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Machines, Volume 13, Issue 9 (September 2025) – 96 articles

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15 pages, 3478 KB  
Article
Second-Order Complex-Coefficient Flux Observer with Stator Resistance Estimation for Induction Motor Sensorless Drives
by Kun Zhao, Bao Song, Xiaoqi Tang and Xiangdong Zhou
Machines 2025, 13(9), 845; https://doi.org/10.3390/machines13090845 (registering DOI) - 11 Sep 2025
Abstract
The voltage model (VM) is widely used in sensorless induction motor drives owing to its structural simplicity and speed-independence. However, DC offsets in back electromotive force (BEMF) caused by measurement errors can degrade the accuracy of flux and speed estimation. To address this [...] Read more.
The voltage model (VM) is widely used in sensorless induction motor drives owing to its structural simplicity and speed-independence. However, DC offsets in back electromotive force (BEMF) caused by measurement errors can degrade the accuracy of flux and speed estimation. To address this issue, this article proposes a second-order complex-coefficient flux observer (SCFO) that effectively eliminates DC offsets without introducing phase delay and amplitude attenuation, while maintaining excellent dynamic performance. Furthermore, to enhance the robustness of the flux observer against stator resistance variations, an improved stator resistance adaptive law based on the rotating reference frame is proposed. Ultimately, experimental validation on a 1.5 kW induction motor drive platform confirms the effectiveness of the proposed sensorless scheme. Full article
(This article belongs to the Section Electrical Machines and Drives)
42 pages, 7474 KB  
Review
A Critical Review of Ultrasonic-Assisted Machining of Titanium Alloys
by Muhammad Fawad Jamil, Qilin Li, Mohammad Keymanesh, Pingfa Feng and Jianfu Zhang
Machines 2025, 13(9), 844; https://doi.org/10.3390/machines13090844 - 11 Sep 2025
Abstract
Ultrasonic-assisted machining (UAM) has emerged as a transformative technology for increasing material removal efficiency, improving surface quality and extending tool life in precision manufacturing. This review specifically focuses on the application of it to titanium aluminide (TiAl) alloys. These alloys are widely used [...] Read more.
Ultrasonic-assisted machining (UAM) has emerged as a transformative technology for increasing material removal efficiency, improving surface quality and extending tool life in precision manufacturing. This review specifically focuses on the application of it to titanium aluminide (TiAl) alloys. These alloys are widely used in aerospace and automotive sectors due to their low density, high strength and poor machinability. This review covers various aspects of UAM, including ultrasonic vibration-assisted turning (UVAT), milling (UVAM) and grinding (UVAG), with emphasis on their influence on the machinability, tool wear behavior and surface integrity. It also highlights the limitations of single-energy field UAM, such as inconsistent energy transmission and tool fatigue, leading to the increasing demand for multi-field techniques. Therefore, the advanced machining strategies, i.e., ultrasonic plasma oxidation-assisted grinding (UPOAG), protective coating-assisted cutting, and dual-field ultrasonic integration (e.g., ultrasonic-magnetic or ultrasonic-laser machining), were discussed in terms of their potential to further improve TiAl alloys processing. In addition, the importance of predictive force models in optimizing UAM processes was also highlighted, emphasizing the role of analytical and AI-driven simulations for better process control. Overall, this review underscores the ongoing evolution of UAM as a cornerstone of high-efficiency and precision manufacturing, while providing a comprehensive outlook on its current applications and future potential in machining TiAl alloys. Full article
(This article belongs to the Special Issue Non-Conventional Machining Technologies for Advanced Materials)
23 pages, 2209 KB  
Article
Rotor-Driven Blade Rotor Volumetric Pump: Enhanced Stability and Flow Uniformity via Kinematic Optimization
by Yuanping He, Feifei Zhao, Bin Lin, Tianyi Sui, Liang Fang and Xingfu Hong
Machines 2025, 13(9), 843; https://doi.org/10.3390/machines13090843 - 11 Sep 2025
Abstract
The Blade Rotor Volumetric Pump (BRVP) integrates the operational advantages of vane pumps and positive displacement pumps, enabling a single unit to efficiently achieve both a high flow rate and a high head. This represents a significant expansion of the existing pump design [...] Read more.
The Blade Rotor Volumetric Pump (BRVP) integrates the operational advantages of vane pumps and positive displacement pumps, enabling a single unit to efficiently achieve both a high flow rate and a high head. This represents a significant expansion of the existing pump design spectrum. However, performance testing of the initial Blade-Driven BRVP (BD-BRVP) prototype revealed critical challenges requiring resolution, including the absence of established design theory and unsatisfactory operational smoothness. This study presents a comprehensive analysis of the BD-BRVP’s design principles, mechanical system, and flow characteristics, grounded in the kinematics of a rotationally symmetric crank-guide rod mechanism. Building on this analysis, we propose an innovative Rotor-Driven BRVP (RD-BRVP) configuration. Our results demonstrate that the RD-BRVP significantly outperforms the BD-BRVP in force transmission efficiency and operational smoothness. Specifically, the RD-BRVP exhibits a 42.5% reduction in rotational speed fluctuation and a 20.75% decrease in flow pulsation rate compared to the BD-BRVP. These performance enhancements are conclusively validated through experimental testing. This research advances the technological maturity of the BRVP concept and establishes a foundation for its future practical deployment. Full article
(This article belongs to the Section Turbomachinery)
23 pages, 4276 KB  
Article
Mechanistic Analysis of Textured IEL and Meshing ASLBC Synergy in Heavy Loads: Characterizing Predefined Micro-Element Configurations
by Jiafu Ruan, Xigui Wang, Yongmei Wang and Weiqiang Zou
Machines 2025, 13(9), 842; https://doi.org/10.3390/machines13090842 - 11 Sep 2025
Abstract
Friction contact regulation has been widely acknowledged, yet research on micro-textured meshing interfaces appears to have reached an impasse. Conventional wisdom holds that the similarity of micro-element configurations is the key factor contributing to textured interface issues. The traditional perception is transcended, and [...] Read more.
