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Actuators, Volume 14, Issue 2 (February 2025) – 56 articles

Cover Story (view full-size image): The high prevalence of foot drop highlights the need for devices that restore gait functionality. A portable, lightweight, low-cost, and efficient active ankle–foot orthosis is in demand. This work presents an active ankle–foot orthosis prototype that aims to fulfill these goals. The device is based on a design previously simulated by our group, evaluated on a test bench for low-level control. A cam-based actuator assists with dorsiflexion without affecting plantar flexion. The system’s dynamical behavior was assessed on a test bench using a PID controller. Performance metrics showed low errors for step inputs and periodic perturbations, with root-mean-squared tracking errors ranging from 0.1 to 6.5 degrees, depending on speed. View this paper
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23 pages, 1136 KiB  
Article
A Reasoned Attempt to Mitigate Vibrations in Nonlinear Flexible Systems Influenced by Tractive–Elastic Rolling Contact Friction Through Input Shaping: A Case Study on a Trolley–Pipe Benchmark Transport System
by Gerardo Peláez, Pablo Izquierdo, Gustavo Peláez and Higinio Rubio
Actuators 2025, 14(2), 97; https://doi.org/10.3390/act14020097 - 17 Feb 2025
Viewed by 132
Abstract
The well-regarded feedforward control strategy known as Input Shaping is aimed at improving the dynamic response of flexible mechanical systems by reducing overshoot and residual vibration amplitude. Its validity has been confirmed by numerous studies dealing with linear system dynamics. However, its application [...] Read more.
The well-regarded feedforward control strategy known as Input Shaping is aimed at improving the dynamic response of flexible mechanical systems by reducing overshoot and residual vibration amplitude. Its validity has been confirmed by numerous studies dealing with linear system dynamics. However, its application in nonlinear systems, particularly those influenced by tractive–elastic rolling contact friction, remains a challenging and less explored open research area. This paper investigates whether Input Shaping, without tractive rolling friction compensation, can effectively mitigate vibrations in a trolley–pipe benchmark transport system. In this system, the pipe is modeled as a rolling disc attached to the trolley by a spring at its center of mass, while the trolley itself is connected to a guiding body frame by an additional spring acting as a proportional control. The natural frequencies of the system are analytically estimated and numerically verified from a corresponding well-suited multibody model. Thus, tailored two-mode shapers are designed based on simultaneous constraints and the convolution sum, respectively. Through multibody simulations, this study evaluates the performance of Input Shaping under tractive–elastic rolling contact friction conditions. The findings highlight both the potential and limitations of this control method in addressing nonlinear mechanical systems influenced by tractive–elastic rolling contact friction. Full article
(This article belongs to the Special Issue Nonlinear Active Vibration Control)
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20 pages, 7919 KiB  
Article
Design and Performance Analysis of an All-Metal Phase-Change-Material Actuator for Enhanced Sealing and Displacement Output Characteristics
by Shuaiqi Guo, Xianwei Yang and Qingwen Wu
Actuators 2025, 14(2), 96; https://doi.org/10.3390/act14020096 - 16 Feb 2025
Viewed by 182
Abstract
The phase-change-material (PCM) actuator, a non-pyrotechnic technology in aerospace, offers enhanced safety and convenience. This paper presents a novel PCM actuator featuring an all-metal construction to improve reliability and sealing. Characterized by high energy density and temperature-dependent actuation, the actuator’s displacement output characteristics [...] Read more.
The phase-change-material (PCM) actuator, a non-pyrotechnic technology in aerospace, offers enhanced safety and convenience. This paper presents a novel PCM actuator featuring an all-metal construction to improve reliability and sealing. Characterized by high energy density and temperature-dependent actuation, the actuator’s displacement output characteristics (DOCs) are examined through visualization experiments. The results show the formation of a concave gap within the PCM upon cooling, which can be controlled by adjusting the cooling load and temperature to minimize its impact on displacement output. A two-dimensional physical model is developed to investigate how varying thermophysical parameters and boundary conditions affect the phase change process and DOC. The study finds that increasing the thermal conductivity of the PCM and surface heat flow enhances displacement velocity, although the effect diminishes at higher values. Additionally, reducing latent heat significantly boosts output velocity. For a fixed surface heat flow, changes in wall thickness have a minor impact, with velocity variation under 2%. Full article
(This article belongs to the Section Actuator Materials)
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16 pages, 30872 KiB  
Article
Design, Simulation, and Testing of Active Cooperative Control Strategies for a Light Sensation Transfer Nursing Robot
by Yuansheng Ning, Lingfeng Sang, Zhengcai Wang, Bianca Ghinoiu, Fuqiu Lu, Hongbo Wang and Luige Vlădăreanu
Actuators 2025, 14(2), 95; https://doi.org/10.3390/act14020095 - 15 Feb 2025
Viewed by 177
Abstract
The transfer of patients, especially elderly or long-term bedridden individuals, has emerged as an important problem due to the growing aging population. The advancement of transfer nursing robots provides an intelligent solution to this problem. This paper presents a Parallel Master–Slave Cross-Coupled (PMSCC) [...] Read more.
The transfer of patients, especially elderly or long-term bedridden individuals, has emerged as an important problem due to the growing aging population. The advancement of transfer nursing robots provides an intelligent solution to this problem. This paper presents a Parallel Master–Slave Cross-Coupled (PMSCC) cooperative control strategy based on adaptive fuzzy controllers to address the motion control challenges of a self-developed light Sensation Transfer Nursing Robot (LSTNR). First, the working principle of the LSTNR is introduced, followed by the establishment of its motion model. Next, the robot’s velocity is designed based on PMSCC cooperative control strategies, with an adaptive fuzzy controller performing motion control. Finally, the proposed cooperative control strategy is simulated and analyzed, and the robot is tested for patient transfer. The results show that the proposed control strategy reduces the velocity cooperation error between the robot’s motors. The average velocity error of the robot is reduced by 92.69%, 92.08%, 47.35%, and 87.78%, respectively, compared to the non-cooperatively controlled robot. This significantly addresses issues such as belt slack, tightness, and patient position deformation during operation, improving the transfer efficiency and effectiveness of the LSTNR. Full article
(This article belongs to the Section Actuators for Robotics)
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16 pages, 28202 KiB  
Article
An Extendable and Deflectable Modular Robot Inspired by Worm for Narrow Space Exploration
by Shufeng Tang, Jianan Yao, Yue Yu and Guoqing Zhao
Actuators 2025, 14(2), 94; https://doi.org/10.3390/act14020094 - 15 Feb 2025
Viewed by 212
Abstract
Inspired by earthworm peristalsis, a novel modular robot suitable for narrow spaces is proposed, capable of elongation, contraction, deflection and crawling. Unlike motor-driven robots, the earthworm-inspired robot achieves extension and deflection in each module through “on–off” control of the SMA springs, utilizing the [...] Read more.
