Machines

20 pages, 13286 KiB

Open AccessEditor’s ChoiceArticle

A Novel Exoskeleton Design and Numerical Characterization for Human Gait Assistance

by Cristian Copilusi, Marco Ceccarelli, Sorin Dumitru, Ionut Geonea, Alexandru Margine and Dorin Popescu

Machines 2023, 11(10), 925; https://doi.org/10.3390/machines11100925 - 26 Sep 2023

Cited by 1 | Viewed by 1237

Abstract

This paper addressed attention to the design of a new lower limb exoskeleton that can be used for human gait assistance as based on kinematic considerations. The designed leg exoskeleton had on its own structure a combination of three mechanism types, namely a [...] Read more.

This paper addressed attention to the design of a new lower limb exoskeleton that can be used for human gait assistance as based on kinematic considerations. The designed leg exoskeleton had on its own structure a combination of three mechanism types, namely a Chebyshev mechanism, a pantograph, and a Stephenson six-bar mechanism. The design core focused on inserting the Stephenson six-bar bar mechanism in order to obtain an imposed motion at the ankle joint level. Numerical simulations of the designed lower limb exoskeleton have been developed and the obtained results demonstrate the engineering feasibility of the proposed prototype, with a characterization of satisfactory operation performance. Full article

(This article belongs to the Special Issue New Trends in Medical and Service Robots—Selected Papers from MESROB 2023)

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14 pages, 2309 KiB

Open AccessEditor’s ChoiceArticle

Reliability Assessment for a Spacecraft Landing Buffer Mechanism Based on Small Sample Data

by Ziang Li, Huimin Fu and Qiong Wu

Machines 2023, 11(9), 917; https://doi.org/10.3390/machines11090917 - 21 Sep 2023

Viewed by 667

Abstract

The landing buffer mechanism (LBM) is a crucial component of aerospace landing explorations, determining the success of the entire mission. Reliability demonstration tests (RDTs) are required to ensure the LBM’s performance meets the design index. However, the RDTs of the LBM often encounter [...] Read more.

The landing buffer mechanism (LBM) is a crucial component of aerospace landing explorations, determining the success of the entire mission. Reliability demonstration tests (RDTs) are required to ensure the LBM’s performance meets the design index. However, the RDTs of the LBM often encounter limited samples and zero-failure data, making traditional binominal test programs and reliability assessment methods based on the maximum likelihood theory unsuitable. This paper introduces a novel small-sample test verification method for the LBM, which transforms traditional binominal tests into more informative metrological tests by measuring the buffer strokes of the LBM’s subsystems. Furthermore, a confidence limit theory for the product of subsystem reliability is developed in conjunction with the reliability series model of the LBM. This theory can use the measurement data of subsystems to assess the confidence limit of the LBM’s reliability. An actual engineering application demonstrates that the proposed method can effectively handle zero-failure data and verifies that the LBM’s reliability exceeds 0.9999 with a confidence of 0.9. Full article

(This article belongs to the Section Automation and Control Systems)

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22 pages, 7035 KiB

Open AccessEditor’s ChoiceArticle

An Adaptive Shift Schedule Design Method for Multi-Gear AMT Electric Vehicles Based on Dynamic Programming and Fuzzy Logical Control

by Xiaodong Liu, Juan Du, Xingqun Cheng, Yan Zhu and Jian Ma

Machines 2023, 11(9), 915; https://doi.org/10.3390/machines11090915 - 20 Sep 2023

Cited by 1 | Viewed by 879

Abstract

This paper proposes an adaptive shift schedule design framework based on dynamic programming (DP) algorithm and fuzzy logical control to promote the shift schedule’s adaptability whilst improving the comprehensive performance of the multi-gear automated manual transmission (AMT) electric vehicles in real-time application. First, [...] Read more.

This paper proposes an adaptive shift schedule design framework based on dynamic programming (DP) algorithm and fuzzy logical control to promote the shift schedule’s adaptability whilst improving the comprehensive performance of the multi-gear automated manual transmission (AMT) electric vehicles in real-time application. First, the DP algorithm is employed to extract an offline optimal gear-shift schedule based on a set of driving conditions, including 11 groups of typical driving cycles. Second, a fuzzy logical controller is formulated considering the variation in the vehicle load and acceleration, where a velocity increment is exported online to adjust the gear-shift velocity of the predesigned DP-based schedule to develop a Fuzzy-DP shift schedule. In addition, multi-objective particle swarm optimization (MOPSO) is utilized to construct a comprehensive shift schedule by simultaneously considering the dynamic and economic performance of the vehicle. Then, the dynamic and economic shift schedules are deployed as the benchmark to examine the performance of the proposed shift schedule. Finally, the effectiveness of the Fuzzy-DP shift schedule is evaluated by comparison with others under various combined driving cycles (including vehicle load and velocity). The comparisons demonstrate the remarkable promotion in the adaptability of the Fuzzy-DP shift schedule in terms of acceleration time, energy-saving potential, and shift frequency. The most significant improvements in the dynamic, economic, and shift frequency can reach 8.86%, 10.12%, and 8.56%, respectively, in contrast to the MOPSO-based shift schedule. Full article

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

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16 pages, 6374 KiB

Open AccessEditor’s ChoiceArticle

Application of TRIZ Innovation Method to In-Pipe Robot Design

by Qizhi Xie and Qiang Liu

Machines 2023, 11(9), 912; https://doi.org/10.3390/machines11090912 - 16 Sep 2023

Cited by 1 | Viewed by 1342

Abstract

The peristaltic in-pipe robot incorporates multiple actuators, and achieving precise cooperative control among these actuators poses significant complexity. To address these issues, the Theory of Inventive Problem Solving (TRIZ) is applied to identify and resolve physical and technical conflicts in the creative design [...] Read more.

The peristaltic in-pipe robot incorporates multiple actuators, and achieving precise cooperative control among these actuators poses significant complexity. To address these issues, the Theory of Inventive Problem Solving (TRIZ) is applied to identify and resolve physical and technical conflicts in the creative design process of peristaltic in-pipe robots. By highlighting the insights on and technical guidance offered by TRIZ’s inventive principles, this paper examines the method for realizing a single-motor-driven peristaltic in-pipe robot from a transmission perspective. By employing a combination of connecting rods, cam mechanisms, and gear systems, a one-DOF peristaltic in-pipe robot was devised. Subsequently, a prototype was constructed, and successful bidirectional motion tests were conducted within pipes. The findings highlight the efficacy of the TRIZ-based design approach in innovatively designing one-DOF in-pipe robots and the unnecessary employment of complex multi-drive cooperative control in peristaltic in-pipe robots. Full article

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

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13 pages, 5619 KiB

Open AccessEditor’s ChoiceArticle

A Theoretical and Experimental Identification with Featured Structures for Crucial Position-Independent Geometric Errors in Ultra-Precision Machining

by Li Zhang and Shaojian Zhang

Machines 2023, 11(9), 909; https://doi.org/10.3390/machines11090909 - 14 Sep 2023

Viewed by 664

Abstract

In ultra-precision machining (UPM), position-independent geometric errors (PIGEs), i.e., squareness errors, have a crucial impact upon the form accuracy of a machined surface. Accordingly, more research work has been conducted in PIGE identification, to improve the form accuracy. However, the general identification methods [...] Read more.

