Machines

41 pages, 12528 KB

Open AccessArticle

Effects of Tip-Cavity Film Cooling on the Heat Transfer Characteristics of Gas Turbine Blades with Various Squealer Tip Geometries

by Dae Hyun Kim and Jin Taek Chung

Machines 2026, 14(5), 545; https://doi.org/10.3390/machines14050545 (registering DOI) - 13 May 2026

Abstract

Blade tip leakage flow in gas turbines is associated with aerodynamic loss and local heat transfer variation in the tip region. In this study, the flow structure, total pressure loss coefficient, heat transfer coefficient (HTC), and film cooling effectiveness (FCE) were numerically investigated [...] Read more.

Blade tip leakage flow in gas turbines is associated with aerodynamic loss and local heat transfer variation in the tip region. In this study, the flow structure, total pressure loss coefficient, heat transfer coefficient (HTC), and film cooling effectiveness (FCE) were numerically investigated for a plane tip (PLN) and five squealer tip geometries: a conventional squealer tip (SQR), cutback squealer tip (CBS), multi-cavity squealer tip (MCS), triangular-grooved suction-side squealer tip (GSS), and multi-cavity triangular-grooved suction-side squealer tip (MGS). All configurations were compared under the same cascade geometry, tip-clearance condition, and inlet/outlet boundary conditions to examine the geometry-dependent relationship among aerodynamic loss, heat transfer, and film cooling performance. Film cooling was evaluated at blowing ratios of M = 1 and 2 using a camber-line hole arrangement, and the effect of hole rearrangement was further examined at the same blowing ratio and with the same number of cooling holes. The results indicate that the aerodynamic and thermal characteristics of the tip region vary with the leakage-flow path, cavity recirculation, and reattachment behavior formed by each tip geometry. Under the present conditions, SQR showed the lowest downstream total pressure loss coefficient, with a 7.27% reduction relative to PLN, whereas MGS showed the lowest geometry-normalized heat transfer rate among the tested geometries. Increasing the blowing ratio tended to increase FCE, although local cooling performance was affected by high-pressure or reattachment-dominated regions where coolant ejection, surface attachment, or lateral spreading was limited. Compared with the camber-line arrangement, the rearranged hole configuration increased local FCE by up to 29.6% for CBS and 23.3% for MGS at the same blowing ratio. These results may be used as comparative data for evaluating squealer tip geometries and cooling-hole placement during preliminary blade tip cooling design. Full article

(This article belongs to the Section Turbomachinery)

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25 pages, 6521 KB

Open AccessArticle

Implementing Sensor Signal Fusion for Accurate Positioning of Micro-Robotic Systems

by Viktor Masalskyi, Ujjawal Malani, Sigitas Petkevičius, Jūratė-Jolanta Petronienė, Andrius Dzedzickis, Giedrius Garbinčius and Vytautas Bučinskas

Machines 2026, 14(5), 544; https://doi.org/10.3390/machines14050544 (registering DOI) - 13 May 2026

Abstract

Modern scanning microscopes and robotic scanning systems increasingly use visual recognition and machine learning technologies to extract complex data from acquired images. This study examined sensor data fusion in optical imaging to detect and control the deviation of the position of the tool [...] Read more.

Modern scanning microscopes and robotic scanning systems increasingly use visual recognition and machine learning technologies to extract complex data from acquired images. This study examined sensor data fusion in optical imaging to detect and control the deviation of the position of the tool during various micro-manipulations for biologic and microscale engineering. The sensor data fusion study was performed using a scanning micro-robotic system with an integrated optical microscope and a vision sensor providing an image of the object’s bottom. The bottom vision sensor is a typical complementary metal–oxide–semiconductor sensor that is used to observe micrometer-sized semi-transparent objects. The challenge for sensor fusion in such a study is not only data fusion, but also the trajectory deviation inherent in directing the manipulator in the X and Y directions according to the selected trajectory. The data fusion method was applied to estimate deviations from the given trajectory of the scanning microscope. The unique novelty of this work is that an additional vision sensor is used to increase the accuracy of positioning determination of a scanning micro-robotic system, placed under the semi-transparent object, using the fusion of the obtained data, thus additionally controlling the objective deviations. By testing several known data fusion methods, a unique solution was achieved. The proposed sensor fusion method achieved a positioning accuracy of less than 0.5 μm at speeds up to 5 mm/s. Experimental results demonstrate that the system maintains high stability. This quantitative performance proves the system’s suitability for high-precision biological micro-manipulation, where mechanical drift was previously a limiting factor. Full article

(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)

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30 pages, 15679 KB

Open AccessArticle

Prescribed-Time Formation Tracking Control of Fixed-Wing UAVs with Disturbance and Failures

by Gongxian Lou and Maolong Lv

Machines 2026, 14(5), 543; https://doi.org/10.3390/machines14050543 (registering DOI) - 12 May 2026

Abstract

This paper proposes a novel prescribed-time formation tracking control farmework of multi-fixed-wing UAVs under external disturbance and actuator failures. As the complexity of aerial missions intensifies, achieving precise position and attitude tracking within a user-defined upper bound of settling time becomes a paramount [...] Read more.