Friction contact regulation has been widely acknowledged, yet research on micro-textured meshing interfaces appears to have reached an impasse. Conventional wisdom holds that the similarity of micro-element configurations is the key factor contributing to textured interface issues. The traditional perception is transcended, and a novel method for presetting the optimal parameters of gradientized micro-textured interface elements is proposed. The study has analyzed the Interface Enriched Lubrication (IEL) performance and meshing Anti-Scuffing Load-Bearing Capacity (ASLBC) of periodic symmetrical and continuously gradient micro-elements. By actively regulating IEL behavior through geometric constraint effects, dynamic micro-cavity lubrication storage units are formed, thereby extending the retention time of medium film layers. The textured edges induce micro-vortices, delaying scuffing failures induced by load-bearing. Validation analyses demonstrate that optimal micro-element configurations can distribute contact stress to achieve stress homogenization, with the maximum contact stress reduced by 21%. The localized hydrodynamic effect of micro-textured elements increases interfacial meshing stiffness by 5.32% while decreasing friction torque by 27.3%. This investigation reveals a synergistic mechanism between IEL performance and meshing ASLBC under heavy loads conditions. The findings confirm that gradient-based micro-textured element configuration presetting offers an effective solution to reconcile the inherent trade-off between lubrication and load-bearing performance in heavy loads applications. Full article
(This article belongs to the Section Friction and Tribology)
32 pages, 38675 KB  
Article
Comparative Study and Multi-Objective Optimization of Electromagnetic Performance of Permanent Magnet Vernier Motors with Rotor Auxiliary Teeth
by Yujun Shi, Wenlei Zhao, Qingqing Liu, Jiwei Wang, Yaogang Liu and Haifeng Lu
Machines 2025, 13(9), 841; https://doi.org/10.3390/machines13090841 - 11 Sep 2025
Abstract
Permanent magnet vernier motors (PMVMs) have significant advantages in low-speed direct-drive fields on account of their high torque density, and their performance improvement is still a research hotspot. To enhance the overall electromagnetic performance and provide an alternative solution for low-speed direct-drive applications, [...] Read more.
Permanent magnet vernier motors (PMVMs) have significant advantages in low-speed direct-drive fields on account of their high torque density, and their performance improvement is still a research hotspot. To enhance the overall electromagnetic performance and provide an alternative solution for low-speed direct-drive applications, this paper proposes a permanent magnet vernier motor with rotor auxiliary teeth (denoted as “RAT-PMVM”). Firstly, the structure and working principle of RAT-PMVM are introduced. Then, the two-dimensional (2D) finite element method (FEM) is used to comparatively study the influence of the number, position, and tooth profile of the rotor auxiliary teeth on the electromagnetic performance of the proposed motor. The results show that the RAT-PMVM with trapezoidal teeth (denoted as “TT-PMVM”) achieved improvement in output torque, efficiency, and power factor: the output torque increased from 11.32 Nm to 14.19 Nm, the efficiency increased from 88.5% to 92.2%, and the power factor increased from 0.60 to 0.71. Finally, in order to further reduce the torque ripple and improve the torque, power factor, and efficiency, multi-objective optimization of the TT-PMVM is carried out. The optimization yields a 27.3% increase in torque, a 31.8% reduction in torque ripple ratio, an efficiency improvement from 92.2% to 93%, and a power factor enhancement from 0.73 to 0.81, demonstrating significant potential for low-speed direct-drive applications like industrial robots and wind power generation. Full article
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3 pages, 176 KB  
Correction
Correction: Li et al. Mechanism Design of a Novel Device to Facilitate Mobility, Sit-to-Stand Transfer Movement, and Walking Assistance. Machines 2025, 13, 134
by Bo Li, Xinzhili Chen, Hailiang Liu, Dong Yuan, Jiafeng Zhang and Shiqing Lu
Machines 2025, 13(9), 840; https://doi.org/10.3390/machines13090840 - 11 Sep 2025
Abstract
In the original publication [...] Full article
20 pages, 5202 KB  
Article
Orifice Leak Detection in Atmospheric Vertical Cylindrical Storage Tanks Based on SVM
by Gengfeng Zheng, Fuqiang Chen, Xiaohan Liu, Feng Liu and Jinhua Ye
Machines 2025, 13(9), 839; https://doi.org/10.3390/machines13090839 - 10 Sep 2025
Abstract
Leak detection in atmospheric vertical storage tanks is crucial for preventing environmental pollution, ensuring production safety, and reducing economic losses. This study investigates orifice leaks in vertical cylindrical storage tanks under atmospheric pressure using FLUENT 16.0. The simulation reveals a significant abrupt pressure [...] Read more.
Leak detection in atmospheric vertical storage tanks is crucial for preventing environmental pollution, ensuring production safety, and reducing economic losses. This study investigates orifice leaks in vertical cylindrical storage tanks under atmospheric pressure using FLUENT 16.0. The simulation reveals a significant abrupt pressure change at the leak location. Based on the simulation findings, the actual acquired pressure signals during leakage are processed with wavelet threshold denoising, confirming the abrupt pressure change characteristic. Time-domain and waveform features of the denoised signals are extracted to establish a support vector machine (SVM)-based leak detection model. The performance of different kernel functions is compared, with the linear kernel achieving the highest accuracy of 96.55%. Full article
(This article belongs to the Section Machines Testing and Maintenance)
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30 pages, 7047 KB  
Article
Performance Optimization of Savonius VAWTs Using Wind Accelerator and Guiding Rotor House for Enhanced Rooftop Urban Energy Harvesting
by Farzad Ghafoorian, Seyed Reza Mirmotahari, Shayan Farajyar, Mehdi Mehrpooya and Mahmood Shafiee
Machines 2025, 13(9), 838; https://doi.org/10.3390/machines13090838 - 10 Sep 2025
Abstract
Savonius drag-based rotors, a type of vertical-axis wind turbine (VAWT), are well-suited for urban environments—particularly residential rooftops—owing to their compact design and ability to capture wind from all directions. However, their relatively low efficiency and narrow operational range pose significant challenges, such as [...] Read more.
Savonius drag-based rotors, a type of vertical-axis wind turbine (VAWT), are well-suited for urban environments—particularly residential rooftops—owing to their compact design and ability to capture wind from all directions. However, their relatively low efficiency and narrow operational range pose significant challenges, such as limited energy output under variable wind conditions and reduced performance across a broad range of tip speed ratios. To address these issues, this study explores flow augmentation using strategically placed deflectors, referred to as Wind Accelerators and Guiding Rotor Houses (WAG-RHs). Four different configurations, including double, triple, oblique, and straight designs, were evaluated against both omni-directional guide vanes (ODGVs) and a conventional rotor. The findings show that the ODGV configuration successfully extends the operational range from a tip speed ratio of 0.5 to 0.6—termed the extended performance point (EPP)—and increases the power coefficient (Cp) by up to 300% compared to the conventional design. Among all setups, the straight WAG-RH configuration proved most effective, not only achieving the EPP but also delivering a 385% and 264.3% increase in local and AVE Cp values, respectively compared to the conventional rotor. It also outperformed the ODGV-equipped rotor by 25%, thanks to its radial and dual-plane arrangement. Full article
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16 pages, 2638 KB  
Article
Global Stiffness Modeling of Robot Drilling System Incorporating End-Effector and Arm Flexibility Based on Virtual Joint Method
by Yao-Feng Zhang, Bao-Guo Yao, Fei Zhang, Xi-Feng Liang, Geng Tao, Yu-Xun Ge and Teng-Fei Niu
Machines 2025, 13(9), 837; https://doi.org/10.3390/machines13090837 - 9 Sep 2025
Abstract
In the new digital era, industrial robots are central to machining and flexible production in intelligent manufacturing. However, the rigidity of the six degrees-of-freedom (DOFs) serial robot is insufficient, which leads to chatter during machining and limits its application in high-precision machining, especially [...] Read more.
