Actuators

18 pages, 7242 KiB

Open AccessArticle

Active Disturbance Rejection for Linear Induction Motors: A High-Order Sliding-Mode-Observer-Based Twisting Controller

by Yongwen Liu, Lei Zhang, Pu Li and Yaoli Xu

Actuators 2025, 14(4), 200; https://doi.org/10.3390/act14040200 - 21 Apr 2025

Viewed by 108

This paper presents a twisting controller (TC) based on a high-order sliding mode observer (HOSMO) for linear induction motors (LIMs), accounting for dynamic end effects. Based on the LIM model in the field-oriented frame, two extended subsystems are developed: a velocity extended model [...] Read more.

This paper presents a twisting controller (TC) based on a high-order sliding mode observer (HOSMO) for linear induction motors (LIMs), accounting for dynamic end effects. Based on the LIM model in the field-oriented frame, two extended subsystems are developed: a velocity extended model and a flux extended model. Using these models, two HOSMOs are designed to estimate the disturbances in each subsystem. The HOSMO outputs are then used for disturbance rejection, resulting in two second-order systems with small bounded disturbances. Two TCs are subsequently implemented to achieve finite-time velocity and flux tracking of the LIM. The primary advantage of this strategy lies in its ability to reduce chattering through active disturbance rejection. Hardware-in-the-loop (HIL) experiments validate the effectiveness of the proposed TC-HOSMO scheme. Full article

(This article belongs to the Section Control Systems)

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31 pages, 2525 KiB

Open AccessArticle

An Optimized Position Control via Reinforcement-Learning-Based Hybrid Structure Strategy

by Nebiyeleul Daniel Amare, Sun Jick Yang and Young Ik Son

Actuators 2025, 14(4), 199; https://doi.org/10.3390/act14040199 - 21 Apr 2025

Viewed by 97

Abstract

Most control system implementations rely on single structures optimized for specific performance criteria through rigorous derivation. While effective for their intended purpose, such controllers often underperform in areas outside their primary optimization focus and involve performance trade-offs. A notable example is the Internal [...] Read more.

Most control system implementations rely on single structures optimized for specific performance criteria through rigorous derivation. While effective for their intended purpose, such controllers often underperform in areas outside their primary optimization focus and involve performance trade-offs. A notable example is the Internal Model Principle (IMP) controller, renowned for its robustness and precision in reference tracking under periodic disturbances. However, IMP controllers exhibit poor transient-state performance, characterized by significant overshoot and oscillatory responses, which remains a persistent challenge. To address this limitation, this paper proposes a reinforcement learning (RL)-based hybrid control scheme that overcomes the trade-off in IMP controllers between achieving zero steady-state tracking error and a fast transient response. The proposed method integrates a cascade control structure, optimized for transient-state performance, with an IMP controller, optimized for robust reference tracking under sinusoidal disturbances, through switching logic governed by a Deep Q-Network model. Smooth transitions between control modes are ensured using an internal state update mechanism. The proposed approach is validated through simulations and experimental tests on a direct current (DC) motor position control system. The results demonstrate that the hybrid structure effectively resolves the trade-off associated with IMP controllers, yielding improved performance metrics, such as rapid convergence to the reference, reduced transient overshoot, and enhanced nominal performance recovery against disturbances. Full article

(This article belongs to the Special Issue Analysis and Design of Linear/Nonlinear Control System)

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22 pages, 6697 KiB

Open AccessArticle

Research on the Bearingless Brushless DC Motor Structure with Like-Tangential Parallel-Magnetization Interpolar Magnetic Poles and Its Air-Gap Magnetic Field Analytical Calculation

by Wenshao Bu, Zongang Fan, Jinghui Zhang and Wenqing Tao

Actuators 2025, 14(4), 198; https://doi.org/10.3390/act14040198 - 19 Apr 2025

Viewed by 130

Abstract

This work focuses on the small Bearingless Brushless DC Motor (BL-BLDCM), to solve the problems, such as larger commutation torque ripple and difficult solution of air-gap magnetic field, a novel BL-BLDCM structure with like-tangential parallel-magnetization interpolar magnetic poles (LTPMIMPs) is proposed, which is [...] Read more.

This work focuses on the small Bearingless Brushless DC Motor (BL-BLDCM), to solve the problems, such as larger commutation torque ripple and difficult solution of air-gap magnetic field, a novel BL-BLDCM structure with like-tangential parallel-magnetization interpolar magnetic poles (LTPMIMPs) is proposed, which is abbreviated as BL-BLDCM-LTPMIMP in this work, and the analytical calculation model of its air-gap magnetic field has been investigated. First, inserting a like-tangential parallel magnetizing auxiliary magnetic pole between every two adjacent single-radial-magnetizing main poles, and forming several combination magnetic poles, each of which is composed of a radial-magnetizing main magnetic pole and two semi-auxiliary-magnetic-poles (with different magnetization directions) located on both sides. Then, by solving the Laplace equation and Poisson equation in every subdomain, and combining the relative permeability function, the analytical expressions of the air-gap magnetic fields for the BL-BLDCM-LTPMIMP was obtained. The armature reaction magnetic fields of the torque windings and suspension windings are also analyzed. Finally, through the finite element method (FEM), the correctness and computational accuracy of the analytical calculation model for the air-gap magnetic field is proven. Additionally, the comparison of electromagnetic characteristics with ordinary BL-BLDCM shows that the BL-BLDCM-LTPMIMP can not only effectively improve the amplitude and stability of electromagnetic torque on the basis of obtaining a shoulder-shrugged trapezoidal wave air-gap magnetic field but also has stable radial magnetic levitation force control characteristics. Full article

(This article belongs to the Special Issue Actuators in Magnetic Levitation Technology and Vibration Control)

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15 pages, 4729 KiB

Open AccessArticle

Intelligent Robust Motion Control of Aerial Robot

by Cao-Tri Dinh, Thien-Dinh Nguyen, Young-Bok Kim, Thinh Huynh and Jung-Suk Park

Actuators 2025, 14(4), 197; https://doi.org/10.3390/act14040197 - 18 Apr 2025

Viewed by 134

Abstract

This study presents the design of an intelligent robust controller for the 3-degree-of-freedom motion of an aerial robot using waterpower. The proposed controller consists of two parts: (1) an anti-windup super-twisting algorithm that provides stability to the system under actuator saturation; and (2) [...] Read more.