This paper proposes a novel prescribed-time formation tracking control farmework of multi-fixed-wing UAVs under external disturbance and actuator failures. As the complexity of aerial missions intensifies, achieving precise position and attitude tracking within a user-defined upper bound of settling time becomes a paramount challenge for intelligent swarm systems. Unlike traditional finite or fixed-time methods, where convergence depends on initial states or suffers from conservative estimation, the proposed approach ensures stability within a prescribed time independent of initial conditions. A key innovation is the introduction of a piecewise reference convergence differential function. This mechanism eliminates the need for state transitions, thereby reducing computational complexity while ensuring smooth tracking without control surface chattering across the entire mission. Additionally, a prescribed-time sliding mode disturbance observer is developed to provide precise and timely compensation for external disturbances and actuator faults. Rigorous Lyapunov analysis proves that all closed-loop signals are bounded and the tracking errors converge to a small neighborhood of zero within the predefined time. Numerical simulations demonstrate that, under time-varying disturbances and actuator faults, the disturbance estimation errors converge within 4 s, while both attitude and velocity tracking errors converge within 6 s, achieving fast transient response and high tracking accuracy. The UAV swarm successfully maintains the desired formation during aggressive maneuvers, including speed variations, climbing, and diving. These results verify that the proposed method provides a computationally efficient, robust, and high-precision solution for time-critical formation control of fixed-wing UAV swarms under complex uncertainties. Full article

(This article belongs to the Special Issue Intelligent Control Techniques for Unmanned Aerial Vehicles)

35 pages, 6549 KB

Open AccessArticle

Differential Flatness-Based Model Predictive Speed Control for Direct Current Motor–Gearhead Drive Systems

by Elizabeth Delgadillo-Perez, Hugo Yañez-Badillo, Carlos Sotelo, David Sotelo, Francisco Beltran-Carbajal and Jesus C. Hernandez

Machines 2026, 14(5), 542; https://doi.org/10.3390/machines14050542 (registering DOI) - 12 May 2026

Abstract

This paper introduces a new speed control framework design for direct current electric motors coupled with a gearhead. The proposed framework suitably integrates differential flatness, model predictive control, and Kalman filter theory for efficient speed tracking in disturbed scenarios. The performance of the [...] Read more.

This paper introduces a new speed control framework design for direct current electric motors coupled with a gearhead. The proposed framework suitably integrates differential flatness, model predictive control, and Kalman filter theory for efficient speed tracking in disturbed scenarios. The performance of the proposed control framework is compared against a flat feed-forward proportional–integral–derivative controller, an extended state offset-free model predictive control, and a linear quadratic integral controller. The results show improved tracking performance with reductions of up to 60% in NRMSE and 50% in ITAE compared to the baseline controllers while maintaining a comparable and bounded control effort due to the constraints enforced in the framework formulation. These results show that the proposed approach effectively captures the dominant disturbance behaviour under varying operating conditions. Thus, it is demonstrated that the flat system formulation allows for proper speed control, providing practical insights for advanced motor control in industrial automation, robotics, and electric mobility applications. Full article

(This article belongs to the Special Issue Control of Power Electronic Converters and Motor Drive Systems)

29 pages, 5812 KB

Open AccessArticle

Transient Cavitation Suppression in Closed-Circuit Pump Under Extreme Loading: Mechanism Analysis and Multi-Objective Optimization

by Yue Wang, Yuhang Zhao, Mingyue Wang, Jin Zhang, Xu Wang, Ying Li and Xiangdong Kong

Machines 2026, 14(5), 541; https://doi.org/10.3390/machines14050541 (registering DOI) - 12 May 2026

Abstract

Closed-circuit axial piston pumps in the travel hydraulic systems of heavy-duty engineering vehicles are highly vulnerable to severe transient cavitation during emergency braking. Rapid pressure reversal at the interface between the cylinder bore and the valve plate causes volumetric efficiency loss, intensified pressure [...] Read more.