In the new digital era, industrial robots are central to machining and flexible production in intelligent manufacturing. However, the rigidity of the six degrees-of-freedom (DOFs) serial robot is insufficient, which leads to chatter during machining and limits its application in high-precision machining, especially in the field of drilling, reaming and milling. A new method was proposed for modeling the global stiffness of the robot drilling system that incorporated the end-effector. Based on the virtual joint method and linear superposition principle, and considering the flexibility of the robot arm, the global stiffness model of the robot drilling system was established by simplifying the modeling process with dual quaternion. The results of the model validation experiments of deformation show that the maximum relative error of resultant end deformation is 8.80%, and the average relative error of resultant end deformation is 7.21%. This method provides a new method of global stiffness modeling for the robot drilling system, including the end-effector, and a new approach for stiffness improvement to overcoming the problem of insufficient robot stiffness in intelligent manufacturing industry. Full article
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14 pages, 2508 KB  
Article
Automated Weld Defect Detection in Radiographic Images Using Normalizing Flows
by Morteza Mahvelatishamsabadi and Sudong Lee
Machines 2025, 13(9), 836; https://doi.org/10.3390/machines13090836 - 9 Sep 2025
Abstract
Anomaly detection is a pressing issue, particularly in industrial images. Detecting weld defects in radiographic images is a challenge due to the small signal-to-noise ratio (SNR) and the limited availability of data. In this paper, we propose an automated weld defect detection method [...] Read more.
Anomaly detection is a pressing issue, particularly in industrial images. Detecting weld defects in radiographic images is a challenge due to the small signal-to-noise ratio (SNR) and the limited availability of data. In this paper, we propose an automated weld defect detection method using Normalizing Flows (NFs). We employed various state-of-the-art NF architectures with different feature extractors to detect defects in radiographic images of welds, comprehensively comparing the results with radiographic images of welded steel pipes collected from industrial sites. The results show that the combination of CFlow-AD with a wide residual network-50-2 (WRN-50-2) outperformed the other methods, indicating its effectiveness in anomaly detection. Full article
(This article belongs to the Special Issue Reliability in Mechanical Systems: Innovations and Applications)
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34 pages, 951 KB  
Article
The Digital Maturity of Small- and Medium-Sized Enterprises in the Saguenay-Lac-Saint-Jean Region
by Gautier George Yao Quenum, Stéfanie Vallée and Myriam Ertz
Machines 2025, 13(9), 835; https://doi.org/10.3390/machines13090835 - 9 Sep 2025
Abstract
This study examines the digital maturity of small- and medium-sized enterprises (SMEs) in the context of Industry 4.0. Despite growing awareness of the importance of digital transformation, many SMEs encounter structural and strategic challenges that impede their progress. Among their obstacles is the [...] Read more.
This study examines the digital maturity of small- and medium-sized enterprises (SMEs) in the context of Industry 4.0. Despite growing awareness of the importance of digital transformation, many SMEs encounter structural and strategic challenges that impede their progress. Among their obstacles is the inadequacy of digital maturity models used to diagnose digital maturity levels in SMEs due to their typological, sectoral, geographical, and other specific characteristics. Using a constructivist and qualitative approach, we have developed a simplified, inclusive, and holistic assessment framework comprising six key dimensions (technology, culture, organization, people and human resources, strategic planning), associated with six progressive maturity levels. Our findings reveal that most SMEs studied in 2023 exhibit a beginner level of digital maturity. These enterprises are characterized by small-scale digital initiatives, often lacking a clear strategy, with limited or partial digitization of processes and heterogeneous technology adoption. The resulting self-assessment tool provides SMEs with practical guidance to launch, evaluate, and accelerate their digital transformation. This study contributes theoretically by proposing a practical digital maturity model and offering a tool to support SMEs and public policy. It highlights the need for tailored support, strategic alignment, and continuous training to unlock the full potential of Industry 4.0 in less urbanized and resource-constrained areas. Full article
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25 pages, 10618 KB  
Article
Study of the Water Vapor Desublimation Effect on the Camber Morphing Wing Considering Cryogenic Environments
by Yu Zhang, Baobin Hou, Yuchen Li, Yuanjing Wang, Binbin Lv, Guojun Lai and Jingyuan Wang
Machines 2025, 13(9), 834; https://doi.org/10.3390/machines13090834 - 9 Sep 2025
Abstract
The variable camber morphing wing has the potential to achieve improved flight performance across different flight conditions by changing its geometry according to changing flight conditions. Evaluating the subtle aerodynamic benefits of variable camber technology necessitates wind tunnel testing under flight Reynolds number [...] Read more.
The variable camber morphing wing has the potential to achieve improved flight performance across different flight conditions by changing its geometry according to changing flight conditions. Evaluating the subtle aerodynamic benefits of variable camber technology necessitates wind tunnel testing under flight Reynolds number conditions. In high Reynolds number wind tunnels, the cryogenic environment readily damages model surface profiles through desublimation and frost, compromising test data accuracy. Consequently, cryogenic wind tunnels must enforce rigorous water vapor control standards. To address potential water vapor effects during cryogenic wind tunnel testing, high-resolution optical measurement techniques were employed to quantify the spatiotemporal evolution of desublimation frost thickness on a typical supercritical airfoil surface. Combined with numerical simulations, the mechanisms governing the frost layer’s influence on aerodynamic characteristics and flow field structures were systematically investigated. The results reveal that the influence of water vapor desublimation on the aerodynamic characteristics under diverse cryogenic working conditions has a commonality, and the difference in aerodynamic parameters shows an increasing tendency as the frost time increases; water vapor desublimation has an obvious influence on the flow structure of the airfoil and its pressure distribution on the surface, which increases flow instability and leads to the backward shift of the shock wave position; larger frost thickness gradients along the flow direction cause more drastic changes in pressure distribution and flow structure; and a larger rate of water vapor desublimation results from a lower temperature and a higher concentration of water vapor in the test environment, which causes frosting to have a more severe impact on the airfoil’s aerodynamic characteristics and flow structure. The findings establish a technical basis for cryogenic wind tunnel moisture control standards and provide a solid foundation for the refined assessment of aerodynamic benefits of the camber morphing wing. Full article
(This article belongs to the Special Issue Smart Structures and Applications in Aerospace Engineering)
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16 pages, 9817 KB  
Article
Synthesizing a Spatial Mechanism with a Hollow Core for Use in a Wrist Pronation and Supination Orthotic
by Tianze Xu, David H. Myszka, Clément Trotobas, Christine Azevedo and Andrew P. Murray
Machines 2025, 13(9), 833; https://doi.org/10.3390/machines13090833 - 9 Sep 2025
Abstract
Full use of the upper limb is necessary to carry out most tasks of daily life. Upper limb deficiencies, whether through complete or incomplete paralysis, inevitably lead to a loss of autonomy. Assistive orthoses are a potential method for restoring some autonomy. Pronation [...] Read more.