Inspired by earthworm peristalsis, a novel modular robot suitable for narrow spaces is proposed, capable of elongation, contraction, deflection and crawling. Unlike motor-driven robots, the earthworm-inspired robot achieves extension and deflection in each module through “on–off” control of the SMA springs, utilizing the cooperation of mechanical skeletons and gears to avoid posture redundancy. The return to the initial posture and the maintenance of the posture are achieved through tension and torsion springs. To study the extension and deflection characteristics, we established a model through kinematic and force analysis to estimate the relationship between the length change and tensile characteristics of the SMA on both sides and the robot’s extension length and deflection angle. Through model verification and experiments, the robot’s extension, deflection and movement characteristics in narrow spaces and varying curvature narrow spaces were comprehensively studied. The results show that the earthworm-inspired robot, as predicted by the model, possesses accurate extension and deflection performance, and can perform inspection tasks in complex and narrow space environments. Additionally, compared to motor-driven robots, the robot designed in this study does not require insulation in low-temperature environments, and the cold conditions can improve its movement efficiency. This new configuration design and the extension and deflection characteristics provide valuable insights for the development of new modular robots and robot drive designs for extremely cold environments. Full article
(This article belongs to the Section Actuators for Robotics)
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20 pages, 10631 KiB  
Article
Improving Low-Frequency Vibration Energy Harvesting of a Piezoelectric Cantilever with Quasi-Zero Stiffness Structure: Theory and Experiment
by Chunli Hua, Donglin Zou and Guohua Cao
Actuators 2025, 14(2), 93; https://doi.org/10.3390/act14020093 - 14 Feb 2025
Viewed by 236
Abstract
In this study, a novel cantilever piezoelectric energy harvester is constructed by using a quasi-zero stiffness (QZS) structure. The QZS structure consists of a classic piezoelectric cantilever beam combined with some accessories that include two pre-compression springs, rolling bearings, slideways and a cylindrical [...] Read more.
In this study, a novel cantilever piezoelectric energy harvester is constructed by using a quasi-zero stiffness (QZS) structure. The QZS structure consists of a classic piezoelectric cantilever beam combined with some accessories that include two pre-compression springs, rolling bearings, slideways and a cylindrical cam. The purpose of the QZS structure is to reduce the natural frequencies of the harvester, so that it can more efficiently collect low-frequency vibration energy. In this study, firstly, the extended Hamilton variational principle is used to establish the dynamic equations of the continuous system. Secondly, the Galerkin method is used to discretize the partial differential equation, and then the analytical solutions of the output voltage, current, power and vibration response of the harvester are obtained. Finally, the influence of the QZS structure on energy harvesting characteristics is studied. Theoretical research shows that the QZS structure can effectively reduce the fundamental natural frequency of the cantilever beam and improve its energy harvesting efficiency. When the spring stiffness is about half of the bending stiffness of the cantilever beam, the uncoupled fundamental natural frequency of the harvester is quasi-zero. For the experimental device considered here, experiments show that the QZS structure can reduce the fundamental natural frequency from 76.4 Hz to 54.1 Hz, decreasing by 22.3 Hz. The maximum output power is increased from 1.43 mW/g2 to 1.95 mW/g2, an increase of 36.4%. The experimental results validate the theoretical model. In short, this paper provides a new idea for the design of energy harvesters suitable for low-frequency vibration. Full article
(This article belongs to the Section Actuator Materials)
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17 pages, 1905 KiB  
Article
A Dual-Motor Actuator for Ceiling Lift with High-Force and High-Speed Capabilities
by Ian Lalonde, Jeff Denis, Mathieu Lamy and Alexandre Girard
Actuators 2025, 14(2), 92; https://doi.org/10.3390/act14020092 - 14 Feb 2025
Viewed by 179
Abstract
Patient transfer devices allow for passive movement of patients in hospitals and care centers. Instead of hoisting the patient, it would be beneficial in some cases to assist their movement, enabling them to move by themselves and reducing hospitalization time. However, patient assistance [...] Read more.
Patient transfer devices allow for passive movement of patients in hospitals and care centers. Instead of hoisting the patient, it would be beneficial in some cases to assist their movement, enabling them to move by themselves and reducing hospitalization time. However, patient assistance requires devices capable of precisely controlling output forces at significantly higher speeds than those used for patient transfers alone, and a single-motor solution would be over-sized and would show poor efficiency for accomplishing both functions. This paper presents a ceiling robot, using a dual-motor actuator and adapted control schemes, that can be used to transfer patients, assist patients in their movement, and help prevent falls. The prototype is shown to be able to lift patients weighing up to 318 kg and to assist a patient with a desired force of up to 100 kg with a precision of 7.8%. Also, a smart control scheme to manage falls is shown to be able to stop a patient who is falling by applying a desired deceleration. Full article
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23 pages, 8148 KiB  
Article
Energy-Coupling-Based Control for Unmanned Quadrotor Transportation Systems: Exploiting Beneficial State-Coupling Effects
by Lincong Han, Zengcheng Zhou, Ming Li, Haokun Geng, Gang Li and Menghua Zhang
Actuators 2025, 14(2), 91; https://doi.org/10.3390/act14020091 - 13 Feb 2025
Viewed by 225
Abstract
Cable suspension transport is a crucial method for quadrotors to transport goods and materials. During transportation, the quadrotor transport system (QTS) faces external disturbances and system uncertainties. Particularly, the underactuated nature of the system poses significant challenges to its stable operation. To solve [...] Read more.