Closed-circuit axial piston pumps in the travel hydraulic systems of heavy-duty engineering vehicles are highly vulnerable to severe transient cavitation during emergency braking. Rapid pressure reversal at the interface between the cylinder bore and the valve plate causes volumetric efficiency loss, intensified pressure pulsation, and erosion damage; however, the coupled mechanism by which throttling, vortex formation, and cavitation interact in this region, together with its structural regulation pathway, remains insufficiently understood. To address this gap, a closed-circuit axial piston pump for cotton pickers was investigated under emergency braking as a representative extreme loading scenario. A full-passage transient CFD model was established and validated against steady-state volumetric efficiency tests on a heavy-load test bench, as well as against PIV internal flow visualization on a Reynolds-scaled transparent model. Parametric transient CFD sweeps were then performed, and a multi-objective optimization model was developed and solved using a Kriging-assisted NSGA-II algorithm with entropy-weighted TOPSIS decision-making. The results identify the interface between the cylinder bore and the valve plate as the primary cavitation zone, with cavitation driven by local throttling and wall-attached vortices rather than by global low pressure. The optimized cylinder bore configuration reduces the peak gas volume fraction by 34.7% in the total flow domain and by 15.7% in the valve plate region, while maintaining volumetric efficiency above 97.8%; the port plate pressure pulsation increases by 12.97%. The key takeaway is that targeted optimization of the cylinder bore alone, without altering the overall valve plate or piston block architecture, can effectively suppress transient cavitation, while revealing an inherent trade-off with pressure pulsation control. In conclusion, this work clarifies the cavitation mechanism, provides a validated numerical and experimental framework, and offers an implementable design pathway for transient cavitation control of closed-circuit piston pumps under extreme loading conditions. Full article

(This article belongs to the Section Machine Design and Theory)

17 pages, 8208 KB

Open AccessArticle

Transient Coupled Dynamics Analysis of a High-Pressure Plunger Pump with Electrical–Mechanical–Hydraulic Interaction

by Yanbo Wang, Tao Shen, Yongming Xu and Ziyi Xu

Machines 2026, 14(5), 540; https://doi.org/10.3390/machines14050540 (registering DOI) - 12 May 2026

Abstract

Plunger pumps are widely used in high-pressure and high-flow applications and exhibit strong adaptability to different fluid media. In addition to the interaction between the valve and the fluid, a potential coupling effect may exist between the flow characteristics of the pump and [...] Read more.

Plunger pumps are widely used in high-pressure and high-flow applications and exhibit strong adaptability to different fluid media. In addition to the interaction between the valve and the fluid, a potential coupling effect may exist between the flow characteristics of the pump and the electromagnetic characteristics of the motor. To investigate the electromagnetic–mechanical–hydraulic coupling effect in a motor–pump system, a transient coupled dynamics model integrating electromagnetic fields (EMF), multi-body dynamics (MBD), and computational fluid dynamics (CFD) is developed. The motion of the valve is incorporated into the model through dynamic mesh and user-defined function (UDF) techniques. The different physical models are coupled through torque, speed, force, and displacement. Based on the proposed model, the coupling characteristics of the system are analyzed. The results show that pulsating components associated with the reciprocating frequency appear in both the rotational speed and torque of the motor, resulting in fluctuations of approximately 2.11% in speed and 29.57% in torque. These pulsations are also reflected in the stator current spectrum. In addition, the valve motion at different crank angles and the flow patterns in the pump chamber are analyzed. The electromagnetic characteristics of the motor have a limited influence on the internal flow behavior of the pump. Full article

(This article belongs to the Section Electromechanical Energy Conversion Systems)

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18 pages, 6384 KB

Open AccessArticle

Dynamic Response of Planetary Bearings in a Double Planetary Gear Train with Forward and Reverse Carrier Rotations

by Yudong Zhang, Biao Ma, Kun Liu, Liang Yu, Jing Zhang, Run Mao and Hanqiao Sun

Machines 2026, 14(5), 539; https://doi.org/10.3390/machines14050539 (registering DOI) - 12 May 2026

Abstract

Planetary bearings are critical components in double planetary gear trains. The influence of carrier rotation direction on bearing dynamic behavior remains insufficiently understood, which hinders accurate reliability assessment and optimal design. To investigate this issue, a dynamic model of the double planetary gear [...] Read more.