In ultra-precision machining (UPM), position-independent geometric errors (PIGEs), i.e., squareness errors, have a crucial impact upon the form accuracy of a machined surface. Accordingly, more research work has been conducted in PIGE identification, to improve the form accuracy. However, the general identification methods were developed without consideration of the specific squareness errors for crucial PIGEs under the form errors of the machining process. Therefore, a new method with featured structures was proposed, to identify crucial PIGEs in UPM. Firstly, a volumetric error model was developed for PIGEs, to discuss the relationship between squareness errors and their resulting machining form errors. Secondly, following the developed model, some featured structures have been proposed with their machining form errors, to significantly indicate crucial PIGEs. Finally, a series of UPM and measuring experiments were conducted for the featured structures, and then their machining form errors were measured and extracted with specific squareness errors for the identification of crucial PIGEs. The theoretical and experimental results revealed that the proposed method is simple and efficient with the featured structures to accurately identify crucial PIGEs in UPM. Significantly, the study offers a deep insight into high-quality fabrication in UPM. Full article

(This article belongs to the Special Issue Precision Engineering in Manufacturing: Challenges and Future)

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19 pages, 3634 KiB

Open AccessEditor’s ChoiceArticle

Sustainable Energy Harvesting Mechanism with Flow-Induced Vibration

by Marvin H. Cheng, Yuejuan Li, Hugo E. Camargo and Ezzat G. Bakhoum

Machines 2023, 11(9), 902; https://doi.org/10.3390/machines11090902 - 11 Sep 2023

Viewed by 999

Abstract

This study investigates the feasibility of utilizing a flow-induced vibration actuator as a potential energy source using piezoelectric energy harvesting. The focus is on exploring the behavior of piezo films configured as cantilever beams subjected to flow-induced vibration, which can be induced with [...] Read more.

This study investigates the feasibility of utilizing a flow-induced vibration actuator as a potential energy source using piezoelectric energy harvesting. The focus is on exploring the behavior of piezo films configured as cantilever beams subjected to flow-induced vibration, which can be induced with fluid or wind streams. The primary objective is to maximize the harvested energy from the vibrating structure. This paper develops theoretical models to analyze the resonant frequencies and energy-harvesting potential of the piezo films in the context of flow-induced vibration. Experimental validations are conducted to verify the theoretical predictions. The findings indicate that higher operating frequencies in the second mode offer improved energy harvesting efficiency compared with lower modes. With the strategic adjustment of resonant frequencies using attached masses on individual piezo films, the harvestable energy output of a single film can be significantly increased from less than 1 μW to approximately 18 μW. However, the phase differences among individual piezo films can impact frequency measurements, necessitating careful fine-tuning of the physical conditions of individual components. To optimize energy harvesting, this study emphasizes the importance of implementing efficient charging mechanisms. By identifying suitable environmental vibration sources, the required charging duration for a synthesized energy harvesting array can be reduced by 25% as well. Despite certain challenges, such as phase deviations and turbulence, this study demonstrates the promising potential of flow-induced vibration resonators as sustainable energy sources. This work lays the foundation for further advancements in energy harvesting technology, offering environmentally friendly and renewable energy solutions. Full article

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

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15 pages, 7641 KiB

Open AccessEditor’s ChoiceArticle

Analysis of Cooling Characteristics of Permanent Magnet Synchronous Motor with Different Water Jacket Design Using Electromagnetic–Thermal Fluid Coupled Analysis and Design of Experiment

by Kyunghun Jeon, Myungwoo Park, Jongjin Park, Hongjun Choi, Ki-Deok Lee, Jeong-Jong Lee and Chang-Wan Kim

Machines 2023, 11(9), 903; https://doi.org/10.3390/machines11090903 - 11 Sep 2023

Viewed by 1168

Abstract

Electrical losses are converted into thermal energy in motors, which heats each component. It is a significant factor in decreasing motor mechanical performance. In this paper, the motor cooling characteristics were analyzed according to the design factors of the water jacket to investigate [...] Read more.

Electrical losses are converted into thermal energy in motors, which heats each component. It is a significant factor in decreasing motor mechanical performance. In this paper, the motor cooling characteristics were analyzed according to the design factors of the water jacket to investigate the cooling performance of a permanent magnet synchronous motor (PMSM). First, the electrical losses generated in PMSM were calculated using electromagnetic finite element (FE) analysis. Secondly, a 3D electromagnetic–thermal fluid coupled FE analysis was performed to analyze the temperature distribution inside the motor by applying electrical loss as the heat source. Finally, the motor cooling performance according to the design factors of the water jacket was statistically analyzed using the design of experiment (DOE) method. It was found that the mass flow rate of 0.02547 kg/s and six passes of the water jacket with one inlet and two outlets could be considered the optimum conditions in terms of the maximum motor temperature. Full article

(This article belongs to the Special Issue Electrical Machines in Electric Vehicles)

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23 pages, 23243 KiB

Open AccessEditor’s ChoiceReview

Advanced Manufacturability of Electrical Machine Architecture through 3D Printing Technology

by Ahmed Selema, Mohamed N. Ibrahim and Peter Sergeant

Machines 2023, 11(9), 900; https://doi.org/10.3390/machines11090900 - 10 Sep 2023

Cited by 1 | Viewed by 2015

Abstract

The rapid evolution of electric machines requires innovative approaches to boost performance, efficiency, and sustainability. Additive Manufacturing (AM) has emerged as a transformative technique, reshaping the landscape of electric machine components, ranging from magnetic materials to windings and extending to thermal management. In [...] Read more.

The rapid evolution of electric machines requires innovative approaches to boost performance, efficiency, and sustainability. Additive Manufacturing (AM) has emerged as a transformative technique, reshaping the landscape of electric machine components, ranging from magnetic materials to windings and extending to thermal management. In the area of magnetic materials, AM’s capacity to fabricate intricate structures optimizes magnetic flux dynamics, yielding advanced shape-profile cores and self-coating laminations for superior performance. In windings, AM’s prowess is evident through innovative concepts, effectively mitigating AC conduction effects while reducing weight. Furthermore, AM revolutionizes thermal management, as exemplified by 3D-printed ceramic heat exchangers, intricate cooling channels, and novel housing designs, all contributing to enhanced thermal efficiency and power density. The integration of AM not only transcends conventional manufacturing constraints but also promises to usher in an era of unprecedented electric machine innovation, addressing the intricate interplay of magnetic, winding, and thermal dynamics. Full article

(This article belongs to the Section Advanced Manufacturing)

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19 pages, 27127 KiB

Open AccessEditor’s ChoiceArticle

A Study of Frequency Domain Reflectometry Technique for High-Voltage Rotating Machine Winding Condition Assessment

by Jialu Cheng, Yizhou Zhang, Hao Yun, Liang Wang and Nathaniel Taylor

Machines 2023, 11(9), 883; https://doi.org/10.3390/machines11090883 - 02 Sep 2023

Viewed by 903

Abstract

Detecting and locating local degradations at an incipient stage is very important for mission-critical high-voltage rotating machines. One particular challenge in the existing testing techniques is that the characteristic of a local incipient defect is not prominent due to various factors such as [...] Read more.