This study presents the design of an intelligent robust controller for the 3-degree-of-freedom motion of an aerial robot using waterpower. The proposed controller consists of two parts: (1) an anti-windup super-twisting algorithm that provides stability to the system under actuator saturation; and (2) a fully adaptive radial basis function neural network that estimates and compensates for unexpected influences, i.e., system uncertainties, water hose vibration, and external disturbances. The stability of the entire closed-loop system is analyzed using the Lyapunov stability theory. The controller parameters are optimized such that the effect of these unexpected influences on the control system is minimized. This optimization problem is interpreted in the form of an eigenvalue problem, which is solved using the method of centers. Experiments are conducted where a proportional-integral-derivative controller and a conventional sliding mode controller are deployed for comparison. The results demonstrate that the proposed control system outperforms the others, with small tracking errors and strong robustness against unexpected influences. Full article

(This article belongs to the Section Control Systems)

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21 pages, 18629 KiB

Open AccessArticle

High-Precision Control of Control Moment Gyroscope Gimbal Servo Systems via a Proportional–Integral–Resonant Controller and Noise Reduction Extended Disturbance Observer

by Zhihao Lu and Zhong Wu

Actuators 2025, 14(4), 196; https://doi.org/10.3390/act14040196 - 18 Apr 2025

Viewed by 202

Abstract

Speed control accuracy of gimbal servo systems for control moment gyroscopes (CMGs) is crucial for spacecraft attitude control. However, multiple disturbances from internal and external factors severely degrade the speed control accuracy of gimbal servo systems. To suppress the effects of these complex [...] Read more.

Speed control accuracy of gimbal servo systems for control moment gyroscopes (CMGs) is crucial for spacecraft attitude control. However, multiple disturbances from internal and external factors severely degrade the speed control accuracy of gimbal servo systems. To suppress the effects of these complex disturbances on speed control accuracy, a control method based on a proportional–integral–resonant (PIR) controller and a noise reduction extended disturbance observer (NREDO) is proposed in this paper. First, the disturbance dynamic model of an

(n + 1)

th-order NREDO is derived. The integral of the virtual measurement of the lumped disturbance is an augmented state in the model. NREDO states are updated by using the estimation error of the augmented state. The NREDO significantly enhances the measurement noise suppression performance compared with an EDO. Second, a resonant controller is introduced to suppress the high-frequency rotor dynamic imbalance torque. The PIR controller is composed of a resonant controller in parallel with a PI controller. Numerical simulation and experimental results demonstrate the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue New Control Schemes for Actuators—2nd Edition)

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15 pages, 4320 KiB

Open AccessArticle

Design and Experimental Research of a New Bistable Electronic Parking Brake System for Commercial Vehicles

by Feng Chen, Zhiquan Fu, Baoxiang Qiu, Gangqiang Chen, Leyong Mao, Qijiang He, Lai Yang, Xinni Mo and Xiaoqing Sun

Actuators 2025, 14(4), 195; https://doi.org/10.3390/act14040195 - 17 Apr 2025

Viewed by 156

Abstract

To further solve the problems of commercial vehicle electronic parking brake systems under typical operating conditions, such as manual parking/release, emergency parking, ramp parking leakage, and so on, a new bistable electronic parking brake system (EPB) is proposed and studied in this paper. [...] Read more.

To further solve the problems of commercial vehicle electronic parking brake systems under typical operating conditions, such as manual parking/release, emergency parking, ramp parking leakage, and so on, a new bistable electronic parking brake system (EPB) is proposed and studied in this paper. First, the principle of the proposed bistable electronic parking brake system is described. Then, the control parameters of the electronic parking brake system are presented in detail, and the design scheme of the automatic parking/release control strategy is listed. Subsequently, an experimental road test system is designed, and the excellent performance of the designed bistable EPB is demonstrated by said road experiments. The research results show that the presented bistable EPB can effectively solve the problems of high-speed parking and ramp parking failure and significantly improve the braking safety of the whole vehicle. Full article

(This article belongs to the Section Actuators for Surface Vehicles)

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18 pages, 611 KiB

Open AccessArticle

Finite-Time Control for Maneuvering Aircraft with Input Constraints and Disturbances

by Zhangyong Zhou, Yaohua Shen and Mou Chen

Actuators 2025, 14(4), 194; https://doi.org/10.3390/act14040194 - 14 Apr 2025

Viewed by 140

Abstract

In this paper, a finite-time control method integrating a high-order disturbance observer (HODO) and a finite-time auxiliary system (FTAS) is proposed for maneuvering aircraft under disturbances and input constraints. To attenuate the adverse effects of disturbances, the HODOs were designed to obtain their [...] Read more.

In this paper, a finite-time control method integrating a high-order disturbance observer (HODO) and a finite-time auxiliary system (FTAS) is proposed for maneuvering aircraft under disturbances and input constraints. To attenuate the adverse effects of disturbances, the HODOs were designed to obtain their estimations, which were then incorporated into the control channel as feedforward compensation. To solve the issue of input constraints, a novel FTAS was developed to ensure effective control performance. To achieve rapid attitude tracking for maneuvering aircraft and address the issue of singularity caused by the virtual control derivative, finite-time control with a piecewise function technique was employed. Furthermore, the stability analysis of the closed-loop system was conducted through Lyapunov stability theory. Finally, the efficacy of the proposed control method was demonstrated by simulation results. Full article

(This article belongs to the Section Aerospace Actuators)

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17 pages, 4339 KiB

Open AccessArticle

Modeling and Hysteresis Inverse Compensation Control of Soft Pneumatic Gripper for Gripping Phosphorites

by Yang Zhang, Junjie Lu, Zixin Huang and Bing Feng

Actuators 2025, 14(4), 193; https://doi.org/10.3390/act14040193 - 14 Apr 2025

Viewed by 210

Abstract

The emergence of soft robots provides new opportunities for developing phosphorite processing equipment. In this article, a soft pneumatic gripper (SPG) for gripping phosphorites is designed. On this basis, the dynamic modeling method and hysteresis inverse compensation control method for the SPG are [...] Read more.

The emergence of soft robots provides new opportunities for developing phosphorite processing equipment. In this article, a soft pneumatic gripper (SPG) for gripping phosphorites is designed. On this basis, the dynamic modeling method and hysteresis inverse compensation control method for the SPG are proposed. First, an SPG for gripping phosphorites is designed based on pneumatic actuation technology. Meanwhile, the gripping ability of the designed SPG is experimentally examined. Next, a dynamic model of the SPG is established by combining the Bouc–Wen model and a linear dynamic model. The output of the established dynamic model can fit the experimental data well, which shows that the established dynamic model of the SPG can describe its motion characteristics. Then, by constructing the inverse expression of the established dynamic model, the hysteresis inverse compensation control method for the SPG is presented to realize its motion control. Finally, the result of the control system simulation illustrates that the presented control method is effective. Full article

(This article belongs to the Special Issue Advancement in the Design and Control of Robotic Grippers—Second Edition)

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22 pages, 6830 KiB

Open AccessArticle

Topological Design and Modeling of 3D-Printed Grippers for Combined Precision and Coarse Robotics Assembly

by Mohammad Mayyas, Naveen Kumar, Zahabul Islam, Mohammed Abouheaf and Muteb Aljasem

Actuators 2025, 14(4), 192; https://doi.org/10.3390/act14040192 - 14 Apr 2025

Viewed by 248

Abstract

This study presents a topological design and modeling framework for 3D-printed robotic grippers, tailored for combined precision and coarse robotics assembly. The proposed methodology leverages topology optimization to develop multi-scale-compliant mechanisms, comprising a symmetrical continuum structure of five beams. The proposed methodology centers [...] Read more.