Planetary bearings are critical components in double planetary gear trains. The influence of carrier rotation direction on bearing dynamic behavior remains insufficiently understood, which hinders accurate reliability assessment and optimal design. To investigate this issue, a dynamic model of the double planetary gear train is developed. The model captures the coupled interactions and motion characteristics of both gears and bearings. Furthermore, an experimental platform is constructed to validate the accuracy of the proposed model. A comparative analysis is conducted to examine the dynamic loads and vibration responses of the planetary bearings under forward and reverse carrier rotations. The results show that reverse rotation significantly intensifies collision forces, particularly under low-speed and high-torque conditions, where the increases for inner and outer bearings reach 38.34% and 31.25%, respectively. In terms of contact forces, the inner bearing exhibits higher loads under reverse rotation, whereas the outer bearing carries greater loads under forward rotation. Vibration response analysis reveals that the carrier rotation direction has a limited effect on the vibration of the inner bearing, but significantly amplifies that of the outer bearing. Under reverse rotation, the acceleration amplitudes of the outer cage in the x- and y-directions increase by 96.20% and 95.74%, respectively, markedly exceeding the approximate 26% increase observed for the inner bearing. This study provides new insights into the asymmetric tribological behavior of planetary bearings under bidirectional rotation. These findings provide theoretical guidance for the design and optimization of planetary bearings in double planetary gear trains. Full article

(This article belongs to the Section Machine Design and Theory)

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20 pages, 3142 KB

Open AccessArticle

The Influence of Non-Oriented Silicon Steel Core Material on Motor Performance

by Guanglin Li, Jing Zhao, Xiaoqing Guan, Zhizhou Chen and Bin Wang

Machines 2026, 14(5), 538; https://doi.org/10.3390/machines14050538 (registering DOI) - 11 May 2026

Abstract

Interior permanent magnet synchronous motors (IPMSMs) offer performance advantages such as saliency effect, high mechanical strength, and a wide speed regulation range. The magnetic and mechanical properties of the core material significantly influence IPMSM performance. By investigating the effects of different core materials [...] Read more.

Interior permanent magnet synchronous motors (IPMSMs) offer performance advantages such as saliency effect, high mechanical strength, and a wide speed regulation range. The magnetic and mechanical properties of the core material significantly influence IPMSM performance. By investigating the effects of different core materials on IPMSM performance, an optimal material combination can be identified to enhance the overall motor performance. This paper takes a

\bar{V}

-shaped IPMSM for use as a main drive motor in new energy vehicles as the research object. First, the influence of the iron loss characteristics of non-oriented silicon steel (NOSS) on IPMSM performance is analyzed, and the material selection principles for the stator and rotor cores under this condition are summarized. Subsequently, the influence of the magnetic flux density characteristics of NOSS on IPMSM performance is analyzed, and the corresponding material selection principles for the stator and rotor cores are summarized. Furthermore, ultra-high-yield-strength NOSS is applied as the motor core material to reduce the width of the rotor magnetic flux barrier, and the resulting performance advantages for the IPMSM are analyzed. Finally, prototypes of the IPMSM are manufactured and tested to validate the results of the analysis. Full article

(This article belongs to the Special Issue Electromagnetic and Multi-Physics Analysis and Design of Electric Machines)

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16 pages, 1128 KB

Open AccessArticle

State Recognition and Control of a Hip Exoskeleton for Tower Climbing

by Ming Li, Jia Yao, Haoyuan Chen, Hongwei Hu, Yalun Liu, Yanlong Liu, Wenhang Xu, Hongtao Lu and Zhao Guo

Machines 2026, 14(5), 537; https://doi.org/10.3390/machines14050537 (registering DOI) - 11 May 2026

Abstract

To address the high physical demands faced by personnel engaged in power maintenance operations, this study develops a hip assistive exoskeleton capable of state recognition between level-ground walking and transmission tower climbing. The mechanical structure of the exoskeleton is designed based on motion [...] Read more.

To address the high physical demands faced by personnel engaged in power maintenance operations, this study develops a hip assistive exoskeleton capable of state recognition between level-ground walking and transmission tower climbing. The mechanical structure of the exoskeleton is designed based on motion data analysis of human level-ground walking and tower climbing activities. A dynamic model of the human lower limb is conducted to support state-based torque control of the actuators. To accommodate different locomotion scenarios, a control strategy based on a hierarchical finite state machine (HFSM) is proposed to achieve adaptive state recognition and enable the exoskeleton to provide state-specific torque output. State recognition and transition experiments, alongside laboratory and field transmission tower climbing experiments, are conducted. The results show that the exoskeleton can reliably recognize transitions between walking and climbing, providing effective assistance during transmission tower climbing operations. Furthermore, laboratory and field transmission tower climbing experiments show that exoskeleton assistance reduces integrated EMG (IEMG), root mean square (RMS) and maximum absolute value (MAXABS) values of the biceps femoris (BF), rectus femoris (RF), and vastus medialis (VM), demonstrating the effectiveness of the exoskeleton. Full article

(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)

22 pages, 7778 KB

Open AccessArticle

MTPA Control Strategy for Brushless DC Motors Based on Zero-Sequence Current Injection

by Tianpeng Zheng, Zhongming Xiong, Zhihao Yuan and Zhenguo Li

Machines 2026, 14(5), 536; https://doi.org/10.3390/machines14050536 (registering DOI) - 11 May 2026

Abstract

Under ideal trapezoidal back electromotive force (EMF) conditions, a brushless direct current (BLDC) motor can produce constant instantaneous electromagnetic torque when supplied with ideal three-phase square-wave currents. However, this operating mode may result in relatively high copper loss. In practical applications, where both [...] Read more.