Cable suspension transport is a crucial method for quadrotors to transport goods and materials. During transportation, the quadrotor transport system (QTS) faces external disturbances and system uncertainties. Particularly, the underactuated nature of the system poses significant challenges to its stable operation. To solve these problems, this paper proposes a hierarchical control scheme that enhances coupling and leverages advantageous state-coupling to achieve precise positioning and eliminate payload swings for QTS. By leveraging the cascading characteristics of QTS, the design process is greatly simplified through the separate design of the torque input for the inner loop and the force input for the outer loop. Simulation results demonstrate the effective control performance of this method. Full article
(This article belongs to the Special Issue Modeling and Nonlinear Control for Complex MIMO Mechatronic Systems)
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23 pages, 30439 KiB  
Article
Couple Anti-Swing Obstacle Avoidance Control Strategy for Underactuated Overhead Cranes
by Shuo Meng, Weikai He, Na Liu, Rui Zhang and Cungen Liu
Actuators 2025, 14(2), 90; https://doi.org/10.3390/act14020090 - 13 Feb 2025
Viewed by 297
Abstract
Overhead cranes are widely used for transportation in factories. They move slowly by manual operation to prevent the payload from swinging sharply or colliding with sudden obstacles. To address these issues and enhance work efficiency, this paper proposes a couple anti-swing obstacle avoidance [...] Read more.
Overhead cranes are widely used for transportation in factories. They move slowly by manual operation to prevent the payload from swinging sharply or colliding with sudden obstacles. To address these issues and enhance work efficiency, this paper proposes a couple anti-swing obstacle avoidance control method for 5-DOF overhead cranes. Time polynomial fitting is employed for trajectory planning to achieve obstacle avoidance. To achieve anti-swing of the payloads, a coupled variable incorporating both actuated and underactuated states is defined, alongside a boundary for dynamic performance. Finally, MATLAB simulation and hardware experiments are carried out to verify the reliability and compared with some existing control methods. Full article
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27 pages, 10913 KiB  
Article
Observer-Based Sliding Mode Control for Vehicle Way-Point Tracking with Unknown Disturbances and Obstacles
by Jiacheng Song, Mingjie Shen and Yanan Zhang
Actuators 2025, 14(2), 89; https://doi.org/10.3390/act14020089 - 13 Feb 2025
Viewed by 284
Abstract
In this paper, an advanced vehicle way-point tracking control method, including kinematic control, dynamic control and an obstacle avoidance strategy, is introduced. In the kinematic part, a vehicle kinematic model is established, along with the coordinate transformation between the vehicle and its target. [...] Read more.
In this paper, an advanced vehicle way-point tracking control method, including kinematic control, dynamic control and an obstacle avoidance strategy, is introduced. In the kinematic part, a vehicle kinematic model is established, along with the coordinate transformation between the vehicle and its target. A way-point tracking control law is developed to optimize the vehicle’s movement along predefined way-points. In the dynamic part, a dynamic model considering the actual disturbances and losses is established. An observer compensation technique is utilized to monitor and mitigate disturbances, while sliding mode control, enhanced by a HyperSpiral algorithm, ensures accurate and stable tracking performance. Furthermore, to tackle real-world path planning challenges, an improved way-point tracking obstacle-avoidance algorithm is developed to generate effective way-points for navigating around obstacles. Finally, simulation results validate that the vehicle consistently tracks target way-points in complex scenarios, highlighting the robustness and effectiveness of the proposed method. Full article
(This article belongs to the Special Issue Integrated Intelligent Vehicle Dynamics and Control)
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26 pages, 1267 KiB  
Article
An Improved Nonlinear Health Index CRRMS for the Remaining Useful Life Prediction of Rolling Bearings
by Yongze Jin, Xubo Yang, Junqi Liu, Yanxi Yang, Xinhong Hei and Anqi Shangguan
Actuators 2025, 14(2), 88; https://doi.org/10.3390/act14020088 - 11 Feb 2025
Viewed by 319
Abstract
In this article, a novel prediction index is constructed, a hybrid filtering is proposed, and a remaining useful life (RUL) prediction framework is developed. In the proposed framework, different models are built for different operation states of rolling bearings. In the normal state, [...] Read more.
In this article, a novel prediction index is constructed, a hybrid filtering is proposed, and a remaining useful life (RUL) prediction framework is developed. In the proposed framework, different models are built for different operation states of rolling bearings. In the normal state, a linear model is built, and a Kalman filter (KF) is implemented to determine the failure start time (FST). In the degradation state, a dimensionless prediction index CRRMS is constructed, based on the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and wavelet threshold. Then, a double exponential model is established, and the hybrid filtering is proposed to estimate the future trend of CRRMS, which is combined by a particle filter (PF) and an unscented Kalman filter (UKF). At the same time, dynamic failure threshold technology is adaptively used to determine the failure thresholds of different bearings. Furthermore, the RUL is extrapolated at the moment the prediction index exceeds the failure threshold. Finally, the effectiveness and practicability of the proposed method is verified on the bearing dataset given by the PRONOSTIA platform. Full article
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13 pages, 2708 KiB  
Article
Passivity-Based Twisting Sliding Mode Control for Series Elastic Actuators
by Hui Zhang, Jilong Wang, Lei Zhang, Shijie Zhang, Jing Zhang and Zirong Zhang
Actuators 2025, 14(2), 87; https://doi.org/10.3390/act14020087 - 11 Feb 2025
Viewed by 325
Abstract
This paper presents a passivity-based twisting sliding mode control (PBSMC) approach for series elastic actuators (SEAs). To address the time-varying position trajectory tracking control problem in SEAs, a fourth-order dynamic model is developed to accurately characterize the system. The control framework comprises an [...] Read more.
This paper presents a passivity-based twisting sliding mode control (PBSMC) approach for series elastic actuators (SEAs). To address the time-varying position trajectory tracking control problem in SEAs, a fourth-order dynamic model is developed to accurately characterize the system. The control framework comprises an internal loop and an external loop controller, each designed to ensure precise trajectory tracking. The internal loop controller manages the second derivative of the joint trajectory position error, while the external loop focuses on the error itself. Both controllers are based on the PBSMC methodology to reduce complex nonlinear disturbances and minimize tracking errors. The finite-time convergence of the proposed method is rigorously analyzed. The performance and advantages of the method are evaluated and compared through various simulations. Full article
(This article belongs to the Section Control Systems)
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22 pages, 9746 KiB  
Article
Stiffness Optimization of a Robotic Drilling System for Enhanced Accuracy in Aerospace Assembly
by Haiyang Xu, Jixiao Xue, Gaojie Guo, Yankai Liu, Mingqi Liu and Deyuan Zhang
Actuators 2025, 14(2), 86; https://doi.org/10.3390/act14020086 - 11 Feb 2025
Viewed by 274
Abstract
The low stiffness of robots significantly limits their applicability within the aerospace assembly and manufacturing sectors. The majority of existing research focuses on optimizing robot posture; however, the efficacy of these approaches is constrained in situations with minimal posture variation. To address this [...] Read more.