This study presents a topological design and modeling framework for 3D-printed robotic grippers, tailored for combined precision and coarse robotics assembly. The proposed methodology leverages topology optimization to develop multi-scale-compliant mechanisms, comprising a symmetrical continuum structure of five beams. The proposed methodology centers on the hybrid kinematics for precision and coarse operations of the gripper, parametrizing beam deformations in response to a defined set of boundary conditions and varying input loads. The research employs topology analysis to draw a clear correlation between input load and resultant motion, with a particular emphasis on the mechanism’s capacity to integrate both fine and coarse movements efficiently. Additionally, the paper pioneers an innovative solution to the ubiquitous point-contact problem encountered in grasping, intricately weaving it with the stiffness matrix. The overarching aim remains to provide a streamlined design methodology, optimized for manufacturability, by harnessing the capabilities of contemporary 3D fabrication techniques. This multifaceted approach, underpinned by the multiscale grasping method, promises to significantly advance the domain of robotic gripping and manipulation across applications such as micro-assembly, biomedical manipulation, and industrial robotics. Full article

(This article belongs to the Special Issue Advancement in the Design and Control of Robotic Grippers—Second Edition)

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16 pages, 2155 KiB

Open AccessArticle

Research on Simplified Design of Model Predictive Control

by Qing Zhang, Chi Zhang, Qi Wang, Shiyun Dong and Aoqi Xiao

Actuators 2025, 14(4), 191; https://doi.org/10.3390/act14040191 - 13 Apr 2025

Viewed by 235

Abstract

PID controllers have been dominant in the field of process control for a long time, but their control quality is not ideal and the difficulty of parameter tuning has always been a problem. MPCs have good control quality and robustness, but due to [...] Read more.

PID controllers have been dominant in the field of process control for a long time, but their control quality is not ideal and the difficulty of parameter tuning has always been a problem. MPCs have good control quality and robustness, but due to the complexity of the algorithm, most are limited to software on PC machines. Although there are examples of implementations on hardware, they are restricted to specific scenarios and are of an experimental nature. The barriers to application and maintenance are high, and therefore, it has not become as popular as PID. The common self-balancing industrial objects are approximated as a first order plus dead time (FOPDT) model, and various parameters are simplified to obtain the control law of the simplified MPC controller. The control law has a small amount of calculation, good control quality, simple parameter settings, and is suitable for embedding in the field controller. Coupled with the auxiliary identification method, field technicians can easily use it. MATLAB (2016a) comparative simulation experiments show that the simplified MPC controller has obvious control advantages over PID. The results of field engineering applications also show that the simplified MPC controller can feasibly replace the PID algorithm in industrialization. Full article

(This article belongs to the Section Control Systems)

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19 pages, 4968 KiB

Open AccessArticle

Event-Triggered Control for Flapping-Wing Robot Aircraft System Based on High-Gain Observers

by Chenxu Xiao, Li Tang, Fei Wang, Sheng You, Hao Xu, Mingchuang Chen and Zhiyuan Lu

Actuators 2025, 14(4), 190; https://doi.org/10.3390/act14040190 - 13 Apr 2025

Viewed by 142

Abstract

In this paper, an event-triggered (ET) control strategy for a flapping-wing robot aircraft system (FWRA) based on high-gain observers is investigated. To solve the vibration problems of bending deformation and torsional deformation that may be encountered in an FWRA during flight, a novel [...] Read more.

In this paper, an event-triggered (ET) control strategy for a flapping-wing robot aircraft system (FWRA) based on high-gain observers is investigated. To solve the vibration problems of bending deformation and torsional deformation that may be encountered in an FWRA during flight, a novel control method is proposed. Firstly, high-gain observers are used to accurately estimate the unmeasured states of the system, and then output feedback ET controllers are designed by combining ET mechanisms. These controllers can effectively suppress the vibrations and ensure the stability of the system, and the occurrence of the Zeno phenomenon is effectively prevented, while the communication burden is reduced. Finally, the simulation results verify the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Advances in Intelligent Control of Actuator Systems)

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14 pages, 1098 KiB

Open AccessArticle

Disturbance Rejection Approach for Nonlinear Systems Using Kalman-Filter-Based Equivalent-Input-Disturbance Estimator

by Gao Huang, Xuefei Zhao, Bohao Zhao, Lianqiang Han and Pan Yu

Actuators 2025, 14(4), 189; https://doi.org/10.3390/act14040189 - 11 Apr 2025

Viewed by 179

Abstract

In this paper, a novel disturbance rejection approach is developed for a class of nonlinear systems, which incorporates the Kalman filter into the equivalent-input-disturbance (EID) structure. First, the EID-based control system and the configuration of the Kalman Filter are illustrated. Then, an optimal [...] Read more.

In this paper, a novel disturbance rejection approach is developed for a class of nonlinear systems, which incorporates the Kalman filter into the equivalent-input-disturbance (EID) structure. First, the EID-based control system and the configuration of the Kalman Filter are illustrated. Then, an optimal estimation theorem is obtained by analyzing the dynamic of the Kalman filter, and a special Kalman gain is derived. Next, the dynamics of the closed-loop system are deduced, and stability is guaranteed based on the Lyapunov function. Finally, simulations with comparison are carried out to demonstrate the excellent performance of both disturbance rejection and noise attenuation. Full article

(This article belongs to the Section Control Systems)

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12 pages, 5182 KiB

Open AccessArticle

Testing the Influence of Null-Flux Coil Geometry Parameters on Levitation and Stability of Electrodynamic Suspension Systems Using a New Stationary Simulation Platform

by Jianru Liu, Jun Zheng and Yuhang Yuan

Actuators 2025, 14(4), 188; https://doi.org/10.3390/act14040188 - 11 Apr 2025

Viewed by 170

Abstract

The geometric parameters of the Null-Flux coil (NFC) are crucial to the load capacity and economic viability of electrodynamic suspension (EDS) systems. This study investigates the influence of NFC geometry on the electromagnetic force characteristics in EDS systems. Through the electromagnetic modeling of [...] Read more.