Detecting and locating local degradations at an incipient stage is very important for mission-critical high-voltage rotating machines. One particular challenge in the existing testing techniques is that the characteristic of a local incipient defect is not prominent due to various factors such as averaging with the healthy remainder, attenuation in signal propagation, interference, and varied operating conditions. This paper proposes and investigates the frequency domain reflectometry (FDR) technique based on the scattering parameter measurement. The FDR result presents the object length, wave impedance, and reflections due to impedance discontinuity along the measured windings. Experiments were performed on two commercial coils with artificially created defects. These defects include turn-to-turn short, surface creepage, loose coils, insufficient end-winding spacing, and local overheating, which are commonly seen in practice. Two practical water pumps in the field were also selected for investigation. The study outcome shows that FDR can identify and locate structural and insulation degradation in both shielded and unshielded objects with good sensitivity. This makes FDR a complementary technique for machine fault diagnosis and aging assessment. Full article

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

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30 pages, 11533 KiB

Open AccessEditor’s ChoiceArticle

Application of UAVs and Image Processing for Riverbank Inspection

by Chang-Hsun Chiang and Jih-Gau Juang

Machines 2023, 11(9), 876; https://doi.org/10.3390/machines11090876 - 01 Sep 2023

Cited by 2 | Viewed by 1057

Abstract

Many rivers are polluted by trash and garbage that can affect the environment. Riverbank inspection usually relies on workers of the environmental protection office, but sometimes the places are unreachable. This study applies unmanned aerial vehicles (UAVs) to perform the inspection task, which [...] Read more.

Many rivers are polluted by trash and garbage that can affect the environment. Riverbank inspection usually relies on workers of the environmental protection office, but sometimes the places are unreachable. This study applies unmanned aerial vehicles (UAVs) to perform the inspection task, which can significantly relieve labor work. Two UAVs are used to cover a wide area of riverside and capture riverbank images. The images from different UAVs are stitched using the scale-invariant feature transform (SIFT) algorithm. Static and dynamic image stitching are tested. Different you only look once (YOLO) algorithms are applied to identify riverbank garbage. Modified YOLO algorithms improve the accuracy of riverine waste identification, while the SIFT algorithm stitches the images obtained from the UAV cameras. Then, the stitching results and garbage data are sent to a video streaming server, allowing government officials to check waste information from the real-time multi-camera stitching images. The UAVs utilize 4G communication to transmit the video stream to the server. The transmission distance is long enough for this study, and the reliability is excellent in the test fields that are covered by the 4G communication network. In the automatic reconnection mechanism, we set the timeout to 1.8 s. The UAVs will automatically reconnect to the video streaming server if the disconnection time exceeds the timeout. Based on the energy provided by the onboard battery, the UAV can be operated for 20 min in a mission. The UAV inspection distance along a preplanned path is about 1 km at a speed of 1 m/s. The proposed UAV system can replace inspection labor, successfully identify riverside garbage, and transmit the related information and location on the map to the ground control center in real time. Full article

(This article belongs to the Special Issue Advanced Control of Unmanned Aerial Vehicles (UAV))

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27 pages, 23202 KiB

Open AccessEditor’s ChoiceArticle

Circulating Current Control in Interleaved and Parallel Connected Power Converters

by Khalid Javed, Ruben De Croo, Lieven Vandevelde and Frederik De Belie

Machines 2023, 11(9), 878; https://doi.org/10.3390/machines11090878 - 01 Sep 2023

Viewed by 1365

Abstract

This article analyzes circulating current control in single-phase power electronic converters, focusing on two different topologies: interleaved and parallel configurations. The study involves a bridgeless interleaving topology with two boost converters for increased efficiency. A parallel connection is also examined for monitoring line [...] Read more.

This article analyzes circulating current control in single-phase power electronic converters, focusing on two different topologies: interleaved and parallel configurations. The study involves a bridgeless interleaving topology with two boost converters for increased efficiency. A parallel connection is also examined for monitoring line current, circulating currents, and power factor control. The article widely explains all current loops, including Common Mode Circulating Currents (CMCC) in the bridgeless interleaved topology and Differential Mode Circulating Currents (DMCC) in parallel-connected interleaved power converters. The proposed control scheme employs voltage and current control loops for output voltage and line current control and introduces CMCC and DMCC compensators to eliminate all types of circulating currents. An efficient Power Factor Correction (PFC) and output voltage control method is presented in this article. The effectiveness of the proposed schemes is validated through comparisons with modern control systems. The results are verified using Simulink/MATLAB and experimental setups with TI Instruments Piccolo prototypes and C2000 (TMS320F28035 microcontroller MCU) microcontrollers in parallel configurations. Full article

(This article belongs to the Special Issue Advanced Power Electronic Technologies in Electric Drive Systems)

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19 pages, 6638 KiB

Open AccessEditor’s ChoiceArticle

Modeling and Optimization of Surface Integrity and Sliding Wear Resistance of Diamond-Burnished Holes in Austenitic Stainless Steel Cylinder Lines

by Galya Duncheva, Jordan Maximov, Angel Anchev, Vladimir Dunchev, Yaroslav Argirov and Svetlozar Velkov

Machines 2023, 11(9), 872; https://doi.org/10.3390/machines11090872 - 30 Aug 2023

Viewed by 797

Abstract

This article outlines a technology for hole-finishing in short-length cylinder lines to improve wear resistance. The technology is based on an optimized diamond-burnishing (DB) process. The latter was implemented on conventional and CNC lathes, milling machines, and machining centers using a simple burnishing [...] Read more.

This article outlines a technology for hole-finishing in short-length cylinder lines to improve wear resistance. The technology is based on an optimized diamond-burnishing (DB) process. The latter was implemented on conventional and CNC lathes, milling machines, and machining centers using a simple burnishing device with an elastic beam. The material used in this study was AISI 321 austenitic stainless steel. The governing factors used were the radius of the diamond insert, burnishing force and feed rate. The objective functions relating to surface integrity characteristics were selected on the basis of their functional importance relative to the wear resistance of the processed hole surface: height and shape roughness parameters, surface microhardness, and surface residual axial and hoop stresses. The one-factor-at-a-time method (used to reduce the factor space), a planned experiment, and regression analyses were used. The multi-objective optimization tasks, which were defined for three diamond insert radius values of 2, 3, and 4 mm, were solved via the Pareto-optimal solutions approach available for a non-dominated sorting genetic algorithm (NSGA-II). Using the optimal values of the governing factors selected from the Pareto fronts, cylinder lines were processed. Samples were then cut from these cylinder lines for reciprocating sliding wear tests under two modes: dry friction and boundary lubrication friction. Additionally, wear test samples were cut from the cylinder line, which was finished with traditional grinding. A finite element simulation was then used to select an appropriate pressing force. The results obtained from the reciprocating sliding wear tests under both the dry and boundary lubrication friction regimes show that to minimize the wear on cylinder lines made of AISI 321 steel, DB with a diamond insert of radius 2 mm is the optimal finishing process. Full article

(This article belongs to the Special Issue Recent Advances in Surface Processing of Metals and Alloys)

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16 pages, 17947 KiB

Open AccessEditor’s ChoiceArticle

Experimental Study on the Effect of Microchannel Spacing and Fractal Angle on Bubble Growth Behavior

by Xianming Gao, Fangcai Lu, Wang Zhang and Wenxuan Yang

Machines 2023, 11(9), 862; https://doi.org/10.3390/machines11090862 - 28 Aug 2023

Viewed by 753

Abstract

Bubble growth behavior significantly influences boiling heat transfer performance, and different microchannel structures and configurations affect bubble growth behavior. To explore the impact of microchannel structures and configurations on the growth behavior of boiling bubbles, two types of microchannel test plates were fabricated [...] Read more.