The low stiffness of robots significantly limits their applicability within the aerospace assembly and manufacturing sectors. The majority of existing research focuses on optimizing robot posture; however, the efficacy of these approaches is constrained in situations with minimal posture variation. To address this challenge, this study examines a robotic drilling system designed for use in confined spaces. An in-depth analysis of its stiffness model is conducted, and the system’s stiffness limitations are identified using the stiffness ellipsoid evaluation method. Based on the mechanical analysis of the drilling state, a stiffness enhancement method grounded in the local force closure of the end effector is proposed. This method involves locking the end effector’s expansion module with the substrate during the drilling process, thereby enabling the axial drilling forces to be jointly borne by the expansion module and the robot’s base joints. Consequently, the system’s stiffness, particularly in the axial direction, is substantially improved. A series of experiments rigorously validate the effectiveness of the proposed stiffness enhancement method. The experimental results demonstrate that the stiffness-optimized robot reduces axial deformation during drilling by a factor of ten and significantly improves hole quality and exit burr height. Full article
(This article belongs to the Section Actuators for Robotics)
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18 pages, 877 KiB  
Review
Collision/Obstacle Avoidance Coordination of Multi-Robot Systems: A Survey
by Guanghong Yang, Liwei An and Can Zhao
Actuators 2025, 14(2), 85; https://doi.org/10.3390/act14020085 - 11 Feb 2025
Viewed by 363
Abstract
Multi-robot systems (MRSs) are widely applied in the fields of joint search and rescue, exploration, and carrying. To achieve cooperative tasks and guarantee physical safety, the robots should avoid inter-robot collisions as well as robot–obstacle collisions. However, the collision/obstacle avoidance task usually conflicts [...] Read more.
Multi-robot systems (MRSs) are widely applied in the fields of joint search and rescue, exploration, and carrying. To achieve cooperative tasks and guarantee physical safety, the robots should avoid inter-robot collisions as well as robot–obstacle collisions. However, the collision/obstacle avoidance task usually conflicts with the given cooperative task, which poses a significant challenge for the achievement of multi-robot cooperative tasks. This paper provides a review of the state-of-the-art results in the collision/obstacle avoidance cooperative control of MRSs. Specifically, the latest developments of collision/obstacle avoidance cooperative control are summarized according to different planning strategies and classified into three categories: (1) offline planning; (2) receding horizon planning; and (3) reactive control. Furthermore, specific design solutions for existing reference/command governors are highlighted to demonstrate the latest research advances. Finally, several challenging issues are discussed to guide future research. Full article
(This article belongs to the Section Actuators for Robotics)
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17 pages, 3174 KiB  
Article
Real-Time Motor Control Using a Raspberry Pi, ROS, and CANopen over EtherCAT, with Application to a Semi-Active Prosthetic Ankle
by Kieran M. Nichols, Rebecca A. Roembke and Peter G. Adamczyk
Actuators 2025, 14(2), 84; https://doi.org/10.3390/act14020084 - 10 Feb 2025
Viewed by 420
Abstract
This paper focused on the implementation method and results of modifying a Raspberry Pi 4 for real-time control of brushless direct-current motors, with application in a semi-active two-axis ankle prosthesis. CANopen over EtherCAT was implemented directly on the Raspberry Pi to synchronize real-time [...] Read more.
This paper focused on the implementation method and results of modifying a Raspberry Pi 4 for real-time control of brushless direct-current motors, with application in a semi-active two-axis ankle prosthesis. CANopen over EtherCAT was implemented directly on the Raspberry Pi to synchronize real-time communication between it and the motor controllers. Kinematic algorithms for setting ankle angles of zero to ten degrees in any combination of sagittal and frontal angles were implemented. To achieve reliable motor communication, where the motors continuously move, the distributed clock synchronization of Linux and Motor driver systems needs to have a finely tuned Proportional-Integral compensation and a consistent sampling period. Data collection involved moving the ankle through 33 unique pre-selected ankle configurations nine times. The system allowed for quick movement (mean settling time 0.192 s), reliable synchronization (standard deviation of 4.51 microseconds for sampling period), and precise movement (mean movement error less than 0.2 deg) for ankle angle changes and also a high update rate (250 microseconds sampling period) with modest CPU load (12.48%). This system aims to allow for the prosthesis to move within a single swing phase, enabling it to efficiently adapt to various speeds and terrains, such as walking on slopes, stairs, or around corners. Full article
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18 pages, 5087 KiB  
Article
Load-Current-Compensation-Based Robust DC-Link Voltage Control for Flywheel Energy Storage Systems
by Hongjin Hu, Wentao Liang, Guang-Zhong Cao, Jingbo Wei and Kun Liu
Actuators 2025, 14(2), 83; https://doi.org/10.3390/act14020083 - 9 Feb 2025
Viewed by 469
Abstract
DC-link voltage control needs to be achieved for flywheel energy storage systems (FESSs) during discharge. However, load disturbances and model nonlinearity affect the voltage control performance. Therefore, this paper proposes a load-current-compensation-based robust DC-link voltage control method for FESSs. In the proposed method, [...] Read more.
DC-link voltage control needs to be achieved for flywheel energy storage systems (FESSs) during discharge. However, load disturbances and model nonlinearity affect the voltage control performance. Therefore, this paper proposes a load-current-compensation-based robust DC-link voltage control method for FESSs. In the proposed method, the model is linearized via load current feedforward compensation and dq-axis current-to-DC-current conversion. The uncertainty of the linear model is analyzed and an H robust control method is applied to overcome the uncertainty. Furthermore, experiments involving the proposed method are conducted on a 1.2 kWh magnetic suspended FESS prototype. Compared with the general proportional integral control method, the proposed method can increase the voltage response speed by 37.1% and reduce the voltage fluctuations by 29.5%. The effectiveness of the proposed method is verified experimentally. Full article
(This article belongs to the Special Issue Actuators in Magnetic Levitation Technology and Vibration Control)
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21 pages, 9153 KiB  
Article
Theoretical Analysis and Experimental Verification of 2-DOF Linkage Piezoelectric Energy Harvesting
by Yuanyuan Song, Huawen Nan, Ran Zhou, Fangchao Xu and Feng Sun
Actuators 2025, 14(2), 82; https://doi.org/10.3390/act14020082 - 9 Feb 2025
Viewed by 350
Abstract
In the process of energy harvesting, vibration energy harvesting still has several disadvantages, including a high-threshold excitation and a narrow working bandwidth. Therefore, a 2-degrees-of-freedom piezoelectric energy harvester is proposed. By introducing a nonlinear magnetic force to the system, the working bandwidth and [...] Read more.