The geometric parameters of the Null-Flux coil (NFC) are crucial to the load capacity and economic viability of electrodynamic suspension (EDS) systems. This study investigates the influence of NFC geometry on the electromagnetic force characteristics in EDS systems. Through the electromagnetic modeling of EDS mechanisms, an analytical model for EDS systems is established. Systematic experiments compare electromagnetic forces under varying NFC lengths and gaps, supported by a self-developed stationary EDS dynamic simulation platform. The results demonstrate that the average levitation force is positively correlated with the coil length, and it is larger when the coil length is close to its width. Meanwhile, the NFC length has a significant impact on the lift-to-drag ratio, while the NFC gap has a relatively smaller effect on it. This work provides a complete methodology integrating analytical modeling and experimental validation, offering practical guidelines for NFC design in maglev actuators. The findings advance EDS system optimization through quantifiable geometric criteria, particularly for transportation applications requiring precision electromagnetic force control. Full article

(This article belongs to the Special Issue Actuators in Magnetic Levitation Technology and Vibration Control)

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20 pages, 3488 KiB

Open AccessArticle

A Novel Cycloid Tooth Profile for Harmonic Drive with Fully Conjugate Features

by Yunpeng Yao, Longsheng Lu, Xiaoxia Chen, Yingxi Xie, Yuankai Yang and Jingzhong Xing

Actuators 2025, 14(4), 187; https://doi.org/10.3390/act14040187 - 11 Apr 2025

Viewed by 208

Abstract

A harmonic drive (HD) is a precision reduction device widely utilized in the core joints of high-end equipment such as spacecraft and robots. The design of an excellent tooth profile is the core challenge related to the performance of HD. This investigation aims [...] Read more.

A harmonic drive (HD) is a precision reduction device widely utilized in the core joints of high-end equipment such as spacecraft and robots. The design of an excellent tooth profile is the core challenge related to the performance of HD. This investigation aims to propose a design method of a fully conjugated cycloid tooth profile (CTP) for HD. Firstly, the rationality of CTP use for HD is analyzed, and the cycloidal characteristics of the tooth trajectory are studied by use of canonical warping distance. Then, initial CTP equations are constructed, adopting the trajectory mapping results. Presetting the addendum CTP of circular spline, the conjugate CTP of flexspline is then designed using the envelope method. Subsequently, the envelope of the designed flexspline addendum is used to reverse-design the circular spline dedendum. The backlash is calculated to evaluate the CTPs designed with different radial displacement coefficients. Research shows that the tooth trajectory has cycloidal characteristics; therefore, the HDs that use CTP can realize a fully conjugate engagement. Moreover, the variable control parameters enable the proposed CTP expression to have excellent fitting characteristics, resulting in small and uniform mesh backlash distribution. The CTP is expected to become one of the ideal tooth profiles of HD. Full article

(This article belongs to the Section Precision Actuators)

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17 pages, 3368 KiB

Open AccessArticle

Safe 3D Coverage Control for Multi-Agent Systems

by Wenbin Liu, Kritapas Borikarnphanichphaisal, Jie Song, Olga Vasilieva and Mikhail Svinin

Actuators 2025, 14(4), 186; https://doi.org/10.3390/act14040186 - 10 Apr 2025

Viewed by 240

Abstract

Multi-agent coverage control plays a crucial role in the modeling and coordination of complex systems, especially for teams of robots that, through frequent interactions with each other and their environment, can accomplish complex tasks in a distributed and parallel manner. However, most existing [...] Read more.

Multi-agent coverage control plays a crucial role in the modeling and coordination of complex systems, especially for teams of robots that, through frequent interactions with each other and their environment, can accomplish complex tasks in a distributed and parallel manner. However, most existing studies on coverage control for multi-agent systems are limited to two-dimensional environments, with few addressing the height factor critical to three-dimensional spaces. This study proposes a novel approach that adapts centroidal Voronoi tessellation (CVT) with a time-varying density function and Control Barrier Functions (CBFs) for dynamic coverage in 3D environments. By reconfiguring these methodologies, this approach enhances distribution and coordination efficiency within 3D spaces while ensuring safe, collision-free navigation. The simulation results validate the effectiveness of the proposed approach, demonstrating its potential for the efficient deployment of multi-robot systems, such as unmanned autonomous vehicles and unmanned autonomous underwater vehicles, in diverse operational contexts. Full article

(This article belongs to the Special Issue Analysis and Design of Linear/Nonlinear Control System)

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26 pages, 9389 KiB

Open AccessArticle

Real-Time Data-Driven Method for Bolt Defect Detection and Size Measurement in Industrial Production

by Jinlong Yang and Chul-Hee Lee

Actuators 2025, 14(4), 185; https://doi.org/10.3390/act14040185 - 9 Apr 2025

Viewed by 232

Abstract

To enhance the automatic quality monitoring of bolt production, YOLOv10, Intel RealSense D435, and OpenCV were integrated to leverage GPU parallel computing capabilities for defect recognition and size measurement. To improve the model’s effectiveness across various industrial production environments, data augmentation techniques were [...] Read more.

To enhance the automatic quality monitoring of bolt production, YOLOv10, Intel RealSense D435, and OpenCV were integrated to leverage GPU parallel computing capabilities for defect recognition and size measurement. To improve the model’s effectiveness across various industrial production environments, data augmentation techniques were employed, resulting in a trained model with notable precision, accuracy, and robustness. A high-precision camera calibration method was used, and image processing was accelerated through GPU parallel computing to ensure efficient and real-time target size measurement. In the real-time monitoring system, the average defect prediction time was 0.009241 s, achieving an accuracy of 99% and demonstrating high stability under varying lighting conditions. The average size measurement time was 0.021616 s, and increasing the light intensity could reduce the maximum error rate to 1%. These results demonstrated that the system excelled in real-time performance, accuracy, robustness, and efficiency, effectively addressing the demands of industrial production lines for rapid and precise defect detection and size measurement. In the dynamic and variable context of industrial applications, the system can be optimized and adjusted according to specific production environments and requirements, further enhancing the accuracy of defect detection and size measurement tasks. Full article

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24 pages, 16211 KiB

Open AccessArticle

Snake Robot Gait Design for Climbing Eccentric Variable-Diameter Obstacles on High-Voltage Power Lines

by Zhiyong Yang, Cheng Ning, Yuhong Xiong, Fan Wang, Xiaoyan Quan and Chao Zhang

Actuators 2025, 14(4), 184; https://doi.org/10.3390/act14040184 - 9 Apr 2025

Viewed by 218

Abstract

This paper presents a novel gait design for serpentine robots to smoothly wrap around and traverse vibration-damping hammers along overhead power lines. Cubic quasi-uniform B-spline curves are utilized to seamlessly transition between helical segments of varying diameters during obstacle crossing, effectively reducing motion-induced [...] Read more.