Bubble growth behavior significantly influences boiling heat transfer performance, and different microchannel structures and configurations affect bubble growth behavior. To explore the impact of microchannel structures and configurations on the growth behavior of boiling bubbles, two types of microchannel test plates were fabricated on copper substrates using laser machining technology. It was a parallel configuration plate with five different microchannel spacings and a blade vein configuration plate with four different fractal angles. The bubble growth behavior on these two types of surfaces was studied through visual experiments. The results show that smaller microchannel spacing leads to earlier bubble coalescence and departure times under the same degree of superheat. The 3.00 mm microchannel spacing is the critical interfering distance for the parallel configuration plates, while interference behavior occurs for the bubbles on the simulated vein configuration plates at any fractal angle. Furthermore, in different ranges of superheat, the bubble departure diameter increases with increasing superheat, and the frequency of bubble departure initially increases and then decreases with increasing superheat. This study provides experimental data support and design reference for the design of heat transfer plate structures. Full article

(This article belongs to the Section Micro/Nano Electromechanical Systems (MEMS/NEMS))

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21 pages, 4026 KiB

Open AccessEditor’s ChoiceArticle

Wind/Wave Testing of a 1:70-Scale Performance-Matched Model of the IEA Wind 15 MW Reference Wind Turbine with Real-Time ROSCO Control and Floating Feedback

by Matthew Fowler, Eben Lenfest, Anthony Viselli, Andrew Goupee, Richard Kimball, Roger Bergua, Lu Wang, Daniel Zalkind, Alan Wright and Amy Robertson

Machines 2023, 11(9), 865; https://doi.org/10.3390/machines11090865 - 28 Aug 2023

Viewed by 1672

Abstract

Experimental results from the Floating Offshore-wind and Controls Advanced Laboratory (FOCAL) experimental program, which tested a performance-matched model of the IEA Wind 15 MW Reference Turbine on a 1:70 scale floating semisubmersible platform, are compared with OpenFAST simulations. Four experimental campaigns were performed, [...] Read more.

Experimental results from the Floating Offshore-wind and Controls Advanced Laboratory (FOCAL) experimental program, which tested a performance-matched model of the IEA Wind 15 MW Reference Turbine on a 1:70 scale floating semisubmersible platform, are compared with OpenFAST simulations. Four experimental campaigns were performed, and data from the fourth campaign, which focused on wind and wave testing of the scaled floating wind turbine system, are considered. Simulations of wave-only, wind-only, and wind/wave environments are performed in OpenFAST, and results for key metrics are compared with the experiment. Performance of the real-time Reference OpenSource COntroller (ROSCO) in above-rated wind conditions, including the effects of the floating feedback loop, are investigated. Results show good agreement in mean values for key metrics, and hydrodynamic effects are matched well. Differences in the surge resonant behavior of the platform are identified and discussed. The effect of the controller and floating feedback loop is evident in both the experiment and OpenFAST, showing significant reduction in platform pitch response and tower base bending load near the platform pitch natural frequency. Full article

(This article belongs to the Special Issue Wind Turbine Technologies)

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20 pages, 3294 KiB

Open AccessEditor’s ChoiceArticle

Multiparameter Estimation-Based Sensorless Adaptive Direct Voltage MTPA Control for IPMSM Using Fuzzy Logic MRAS

by Alaref Elhaj, Mohamad Alzayed and Hicham Chaoui

Machines 2023, 11(9), 861; https://doi.org/10.3390/machines11090861 - 28 Aug 2023

Cited by 1 | Viewed by 757

Abstract

This paper introduces a parameter-estimation-based sensorless adaptive direct voltage maximum torque per ampere (MTPA) control strategy for interior permanent magnet synchronous machines (IPMSMs). In direct voltage control, the motor’s electrical parameters, speed, and rotor position are of great significance. Thus, any mismatch in [...] Read more.

This paper introduces a parameter-estimation-based sensorless adaptive direct voltage maximum torque per ampere (MTPA) control strategy for interior permanent magnet synchronous machines (IPMSMs). In direct voltage control, the motor’s electrical parameters, speed, and rotor position are of great significance. Thus, any mismatch in these parameters or failure to acquire accurate speed or position information leads to a significant deviation in the MTPA trajectory, causing high current consumption and hence affecting the performance of the entire control system. In view of this problem, a fuzzy logic control-based cascaded model reference adaptive system (FLC-MRAS) is introduced to mitigate the effect of parameter variation on the tracking of the MTPA trajectory and to provide precise information about the rotor speed and position. The cascaded scheme consists of two parallel FLC-MRAS for speed and multiparameter estimation. The first MRAS is utilized to estimate motor speed and rotor position to achieve robust sensorless control. However, the speed estimator is highly dependent on time-varying motor parameters. Therefore, the second MRAS is designed to identify the quadratic inductance and permanent magnet flux and continuously update both the speed estimator and control scheme with the identified values to ensure accurate speed estimation and real-time MTPA trajectory tracking. Unlike conventional MRAS, which uses linear proportional-integral controllers (PI-MRAS), an FLC is adopted to replace the PI controllers, ensuring high estimation accuracy and enhancing the robustness of the control system against sudden changes in working conditions. The effectiveness of the proposed scheme is evaluated under different speed and torque conditions. Furthermore, a comparison against the conventional PI-MRAS is extensively investigated to highlight the superiority of the proposed scheme. The evaluation results and our quantitative assessment show the ability of the designed strategy to achieve high estimation accuracy, less oscillation, and a faster convergence rate under different working conditions. The quantitative assessment reveals that the FLC-MRAS can improve the estimation accuracy of speed, permanent magnet flux, and quadratic inductance by 19%, 55.8% and 44.55%, respectively. Full article

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

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17 pages, 6995 KiB

Open AccessEditor’s ChoiceArticle

Kinematics and Dynamics Analysis of a 3UPS-UPU-S Parallel Mechanism

by Jing-Shan Zhao, Xiao-Cheng Sun and Song-Tao Wei

Machines 2023, 11(8), 840; https://doi.org/10.3390/machines11080840 - 18 Aug 2023

Viewed by 857

Abstract

In this paper, a two-rotational degrees of freedom parallel mechanism with five kinematic subchains (3UPS-UPU-S) (U, P, and S stand for universal joints, prismatic joints, and spherical joints) for an aerospace product is introduced, and its kinematic and dynamic characteristics are subsequently analyzed. [...] Read more.

In this paper, a two-rotational degrees of freedom parallel mechanism with five kinematic subchains (3UPS-UPU-S) (U, P, and S stand for universal joints, prismatic joints, and spherical joints) for an aerospace product is introduced, and its kinematic and dynamic characteristics are subsequently analyzed. The kinematic and dynamic analyses of this mechanism are carried out in screw coordinates. Firstly, the inverse kinematics is performed through the kinematic equations established by the velocity screws of each joint to obtain the position, posture, and velocity of each joint within the mechanism. Then, a dynamic modeling method with screw theory for multi-body systems is proposed. In this method, the momentum screws are established by the momentum and moment of momentum according to the fundamentals of screws. By using the kinematic parameters of joints, the dynamic analysis can be carried out through the dynamic equations formed by momentum screws and force screws. This method unifies the kinematic and dynamic analyses by expressing all parameters in screw form. The approach can be employed in the development of computational dynamics because of its simplified and straightforward analysis procedure and its high adaptability for different kinds of multi-body systems. Full article

(This article belongs to the Section Automation and Control Systems)

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26 pages, 9870 KiB

Open AccessEditor’s ChoiceArticle

Contactless Method for Measurement of Surface Roughness Based on a Chromatic Confocal Sensor

by Natalia Lishchenko, Garret E. O’Donnell and Mark Culleton

Machines 2023, 11(8), 836; https://doi.org/10.3390/machines11080836 - 17 Aug 2023

Cited by 1 | Viewed by 1507

Abstract

The methodology for assigning and assessing the surface quality is used at various stages of the product life cycle: during the design and technological preparation of production, the production itself, and during the control (testing) of products. The development of advanced technologies requires [...] Read more.