Full use of the upper limb is necessary to carry out most tasks of daily life. Upper limb deficiencies, whether through complete or incomplete paralysis, inevitably lead to a loss of autonomy. Assistive orthoses are a potential method for restoring some autonomy. Pronation and supination, the turning of the wrist relative to the elbow, receives less focus than other joint movements in the arm. First, the utility of this degree-of-freedom in the arm is less obvious. Second, when compared to flexion and extension of the elbow, wrist prono-supination has no clear center of rotation due to the combined movement of the ulna and the radius bones as they cross and uncross in the forearm. This paper presents initial work in the design of a mechanism for a portable assistive orthosis that is expected to include powered prono-supination. The component proposed in this work is based on a spherical mechanism architecture. The capacity of these mechanisms to have a hollow center and to produce paths that follow arcs on spheres makes them worth consideration in this application. An optimization was carried out to perform path generation of a single spherical four-bar with the intent of replicating it three times to create the device proposed in this work. The mechanical design was modeled and a conceptual prototype was constructed to perform preliminary operational evaluations. Full article
(This article belongs to the Collection Machines, Mechanisms and Robots: Theory and Applications)
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13 pages, 2418 KB  
Article
Pareto Front Optimization for Spiral-Grooved High-Speed Thrust Bearings: Comparison Between Analytical and Numerical Models
by Federico Colombo, Edoardo Goti and Luigi Lentini
Machines 2025, 13(9), 832; https://doi.org/10.3390/machines13090832 - 9 Sep 2025
Abstract
This paper compares two multi-objective optimization strategies for spiral-grooved dynamic gas thrust bearings. The first optimization is carried out using an analytical model, which is valid under the assumption of a high number of grooves. The second one is carried out by using [...] Read more.
This paper compares two multi-objective optimization strategies for spiral-grooved dynamic gas thrust bearings. The first optimization is carried out using an analytical model, which is valid under the assumption of a high number of grooves. The second one is carried out by using a numerical model based on a finite difference (FD) technique, which is valid also in case of a limited number of grooves. The FD model was validated with data from the literature, then it was compared with the analytical model. The multi-objective optimization is based on a genetic algorithm and it is aimed at maximizing the load-carrying capacity (LCC) of the thrust bearing while minimizing its friction torque. It was found that the analytical model overestimates both the friction torque and the load capacity compared to the FD model, and that the Pareto front optimizations reveal almost identical trends in the optimized parameters. Full article
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29 pages, 3929 KB  
Article
Large Language Model-Based Autonomous Agent for Prognostics and Health Management
by Minhyeok Cha, Sang-il Yoon, Seongrae Kim, Daeyoung Kang, Keonwoo Nam, Teakyong Lee and Joon-Young Kim
Machines 2025, 13(9), 831; https://doi.org/10.3390/machines13090831 - 9 Sep 2025
Abstract
Prognostics and Health Management (PHM), including fault diagnosis and Remaining Useful Life (RUL) prediction, is critical for ensuring the reliability and efficiency of industrial equipment. However, traditional AI-based methods require extensive expert intervention in data preprocessing, model selection, and hyperparameter tuning, making them [...] Read more.
Prognostics and Health Management (PHM), including fault diagnosis and Remaining Useful Life (RUL) prediction, is critical for ensuring the reliability and efficiency of industrial equipment. However, traditional AI-based methods require extensive expert intervention in data preprocessing, model selection, and hyperparameter tuning, making them less scalable and accessible in real-world applications. To address these limitations, this study proposes an autonomous agent powered by Large Language Models (LLMs) to automate predictive modeling for fault diagnosis and RUL prediction. The proposed agent processes natural language queries, extracts key parameters, and autonomously configures AI models while integrating an iterative optimization mechanism for dynamic hyperparameter tuning. Under identical settings, we compared GPT-3.5 Turbo, GPT-4, GPT-4o, GPT-4o-mini, Gemini-2.0-Flash, and LLaMA-3.2 on accuracy, latency, and cost, using GPT-4 as the baseline. The most accurate model is GPT-4o with an accuracy of 0.96, a gain of six percentage points over GPT-4. It also reduces end-to-end time to 1.900 s and cost to $0.00455 per 1 k tokens, which correspond to reductions of 32% and 59%. For speed and cost efficiency, Gemini-2.0-Flash reaches 0.964 s and $0.00021 per 1 k tokens with accuracy 0.94, an improvement of four percentage points over GPT-4. The agent operates through interconnected modules, seamlessly transitioning from query analysis to AI model deployment while optimizing model selection and performance. Experimental results confirmed that the developed agent achieved stable performance under ideal configurations, attaining accuracy 0.97 on FordA for binary fault classification, accuracy 0.95 on CWRU for multi-fault classification, and an asymmetric score of 380.74 on C-MAPSS FD001 for RUL prediction, while significantly reducing manual intervention. By bridging the gap between domain expertise and AI-driven predictive maintenance, this study advances industrial automation, improving efficiency, scalability, and accessibility. The proposed approach paves the way for the broader adoption of autonomous AI systems in industrial maintenance. Full article
(This article belongs to the Section Automation and Control Systems)
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24 pages, 3501 KB  
Article
Piezoelectric Harvester Proportional–Derivative (PHPD) Control for Nonlinear Dynamics Reduction in Underactuated Hybrid Systems
by Fatma Taha El-Bahrawy, Rageh K. Hussein, Ashraf Taha EL-Sayed and Moamen Wafaie
Machines 2025, 13(9), 830; https://doi.org/10.3390/machines13090830 - 9 Sep 2025
Abstract
This study investigates the nonlinear dynamics and control of an underactuated hybrid system consisting of a Duffing oscillator, a pendulum, and a piezoelectric energy harvester. A novel Piezoelectric Harvester Proportional–Derivative (PHPD) control scheme is introduced, which integrates the harvester’s electrical output directly into [...] Read more.