This paper presents a novel gait design for serpentine robots to smoothly wrap around and traverse vibration-damping hammers along overhead power lines. Cubic quasi-uniform B-spline curves are utilized to seamlessly transition between helical segments of varying diameters during obstacle crossing, effectively reducing motion-induced impacts. The design begins by determining the control points of the B-spline curves to ensure posture continuity and prevent collisions with surrounding hardware obstacles, resulting in the derivation of an obstacle-crossing curve equation. Using this equation, the node coordinates and postures of individual robot units are computed, followed by the calculation of joint angles via inverse kinematics. A dual-chain Hopf oscillator is then employed to generate the obstacle-crossing gait. The feasibility of the proposed gait is validated through simulations in CoppeliaSim and Simulink, which model the robot’s motion as it wraps around and crosses eccentric obstacles with varying diameters. Additionally, a simulation platform is developed to analyze variations in joint angles and angular velocities during obstacle traversal. Results demonstrate that the gait, generated by combining cubic quasi-uniform B-spline curves with a dual-chain Hopf oscillator, achieves smooth and stable wrapping and crossing of vibration-damping hammers. The robot exhibits no abrupt changes in joint angles, smooth angular velocity profiles without sharp peaks, and impact-free joint interactions, ensuring reliable performance in complex environments. Full article

(This article belongs to the Section Actuators for Robotics)

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26 pages, 13612 KiB

Open AccessArticle

Central Dioptric Line Image-Based Visual Servoing for Nonholonomic Mobile Robot Corridor-Following and Doorway-Passing

by Chen Zhong, Qingjia Kong, Ke Wang, Zhe Zhang, Long Cheng, Sijia Liu and Lizhu Han

Actuators 2025, 14(4), 183; https://doi.org/10.3390/act14040183 - 9 Apr 2025

Viewed by 225

Abstract

Autonomous navigation in indoor environments demands reliable perception and control strategies for nonholonomic mobile robots operating under geometric constraints. While visual servoing offers a promising framework for such tasks, conventional approaches often rely on explicit 3D feature estimation or predefined reference trajectories, limiting [...] Read more.

Autonomous navigation in indoor environments demands reliable perception and control strategies for nonholonomic mobile robots operating under geometric constraints. While visual servoing offers a promising framework for such tasks, conventional approaches often rely on explicit 3D feature estimation or predefined reference trajectories, limiting their adaptability in dynamic scenarios. In this paper, we propose a novel nonholonomic mobile robot corridor-following and doorway-passing method based on image-based visual servoing (IBVS) by using a single dioptric camera. Based on the unifying central spherical projection model, we present the projection mechanism of 3D lines and properties of line images for two 3D parallel lines under different robot poses. In the normalized image plane, we define a triangle enclosed by two polar lines in relation to line image conic features, and adopt a polar representation for visual features, which will naturally become zero when the robot follows the corridor middle line. The IBVS control law for the corridor-following task does not need to pre-calculate expected visual features or estimate the 3D information of image features, and is extended to doorway-passing by simply introducing an upper door frame to modify visual features for the control law. Simulations including straight corridor-following, anti-noise performance, convergence of the control law, doorway-passing, and loop-closed corridor-following are conducted. We develop a ROS-based IBVS system on our real robot platform; the experimental results validate that the proposed method is suitable for the autonomous indoor visual navigation control task for a nonholonomic mobile robot equipped with a single dioptric camera. Full article

(This article belongs to the Section Actuators for Robotics)

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19 pages, 8516 KiB

Open AccessArticle

A Novel Overlapped Compensation Structure and Its Effectiveness Verification for Expansion Joints in Plate-Type PMEDS Vehicles

by Shuqing Zhang, Siyi Wu, Hongfu Shi, Zhengyan Li and Zigang Deng

Actuators 2025, 14(4), 182; https://doi.org/10.3390/act14040182 - 9 Apr 2025

Viewed by 191

Abstract

In the plate-type permanent magnet electrodynamic suspension (PMEDS) vehicle, expansion joints in discrete conductive plates trigger the eddy current truncation effect, thereby causing an attenuation in the levitation force. To address this issue, a novel overlapped compensation structure is proposed, and its effectiveness [...] Read more.

In the plate-type permanent magnet electrodynamic suspension (PMEDS) vehicle, expansion joints in discrete conductive plates trigger the eddy current truncation effect, thereby causing an attenuation in the levitation force. To address this issue, a novel overlapped compensation structure is proposed, and its effectiveness is verified via simulation and experiment. First, the overlapped compensation structure and principle are introduced, followed by its theoretical model. Additionally, the comparative time-varying levitation force, along with its attenuation percentages, is analyzed under different guideways. Additionally, the optimal structure specifications covering overlapped thickness and length are studied, followed by a design guideline. In addition, dynamic analysis of a single bogie is carried out to analyze the effectiveness of the overlapped compensation structure in terms of vertical stability improvement. Lastly, the equivalent experiments are implemented to further confirm the proposed overlapped compensation structure. The experiment’s result reveals that compared to the original guideway expansion joint, the overlapped compensation structure can reduce levitation force attenuation by 20%. This work is expected to provide a reference for conductive plate guideway establishment in practical applications. Full article

(This article belongs to the Special Issue Actuators in Magnetic Levitation Technology and Vibration Control)

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22 pages, 36591 KiB

Open AccessArticle

A Generalized Center-Aligned High-Resolution Pulse Width Modulator Implementation Using an Output Serializer in Field Programmable Gate Arrays

by Yixiao Wu and Zhong Wu

Actuators 2025, 14(4), 181; https://doi.org/10.3390/act14040181 - 9 Apr 2025

Viewed by 188

Abstract

A digital pulse width modulator (DPWM) is a key component in digital power electronics. Techniques like space vector modulation, along with rising switching frequencies from wide-bandgap power transistors, create a need for a center-aligned high-resolution PWM (CA-HRPWM). However, existing FPGA-based HRPWM designs primarily [...] Read more.