The methodology for assigning and assessing the surface quality is used at various stages of the product life cycle: during the design and technological preparation of production, the production itself, and during the control (testing) of products. The development of advanced technologies requires in situ part control. A non-contact in situ surface roughness measuring system is proposed in this paper. The proposed system utilizes a chromatic confocal sensor, and profile data, waviness data, roughness data, Ra, and Rz parameters are generated in the developed data-processing software. The assembled measuring system based on the chromatic confocal laser sensor showed its performance in assessing the roughness parameter Ra, from 0.34 µm to more than 12 µm, which covers a common range of milling, turning, and grinding. In this range, measurement relative errors can be controlled within 10%. Frequency analysis and correlation analysis of profilograms were performed. Frequency analysis made it possible to establish the dominant frequency components that occur in the profilogram of the samples, while correlation analysis was used to develop a methodology for identifying the deterministic and random components of the processed surface profile signal. The results of the analysis can be further used to develop diagnostic functions for process monitoring based on profilogram estimates, such as the autocorrelation function and the power spectrum density. Full article

(This article belongs to the Special Issue Innovations in the Design, Simulation, and Manufacturing of Production Systems)

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16 pages, 5500 KiB

Open AccessEditor’s ChoiceArticle

High-Precision Detection Algorithm for Metal Workpiece Defects Based on Deep Learning

by Xiujin Xu, Gengming Zhang, Wenhe Zheng, Anbang Zhao, Yi Zhong and Hongjun Wang

Machines 2023, 11(8), 834; https://doi.org/10.3390/machines11080834 - 16 Aug 2023

Viewed by 1161

Abstract

Computer vision technology is increasingly being widely applied in automated industrial production. However, the accuracy of workpiece detection is the bottleneck in the field of computer vision detection technology. Herein, a new object detection and classification deep learning algorithm called CSW-Yolov7 is proposed [...] Read more.

Computer vision technology is increasingly being widely applied in automated industrial production. However, the accuracy of workpiece detection is the bottleneck in the field of computer vision detection technology. Herein, a new object detection and classification deep learning algorithm called CSW-Yolov7 is proposed based on the improvement of the Yolov7 deep learning network. Firstly, the CotNet Transformer structure was combined to guide the learning of dynamic attention matrices and enhance visual representation capabilities. Afterwards, the parameter-free attention mechanism SimAM was introduced, effectively enhancing the detection accuracy without increasing computational complexity. Finally, using WIoUv3 as the loss function effectively mitigated many negative influences during training, thereby improving the model’s accuracy faster. The experimental results manifested that the mAP@0.5 of CSW-Yolov7 reached 93.3%, outperforming other models. Further, this study also designed a polyhedral metal workpiece detection system. A large number of experiments were conducted in this system to verify the effectiveness and robustness of the proposed algorithm. Full article

(This article belongs to the Section Advanced Manufacturing)

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17 pages, 7913 KiB

Open AccessEditor’s ChoiceArticle

Comparisons of Loss Reduction Techniques Based on Pulsewidth Modulation and Model Predictive Control for Three-Phase Voltage Source Inverters

by Minh Hoang Nguyen, Sangshin Kwak and Seungdeog Choi

Machines 2023, 11(8), 829; https://doi.org/10.3390/machines11080829 - 14 Aug 2023

Cited by 1 | Viewed by 841

Abstract

Due to the lack of comparative studies between discontinuous pulse-width modulation and model predictive control methods for reducing switching losses in two-level three-phase voltage source inverter, a comparative analysis of a generalized discontinuous pulse-width modulation and two model predictive control approaches for reducing [...] Read more.

Due to the lack of comparative studies between discontinuous pulse-width modulation and model predictive control methods for reducing switching losses in two-level three-phase voltage source inverter, a comparative analysis of a generalized discontinuous pulse-width modulation and two model predictive control approaches for reducing switching losses is studied in this paper. Both generalized discontinuous pulse-width modulation and two model predictive control approaches are described and conducted in the simulation and experiment. The output performance is obtained by these methods after conducting in various conditions, including switching frequency, output power, and load conditions. It is validated that the generalized discontinuous pulse-width modulation control scheme achieves a better control performance at steady-state, while two model predictive control schemes have better transient-state performance with a superior dynamic. Additionally, the generalized discontinuous pulse-width modulation approach achieves better reducing switching losses performance and has slightly higher efficiency than that of two model predictive control approaches. Full article

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

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15 pages, 1492 KiB

Open AccessEditor’s ChoiceArticle

Saturation-Induced Variable-Flux Characteristics in a 12-Slot 10-Pole Concentrated Winding Permanent-Magnet Motor

by Yuichi Yokoi and Tsuyoshi Higuchi

Machines 2023, 11(8), 824; https://doi.org/10.3390/machines11080824 - 11 Aug 2023

Viewed by 818

Abstract

This paper proposes a stator core design to achieve variable-flux characteristics enhanced by magnetic saturation in fractional-slot concentrated winding (FSCW) permanent-magnet (PM) motors without additional excitation systems, complicated structures, or active controls. Magnetic saturation induced at suitable locations can enhance variable-flux characteristics because [...] Read more.

This paper proposes a stator core design to achieve variable-flux characteristics enhanced by magnetic saturation in fractional-slot concentrated winding (FSCW) permanent-magnet (PM) motors without additional excitation systems, complicated structures, or active controls. Magnetic saturation induced at suitable locations can enhance variable-flux characteristics because the PM flux linkage is variable with the magnetic saturation in cores. In distributed winding configurations, magnetic saturation is induced symmetrically for each rotor pole by the fundamental that is dominant in the spatial distribution of the air-gap flux density. The magnetic saturation at each rotor pole can enhance variable-flux characteristics. In FSCW configurations, magnetic saturation is not induced symmetrically for each rotor pole because of several dominant space harmonics. The magnetic saturation at several rotor poles cannot enhance variable-flux characteristics. In the proposed design, the stator core has thin tooth tips for inducing magnetic saturation. The magnetic saturation in the stator core achieves the variable-flux characteristics that are effective for expanding the operating region or decreasing electromotive force and increasing torque. The efficacy of the proposed design is determined by estimating motor performance through a finite element method analysis and demonstrating the actual motor performance of a prototype. Full article

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

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22 pages, 26353 KiB

Open AccessEditor’s ChoiceArticle

A Knowledge Discovery Process Extended to Experimental Data for the Identification of Motor Misalignment Patterns

by Sebastian Bold and Sven Urschel

Machines 2023, 11(8), 827; https://doi.org/10.3390/machines11080827 - 11 Aug 2023

Viewed by 820

Abstract

The diagnosis of misalignment plays a crucial role in the area of maintenance and repair since misalignment can lead to expensive downtime. To address this issue, several solutions have been developed, and both offline and online approaches are available. However, online strategies using [...] Read more.