This study investigates the nonlinear dynamics and control of an underactuated hybrid system consisting of a Duffing oscillator, a pendulum, and a piezoelectric energy harvester. A novel Piezoelectric Harvester Proportional–Derivative (PHPD) control scheme is introduced, which integrates the harvester’s electrical output directly into the feedback loop to achieve simultaneous vibration suppression and energy utilization. The nonlinear governing equations are derived and analyzed using the Multiple-Scale Perturbation Technique (MSPT) to obtain reduced-order dynamics. Bifurcation analysis is employed to identify stability boundaries and critical parameter transitions, while numerical simulations based on the fourth-order Runge–Kutta method validate the analytical predictions. Furthermore, frequency response curves (FRCs) and an ideal system are evaluated under multiple controller and system parameter configurations. Bifurcation classification is performed on the analyzed figure to detect various bifurcations within the system, along with the computation of the Largest Lyapunov Exponent (LLE). The results demonstrate that PHPD control significantly reduces vibration amplitude and accelerates convergence, offering a new pathway for energy-efficient, high-performance control in nonlinear electromechanical systems. Full article
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30 pages, 12314 KB  
Article
Design of a High-Performance Biomimetic Butterfly Flyer
by Zhihan Li, Gaolei Qiu, Daqian Zhang and Hongshuang Li
Machines 2025, 13(9), 829; https://doi.org/10.3390/machines13090829 - 8 Sep 2025
Abstract
To achieve miniaturization and lightweight design of a flapping-wing aircraft, a high-performance biomimetic butterfly flyer was designed based on an analysis of the butterfly’s body structure and flight principles. The aircraft has a mass of 20.6 g and a wingspan of 0.295 m. [...] Read more.
To achieve miniaturization and lightweight design of a flapping-wing aircraft, a high-performance biomimetic butterfly flyer was designed based on an analysis of the butterfly’s body structure and flight principles. The aircraft has a mass of 20.6 g and a wingspan of 0.295 m. To validate the rationality of the design, sensitivity analysis of the flapping-wing drive mechanism was first conducted using MATLAB 2022B software, and the length of the driving rod was optimized. Subsequently, a dynamic model was established to calculate the aerodynamic performance of the flapping wing. Then, the aerodynamic performance of the aircraft was verified using simulation software (XFLOW 2022). Finally, the flight stability of the aircraft was validated using the SIMULINK toolbox. Flight test results show that the biomimetic butterfly flyer achieves a maximum flight speed of 0.9 m/s, a climb rate of 0.12 m/s, and a flight endurance of up to 3 min, with good flight stability. This design provides a new approach for the development of small and lightweight flapping-wing aircraft. Full article
(This article belongs to the Section Machine Design and Theory)
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20 pages, 5084 KB  
Article
Stability Enhancement and Bifurcation Mitigation in Nonlinear Inner Plate Oscillations Through PD Control
by Ashraf Taha EL-Sayed, Rageh K. Hussein, Yasser A. Amer and Marwa A. EL-Sayed
Machines 2025, 13(9), 828; https://doi.org/10.3390/machines13090828 - 8 Sep 2025
Abstract
Axially moving wings offer remarkable aerodynamic efficiency and adaptability; however, they are highly susceptible to detrimental vibrations that may compromise flight stability and structural integrity. Previous studies have mainly focused on simplified linear models or passive control approaches, leaving the nonlinear dynamic behavior [...] Read more.
Axially moving wings offer remarkable aerodynamic efficiency and adaptability; however, they are highly susceptible to detrimental vibrations that may compromise flight stability and structural integrity. Previous studies have mainly focused on simplified linear models or passive control approaches, leaving the nonlinear dynamic behavior and active vibration suppression insufficiently addressed. To overcome these limitations, this study models the wing as a simplified cantilever plate and investigates its nonlinear dynamics under varying load conditions. A proportional–derivative (PD) controller is employed, and approximate analytical solutions to the governing equations are derived using the multiple-scale perturbation method (MSPM). The system’s response under primary resonance is analyzed through frequency response and bifurcation studies, while stability is assessed using the Routh–Hurwitz criterion. Analytical findings are validated with numerical simulations in MATLAB R2023b. Furthermore, the influence of key structural parameters on system dynamics and controller performance is examined. The results demonstrate that the PD controller effectively suppresses vibrations, offering a reliable solution for enhancing the stability of axially moving wing systems. Full article
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24 pages, 8037 KB  
Article
Design, Analysis and Multi-Objective Optimization of a New Asymmetric Permanent Magnet Vernier Motor for Low-Speed High-Torque Applications
by Yujun Shi, Qingqing Liu, Wenlei Zhao, Jiwei Wang, Yaogang Liu and Haifeng Lu
Machines 2025, 13(9), 827; https://doi.org/10.3390/machines13090827 - 8 Sep 2025
Abstract
This paper proposes a new Asymmetric Permanent Magnet Vernier Motor (A-PMVM) for low-speed high-torque applications. Unlike conventional symmetric V-shaped PMVMs (SV-PMVMs), the A-PMVM features irregular U-shaped magnet arrays composed of asymmetric V-shaped magnets. Finite element analysis confirms its superior performance: 10.6% higher torque [...] Read more.
This paper proposes a new Asymmetric Permanent Magnet Vernier Motor (A-PMVM) for low-speed high-torque applications. Unlike conventional symmetric V-shaped PMVMs (SV-PMVMs), the A-PMVM features irregular U-shaped magnet arrays composed of asymmetric V-shaped magnets. Finite element analysis confirms its superior performance: 10.6% higher torque (19.67 N·m vs. 17.78 N·m), 22% reduced PM volume (37,500 mm3 vs. 48,000 mm3), and 53% lower cogging torque (0.32 N·m vs. 0.68 N·m peak-peak). While exhibiting higher initial torque ripple ratio (8.65%), multi-objective optimization suppresses torque ripple ratio by 5.32% (from 8.65% to 8.19%), reduces cogging torque 12.5% (from 0.32 N·m to 0.28 N·m), and enhances torque by 0.76% (from 19.67 N·m to 19.82 N·m). The optimized A-PMVM achieves a significant reduction in cogging torque and torque ripple ratio, demonstrating significant potential for applications like wind turbines and electric vehicles. Additionally, this paper confirms that the proposed motor maintains consistent performance during both clockwise and counterclockwise operation. Full article
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34 pages, 12322 KB  
Article
A Mechatronic Design Procedure for Self-Balancing Vehicles According to the MBSE Approach
by Paolo Righettini, Roberto Strada, Filippo Cortinovis and Jasmine Santinelli
Machines 2025, 13(9), 826; https://doi.org/10.3390/machines13090826 - 7 Sep 2025
Viewed by 184
Abstract
Several types of self-balancing vehicles have been successfully developed and commercialized in the past two decades, both as manned vehicles and as autonomous mobile robots. At the same time, due to their characteristic instability and underactuation, a large body of research has been [...] Read more.