A digital pulse width modulator (DPWM) is a key component in digital power electronics. Techniques like space vector modulation, along with rising switching frequencies from wide-bandgap power transistors, create a need for a center-aligned high-resolution PWM (CA-HRPWM). However, existing FPGA-based HRPWM designs primarily focus on achieving fine timing resolution and are not fully optimized for multichannel CA-HRPWM implementations. This paper presents a generalized CA-HRPWM design based on the output serializer (OSERDES) module. The design includes comparison values and dead time calculation, a time base and triangular carrier generation, unary code encoding, and an OSERDES-based data-to-time converter (DTC). The hardware implementation results demonstrate that the design has a minimal overhead compared with a conventional PWM generator. The proposed design achieved an 800 ps resolution for both pulse width and dead time generation with excellent linearity. Additionally, the effectiveness of the design was shown in a PMSM current controller, where it reduced the current ripple by up to 64% compared with a conventional PWM generator. Full article

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

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22 pages, 5838 KiB

Open AccessArticle

Deep Reinforcement Learning-Based Motion Control Optimization for Defect Detection System

by Yuhuan Cai, Liye Zhao, Xingyu Chen and Zhenjun Li

Actuators 2025, 14(4), 180; https://doi.org/10.3390/act14040180 - 9 Apr 2025

Viewed by 290

Abstract

The X-ray defect detection system for weld seams in deep-sea manned spherical shells is nonlinear and complex, posing challenges such as motor parameter variations, external disturbances, coupling effects, and high-precision dual-motor coordination requirements. To address these challenges, this study proposes a deep reinforcement [...] Read more.

The X-ray defect detection system for weld seams in deep-sea manned spherical shells is nonlinear and complex, posing challenges such as motor parameter variations, external disturbances, coupling effects, and high-precision dual-motor coordination requirements. To address these challenges, this study proposes a deep reinforcement learning-based control scheme, leveraging DRL’s capabilities to optimize system performance. Specifically, the TD3 algorithm, featuring a dual-critic structure, is employed to enhance control precision within predefined state and action spaces. A composite reward mechanism is introduced to mitigate potential motor instability, while CP-MPA is utilized to optimize the performance of the proposed m-TD3 composite controller. Additionally, a synchronous collaborative motion compensator is developed to improve coordination accuracy between the dual motors. For practical implementation and validation, a PMSM simulation model is constructed in MATLAB/Simulink, serving as an interactive training platform for the DRL agent and facilitating efficient, robust training. The simulation results validate the effectiveness and superiority of the proposed optimization strategy, demonstrating its applicability and potential for precise and robust control in complex nonlinear defect detection systems. Full article

(This article belongs to the Section Control Systems)

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21 pages, 9318 KiB

Open AccessArticle

Dynamic Analysis of Vibration Attenuation in Dual-Stage Cascade Spring-Mass System (DCSMS) for High-Precision Instrumentation

by Xin Jin, Yihua Kang and Zhiwei Huang

Actuators 2025, 14(4), 179; https://doi.org/10.3390/act14040179 - 7 Apr 2025

Viewed by 193

Abstract

The detrimental effects of low-frequency vibrations on the measurement accuracy of commercial high-precision instrumentation demand urgent resolution, particularly for instruments requiring <1 μm positioning stability. Conventional base-mounted active damping systems exhibit limitations in suppressing the structural resonance induced by passive isolators—especially when the [...] Read more.

The detrimental effects of low-frequency vibrations on the measurement accuracy of commercial high-precision instrumentation demand urgent resolution, particularly for instruments requiring <1 μm positioning stability. Conventional base-mounted active damping systems exhibit limitations in suppressing the structural resonance induced by passive isolators—especially when the environmental vibration intensity surpasses the standard thresholds. Therefore, in this study, we developed an innovative multi-mode control architecture to substantially enhance the vibration-damping capabilities of the DCSMS. The proposed methodology synergistically integrates foundation vibration isolators with embedded passive modules through a dual-stage spring-mass system optimization framework. Experimental validation combining ADAMS–MATLAB multi-physics co-simulation, complemented by a decoupling analytical control model based on the vibrational transmission characteristics of the source propagation path, substantiated the efficacy of the proposed control methodology. Full article

(This article belongs to the Section Actuators for Manufacturing Systems)

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27 pages, 11144 KiB

Open AccessArticle

Adaptive Backstepping Control with Time-Delay Compensation for MR-Damper-Based Vehicle Seat Suspension

by Heting Feng, Yunhu Zhou, Shaoqi Li, Gongxun Cheng, Shang Ma and Yancheng Li

Actuators 2025, 14(4), 178; https://doi.org/10.3390/act14040178 - 6 Apr 2025

Viewed by 286

Abstract

Long-term vibrations endanger driver health and affect ride performance. Semi-active seat suspension systems equipped with magnetorheological (MR) dampers can effectively reduce vibrations transmitted to drivers, exhibiting excellent potential for widespread applications owing to their outstanding performance characteristics. In this paper, we propose an [...] Read more.

Long-term vibrations endanger driver health and affect ride performance. Semi-active seat suspension systems equipped with magnetorheological (MR) dampers can effectively reduce vibrations transmitted to drivers, exhibiting excellent potential for widespread applications owing to their outstanding performance characteristics. In this paper, we propose an adaptive backstepping control system with time-delay compensation (ABC-C) for an MR-damper-based semi-active seat suspension system to enhance ride comfort and stability in commercial vehicles. The control framework integrates a reference model, an adaptive backstepping controller, a time-delay compensator, and an MR damper inverse model. The reference model balances ride comfort and stability using high-pass and low-pass filters, while the adaptive controller ensures robustness against parameter uncertainties and disturbances. A time-delay compensator mitigates delays in the control loop, improving system stability and performance. Numerical simulations under harmonic, bump, and random excitations demonstrated the superior performance of the ABC-C controller. The experimental results show that under random road excitation conditions, the frequency-weighted root mean square (FW-RMS) of acceleration was reduced by 26.9%, the vibration dose value (VDV) decreased by 29.3%, and the root mean square of relative displacement (RMS_rd) was reduced by 58.46%. The results highlight the practical effectiveness of the ABC-C controller in improving ride comfort and safety for drivers of commercial vehicles, offering significant potential for real-world applications. Full article

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17 pages, 3315 KiB

Open AccessReview

Hybrid Fault-Tolerant Control in Cooperative Robotics: Advances in Resilience and Scalability

by Claudio Urrea

Actuators 2025, 14(4), 177; https://doi.org/10.3390/act14040177 - 4 Apr 2025

Viewed by 395

Abstract

Cooperative robotics relies on robust fault-tolerant control (FTC) to maintain resilience in dynamic environments, where actuators are pivotal to system reliability. This review synthesizes advancements in hybrid FTC, integrating mechanical redundancy with electronic adaptability and learning-based techniques like deep reinforcement learning and swarm-optimized [...] Read more.