In the process of energy harvesting, vibration energy harvesting still has several disadvantages, including a high-threshold excitation and a narrow working bandwidth. Therefore, a 2-degrees-of-freedom piezoelectric energy harvester is proposed. By introducing a nonlinear magnetic force to the system, the working bandwidth and the energy-harvesting efficiency of three magnetically coupled piezoelectric cantilever beams can be effectively improved. In this paper, a mathematical model consisting of three electrically coupled magnetically coupled piezoelectric cantilever beam systems is established, and the governing equations of electric coupling are solved numerically and verified experimentally. The dynamic characteristics under different excitations and frequencies are studied. The experiment shows that the working bandwidth can be increased by controlling the distance between three pairs of circular magnets and changing the excitation and frequency to induce resonance. Thus, the self-power requirement of micro-power devices can be realized. Overall, this study provides a promising solution for improving the performance of piezoelectric energy harvesters and offers theoretical insights for designing vibrating piezoelectric energy harvesters. Full article
(This article belongs to the Section Actuator Materials)
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21 pages, 12918 KiB  
Article
Analysis and Optimization Design of Moving Magnet Linear Oscillating Motors
by Minghu Yu, Yuqiu Zhang, Jiekun Lin and Peng Zhang
Actuators 2025, 14(2), 81; https://doi.org/10.3390/act14020081 - 8 Feb 2025
Viewed by 271
Abstract
Permanent Magnet Linear Oscillating Motors (PMLOMs) are popular in micro-positioning systems, biomedical devices, and refrigeration compressors due to their simple structure, high efficiency, rapid response, and quiet operation. This paper proposes a method for the analysis and optimization of electromechanical systems that employs [...] Read more.
Permanent Magnet Linear Oscillating Motors (PMLOMs) are popular in micro-positioning systems, biomedical devices, and refrigeration compressors due to their simple structure, high efficiency, rapid response, and quiet operation. This paper proposes a method for the analysis and optimization of electromechanical systems that employs a moving magnet linear oscillating motor. A simplified magnetic circuit method model was built to derive an electromagnetic thrust formula, and the initial design parameters of the motor and the thrust at the equilibrium position were calculated. Subsequently, a finite element model was developed, and a multi-objective optimization method was applied to refine the key dimensions of the motor to enhance its thrust characteristics. Furthermore, an analysis of the resonant characteristics of the electromechanical coupled system was conducted to identify the optimal operating frequency for the optimization scheme. Finally, the experimental validation of the optimized design was performed on a prototype, with the measured data showing a general correlation with the trends observed in the simulation analysis results. The effectiveness of this system analysis method was validated through experimental data. The results demonstrate that the thrust at the initial position is linearly correlated with both the outer arc radius of the permanent magnet and its mechanical pole arc coefficient. Additionally, the axial length of the outer stator, the axial spacing between the two outer stators, and the axial length of the magnets serve as key influencing parameters for the thrust characteristics within the effective stroke range. Furthermore, when the motor operates at its mechanical resonance frequency, it can attain the maximum efficiency. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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33 pages, 16932 KiB  
Article
Real-Time Simulation-Based Control of an Electro-Hydraulic Flexible Manipulator
by Daniel Hagen, Katrine Als Hansen, Jonas Holmen and Michael Rygaard Hansen
Actuators 2025, 14(2), 80; https://doi.org/10.3390/act14020080 - 8 Feb 2025
Viewed by 279
Abstract
This paper presents the modeling and control of a flexible single-boom crane manipulator using a high-fidelity real-time simulation model. The model incorporates both electro-hydraulic actuation and flexible-body dynamics, with the flexible boom represented via the lumped parameter method. A systematic tuning and validation [...] Read more.
This paper presents the modeling and control of a flexible single-boom crane manipulator using a high-fidelity real-time simulation model. The model incorporates both electro-hydraulic actuation and flexible-body dynamics, with the flexible boom represented via the lumped parameter method. A systematic tuning and validation procedure ensures that the model accurately replicates the physical system’s dynamics, achieving an eigenfrequency accuracy of approximately 97% and a piston-position deviation within 1.2% of the overall stroke length in final tests. The real-time simulation model is utilized in both open-loop and closed-loop control schemes to investigate whether simulated data can reduce dependency on sensor feedback compared to a benchmark controller. While the simulation-based controller alone does not match the fully sensor-based closed-loop accuracy, the simulation-based feedforward improves performance by 83% compared to the standard model-based velocity feedforward. Additionally, integrating the real-time simulation with sensor feedback enhances the benchmark controller’s performance by approximately 16%. These findings highlight the potential of combining real-time, nonlinear simulation with conventional sensor feedback to enhance the control of electro-hydraulic flexible manipulators. Full article
(This article belongs to the Special Issue Control of Hydraulic Robotic Manipulators)
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15 pages, 2160 KiB  
Article
Integrating Strain Gauge Feedback with Adaptive Sliding Mode Motion Control for Piezoelectric Nanopositioning Stage
by Xianfeng Zeng, Feng Nan, Tengfei Li, Changchao Mo, Jiaqiu Su, Kaihong Wei and Xiaozhi Zhang
Actuators 2025, 14(2), 79; https://doi.org/10.3390/act14020079 - 7 Feb 2025
Viewed by 362
Abstract
This paper presents an adaptive sliding mode control (ASMC) scheme based on strain gauge position feedback for compensating for motion errors in a piezoelectric nanopositioning stages and ensures precise and reliable motion tracking control. The innovation of this scheme lies in calibrating the [...] Read more.
This paper presents an adaptive sliding mode control (ASMC) scheme based on strain gauge position feedback for compensating for motion errors in a piezoelectric nanopositioning stages and ensures precise and reliable motion tracking control. The innovation of this scheme lies in calibrating the relationship between the feedback voltage of the strain gauge and the actual stage displacement. Thus, the calibrated feedback displacement is directly used as the position feedback signal for the ASMC scheme. Adaptive rules are employed to adjust the control gains, thereby eliminating the requirement to determine the upper bound of the disturbance. The stability of the ASMC strategy is theoretically proven within the Lyapunov framework. Comparative experiments under external disturbances have confirmed the superiority of the proposed control scheme. Results demonstrate that the proposed control scheme exhibits superior robust tracking performance compared to the traditional sliding mode control (SMC) scheme. Full article
(This article belongs to the Section Precision Actuators)
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13 pages, 2302 KiB  
Article
Passive Frequency Tuning of Kinetic Energy Harvesters Using Distributed Liquid-Filled Mass
by Rahul Adhikari and Nathan Jackson
Actuators 2025, 14(2), 78; https://doi.org/10.3390/act14020078 - 7 Feb 2025
Viewed by 488
Abstract
Micro-scale kinetic energy harvesters are in large demand to function as sustainable power sources for wireless sensor networks and the Internet of Things. However, one of the challenges associated with them is their inability to easily tune the frequency during the manufacturing process, [...] Read more.
