control characteristics of the aircraft’s airflow angle loop, proving the uniformly bounded stability of the controller. Finally, fault-tolerant control simulations are performed under scenarios of wing damage, elevator damage, and actuator jamming faults. The simulation results demonstrate that the proposed method achieves excellent control performance during wing surface failures. Full article

(This article belongs to the Special Issue Actuation and Robust Control Technologies for Aerospace Applications)

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22 pages, 8071 KiB

Open AccessArticle

Reliability Modeling and Verification of Locking Mechanisms Based on Failure Mechanisms

by Ping Qian, Tianying Tu, Wenhua Chen, Fan Yang, Chi Chen and Yucheng Zhu

Actuators 2025, 14(5), 205; https://doi.org/10.3390/act14050205 - 23 Apr 2025

Abstract

The locking mechanism is crucial for the reliable connection and disconnection of electrical connectors. Aiming at the lack of theoretical support for the reliability evaluation in long-term storage, a comprehensive multi-theory modeling method is proposed to solve unlocking failure and related performance-evaluation problems. [...] Read more.

The locking mechanism is crucial for the reliable connection and disconnection of electrical connectors. Aiming at the lack of theoretical support for the reliability evaluation in long-term storage, a comprehensive multi-theory modeling method is proposed to solve unlocking failure and related performance-evaluation problems. An analysis reveals that metal-crystal dislocation glide, causing pull-rod deformation and spring stress relaxation, is the main cause of unlocking failure. Based on Hertz’s contact theory, a locking-state mechanical model is established. Integrating the crystal dislocation-slip theory, an accelerated degradation trajectory model considering design parameters is developed to characterize the friction between the pull rod and steel ball and the spring’s elastic-force degradation. Finally, the model is verified using the unlocking-force accelerated test data. It offers a theoretical basis for the reliability evaluation and design of locking mechanisms in long-term storage environments. Full article

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15 pages, 2184 KiB

Open AccessArticle

Modeling and Adaptive Control of Double-Pendulum Offshore Cranes with Distributed-Mass Payloads and External Disturbances

by Shudong Guo, Nan Li, Qingxiang Wu, Yuxuan Jiao, Yaxuan Wu, Weijie Hou, Yuehua Li, Tong Yang and Ning Sun

Actuators 2025, 14(5), 204; https://doi.org/10.3390/act14050204 - 23 Apr 2025

Abstract

Offshore cranes are widely used in important fields such as wind power construction and ship replenishment. However, large payloads such as wind turbine blades are hoisted by multiple steel wire ropes, which makes it difficult to directly control their movements; that is, the [...] Read more.

Offshore cranes are widely used in important fields such as wind power construction and ship replenishment. However, large payloads such as wind turbine blades are hoisted by multiple steel wire ropes, which makes it difficult to directly control their movements; that is, the number of input degrees of freedom is less than that of the output degrees of freedom. In addition, compared with land cranes, offshore cranes are inevitably affected by waves, wind, etc. The transition from a fixed base to a dynamic base brings severe challenges to their oscillation suppression and precise positioning. At the same time, to improve operational efficiency, the hoisting operation of offshore cranes usually adopts velocity input control patterns that fit the habits of manual operation, and most of them are in the form of dual-axis linkage for pitch and hoisting. Therefore, this paper proposes a fast terminal sliding mode control method for double-pendulum offshore cranes with distributed-mass payloads (DMPs). First, a nonlinear dynamic model of offshore cranes considering DMPs is established, and a dynamic model based on acceleration input control patterns is acquired. Based on this, considering the variation in hoisting rope lengths, a novel adaptive control method is proposed. Finally, simulation results verify the effectiveness of the proposed method, and the robustness of the proposed method to DMP mass parameter uncertainty and disturbances is demonstrated. Full article

(This article belongs to the Special Issue Modeling and Nonlinear Control for Complex MIMO Mechatronic Systems)

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21 pages, 1434 KiB

Open AccessArticle

Chaos Anticontrol and Switching Frequency Impact on MOSFET Junction Temperature and Lifetime

by Cristina Morel and Jean-Yves Morel

Actuators 2025, 14(5), 203; https://doi.org/10.3390/act14050203 - 23 Apr 2025

Abstract

Generating chaos from originally non-chaotic systems is a promising issue. Indeed, chaos has been successfully applied in many fields to improve system performance. In this work, a Buck converter is chaotified using a combination of the switching piecewise-constant characteristic and of anticontrol of [...] Read more.

Generating chaos from originally non-chaotic systems is a promising issue. Indeed, chaos has been successfully applied in many fields to improve system performance. In this work, a Buck converter is chaotified using a combination of the switching piecewise-constant characteristic and of anticontrol of chaos feedback. For electromagnetic compatibility compliance reasons, this feedback control method is able, at the same time, to achieve low spectral emissions and to maintain a small ripple of the output voltage and the inductance current. This new feedback implies a fast and non-linear switching action of the Buck MOSFET on a period of the ramp generator. Thus, it is essential to analyze its thermal performance. This is why we propose an original analysis of the influence of anticontrol of chaos and switching frequency variation on junction temperature: we investigate the correlation between the lifetime of the power electronic switching component and its thermal stress due to the addition of chaos. It appeared that a reduction in the current ripple did not degrade the MOSFET junction thermal performance, despite the fast switching of the MOSFET. Furthermore, a small degradation in the MOSFET lifetime was indicated for chaotic behavior versus periodic behavior. Thus, this leads to the conclusion that using anticontrol of chaos produces a low accumulated fatigue effect on a Buck converter semiconductor. 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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