Under ideal trapezoidal back electromotive force (EMF) conditions, a brushless direct current (BLDC) motor can produce constant instantaneous electromagnetic torque when supplied with ideal three-phase square-wave currents. However, this operating mode may result in relatively high copper loss. In practical applications, where both the back-EMF and the current waveforms deviate from their ideal shapes, significant torque ripple is introduced. To address these issues, this paper proposes a maximum torque per ampere (MTPA) control strategy for BLDC motors based on zero-sequence current injection. An improved Park (3s–3r) is employed to develop the mathematical model, in which the synthesized non-zero-sequence components are mapped exclusively onto the q-axis. By properly regulating the d-axis and 0-axis reference currents, the proposed strategy achieves minimum copper loss operation. Based on this framework, a torque control system incorporating zero-sequence current injection is established to further enhance performance. The feasibility and effectiveness of the proposed control strategy are validated through digital signal processing (DSP)-based experimental results. Full article

(This article belongs to the Section Electrical Machines and Drives)

37 pages, 1616 KB

Open AccessArticle

BIM and PdM of Railway Rolling Stock with Automatic Upgrading Based on GenAI

by João Matos Coutinho, Hugo Raposo, José M. Torres Farinha and Antonio J. Marques Cardoso

Machines 2026, 14(5), 535; https://doi.org/10.3390/machines14050535 (registering DOI) - 11 May 2026

Abstract

The paradigm transition of the life cycle management of physical assets in the railway sector demands new maintenance models that imply the conventional predictive approaches to be surpassed. This paper proposes an innovative methodology that integrates Building Information Modelling (BIM) with predictive maintenance [...] Read more.

The paradigm transition of the life cycle management of physical assets in the railway sector demands new maintenance models that imply the conventional predictive approaches to be surpassed. This paper proposes an innovative methodology that integrates Building Information Modelling (BIM) with predictive maintenance (PdM) systems to be applied to rolling stock and, in this way, be enhanced by Generative Artificial Intelligence (GenAI). The research focuses on the autonomous synchronisation of the Rolling Stock Digital Twin (DT). Unlike static BIM models, the proposed solution enables the use of GenAI algorithms to process continuous data streams from integrated sensors, allowing the digital model to evolve autonomously as physical wear occurs. In this framework, GenAI (via Generative Adversarial Networks—GANs) is essential for data augmentation, enabling the simulation of rare “long-tail” failure events that are scarce in real-world historical data. By synthesising these degradation scenarios, the model learns complex mechanical collapse patterns that otherwise would be ignored by traditional PdM approaches. GenAI is employed to synthesise degradation scenarios, perform real-time parametric updates within the IFC (Industry Foundation Classes) schema, and optimise maintenance workflows. The application of this framework demonstrates a significant reduction in diagnostic latency and optimises the rolling stock’s operational life cycle by automating updates and reducing the need for manual data entry. This study concludes that the convergence among BIM, PdM, and GenAI establishes a robust framework for railway fleet management. While the current validation focuses on bogie systems using Random Forest and LLMs, it paves the way for a future Industrial Metaverse where immersive diagnostics can be integrated into the maintenance lifecycle. Full article

(This article belongs to the Special Issue Condition Monitoring and Fault Diagnosis)

17 pages, 51504 KB

Open AccessArticle

Machine Vision for In Situ Measurement and Control of Wire Stickout in LWDED Process

by Braden McLain, Remy Mathenia, Todd Sparks and Frank Liou

Machines 2026, 14(5), 534; https://doi.org/10.3390/machines14050534 (registering DOI) - 11 May 2026

Abstract

This work presents a machine-vision–based measurement and control framework for laser wire directed energy deposition (LWDED) processes. A visible-light camera system is used to capture meltpool images, from which a novel vision algorithm extracts the wire–meltpool interface location. By utilizing a camera that [...] Read more.