Cooperative robotics relies on robust fault-tolerant control (FTC) to maintain resilience in dynamic environments, where actuators are pivotal to system reliability. This review synthesizes advancements in hybrid FTC, integrating mechanical redundancy with electronic adaptability and learning-based techniques like deep reinforcement learning and swarm-optimized control, drawing from interdisciplinary evidence across manufacturing, healthcare, agriculture, space exploration, and underwater robotics. It examines how these approaches enhance uptime, precision, and coordination in multi-robot systems, reporting significant improvements despite physical validation being limited to approximately one-quarter of strategies. Addressing gaps in prior work by overcoming limitations of traditional methods, it extends to Construction 5.0, supporting human–robot collaboration (HRC) through scalability and adaptability. Future efforts will prioritize broader testing, standardized benchmarks, safety considerations, and optimization under uncertainty to align theoretical gains with practical outcomes, enhancing resilient automation across domains. Full article

(This article belongs to the Section Actuators for Robotics)

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22 pages, 1086 KiB

Open AccessArticle

Design of Experiments Approach for Structural Optimization of Urban Air Mobility Vehicles

by Marco Claudio De Simone, Salvio Veneziano, Alessia Porcaro and Domenico Guida

Actuators 2025, 14(4), 176; https://doi.org/10.3390/act14040176 - 3 Apr 2025

Viewed by 235

Abstract

The current global context demands the development of new solutions that prioritize energy efficiency, time optimization, safety, and sustainability. Urban transportation is one of the sectors undergoing significant transformation. Pursuing new urban transportation solutions has become increasingly intense, involving research institutions and companies. [...] Read more.

The current global context demands the development of new solutions that prioritize energy efficiency, time optimization, safety, and sustainability. Urban transportation is one of the sectors undergoing significant transformation. Pursuing new urban transportation solutions has become increasingly intense, involving research institutions and companies. Considering this context, this study focused on the optimization procedures for designing a new vehicle capable of vertical take-off for urban air mobility applications. This paper reports on the optimization process of a thruster deployment mechanism using statistical techniques. In particular, the authors tested the use of Design of Experiments (DOE) techniques for the optimal design of a structural component of a new vehicle for urban mobility purposes under development at the Applied Mechanics laboratory of the Department of Industrial Engineering of the University of Salerno. For this reason, it was decided that a parametric multibody model would be developed in the Simscape Multibody environment for structural optimization using designed experiment plans to “guide” the designer in the analysis phase and search for an optimal configuration using a minimum number of configurations. Finally, employing FEM analysis, the chosen configuration was validated. This study allowed us to test the use of DOE techniques to design new systems. It allowed us to evaluate different configurations, the static and dynamic behavior, the constraining reactions present in the joints, and the active forces and torques of the actuators, highlighting the correlation between factors that can guide the designer in identifying optimal solutions. Full article

(This article belongs to the Special Issue Advances in Dynamics and Motion Control of Unmanned Aerial/Underwater/Ground Vehicles—2nd Edition)

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21 pages, 5345 KiB

Open AccessArticle

Modeling and Analysis of a Cutting Robot for the “Excavation–Backfill–Retention” Integrated Mining and Excavation Equipment

by Hongwei Ma, Wenda Cui, Chuanwei Wang, Xusheng Xue, Qinghua Mao, Haotian Wang, Limeng Xue, Hao Su, Zukun Yu, Jiashuai Cheng, Yifeng Guo and Kexiang Ma

Actuators 2025, 14(4), 175; https://doi.org/10.3390/act14040175 - 3 Apr 2025

Viewed by 234

Abstract

To meet the mining requirements of the ’excavation–backfill–retention’ tunneling method for inter-panel coal pillars, this paper proposes an integrated ‘excavation–backfill–retention’ equipment system centered on a cutting robot. An interactive design method was employed to analyze the interaction between mining conditions and the cutting [...] Read more.

To meet the mining requirements of the ’excavation–backfill–retention’ tunneling method for inter-panel coal pillars, this paper proposes an integrated ‘excavation–backfill–retention’ equipment system centered on a cutting robot. An interactive design method was employed to analyze the interaction between mining conditions and the cutting robot, constructing a ’requirements–functions–structure’ model. The robot integrates a horizontal drum cutting mechanism with a slider shoe walking mechanism, offering enhanced adaptability to various mining conditions. A parameter model was constructed to explore the relationship between the cutting arm length and the robot’s structural parameters under varying mining heights. Using a hierarchical solution method that combines local search and multi−objective genetic algorithms, the robot’s fundamental parameters were determined, enabling the development of a detailed 3D model. A kinematic model based on the modified D–H method was developed to analyze the cutting arm’s swing angle, cylinder extension, propulsion velocity, and cutting velocity in practical mining scenarios. The working range of the height adjustment and feed cylinders at different mining heights was determined through simulation. A dynamics model of the cutting drum was developed, and a coupled simulation using the discrete element method (DEM) was conducted to analyze the relationship between coal/rock hardness, drum load, and cutting depth. The simulation results indicate that as the cutting depth raises the number of cutting teeth in contact with surrounding rock, the cutting depth grows, resulting in a larger reaction force from the coal seam and greater fluctuations in drum load torque. Once the maximum cutting depth is reached, load torque stabilizes within a specific range. Considering cutting efficiency, the robot achieves a maximum cutting velocity of 1 m/min with a cutting depth of 250 mm for rock strength greater than f3. For rock strength f3, the maximum cutting velocity is 1 m/min with a 400 mm depth, and for f2, it is 2 m/min with a 400 mm depth. These findings provide a theoretical foundation for the development of adaptive cutting strategies in mining operations, contributing to improved performance and efficiency in complex mining conditions. Full article

(This article belongs to the Section Actuators for Robotics)

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27 pages, 8045 KiB

Open AccessArticle

Research on Sensorless Technology of a Magnetic Suspension Flywheel Battery Based on a Genetic BP Neural Network

by Weiyu Zhang and Fei Guo

Actuators 2025, 14(4), 174; https://doi.org/10.3390/act14040174 - 2 Apr 2025

Viewed by 202

Abstract

The research object of this paper is a new type of multi-functional, air-gap-type, vehicle-mounted magnetic suspension flywheel battery. It is a new energy storage technology with a long working life, high energy conversion efficiency, multiple charging and discharging times, low carbon and environmental [...] Read more.