Several types of self-balancing vehicles have been successfully developed and commercialized in the past two decades, both as manned vehicles and as autonomous mobile robots. At the same time, due to their characteristic instability and underactuation, a large body of research has been devoted to their control. However, despite this practical and theoretical interest, the current publicly available literature does not cover their systematic design and development. In particular, overall processes that lead to a finished vehicle starting from a set of requirements and specifications have not been examined in the literature. Within this context, this paper contributes a comprehensive mechatronic, dynamics-based procedure for the design of this class of vehicles; to promote clarity of exposition, the procedure is systematically presented using Model-Based Systems Engineering tools and principles. In particular, the proposed design method is developed and formalized starting from an original description of the vehicle, which is treated as a complex system composed of several interconnected multi-domain components that exchange power and logical flows through suitable interfaces. A key focus of this work is the analysis of these exchanges, with the goal of defining a minimal set of quantities that should be necessarily considered to properly design the vehicle. As a salient result, the design process is organized in a logical sequence of steps, each having well-defined inputs and outputs. The procedure is also graphically outlined using standardized formalisms. The design method is shown to cover all the mechanical, electrical, actuation, measurement and control components of the system, and to allow the unified treatment of a large variety of different vehicle variants. The procedure is then applied to a specific case study, with the goal of developing the detailed design of a full-scale vehicle. The main strengths of the proposed approach are then widely highlighted and discussed. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
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23 pages, 1783 KB  
Article
Training for Industry 5.0: Evaluating Effectiveness and Mapping Emerging Competences
by Alexios Papacharalampopoulos, Olga Maria Karagianni, Matteo Fedeli, Philipp Lackner, Gintare Aleksandraviciene, Massimo Ippolito, Unai Elorza, Antonius Johannes Schröder and Panagiotis Stavropoulos
Machines 2025, 13(9), 825; https://doi.org/10.3390/machines13090825 - 7 Sep 2025
Viewed by 138
Abstract
As Industry 5.0 emerges as a human-centric evolution of industrial systems, this study investigates the effectiveness of training interventions in companies aimed at supporting the transition to Industry 5.0, emphasizing human-centric and resilient skill development. Drawing from multiple case studies involving engineers and [...] Read more.
As Industry 5.0 emerges as a human-centric evolution of industrial systems, this study investigates the effectiveness of training interventions in companies aimed at supporting the transition to Industry 5.0, emphasizing human-centric and resilient skill development. Drawing from multiple case studies involving engineers and operators, the research applies both meta-analysis and meta-regression to assess the added value of experiential learning approaches such as Teaching and Learning Factories. In addition, a novel methodology combining quantitative analyses with qualitative interpretation of emerging competences is presented. Principal Component Analysis and classification frameworks are employed to identify and organize key competence clusters along technological, organizational, and social dimensions. Special attention is given to the emergence of human-centered competences such as decision empowerment, which are shown to complement traditional operational capabilities. The findings confirm that experiential training interventions enhance both self-efficacy and adaptive operational readiness, while the use of fusion techniques enables the generalization of results across heterogeneous corporate settings. This work contributes to ongoing discourse on Industry 5.0 readiness by linking training design to strategic company incentives and highlights the role of structured evaluation in informing future policy and implementation pathways. Full article
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19 pages, 6638 KB  
Article
High-Temperature Degradation of Throttling Performance in While-Drilling Jars Induced by Thermal Expansion and Fluid Rheology
by Zhaoyang Zhao, Zhanghua Lian, Hao Yu, Wei Sun, Senyan Liu, Zhiyong Wan and Jiachang Nie
Machines 2025, 13(9), 824; https://doi.org/10.3390/machines13090824 - 7 Sep 2025
Viewed by 191
Abstract
During deep and ultra-deep well drilling operations, the throttling performance of the hydraulic-while-drilling jar is significantly affected by the combined influence of temperature-induced differential thermal expansion among components and changes in the rheological properties of hydraulic oil. These effects often lead to unstable [...] Read more.
During deep and ultra-deep well drilling operations, the throttling performance of the hydraulic-while-drilling jar is significantly affected by the combined influence of temperature-induced differential thermal expansion among components and changes in the rheological properties of hydraulic oil. These effects often lead to unstable jarring behavior or even complete failure to trigger jarring during stuck pipe events. Here, we propose a high-temperature degradation evaluation model for the throttling performance of the throttle valve in an HWD jar based on thermal expansion testing of individual components and high-temperature rheological experiments of hydraulic oil. By using the variation characteristics of the throttling passage geometry as a linkage, this model integrates the thermo-mechanical coupling of the valve body with flow field simulation. Numerical results reveal that fluid pressure decreases progressively along the flow path through the throttle valve, while flow velocity increases sharply at the channel entrance and exhibits mild fluctuations within the throttling region. Under fluid compression, the throttling areas of both the upper and lower valves expand to some extent, with their spatial distributions closely following the pressure gradient and decreasing gradually along the flow direction. Compared with ambient conditions, thermal expansion under elevated temperatures causes a more pronounced increase in throttling area. Additionally, as hydraulic oil viscosity decreases with increasing temperature, flow velocities and mass flow rates rise significantly, leading to a marked deterioration in the throttling performance of the drilling jar under high-temperature downhole conditions. Full article
(This article belongs to the Section Machine Design and Theory)
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29 pages, 16170 KB  
Article
Digital Twin System for Mill Relining Manipulator Path Planning Simulation
by Mingyuan Wang, Yujun Xue, Jishun Li, Shuai Li and Yunhua Bai
Machines 2025, 13(9), 823; https://doi.org/10.3390/machines13090823 - 6 Sep 2025
Viewed by 149
Abstract
A mill relining manipulator is key maintenance equipment for liners exchanged and operated by workers inside a grinding mill. To improve the operation efficiency and safety, real-time path planning and end deformation compensation should be performed prior to actual execution. This paper proposes [...] Read more.
A mill relining manipulator is key maintenance equipment for liners exchanged and operated by workers inside a grinding mill. To improve the operation efficiency and safety, real-time path planning and end deformation compensation should be performed prior to actual execution. This paper proposes a five-dimensional digital twin framework to realize virtual–real interaction between a physical manipulator and virtual model. First, a real-time digital twin scene is established based on OpenGL. The involved technologies include scene rendering, a camera system, the light design, model importation, joint control, and data transmission. Next, different solving methods are introduced into the service space for relining tasks, including a kinematics model, collision detection, path planning, and end deformation compensation. Finally, a user application is developed to realize real-time condition monitoring and simulation analysis visualization. Through comparison experiments, the superiority of the proposed path planning algorithm is demonstrated. In the case of a long-distance relining task, the planning time and path length of the proposed algorithm are 1.7 s and 15,299 mm, respectively. For motion smoothness, the joint change curve exhibits no abrupt variation. In addition, the experimental results between original and modified end trajectories further verified the effectiveness and feasibility of the proposed end effector compensation method. This study can also be extended to other heavy-duty manipulators to realize intelligent automation. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
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20 pages, 2785 KB  
Article
Dynamic Posture Programming for Robotic Milling Based on Cutting Force Directional Stiffness Performance
by Yuhang Gao, Tianyang Qiu, Ci Song, Senjie Ma, Zhibing Liu, Zhiqiang Liang and Xibin Wang
Machines 2025, 13(9), 822; https://doi.org/10.3390/machines13090822 - 6 Sep 2025
Viewed by 174
Abstract
Robotic milling offers significant advantages for machining large aerospace components due to its low cost and high flexibility. However, compared to computerized numerical control (CNC) machine tools, robot systems exhibit lower stiffness, leading to force-induced deformation during milling process that significantly compromises path [...] Read more.