This work presents a machine-vision–based measurement and control framework for laser wire directed energy deposition (LWDED) processes. A visible-light camera system is used to capture meltpool images, from which a novel vision algorithm extracts the wire–meltpool interface location. By utilizing a camera that is rigidly mounted to the deposition head, the vision algorithm provides a relative measurement of the distance between the nozzle tip and the workpiece, also referred to as wire stickout. A proportional-derivative (PD) control strategy is implemented using the measured stickout as feedback to adjust deposition feedrate. Results show that the control system successfully compensates for improper layer height increments, enabling thin-wall builds to consistently reach target geometry. Full article

(This article belongs to the Section Machines Testing and Maintenance)

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20 pages, 4675 KB

Open AccessArticle

A Multimodal-Based Point Cloud Segmentation Strategy for Shoe Upper Processing Boundaries Under Complex Interferences

by Xiang Mo, Song Zheng, Yeqi Guan, Zhezhuang Xu and Ping Huang

Machines 2026, 14(5), 533; https://doi.org/10.3390/machines14050533 (registering DOI) - 9 May 2026

Abstract

Accurate segmentation of shoe upper processing boundaries is crucial for automated trajectory generation and high-precision robotic control. However, developing a robust method is challenging due to the frequent style changes in High-Mix Low-Volume production. The reliance on large-scale annotated datasets renders traditional supervised [...] Read more.

Accurate segmentation of shoe upper processing boundaries is crucial for automated trajectory generation and high-precision robotic control. However, developing a robust method is challenging due to the frequent style changes in High-Mix Low-Volume production. The reliance on large-scale annotated datasets renders traditional supervised methods impractical due to the prohibitive cost of annotation and retraining. To address these issues, a multimodal-based point cloud segmentation strategy is proposed for shoe upper processing boundaries. First, an unsupervised adaptive local spectral contrast filtering algorithm is designed to remove large amounts of background noise and isolate potential target regions by exploiting boundary color characteristics. Then, an unsupervised dynamic ellipsoidal neighborhood color-spatial region growing algorithm is developed based on geometric features of slender and closed boundary shapes to suppress interferences flanking the boundaries. Finally, a Siamese network is designed to perform few-shot matching against boundary templates exported from Shoemaster, effectively decoupling intrinsic boundary signals from complex extrinsic interferences to achieve precise segmentation. Experimental results demonstrate that the proposed method achieves a stable mean Intersection over Union (mIoU) of approximately 0.80. Compared to existing supervised and unsupervised baselines, this strategy exhibits superior generalization across diverse styles and effectively resolves the data dependency bottleneck. Full article

(This article belongs to the Special Issue Visual Measurement and Intelligent Robotic Manufacturing)

18 pages, 3242 KB

Open AccessArticle

Determination and Progress in Establishing the Robotic Observatory of Space Objects (ROSO)

by Francisco Espartero, Javier Cubas and Santiago Pindado

Machines 2026, 14(5), 532; https://doi.org/10.3390/machines14050532 (registering DOI) - 9 May 2026

Abstract

The gradual increase in man-made objects in the space surrounding our planet is becoming increasingly evident. This significant rise in terrestrial materials is reflected in a greater presence of artificial satellites, space debris and waste from space missions. These objects orbiting close to [...] Read more.

The gradual increase in man-made objects in the space surrounding our planet is becoming increasingly evident. This significant rise in terrestrial materials is reflected in a greater presence of artificial satellites, space debris and waste from space missions. These objects orbiting close to Earth pose a significant risk in the event of uncontrolled re-entry, as well as collisions between the artificial satellites themselves, launch vehicles and space stations in Earth orbit. This article presents the experimental progress achieved during the prototype phase of a new model of robotic satellite observatory (SRO), featuring significant advances in its design and capabilities. These new SROs are intended to have dual capability to operate simultaneously in both scientific and military contexts. The possibility of forming a network with these devices will provide a system that substantially improves orbital determination and the identification of space objects of interest. The result presented here is an advanced model of the SRO, featuring substantial design improvements from both an ergonomic and economic perspective, as well as a significant enhancement in its ability to monitor and track space objects of uncertain origin that may be of interest or considered a threat to security, thereby expanding its Space Situational Awareness (SSA). Full article

(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)

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12 pages, 3319 KB

Open AccessArticle

Bearing-Fault Classification via Physics-Guided Representation Alignment and Group Ordinal Labeling

by Yani Liu, Tongli Ren, Meiling Jiang, Li Zhang and Tingting Liu

Machines 2026, 14(5), 531; https://doi.org/10.3390/machines14050531 (registering DOI) - 9 May 2026

Abstract

Substantial progress has been made in bearing-fault classification under same-condition settings, yet cross-condition diagnosis remains affected by three coupled issues: speed-induced temporal-scale perturbation, insufficient use of structured label information, and domain shift across operating conditions. To address these issues, this paper presents BearingPRO, [...] Read more.