The diagnosis of misalignment plays a crucial role in the area of maintenance and repair since misalignment can lead to expensive downtime. To address this issue, several solutions have been developed, and both offline and online approaches are available. However, online strategies using a small number of sensors show a higher false positive rate than other approaches. The problem is a lack of knowledge regarding the interrelations of a fault, disturbances during the diagnosis process, and capable features and feature vectors. Knowledge discovery in database is a framework that allows extracting the missing knowledge. For technical systems, optimal results were achieved by aligning (partially) automated experiments with a data mining strategy, in this case classification. The results yield a greater understanding of the interrelations regarding parallel misalignment, i.e., feature vectors that show good results also with varying load and realistic fault levels. Moreover, the test data confirm a specificity (range 0 to 1) for classification between 0.87 and 1 with the found feature vectors. For angular misalignment, potential vectors were identified, but these need further validation with a modified experiment in future work. For the study, two induction motors with 1.1 kW and 7.5 kW were considered. Furthermore, the findings were compared with additional motors of the same rated power. The findings of this work can help to improve the implementation of sensorless diagnostics on machines and advance the research in this field. Full article

(This article belongs to the Special Issue Machine Health Diagnosis & Prognosis by Advanced Sensing and Data Driven Techniques)

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30 pages, 7567 KiB

Open AccessEditor’s ChoiceArticle

Research on Lane-Change Decision and Planning in Multilane Expressway Scenarios for Autonomous Vehicles

by Chuanyin Tang, Lv Pan, Jifeng Xia and Shi Fan

Machines 2023, 11(8), 820; https://doi.org/10.3390/machines11080820 - 10 Aug 2023

Cited by 2 | Viewed by 1004

Abstract

Taking into account the issues faced by self-driving vehicles in multilane expressway scenarios, a lane-change decision planning framework that considers two adjacent lanes is proposed. Based on this framework, the lateral stability of an autonomous vehicle under near-limit conditions during lane change is [...] Read more.

Taking into account the issues faced by self-driving vehicles in multilane expressway scenarios, a lane-change decision planning framework that considers two adjacent lanes is proposed. Based on this framework, the lateral stability of an autonomous vehicle under near-limit conditions during lane change is studied by the phase-plane method. Firstly, a state-machine-based driving logic is designed and a decision method is proposed to design the lane-change intention based on the surrounding traffic information and to consider the influence of the motion state of other vehicles in the adjacent lanes on the self-driving vehicle. In order to realize adaptive cruising under the full working conditions of the vehicle, a safety distance model is established for different driving speeds and switching strategies for fixed-speed cruising, following driving, and emergency braking are developed. Secondly, for the trajectory planning problem, a lane-change trajectory based on a quintuple polynomial optimization method is proposed. Then, the vehicle lateral stability boundary is investigated; the stability boundary and rollover boundary are incorporated into the designed path-tracking controller to improve the tracking accuracy while enhancing the rollover prevention capability. Finally, a simulation analysis is carried out through a joint simulation platform; the simulation results show that the proposed method can ensure the driving safety of autonomous vehicles in a multilane scenario. Full article

(This article belongs to the Special Issue Advances in Autonomous Vehicles Dynamics and Control)

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18 pages, 1675 KiB

Open AccessEditor’s ChoiceArticle

Simulation of the Circulating Bearing Currents for Different Stator Designs of Electric Traction Machines

by Yusa Tombul, Philipp Tillmann and Jakob Andert

Machines 2023, 11(8), 811; https://doi.org/10.3390/machines11080811 - 07 Aug 2023

Cited by 1 | Viewed by 1051

Abstract

Pulse–width modulated inverters are commonly used to control electrical drives, generating a common mode voltage and current with high–frequency components that excite the parasitic capacitances within electric machines, such as permanent magnet synchronous machines or induction machines. This results in different types of [...] Read more.

Pulse–width modulated inverters are commonly used to control electrical drives, generating a common mode voltage and current with high–frequency components that excite the parasitic capacitances within electric machines, such as permanent magnet synchronous machines or induction machines. This results in different types of bearing currents that can shorten the service life of electric machines. One significant type of inverter–induced bearing currents are high–frequency circulating bearing currents. In this context, this work employs finite element analysis and time-domain simulations to determine the common mode current and circulating bearing current for various permanent magnet synchronous machine designs based on the traction machines of commercial electric vehicles with a focus on the stator. The results suggest that the ratio between the circulating bearing current and common mode current is much smaller in permanent magnet synchronous machines for traction applications than previously established in conventional induction machines, with values below 10% for all analyzed designs. A further increase in the robustness of such electric machines to the detrimental effects caused by the inverter supply could be achieved by reducing the parasitic winding–to–stator capacitance or by increasing the stator endwinding leakage inductance. Full article

(This article belongs to the Special Issue Robust Control of Permanent Magnet Synchronous Motors (PMSM) and Induction Motors (IM))

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20 pages, 13342 KiB

Open AccessEditor’s ChoiceArticle

Integration of Deep Learning for Automatic Recognition of 2D Engineering Drawings

by Yi-Hsin Lin, Yu-Hung Ting, Yi-Cyun Huang, Kai-Lun Cheng and Wen-Ren Jong

Machines 2023, 11(8), 802; https://doi.org/10.3390/machines11080802 - 04 Aug 2023

Cited by 4 | Viewed by 3248

Abstract

In an environment where manufacturing precision requirements are increasing, complete project plans can consist of hundreds of engineering drawings. The presentation of these drawings often varies based on personal preferences, leading to inconsistencies in format and symbols. The lack of standardization in these [...] Read more.

In an environment where manufacturing precision requirements are increasing, complete project plans can consist of hundreds of engineering drawings. The presentation of these drawings often varies based on personal preferences, leading to inconsistencies in format and symbols. The lack of standardization in these aspects can result in inconsistent interpretations during subsequent analysis. Therefore, proper annotation of engineering drawings is crucial as it determines product quality, subsequent inspections, and processing costs. To reduce the time and cost associated with interpreting and analyzing drawings, as well as to minimize human errors in judgment, we developed an engineering drawing recognition system. This study employs geometric dimensioning and tolerancing (GD&T) in accordance with the ASME (American Society of Mechanical Engineers) Y14.5 2018 specification to describe the language of engineering drawings. Additionally, PyTorch, OpenCV, and You Only Look Once (YOLO) are utilized for training. Existing 2D engineering drawings serve as the training data, and image segmentation is performed to identify objects such as dimensions, tolerances, functional frames, and geometric symbols in the drawings using the network model. By reading the coordinates corresponding to each object, the correct values are displayed. Real-world cases are utilized to train the model with multiple engineering drawings containing mixed features, resulting in recognition capabilities surpassing those of single-feature identification. This approach improves the recognition accuracy of deep learning models and makes engineering drawing and image recognition more practical. The recognition results are directly stored in a database, reducing product verification time and preventing errors that may occur due to manual data entry, thereby avoiding subsequent quality control issues. The accuracy rates achieved are as follows: 85% accuracy in detecting views in 2D engineering drawings, 70% accuracy in detecting annotation groups and annotations, and 80% accuracy in text and symbol recognition. Full article

(This article belongs to the Special Issue Smart Manufacturing and Industrial Automation)

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12 pages, 24388 KiB

Open AccessEditor’s ChoiceArticle

Design, Realization, and Test of Ultraviolet-C LED Arrays Suitable for Long-Lasting Irradiation of Biological Samples

by Sarah Bollanti, Paolo Di Lazzaro, Francesco Flora, Gian Piero Gallerano, Luca Mezi, Daniele Murra and Massimo Aquilini

Machines 2023, 11(8), 792; https://doi.org/10.3390/machines11080792 - 01 Aug 2023

Viewed by 833

Abstract

We present the electrical and optical design, assembling, and thorough experimental characterization of two compact arrays of short-wavelength ultraviolet (UV-C) light-emitting diodes (LEDs) suitable for near-field irradiation. Through a combination of technical expedients, we have achieved effective thermal management such that long-lasting irradiations [...] Read more.