Micro-scale kinetic energy harvesters are in large demand to function as sustainable power sources for wireless sensor networks and the Internet of Things. However, one of the challenges associated with them is their inability to easily tune the frequency during the manufacturing process, requiring devices to be custom-made for each application. Previous attempts have either used active tuning, which consumes power, or passive devices that increase their energy footprint, thus decreasing power density. This study involved developing a novel passive method that does not alter the device footprint or power density. It involved creating a proof mass with an array of chambers or cavities that can be individually filled with liquid to alter the overall proof mass as well as center of gravity. The resonant frequency of a rectangular cantilever can then be altered by changing the location, density, and volume of the liquid-filled mass. The resolution can be enhanced by increasing the number of chambers, whereas the frequency tuning range can be increased by increasing the amount of liquid or density of the liquids used to fill the cavities. A piezoelectric cantilever with a 340 Hz initial resonant frequency was used as the testing device. Liquids with varying density (silicone oil, liquid sodium polytungstate, and Galinstan) were investigated. The resonant frequencies were measured experimentally by filling various cavities with these liquids to determine the tuning frequency range and resolution. The tuning ranges of the first resonant frequency mode for the device were 142–217 Hz, 108–217 Hz, and 78.4–217 Hz for silicone oil, liquid sodium polytungstate, and Galinstan, respectively, with a sub Hz resolution. Full article
(This article belongs to the Section Actuators for Robotics)
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19 pages, 7224 KiB  
Article
Designing a Composite Hydraulic Cylinder Using Genetic Algorithms
by Michał Stosiak, Marek Lubecki and Mykola Karpenko
Actuators 2025, 14(2), 77; https://doi.org/10.3390/act14020077 - 7 Feb 2025
Viewed by 502
Abstract
The paper points out the growing interest in the use of composite materials for load-bearing parts, including hydraulic components. The non-negligible benefits of using composite materials in mechanical engineering are pointed out. However, applications of new materials sometimes give rise to new challenges. [...] Read more.
The paper points out the growing interest in the use of composite materials for load-bearing parts, including hydraulic components. The non-negligible benefits of using composite materials in mechanical engineering are pointed out. However, applications of new materials sometimes give rise to new challenges. The strength parameters of a new structure, such as a composite cylinder for a hydraulic actuator, depend on its structure, including the number of layers and the fibre angle. This paper presents the application of a genetic algorithm to optimise the process of selecting the structure of a composite cylinder for a hydraulic actuator. The operation of the algorithm and the process of selecting global parameters (hyperparameters) are described. A block diagram of the algorithm for optimising the structure selection process is presented, and the designed structure is verified. Full article
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20 pages, 12818 KiB  
Article
Modal Vibration Suppression for Magnetically Levitated Rotor Considering Significant Gyroscopic Effects and Interface Contact
by Kun Zeng, Yang Zhou, Yuanping Xu and Jin Zhou
Actuators 2025, 14(2), 76; https://doi.org/10.3390/act14020076 - 6 Feb 2025
Viewed by 320
Abstract
Featured with optimal power consumption, active magnetic bearings (AMBs) have been extensively integrated into turbomachinery applications. For turbomachinery components, including the rotor and impeller, their connection is generally based on bolted joints, which would easily induce excessive interface contact. As a result, the [...] Read more.
Featured with optimal power consumption, active magnetic bearings (AMBs) have been extensively integrated into turbomachinery applications. For turbomachinery components, including the rotor and impeller, their connection is generally based on bolted joints, which would easily induce excessive interface contact. As a result, the pre-tightening torque can induce modal vibrations in the rotor upon levitation. Although a notch filter can be adopted to suppress the vibrations, it should be noted that the current reported notch filters are based on fixed center frequency, making it challenging to enable high effectiveness over a broad range of rotor speeds, particularly in cases where the gyroscopic effect is significant. Herein, a modal vibration suppression based on a varying-frequency notch filter is proposed, considering gyroscopic effect and interface contact. First, the rotor–AMB system was developed, taking into consideration the bolted-joint interface contact. This modeled the effect of the interface contact as a time-varying force in the positive feedback. Secondly, the relationship between vibration frequency and rotational speed was obtained, based on simulations. Lastly, a test rig was configured to validate the performance of the frequency-varying notch filter. The experimental data confirm that the filter is capable of attenuating the modal vibrations resulting from interface contact across all operational speeds. Full article
(This article belongs to the Special Issue Advanced Theory and Application of Magnetic Actuators—2nd Edition)
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16 pages, 6005 KiB  
Article
Nonlinear Optimal Control for Spacecraft Rendezvous and Docking Using Symplectic Numerical Method
by Zhengtao Wei, Jie Yang, Hao Wen, Dongping Jin and Ti Chen
Actuators 2025, 14(2), 75; https://doi.org/10.3390/act14020075 - 6 Feb 2025
Viewed by 339
Abstract
This paper addresses the autonomous rendezvous and docking between a chaser spacecraft and a target spacecraft. An optimal control method is employed to plan the rendezvous and docking maneuver, considering various constraints, including force, velocity, field of view, and collision avoidance with a [...] Read more.
This paper addresses the autonomous rendezvous and docking between a chaser spacecraft and a target spacecraft. An optimal control method is employed to plan the rendezvous and docking maneuver, considering various constraints, including force, velocity, field of view, and collision avoidance with a diamond-shaped obstacle. The optimal trajectories are derived using a symplectic algorithm, which ensures high accuracy and enhances computational efficiency. These trajectories serve as the reference for the maneuver. A PD-based tracking control method is proposed to enable real-time feedback control. An air-bearing experimental system, encompassing state measurement, data transmission, and processing, is established to conduct ground-based tracking experiments. Furthermore, specialized simulators for the chaser and target spacecraft, equipped with a docking mechanism, are designed. Experimental results validate both the feasibility of the reference trajectories and the effectiveness of the PD tracking control approach. Full article
(This article belongs to the Special Issue Dynamics and Control of Aerospace Systems—2nd Edition)
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24 pages, 6972 KiB  
Article
Efficient and High-Precision Method of Calculating Maximum Singularity-Free Space in Stewart Platform Based on K-Means Clustering and CNN-LSTM-Attention Model
by Jie Tao, Huicheng Zhou and Wei Fan
Actuators 2025, 14(2), 74; https://doi.org/10.3390/act14020074 - 6 Feb 2025
Viewed by 265
Abstract
The determination of maximum singularity-free space is critical to structural design and motion control strategy in the Stewart platform. Nevertheless, in practical applications, there exist several limitations such as computational efficiency, calculation precision, and the reliability of computational results. To overcome those shortcomings, [...] Read more.