Robotic milling offers significant advantages for machining large aerospace components due to its low cost and high flexibility. However, compared to computerized numerical control (CNC) machine tools, robot systems exhibit lower stiffness, leading to force-induced deformation during milling process that significantly compromises path accuracy. This study proposed a dynamic robot posture programming method to enhance the stiffness for aluminum alloy milling task. Firstly, a milling force prediction model is established and validated under multiple postures and various milling parameters, confirming its stability and reliability. Secondly, a robot stiffness model is developed by combining system stiffness and milling forces within the milling coordinate system to formulate an optimization index representing stiffness performance in the actual load direction. Finally, considering the constraints of joint limit, singular position and joint motion smoothness and so on, the robot posture in the milling trajectory is dynamically programmed, and the joint angle sequence with the optimal average stiffness from any cutter location (CL) point to the end of the trajectory is obtained. Under the assumption that positioning errors were effectively compensated, the experimental results demonstrated that the proposed method can control both axial and radial machining errors within 0.1 mm at discrete points. For the specific milling trajectory, compared to the single-step optimization algorithm starting from the initial optimal posture, the proposed method reduced the axial error by 12.23% and the radial error by 8.61%. Full article
(This article belongs to the Section Advanced Manufacturing)
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25 pages, 3176 KB  
Article
Error Correction Methods for Accurate Analysis of Milling Stability Based on Predictor–Corrector Scheme
by Yi Wu, Bin Deng, Qinghua Zhao, Tuo Ye, Wenbo Jiang and Wenting Ma
Machines 2025, 13(9), 821; https://doi.org/10.3390/machines13090821 - 6 Sep 2025
Viewed by 164
Abstract
Chatter vibration in machining operations has been identified as one of the major obstacles to improving surface quality and productivity. Therefore, efficiently and accurately predicting stable cutting regions is becoming increasingly important, especially in high-speed milling processes. In this study, on the basis [...] Read more.
Chatter vibration in machining operations has been identified as one of the major obstacles to improving surface quality and productivity. Therefore, efficiently and accurately predicting stable cutting regions is becoming increasingly important, especially in high-speed milling processes. In this study, on the basis of a predictor–corrector scheme, the following three error correction methods are developed for milling stability analysis: the Correction Hamming–Milne-based method (CHM), the Correction Adams–Milne-based method (CAM) and the Predictor–Corrector Hamming–Adams–Milne-based method (PCHAM). Firstly, we employ the periodic delay differential equations (DDEs), which are usually adopted to describe mathematical models of milling dynamics, and the time period of the coefficient matrix is divided into two unequal subintervals based on an analysis of the vibration modes. Then, the Hamming method and the fourth-order implicit Adams–Moulton method are separately utilized to predict the state term, and the Milne method is adopted to correct the state term. Based on local truncation error, combining the Hamming and Milne methods creates a CHM that can more precisely approximate the state term. Similarly, combining the fourth-order implicit Adams–Moulton method and the Milne method creates a CAM that can more accurately approximate the state term. More importantly, the CHM and the CAM are employed together to acquire the state transition matrix. Thereafter, the effectiveness and applicability of the three error correction methods are verified by comparing them with three existing methods. The results demonstrate that the three error correction methods achieve higher prediction accuracy without sacrificing computational efficiency. Compared with the 2nd SDM, the calculation times of the CHM, CAM and PCHAM are reduced by around 56%, 56% and 58%, respectively. Finally, verification experiments are carried out using a CNC machine (EMV650) to further validate the reliability of the proposed methods, where ten groups of cutting tests illustrate that the stability lobes predicted by the three error correction methods exhibit better agreement with the experimental results. Full article
(This article belongs to the Section Advanced Manufacturing)
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33 pages, 4897 KB  
Review
Recent Advances in Sensor Fusion Monitoring and Control Strategies in Laser Powder Bed Fusion: A Review
by Alexandra Papatheodorou, Nikolaos Papadimitriou, Emmanuel Stathatos, Panorios Benardos and George-Christopher Vosniakos
Machines 2025, 13(9), 820; https://doi.org/10.3390/machines13090820 - 6 Sep 2025
Viewed by 296
Abstract
Laser Powder Bed Fusion (LPBF) has emerged as a leading additive manufacturing (AM) process for producing complex metal components. Despite its advantages, the inherent LPBF process complexity leads to challenges in achieving consistent quality and repeatability. To address these concerns, recent research efforts [...] Read more.
Laser Powder Bed Fusion (LPBF) has emerged as a leading additive manufacturing (AM) process for producing complex metal components. Despite its advantages, the inherent LPBF process complexity leads to challenges in achieving consistent quality and repeatability. To address these concerns, recent research efforts have focused on sensor fusion techniques for process monitoring, and on developing more elaborate control strategies. Sensor fusion combines information from multiple in situ sensors to provide more comprehensive insights into process characteristics such as melt pool behavior, spatter formation, and layer integrity. By leveraging multimodal data sources, sensor fusion enhances the detection and diagnosis of process anomalies in real-time. Closed-loop control systems may utilize this fused information to adjust key process parameters–such as laser power, focal depth, and scanning speed–to mitigate defect formation during the build process. This review focuses on the current state-of-the-art in sensor fusion monitoring and control strategies for LPBF. In terms of sensor fusion, recent advances extend beyond CNN-based approaches to include graph-based, attention, and transformer architectures. Among these, feature-level integration has shown the best balance between accuracy and computational cost. However, the limited volume of available experimental data, class-imbalance issues and lack of standardization still hinder further progress. In terms of control, a trend away from purely physics-based towards Machine Learning (ML)-assisted and hybrid strategies can be observed. These strategies show promise for more adaptive and effective quality enhancement. The biggest challenge is the broader validation on more complex part geometries and under realistic conditions using commercial LPBF systems. Full article
(This article belongs to the Special Issue In Situ Monitoring of Manufacturing Processes)
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26 pages, 8009 KB  
Article
Bearing Fault Diagnosis Based on Golden Cosine Scheduler-1DCNN-MLP-Cross-Attention Mechanisms (GCOS-1DCNN-MLP-Cross-Attention)
by Aimin Sun, Kang He, Meikui Dai, Liyong Ma, Hongli Yang, Fang Dong, Chi Liu, Zhuo Fu and Mingxing Song
Machines 2025, 13(9), 819; https://doi.org/10.3390/machines13090819 - 6 Sep 2025
Viewed by 196
Abstract
In contemporary industrial machinery, bearings are a vital component, so the ability to diagnose bearing faults is extremely important. Current methodologies face challenges in feature extraction and perform suboptimally in environments with high noise levels. This paper proposes an enhanced, multimodal, feature-fusion-bearing fault [...] Read more.