The research object of this paper is a new type of multi-functional, air-gap-type, vehicle-mounted magnetic suspension flywheel battery. It is a new energy storage technology with a long working life, high energy conversion efficiency, multiple charging and discharging times, low carbon and environmental protection. However, when the vehicle-mounted flywheel battery is operating, it will inevitably be disturbed by road conditions, resulting in loose sensors and feedback errors, thereby reducing the control accuracy and reliability of the system. To solve these problems, a sensorless control system came into being. It samples the current of the magnetic bearing coil through the hardware circuit and converts it into displacement for real-time control, eliminating the risk of sensor failure. However, the control accuracy of the traditional sensorless system is relatively low. Therefore, this paper adopts a BP (backpropagation) neural network PID controller based on genetic algorithm optimization on the basis of the sensorless control system. Through the joint simulation of the dynamic simulation software ADAMS/VIEW2018 and MATLAB2022b, the optimal PID control parameter database for complex road conditions is established. Through sensorless technology, the current of the flywheel battery is converted into the position error for extensive training so that the genetic BP neural network PID controller can accurately identify the current complex road conditions according to the position error, so as to provide the optimal PID control parameters corresponding to the road conditions to carry out accurate real-time stability control of the flywheel rotor. The experimental results show that the method can effectively reduce feedback errors, improve the control accuracy, and output optimal control parameters in real time under complex road conditions, which significantly improves the reliability and control performance of the vehicle flywheel battery system. Full article

(This article belongs to the Special Issue Advanced Technologies on the Control Method of Electromagnetic Actuator—Second Edition)

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18 pages, 3986 KiB

Open AccessArticle

Modeling and Analysis of Transmission Efficiency for 3K Planetary Gearbox with Flexure-Based Carrier for Backdrivable Robot Joints

by Qinghao Du, Guilin Yang, Weijun Wang, Chin-Yin Chen and Zaojun Fang

Actuators 2025, 14(4), 173; https://doi.org/10.3390/act14040173 - 1 Apr 2025

Viewed by 358

Abstract

A high-gear-ratio anti-backlash 3K planetary gearbox with a preloaded flexure-based carrier is a suitable reducer for robot joints owning to its compact design and high transmission accuracy. However, to design such a 3K planetary gearbox with high bidirectional efficiencies for backdrivable robot joints, [...] Read more.

A high-gear-ratio anti-backlash 3K planetary gearbox with a preloaded flexure-based carrier is a suitable reducer for robot joints owning to its compact design and high transmission accuracy. However, to design such a 3K planetary gearbox with high bidirectional efficiencies for backdrivable robot joints, it is critical to develop an accurate transmission efficiency model to predict the effects of the preloaded flexure-based carrier on the efficiency of the 3K planetary gearbox. To determine the meshing forces of gear pairs in the 3K planetary gearbox, a quasi-static model is formulated according to tangential displacements of planet gears resulting from the preloaded flexure-based carrier. Considering the reverse meshing forces in the anti-backlash 3K planetary gearbox, a modified efficiency model is developed and the bidirectional transmission efficiencies are analyzed. Simulation results show that both forward and backward transmission efficiencies of the anti-backlash 3K planetary gearbox decrease as the preload increases, while they all increase with the increasing load torque. It is also revealed that the preload primarily affects the meshing efficiency of the sun–planet gear pair. Four different carrier prototypes are fabricated for experiments. The average errors between the predicted and measured results for forward and backward transmission efficiencies are 2.30% and 4.01%, respectively. Full article

(This article belongs to the Special Issue AI, Designing, Sensing, Instrumentation, Diagnosis, Controlling, and Integration of Actuators in Digital Manufacturing—2nd Edition)

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33 pages, 8558 KiB

Open AccessArticle

Development of Real-Time Models of Electromechanical Actuators for a Hybrid Iron Bird of a Regional Aircraft

by Antonio Carlo Bertolino, Jean-Charles Maré, Silvio Akitani, Andrea De Martin and Giovanni Jacazio

Actuators 2025, 14(4), 172; https://doi.org/10.3390/act14040172 - 31 Mar 2025

Viewed by 207

Abstract

This study presents the development of a real-time simulation model for electromechanical actuators tailored to a hybrid iron bird for next-generation regional turboprop aircraft. This iron bird is aimed at integrating real and virtual components, enabling advanced validation of flight control systems while [...] Read more.

This study presents the development of a real-time simulation model for electromechanical actuators tailored to a hybrid iron bird for next-generation regional turboprop aircraft. This iron bird is aimed at integrating real and virtual components, enabling advanced validation of flight control systems while balancing risk and cost. The mathematical models of actuators needed for the development and operation of the iron bird must comply with stringent requirements, especially in terms of computational cost. A novel two-step iterative methodology is proposed, combining bottom-up and top-down approaches. This process begins with simplified low-fidelity models. Then, the models are incrementally refined to capture complex dynamics while maintaining computational efficiency. Using the proposed approach, the computational time of the real-time model remained almost unvaried and consistent with the sampling frequency, while the number of state variables and the range of described phenomena grew significantly. The real-time model is validated against simulated data from a reference high-fidelity model and experimental data, achieving excellent agreement while reducing the computational time by 93%. The enhanced model incorporates selected failure modes equivalent models regarding the electric motor, power drive unit, and mechanical transmission, supporting possible future prognostics and health management (PHM) applications. These results showcase a scalable solution for integrating electromechanical actuation in modern aerospace systems, paving the way for full virtual iron birds and greener aviation technologies. Full article

(This article belongs to the Special Issue Flight Control Systems and Dynamic Simulation for Aerospace Applications)

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14 pages, 2949 KiB

Open AccessArticle

Photo-Responsive Liquid Crystal Elastomer Coils Inspired by Tropism Movements of Plants

by Xiyun Zhan, Zhiyu Ran, Jiajun Li, Jiaqi Zhu, Zhibo Zhang and Kun-Lin Yang

Actuators 2025, 14(4), 171; https://doi.org/10.3390/act14040171 - 31 Mar 2025

Viewed by 241

Abstract

Plant tendrils exhibit intriguing tropism motions like bending, twisting, and coiling. Herein, we report the application of a liquid crystal elastomer (LCE) to make a light-sensitive and biomimetic coil to replicate behaviors of plant tendrils. The LCE coil consists of diacrylate azobenzene, diacrylate [...] Read more.

Plant tendrils exhibit intriguing tropism motions like bending, twisting, and coiling. Herein, we report the application of a liquid crystal elastomer (LCE) to make a light-sensitive and biomimetic coil to replicate behaviors of plant tendrils. The LCE coil consists of diacrylate azobenzene, diacrylate mesogens, and thiol-based spacers. These components are first mixed to form a highly viscous prepolymer solution through a thiol-acrylate Michael addition reaction. Subsequently, an extrusion–rolling process is developed to draw the viscous solution into a coil, which is mechanically stretched in a single direction to align mesogens in the LCE. Finally, the coil is photopolymerized under UV light to form an LCE coil with a diameter of 375 µm. The LCE coil possesses good rigidity and flexibility and shows movement upon light exposure. For example, the LCE coil shows a reversible bending up to 120° to 365 nm UV and 30% contraction to 455 nm visible light, respectively, due to trans-cis photoisomerization of azobenzene derivatives. When the coil is irradiated with UV light with an intensity up to 10 mW cm⁻², it can twist and coil up. It can also wrap around the UV light tube in 6 s, similar to a plant tendril. This type of light-responsive coil has great potential in making biomimetic plants or soft robotics. Full article

(This article belongs to the Special Issue Smart Responsive Materials for Sensors and Actuators)

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