Substantial progress has been made in bearing-fault classification under same-condition settings, yet cross-condition diagnosis remains affected by three coupled issues: speed-induced temporal-scale perturbation, insufficient use of structured label information, and domain shift across operating conditions. To address these issues, this paper presents BearingPRO, a unified framework that combines physics-guided representation alignment with group ordinal labeling for bearing-fault classification. The framework contains three modules. First, a TimeWarp module applies controlled temporal stretching and compression to emulate waveform variations induced by speed changes. Second, a Grouped Ordinal module introduces intra-group ordinal constraints according to the hierarchical relation between fault type and fault severity. Third, a Physics-Guided Representation Alignment (PGRA) module uses rotational-speed priors for carrier-frequency calibration, envelope extraction, and cross-domain alignment. On the CWRU bearing dataset, under the 0 HP → 3 HP transfer task, BearingPRO achieves 0.9205 ± 0.0088 accuracy and 0.8962 ± 0.0105 Macro-F1 in the unified reproduction setting used in this study. Relative to the re-implemented comparison methods under the same backbone and training budget, the proposed framework yields higher mean performance and lower variance. Ablation results further indicate that temporal-scale modeling, grouped ordinal supervision, and physics-guided alignment play complementary roles in the current setting. At the same time, the scope of the conclusion is explicitly bounded: the present evidence is obtained on the CWRU test rig, within the considered speed range, and under artificially introduced point defects; therefore, the method is presented as a well-supported cross-condition classifier for this benchmark, not as a universally validated solution for all motors. Full article

(This article belongs to the Topic Predictive Analytics and Fault Diagnosis of Machines with Machine Learning Techniques, 2nd Edition)

15 pages, 2889 KB

Open AccessArticle

Design Analysis and Comparison of a Novel IPM Synchronous Machine with Minimum Rare-Earth PM Usage for EV Industrial Applications

by Wasiq Ullah, Mehroz Fatima, Mohammad A. Abido, Udochukwu B. Akuru, Husam S. Samkari, Mohammed F. Allehyani and Abdul Khalique Junejo

Machines 2026, 14(5), 530; https://doi.org/10.3390/machines14050530 (registering DOI) - 9 May 2026

Abstract

Due to the widespread adoption of high-performance electric vehicles (EVs), Interior Permanent Magnet (IPM) machines have achieved significant advancement in the field of electric motors due to their high torque density and efficiency. However, research has been ongoing for many decades to suppress [...] Read more.

Due to the widespread adoption of high-performance electric vehicles (EVs), Interior Permanent Magnet (IPM) machines have achieved significant advancement in the field of electric motors due to their high torque density and efficiency. However, research has been ongoing for many decades to suppress the rare-earth permanent magnet (PM) usage without sacrificing electromagnetic performance while still achieving the required torque, power, and efficiency. In this regard, various EV manufacturers, such as Honda, Toyota, Chevrolet, BMW, and Nissan, have developed different types of IPM topologies; however, the rare-earth PM usage is extensively high, and the torque density is lower. Thus, to reduce the PM consumption and improve the electromagnetic performance, especially torque density, this paper proposes a novel segmented delta-shaped IPM (SΔ-IPM) with a three-notched rotor pole shape having two different specifications and featuring embedded circular flux barriers and an intermediate flux bridge. Secondly, torque performance is analytically discussed, and electromagnetic performance has been evaluated using 2D finite element analysis (FEA). Due to its unique design featuring improved magnetic field shifting, an average torque of 393.7 Nm with torque ripples of 5.1% and a cogging torque of 0.57 Nm has been achieved. Finally, an extensive comparative analysis of the aforementioned ten state-of-the-art industry models has been conducted, which confirms the effectiveness of the proposed design for high torque density with minimum PM usage. Full article

(This article belongs to the Section Electrical Machines and Drives)

21 pages, 37698 KB

Open AccessArticle

Control of the Finishing Zone by Roller Geometry and Compliance in a Dual-Roller Superfinishing Attachment

by Wojciech Kacalak, Katarzyna Tandecka, Zbigniew Budniak and Thomas G. Mathia

Machines 2026, 14(5), 529; https://doi.org/10.3390/machines14050529 (registering DOI) - 9 May 2026

Abstract

This study describes the design and analysis of a dual-roller superfinishing attachment for the abrasive-film microfinishing process, where two independently mounted compliant conical rollers make contact with separate zones of the abrasive film in order to manage the geometry of the contact zone. [...] Read more.