In contemporary industrial machinery, bearings are a vital component, so the ability to diagnose bearing faults is extremely important. Current methodologies face challenges in feature extraction and perform suboptimally in environments with high noise levels. This paper proposes an enhanced, multimodal, feature-fusion-bearing fault diagnosis model. Integrating a 1DCNN-dual MLP framework with an enhanced two-way cross-attention mechanism enables in-depth feature fusion. Firstly, the raw fault time-series data undergo fast Fourier transform (FFT). Then, the original time-series data are input into a multi-layer perceptron (MLP) and a one-dimensional convolutional neural network (1DCNN) model. The frequency-domain data are then entered into the other multi-layer perceptron (MLP) model to extract deep features in both the time and frequency domains. These features are then fed into a serial bidirectional cross-attention mechanism for feature fusion. At the same time, a GCOS learning rate scheduler has been developed to automatically adjust the learning rate. Following fifteen independent experiments on the Case Western Reserve University bearing dataset, the fusion model achieved an average accuracy rate of 99.83%. Even in a high-noise environment (0 dB), the model achieved an accuracy rate of 90.66%, indicating its ability to perform well under such conditions. Its accuracy remains at 86.73%, even under 0 dB noise and variable operating conditions, fully demonstrating its exceptional robustness. Full article
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34 pages, 2110 KB  
Review
A Survey of Autonomous Driving Trajectory Prediction: Methodologies, Challenges, and Future Prospects
by Miao Xu, Zhi Liu, Bingyi Wang and Shengyan Li
Machines 2025, 13(9), 818; https://doi.org/10.3390/machines13090818 - 6 Sep 2025
Viewed by 147
Abstract
Trajectory prediction is a critical component of autonomous driving decision-making systems, directly impacting driving safety and traffic efficiency. Despite advancements, existing reviews exhibit limitations in timeliness, classification frameworks, and challenge analysis. This paper systematically reviews multi-agent trajectory prediction technologies, focusing on generating future [...] Read more.
Trajectory prediction is a critical component of autonomous driving decision-making systems, directly impacting driving safety and traffic efficiency. Despite advancements, existing reviews exhibit limitations in timeliness, classification frameworks, and challenge analysis. This paper systematically reviews multi-agent trajectory prediction technologies, focusing on generating future position sequences from historical trajectories, high-precision maps, and scene context. We propose a multi-dimensional classification framework integrating input representation, output forms, method paradigms, and interaction modeling. The review comprehensively compares conventional methods and deep learning architectures, including diffusion models and large language models. We further analyze five core challenges: complex interactions, rule and map dependence, long-term prediction errors, extreme-scene generalization, and real-time constraints. Finally, interdisciplinary solutions are prospectively explored. Full article
(This article belongs to the Special Issue New Journeys in Vehicle System Dynamics and Control)
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34 pages, 6930 KB  
Article
A Slip-Based Model Predictive Control Approach for Trajectory Following of Unmanned Tracked Vehicles
by Ismail Gocer and Selahattin Caglar Baslamisli
Machines 2025, 13(9), 817; https://doi.org/10.3390/machines13090817 - 5 Sep 2025
Viewed by 206
Abstract
In the field of tracked vehicle dynamics, studies show that vertical loads are concentrated under road wheels on firm road conditions, allowing slip-based models of tracked vehicles to be designed similar to wheeled vehicle models. This paper proposes a slip-based nonlinear two-track prediction [...] Read more.
In the field of tracked vehicle dynamics, studies show that vertical loads are concentrated under road wheels on firm road conditions, allowing slip-based models of tracked vehicles to be designed similar to wheeled vehicle models. This paper proposes a slip-based nonlinear two-track prediction model for model predictive control (MPC), where track forces under road wheels are calculated with a simplification procedure implemented onto shear displacement theory. The study includes a comparative analysis with a kinematic prediction model, examining scenarios such as constant speed cornering and spiral maneuvers. Validation is carried out by comparing the simulation results of the proposed controller with field test data acquired from a five-wheeled tracked vehicle platform, including measurements on asphalt and stabilized road conditions. The results demonstrate that the slip-based model excels in trajectory tracking, with lateral deviations consistently below 0.25 m and typically around 0.02–0.08 m RMS depending on the scenario. By improving the computational efficiency and ensuring precise navigation, this approach offers an advanced control solution for tracked vehicles on firm terrain. Full article
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22 pages, 37502 KB  
Article
Coordinated Motion Pattern of Dual Forging Manipulators Based on Forging Deformation Behavior and Press Kinematics
by Yangtao Xing, Junqiang Shi, Ruihao Chang, Yanzhe Wang, Xuefeng Han, Zhuo Wang and Fugang Zhai
Machines 2025, 13(9), 816; https://doi.org/10.3390/machines13090816 - 5 Sep 2025
Viewed by 201
Abstract
To address the challenges of short allowable motion windows and complex motion planning inherent in dual forging manipulator systems, this study proposes a coordinated motion pattern tailored to dual-manipulator operations, focusing on forging deformation behavior and press control characteristics. First, six representative long-shaft [...] Read more.
To address the challenges of short allowable motion windows and complex motion planning inherent in dual forging manipulator systems, this study proposes a coordinated motion pattern tailored to dual-manipulator operations, focusing on forging deformation behavior and press control characteristics. First, six representative long-shaft forging materials were classified based on typical industrial applications. Using DEFORM-3D (V11.0) software, the deformation process during the elongation operation was analyzed, and the velocity and displacement characteristics at both ends of the forgings were extracted to clarify the compliant motion requirements of the grippers. Next, a segmented computation method for manipulator allowable motion time was developed based on the motion–time curve of the hydraulic press, significantly improving the time utilization efficiency for coordinated control. Furthermore, experimental tests were carried out to verify the dynamic response performance and motion accuracy of the dual-manipulator system. Finally, the dual-manipulator forging cycle was systematically divided into four stages—pre-forging adjustment, inter-pass compliance, execution phase, and forging completion—resulting in a structured and implementable coordination control framework. This research provides both a theoretical foundation and practical pathway for achieving efficient and precise coordinated motion control in dual forging manipulator systems, offering strong potential for engineering application and industrial deployment. Full article
(This article belongs to the Section Automation and Control Systems)
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