We present the electrical and optical design, assembling, and thorough experimental characterization of two compact arrays of short-wavelength ultraviolet (UV-C) light-emitting diodes (LEDs) suitable for near-field irradiation. Through a combination of technical expedients, we have achieved effective thermal management such that long-lasting irradiations are possible without appreciable deterioration of UV-C emission. We successfully used these compact UV-C LED arrays for long lasting irradiation tests aimed at generating the biosynthesis of defensive metabolites that enhance the resistance of plants and fruits to pathogen attacks. Finally, we comment on the possibility of implementing these compact UV-C sources on robotic systems to make an automated device suitable to reduce pesticide use in agricultural crops. Full article

(This article belongs to the Special Issue 10th Anniversary of Machines—Feature Papers in Advanced Manufacturing)

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20 pages, 9132 KiB

Open AccessEditor’s ChoiceArticle

Measuring Point Planning and Fitting Optimization of the Flange and Spigot Structures of Aeroengine Rotors

by Tianyi Zhou, Lei Hu, Xiaoxiao Jin, Ting Li, Yan Zhang, Jianfeng Chen and Hang Gao

Machines 2023, 11(8), 786; https://doi.org/10.3390/machines11080786 - 31 Jul 2023

Viewed by 854

Abstract

An optimized measuring point planning and fitting method for rotor flange and spigot structures was proposed to achieve precise measurement of position and pose of the aeroengine rotors during docking processes. Firstly, the impact of circumferential phase angle, distribution range angle, total number [...] Read more.

An optimized measuring point planning and fitting method for rotor flange and spigot structures was proposed to achieve precise measurement of position and pose of the aeroengine rotors during docking processes. Firstly, the impact of circumferential phase angle, distribution range angle, total number of measuring points, and number of distribution rings on measurement uncertainty was analyzed. The measuring point planning schemes for flange and spigot were proposed. Secondly, the Gauss Newton iterative solution principle considering damping factors was clarified. Subsequently, an optimized iterative reweighting method consisting of weight iterative estimation, singular value detection under the Chauvenet criterion, and clustering detection was proposed for fitting the flange annular end face. A mapping point total least squares method with practical geometric significance was proposed for fitting the spigot cylinder face. Finally, measuring and fitting experiments were performed. The singular measuring point detection methods were verified. Under the optimized fitting methods, the goodness of fit and average orthogonal distance of flange and spigot structures are 0.756 and 0.089 mm, respectively, which have higher fitting accuracy than the other traditional methods. Full article

(This article belongs to the Section Turbomachinery)

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19 pages, 8523 KiB

Open AccessEditor’s ChoiceArticle

Design and Analysis of a Supine Ankle Rehabilitation Robot for Early Stroke Recovery

by Qingyun Meng, Guanxin Liu, Xin Xu, Qiaoling Meng and Hongliu Yu

Machines 2023, 11(8), 787; https://doi.org/10.3390/machines11080787 - 31 Jul 2023

Cited by 3 | Viewed by 1301

Abstract

Existing ankle rehabilitation robots are large, difficult to move, and mostly designed for seated use, which cannot meet the early bedridden rehabilitation goals of stroke patients. To address these issues, a supine ankle rehabilitation robot (S-ARR) specifically designed for early bedridden rehabilitation of [...] Read more.

Existing ankle rehabilitation robots are large, difficult to move, and mostly designed for seated use, which cannot meet the early bedridden rehabilitation goals of stroke patients. To address these issues, a supine ankle rehabilitation robot (S-ARR) specifically designed for early bedridden rehabilitation of stroke patients has been proposed. The S-ARR is designed to be easily movable and adaptable to different heights. It features a variable workspace with mechanical limiters at the rotating joints. A kinematic model has been constructed, and the kinematic simulation of the S-ARR has been analyzed. A control system scheme for the S-ARR has been proposed. Additionally, experiments have been conducted on the prototype to measure joint range of motion and perform rehabilitation exercises. The simulation and experimental results demonstrate that the S-ARR has a feasible workspace and a relatively smooth motion process, enabling it to achieve supine ankle rehabilitation training. This indicates that the design of the supine ankle rehabilitation robot is reasonable, capable of meeting the requirements for ankle joint rehabilitation training, and has practical utility. Full article

(This article belongs to the Special Issue Recent Advances in Medical Robotics)

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20 pages, 6344 KiB

Open AccessEditor’s ChoiceArticle

Study of the Transmission Characteristics of the Cycloid Gear Based on a Multi-Objective Optimization Modification

by Xueping Song, Yang Chen and Jianming Yang

Machines 2023, 11(8), 775; https://doi.org/10.3390/machines11080775 - 25 Jul 2023

Cited by 1 | Viewed by 1496

Abstract

Due to the advantages of high transmission accuracy and high impact resistance, cycloid-pin gear drives are widely used in precision machinery. In the actual manufacturing and use process, a suitable clearance must be left between the cycloid gear and the pin teeth to [...] Read more.

Due to the advantages of high transmission accuracy and high impact resistance, cycloid-pin gear drives are widely used in precision machinery. In the actual manufacturing and use process, a suitable clearance must be left between the cycloid gear and the pin teeth to meet the requirements of assembly lubrication, so the cycloid gear needs to be modified. In order to improve the performance of the cycloid-pin gear drive, this paper proposes a multi-objective optimization modification method which takes into account the maximum transmission error of the cycloid drive on the basis of the compound modification. Firstly, a compound modification function is constructed based on the equations of the cycloid gear. Tooth contact analysis is carried out on the cycloid gear to obtain the equations for calculating the transmission error and return error of the cycloid pinion drive and to solve for the transmission error and return error of a single cycle with different modification coefficients. Then, a multi-objective optimization model is constructed, and the optimum coefficients are solved by genetic algorithm. By analyzing the forces on the cycloid gear under load, the range, the number and the contact force of meshing teeth are calculated for different modification methods. At the end, the cycloid gear is modeled and finite element analyzed after multi-objective optimization modification and compound modification according to the optimal modification coefficients. By finite element analysis, the correctness of the theoretical calculation of the contact force of the modified cycloid gear and the loading transmission error is solved. The contact forces and transmission error of the multi-objective optimization modification are less than the compound modification. The theoretical calculation and finite element analysis indicate that the cycloid profile with the multi-objective optimization modification is better than the profile with the compound modification. Full article

(This article belongs to the Special Issue Research on Rotor Dynamics and Vibration Control)

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16 pages, 7166 KiB

Open AccessEditor’s ChoiceArticle

Impact of Cycloid’s and Roller’s Dimensional Errors on the Performance of a Cycloidal Drive for Power Transmission

by Lorenzo Fiorineschi, Francesco Saverio Frillici, Luca Pugi and Federico Rotini

Machines 2023, 11(8), 772; https://doi.org/10.3390/machines11080772 - 25 Jul 2023

Cited by 1 | Viewed by 1015

Abstract

Cycloidal roller gearboxes offer good performance in terms of loading capacity and overloading limits, but a precise manufacturing process is required to avoid overloads on relatively small teeth. In addition, these gearboxes are very sensitive to lubrication, which plays an important role on [...] Read more.