The determination of maximum singularity-free space is critical to structural design and motion control strategy in the Stewart platform. Nevertheless, in practical applications, there exist several limitations such as computational efficiency, calculation precision, and the reliability of computational results. To overcome those shortcomings, this work proposes an efficient and high-precision method for computing the maximum singularity-free space within the Stewart platform. Firstly, apply K-Means clustering to group the variables, including the range, mean, and standard deviation of driving rod lengths, and the clustering centroids and extreme rod lengths collectively form a set of scenarios to avoid large-scale searching. An additional sorting methodology with a specific parameter is proposed for sorting the aforementioned scenarios in descending order and detecting singular-prone cases. Secondly, compute the initial solution for maximum singularity-free length without gimbal lock through an analytical solution formula, enabling reduction in the search scope. Thirdly, introduce a novel scaling factor to resolve the problem of dimensional inconsistency between rotation and translation within the Jacobian matrix using dual quaternions, and determine the singularity based on the determinant of the newly proposed Jacobian matrix. Finally, employ a CNN-LSTM-Attention model for a secondary verification procedure, specifically targeting the challenge of singularities encountered when solving the forward kinematics of the Stewart platform using zero-position values. The experiments demonstrate that the accelerated discretization method for maximum singularity-free joint space and workspace is applicable to devices with diverse geometric configurations. For two practical Stewart platforms, compared with two conventional methods, this method improves computational efficiency and precision significantly. The computation time of the first platform is reduced by 97.54% and 98.07% respectively, while that of the second platform is cut by 80.84% and 81.80% respectively. In terms of precision, the first platform demonstrates 95.83% and 78% improvement respectively, and the second platform attains 99.99% improvement over two conventional methods. Full article
(This article belongs to the Section Precision Actuators)
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19 pages, 21955 KiB  
Article
Research on Dynamic Modeling and Control of Magnetorheological Hydro-Pneumatic Suspension
by Yuansi Chen, Min Jiang, Fufeng Yang, Ruijing Qian, Rongjie Zhai, Hongliang Wang and Shaoqing Xv
Actuators 2025, 14(2), 73; https://doi.org/10.3390/act14020073 - 5 Feb 2025
Viewed by 361
Abstract
A novel magnetorheological semi-active hydro-pneumatic suspension system was proposed to overcome the shortcoming of the traditional hydro-pneumatic suspension without adaptive vibration damping function. It is based on the magnetorheological semi-active vibration reduction technology to effectively improve the ride performance of the vehicle. Firstly, [...] Read more.
A novel magnetorheological semi-active hydro-pneumatic suspension system was proposed to overcome the shortcoming of the traditional hydro-pneumatic suspension without adaptive vibration damping function. It is based on the magnetorheological semi-active vibration reduction technology to effectively improve the ride performance of the vehicle. Firstly, a nonlinear model was established with the Bouc–Wen model based on the mechanical property test results of magnetorheological hydro-pneumatic spring. Secondly, the dynamic model of the single-wheel magnetorheological hydro-pneumatic suspension system was established. Subsequently, the ON-OFF and PID-Fuzzy semi-active control strategies of the single-wheel magnetorheological hydro-pneumatic suspension were proposed based on the ON-OFF and PID-Fuzzy control methods. The simulation results demonstrate that the magnetorheological hydro-pneumatic suspension under PID-Fuzzy control has the best vibration reduction effect in comparison with the passive hydro-pneumatic suspension. The sprung mass acceleration, suspension working space, and dynamic tire deformation are reduced by 24.50%, 21.62%, and 21.01%, respectively. The bench test results verify that magnetorheological hydro-pneumatic suspension and its control methods can effectively improve the ride performance of the system. Full article
(This article belongs to the Section Actuators for Surface Vehicles)
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13 pages, 7890 KiB  
Article
Implementation of an Active Ankle-Foot Orthosis Prototype with a Cam-Driven Actuator
by Carlos Armando Lara-Velazquez, Juan-Pablo Ramirez-Paredes, Felipe J. Torres, Israel Martínez-Ramírez, Jeymar Baron-Casique, Diego A. Núñez-Altamirano and Beatriz Verónica González-Sandoval
Actuators 2025, 14(2), 72; https://doi.org/10.3390/act14020072 - 5 Feb 2025
Viewed by 455
Abstract
The high prevalence of conditions leading to foot drop highlights the need for devices that restore functionality, enabling patients to regain a natural gait pattern. There is a demand for a portable, lightweight, low-cost, and efficient active ankle-foot orthosis. In this work, we [...] Read more.
The high prevalence of conditions leading to foot drop highlights the need for devices that restore functionality, enabling patients to regain a natural gait pattern. There is a demand for a portable, lightweight, low-cost, and efficient active ankle-foot orthosis. In this work, we present the prototype of a new design that was simulated in a previous contribution, with a test bench evaluation of the low-level control. The dynamical behavior of a cam suspension interaction with a proportional–integral–derivative controller system for transmission is evaluated. The proposed active orthosis includes a novel cam-based actuator, designed to intervene at the dorsiflexion stage of gait, without influencing the plantar flexion. This design is aimed at specific lower limb ailments that cause a need for assistance only in raising the foot, and it leverages a commercial servomotor to achieve ankle angle tracking. System identification was performed using a test bench, with three degrees of freedom to emulate tibial motion during gait. Response evaluations of the device showed low values for the integral time squared error, peak overshoot, and settling time for step inputs, with and without additional periodic perturbations. The root mean squared error of the device while tracking an ankle angle signal varied from 0.1 to 6.5 degrees, depending on the speed of the changes. Full article
(This article belongs to the Special Issue Actuators and Robotic Devices for Rehabilitation and Assistance)
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17 pages, 17195 KiB  
Article
The Design and Analysis of a Lightweight Robotic Arm Based on a Load-Adaptive Hoisting Mechanism
by Ruchao Wang, Zhiguo Lu, Yiru Wang and Zhongqing Li
Actuators 2025, 14(2), 71; https://doi.org/10.3390/act14020071 - 5 Feb 2025
Viewed by 536
Abstract
This paper presents the design and control of a lightweight three degrees of freedom robotic arm based on a load-adaptive hoisting mechanism. The proposed design integrates a spring-loaded rope and a variable radius reel into the gripper, enabling efficient load adaptability with minimal [...] Read more.