This study describes the design and analysis of a dual-roller superfinishing attachment for the abrasive-film microfinishing process, where two independently mounted compliant conical rollers make contact with separate zones of the abrasive film in order to manage the geometry of the contact zone. In this regard, the geometry-related simulation based on a 3D SolidWorks 2022 model was carried out to analyze the effects of the vertical shift of the contact-zone center point, h = 1–4 mm, and horizontal deformation of the abrasive film, δx = 0.1–0.5 mm. Under each setting, the contact area, Ac, the geometric interference volume, Vint, and the characteristic contact-zone length, lc, were evaluated. Increasing the value of δx from 0.1 mm to 0.5 mm resulted in the growth of the average Ac by 2.27 times, increasing from 79.42 mm² to 180.41 mm², and Vint by 11.4 times, growing from 5.26 mm³ to 59.94 mm³. The effect of h on Ac is relatively small, which means that h mostly affects the positioning of the contact zone, and δx controls its size and geometric interactions. Full article

(This article belongs to the Special Issue Advanced Design, Manufacturing, and Applications of Precision Machine Tools)

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17 pages, 1421 KB

Open AccessArticle

Rigid-Body Dynamics Modeling and Core Functional Component Selection for Heavy-Duty Industrial Robots

by Wei Han, Xianlei Shan, Tong Tong, Haitao Liu and Juliang Xiao

Machines 2026, 14(5), 528; https://doi.org/10.3390/machines14050528 - 8 May 2026

Abstract

The selection and design of core functional components are a primary task in the engineering design of heavy-duty industrial robots, in which joint constraint forces and moments act as essential indicators for component selection. This paper proposes a general inverse rigid-body dynamics model [...] Read more.

The selection and design of core functional components are a primary task in the engineering design of heavy-duty industrial robots, in which joint constraint forces and moments act as essential indicators for component selection. This paper proposes a general inverse rigid-body dynamics model for serial kinematic chains that explicitly incorporates joint constraint forces and moments. On this basis, a rigid-body dynamics model for heavy-duty industrial robots is established, which fully considers inertia, gravity, and balancing forces of the balance system, and is verified through dynamic simulations. Corresponding selection and design criteria are then formulated for joint motors, RV reducers, and balance systems. Simulation analyses and prototype full-load tests jointly confirm that the robot meets the 1000 kg load capacity requirement and validate the effectiveness of the proposed selection and design criteria. This study provides a reliable theoretical and engineering reference for the design and development of heavy-duty industrial robots. Full article

(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)

24 pages, 1665 KB

Open AccessArticle

A Method for Lightweight Pedestrian and Vehicle Detection for Unmanned Ground Vehicles in Open Environments

by Xulong Zhang, Hong Jiang, Dong Han, Hai Guo, Xiangfeng Zhang and Kaige Sun

Machines 2026, 14(5), 527; https://doi.org/10.3390/machines14050527 - 8 May 2026

Abstract

In open environments, lightweight pedestrian and vehicle detection models deployed on edge platforms of Unmanned Ground Vehicles (UGVs) often struggle to balance detection accuracy and inference efficiency when facing complex backgrounds, distant small targets, and occluded objects. To address this, we propose a [...] Read more.

In open environments, lightweight pedestrian and vehicle detection models deployed on edge platforms of Unmanned Ground Vehicles (UGVs) often struggle to balance detection accuracy and inference efficiency when facing complex backgrounds, distant small targets, and occluded objects. To address this, we propose a lightweight object detection model based on YOLO11n, named UGV-Net. This model enhances feature interaction and global context modeling capabilities by introducing the C3k2_PS module, employs Dysample dynamic upsampling to achieve content-aware feature reconstruction, and designs an LSDECD detection head to reduce multi-scale prediction redundancy and computational overhead, thereby balancing detection accuracy and inference efficiency. Compared with the baseline model YOLO11n, UGV-Net improves F1 score, mAP50, and mAP50:95 by 2.19%, 2.26%, and 2.10%, respectively, on the KITTI dataset, while reducing GFLOPs from 6.3 to 4.9 and the number of parameters from 2.58M to 2.41M. Similarly, on the SODA10M and FLIR datasets, the F1 score improves by 1.71% and 1.41%, and mAP50 improves by 1.67% and 2.39%, respectively, demonstrating excellent detection accuracy and generalization ability. Furthermore, experiments on the Jetson Orin Nano platform verify that UGV-Net achieves robust real-time detection performance, making it an efficient, reliable, and lightweight solution for UGV perception in open environments. Full article

(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)

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