This paper presents the design and control of a lightweight three degrees of freedom robotic arm based on a load-adaptive hoisting mechanism. The proposed design integrates a spring-loaded rope and a variable radius reel into the gripper, enabling efficient load adaptability with minimal structural complexity. By leveraging this mechanism, the robotic arm achieves significant weight reduction while maintaining robust performance under variable payloads. The study includes a comprehensive analysis of the system’s kinematics and dynamics, focusing on the interaction between the adaptive gripper and the arm structure. A prototype of the robotic arm was developed and experimentally tested to validate its functionality. Full article
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17 pages, 4557 KiB  
Article
Deep Neural Network for Valve Fault Diagnosis Integrating Multivariate Time-Series Sensor Data
by Eugene Jeong, Jung-Hwan Yang and Soo-Chul Lim
Actuators 2025, 14(2), 70; https://doi.org/10.3390/act14020070 - 5 Feb 2025
Viewed by 407
Abstract
Faults in valves that regulate fluid flow and pressure in industrial systems can significantly degrade system performance. In systems where multiple valves are used simultaneously, a single valve fault can reduce overall efficiency. Existing fault diagnosis methods struggle with the complexity of multivariate [...] Read more.
Faults in valves that regulate fluid flow and pressure in industrial systems can significantly degrade system performance. In systems where multiple valves are used simultaneously, a single valve fault can reduce overall efficiency. Existing fault diagnosis methods struggle with the complexity of multivariate time-series data and unseen fault scenarios. To overcome these challenges, this study proposes a method based on a one-dimensional convolutional neural network (1D CNN) for diagnosing the location and severity of valve faults in a multi-valve system. An experimental setup was constructed with 17 sensors, including 8 pressure sensors at the inlets and outlets of 4 valves, 4 flow sensors, and 5 pressure sensors along the main pipe. Sensor data were collected to observe the sensor values corresponding to valve behavior, and foreign objects of varying sizes were inserted into the valves to simulate faults of different severities. These data were used to train and evaluate the proposed model. The proposed method achieved robust prediction accuracy (MAE: 0.0306, RMSE: 0.0629) compared to existing networks, performing on both trained and unseen fault severities. It identified the location of the faulty valve and quantified fault severity, demonstrating generalization capabilities. Full article
(This article belongs to the Section Actuators for Manufacturing Systems)
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21 pages, 7030 KiB  
Article
Strength Analysis and Design of a Multi-Bridge V-Shaped Rotor for High-Speed Interior Permanent Magnet Synchronous Motors
by Kun Zhou, Dongxiong Wang, Zewen Yu, Xianju Yuan, Ming Zhang and Yu Zheng
Actuators 2025, 14(2), 69; https://doi.org/10.3390/act14020069 - 3 Feb 2025
Viewed by 528
Abstract
High-speed operation is a crucial approach for achieving high power density of drive motors for new energy vehicles. However, mechanical strength of the rotor has become the primary bottleneck in the development of high-speed drive motors. Adopting a multi-bridge structure can effectively enhance [...] Read more.
High-speed operation is a crucial approach for achieving high power density of drive motors for new energy vehicles. However, mechanical strength of the rotor has become the primary bottleneck in the development of high-speed drive motors. Adopting a multi-bridge structure can effectively enhance the mechanical strength of the V-shaped rotors widely used in interior permanent magnet synchronous motors (IPMSMs). Firstly, based on the equivalent centroid principle, the centrifugal forces generated by the rotor’s pole shoes and permanent magnets are calculated. An improved centrifugal force method is proposed to establish an analytical mechanical model of the multi-bridge V-shaped rotor structure. This method comprehensively considers the force conditions, deformation constraints, and material properties of the magnetic bridges. Additionally, stress concentration is taken into account to ensure the accuracy of the model. The effects of various structural parameters on the maximum mechanical stress and deformation are then analyzed. These parameters include the V-angle, pole shoe angle, and the dimensions of three types of magnetic bridges, namely, the central bridge, air-gap bridge, and middle bridge. Finally, recommendations for selecting structural parameters in the mechanical strength design of multi-bridge V-shaped rotors are summarized. The effectiveness of the proposed rotor structure is verified through finite element method and experiments. Full article
(This article belongs to the Section High Torque/Power Density Actuators)
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17 pages, 2258 KiB  
Article
Nonlinearity Harmonic Error Compensation Method Based on Intelligent Identification for Rate Integrating Resonator Gyroscope
by Xiaodi Yi, Gongliu Yang, Qingzhong Cai and Yongqiang Tu
Actuators 2025, 14(2), 68; https://doi.org/10.3390/act14020068 - 3 Feb 2025
Viewed by 454
Abstract
This paper presents an improved intelligent optimizing algorithm based on parameter identification and drift compensation for the rate-integrating resonator gyroscope (RIRG). Besides damping and frequency imperfections, the RIRG measurement accuracy still suffers from limitations due to nonlinear error. Therefore, the dynamic nonlinear error [...] Read more.
This paper presents an improved intelligent optimizing algorithm based on parameter identification and drift compensation for the rate-integrating resonator gyroscope (RIRG). Besides damping and frequency imperfections, the RIRG measurement accuracy still suffers from limitations due to nonlinear error. Therefore, the dynamic nonlinear error model for RIRG has been established to reveal the relationship between the pattern angle and harmonic drifts. Based on this, a dynamic analysis of the gyroscope operating state is carried out using nonlinear motion equations. The optimal harmonic error parameters are then identified by a particle swarm optimization (PSO) algorithm for the drift error compensation. To further improve the measurement accuracy, chaotic technology is integrated with PSO, leading to more precise identification. Subsequently, the harmonic parameters of the bias drifts are efficiently compensated. Experimental results demonstrate that the bias drift is reduced by over 90% after harmonic error compensation, demonstrating the validity of the proposed method in enhancing the measurement accuracy of RIRGs. Full article
(This article belongs to the Section Precision Actuators)
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