Cycloidal roller gearboxes offer good performance in terms of loading capacity and overloading limits, but a precise manufacturing process is required to avoid overloads on relatively small teeth. In addition, these gearboxes are very sensitive to lubrication, which plays an important role on the contact surfaces of rollers and teeth. However, it is acknowledged that an equivalent Cycloidal–Wolfrom configuration can be a possible solution to improve these aspects. In this work, the authors perform a comparison between two equivalent configurations, investigating how tolerances can affect the performances. The investigation approach is based on the use of simulations performed through virtual models of the main wheels of the gearboxes. The outcomes suggest a high suitability of the proposed Wolfrom configuration for applications with high transmitted torques, relatively poor materials, and modest construction tolerances. Full article

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

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19 pages, 6344 KiB

Open AccessEditor’s ChoiceArticle

Design of Z Profile Roller Tooling and Research on Roller Clearance

by Yigang Jing, Qun Sun and Ying Zhao

Machines 2023, 11(7), 767; https://doi.org/10.3390/machines11070767 - 24 Jul 2023

Viewed by 806

Abstract

In metal processing, bending forming is widely applied in various fields. To prevent excessive surface scratching and heavy indentation on the profiles, which can negatively affect the surface quality, it is often necessary to determine the clearances between the rollers and the upper [...] Read more.

In metal processing, bending forming is widely applied in various fields. To prevent excessive surface scratching and heavy indentation on the profiles, which can negatively affect the surface quality, it is often necessary to determine the clearances between the rollers and the upper and lower surfaces of the profiles using experimental methods. However, this experimental approach not only results in material waste but also fails to determine the optimal clearance value. Therefore, orthogonal experiments were conducted to design different clearances between the rollers and the upper and lower surfaces of the profiles to mitigate the issues of excessive surface scratching and poor surface quality during the bending forming process of large-section Z-profiles. Finite element simulation was employed to simulate the different experiments, and a range analysis was performed on the experimental results to obtain the optimal clearance value. The obtained results fall within the range of results obtained from traditional experimental methods, indicating its consistency with actual practice, higher accuracy, and scientific rigor compared with experimental methods. Furthermore, the roller tooling design was revised based on the optimal clearance value for the profile processing. The experimental results demonstrate that the surface quality of the profiles processed with optimal clearance is superior to those processed without it. Additionally, this study presents a comprehensive methodology for roller tooling design and investigates the influence of different loading modes on the local wrinkling deformation of the profiles. Full article

(This article belongs to the Section Advanced Manufacturing)

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17 pages, 6826 KiB

Open AccessEditor’s ChoiceArticle

Design, Modelling and Optimization of a High Power Density Axial Flux SRM with Reduced Torque Ripple for Electric Vehicles

by Akbar Mohammadi Ajamloo, Mohamed N. Ibrahim and Peter Sergeant

Machines 2023, 11(7), 759; https://doi.org/10.3390/machines11070759 - 20 Jul 2023

Cited by 4 | Viewed by 1522

Abstract

Switched reluctance machines (SRMs) are potential candidates for use in the propulsion systems of electric vehicles. However, they suffer from low power density and high torque ripple. In this paper, a segmented rotor double-sided axial flux SRM (DSAFSRM) is chosen for detailed analysis. [...] Read more.

Switched reluctance machines (SRMs) are potential candidates for use in the propulsion systems of electric vehicles. However, they suffer from low power density and high torque ripple. In this paper, a segmented rotor double-sided axial flux SRM (DSAFSRM) is chosen for detailed analysis. A hybrid design algorithm is proposed to take the effects of iron non-linearity into account. The proposed design procedure benefits from simplicity and high accuracy at the same time. A two-step optimization procedure is presented which minimizes the torque ripple of the DSAFSRM without jeopardizing its efficiency. The torque ripple is reduced from 120% to 35% after optimization. In the two-step optimization procedure, both geometrical and switching related parameters are investigated. Moreover, a double-sided radial flux SRM is designed and compared with the proposed DSAFSRM in terms of torque ripple, average torque, efficiency and power density. The results indicate superior performance of the optimized DSAFSRM, especially in terms of average torque, which is 26% higher than the torque produced by the double-sided radial flux SRM. Full article

(This article belongs to the Special Issue Future Trends in Advanced Design of Electrical Machines, Drives and Electric Vehicles Using Additive Manufacturing Approaches)

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18 pages, 7609 KiB

Open AccessEditor’s ChoiceArticle

A Novel Sleeve Design to Reduce the Eddy Current Loss of High-Speed Electrical Machines

by Seung-Heon Lee, Si-Woo Song, Min-Jae Jeong, Won-Ho Kim and Dong-Hoon Jung

Machines 2023, 11(7), 756; https://doi.org/10.3390/machines11070756 - 19 Jul 2023

Cited by 1 | Viewed by 1208

Abstract

Demand for high-speed motors is increasing. Surface-mounted permanent magnet synchronous motors (SPMSM) used in high-speed applications have magnets attached to the rotor, so there is a risk of damage and scattering due to centrifugal force as the speed increases. For this reason, applying [...] Read more.

Demand for high-speed motors is increasing. Surface-mounted permanent magnet synchronous motors (SPMSM) used in high-speed applications have magnets attached to the rotor, so there is a risk of damage and scattering due to centrifugal force as the speed increases. For this reason, applying the retaining sleeve to the rotor is essential. However, when using sleeves, there is a problem of reducing efficiency due to eddy current loss. In this paper, a study was conducted on a motor for a 100 kW building air conditioning system operating at a speed of 20,000 rpm. The purpose of the study is to reduce eddy current loss by optimizing the sleeve geometry. To this end, 3D finite element analysis (FEA) using JMAG 22.1 was conducted to analyze eddy current loss, the minimum safety factor was analyzed through mechanical stiffness analysis using ANSYS Workbench, and the validity of sleeve shape was proved through cause analysis. Through the research results, it is expected that the shape change of the sleeve will have the effect of reducing eddy current loss. Full article

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

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21 pages, 5877 KiB

Open AccessEditor’s ChoiceReview

Research Progress on the Dynamic Characteristics of Planetary Gear Transmission in a Non-Inertial System

by Bingwei Gao, Yongkang Wang and Guangbin Yu

Machines 2023, 11(7), 751; https://doi.org/10.3390/machines11070751 - 18 Jul 2023

Viewed by 1398

Abstract

Planetary gear systems have many advantages over other gear systems. Previous studies on its dynamic characteristics mostly used Earth as the reference system, which is inconsistent with the actual working conditions of many planetary gear systems, such as aircraft maneuvering, vehicle movement changes, [...] Read more.

Planetary gear systems have many advantages over other gear systems. Previous studies on its dynamic characteristics mostly used Earth as the reference system, which is inconsistent with the actual working conditions of many planetary gear systems, such as aircraft maneuvering, vehicle movement changes, etc. By analyzing representative research papers, this study summarizes the lumped-parameter, finite element, and rigid–flexible coupling models commonly used in studying the traditional dynamic characteristics. Then, the research status of gear–rotor and planetary gear systems in inertial and non-inertial systems is summarized. The research progress of load characteristics, vibration characteristics, and vibration control of the traditional planetary gear system is summarized. Finally, some suggestions for future development are put forward. There are a few studies on the non-inertial dynamics of planetary gear systems. The three analysis models have distinct characteristics and applications but can all be used in non-inertial systems. The dynamic analysis method of non-inertial rotor systems can be combined with the dynamic study of gear systems. It is of practical significance to study the non-inertial dynamic characteristics of planetary gear systems. Scholars can refer to the non-inertial dynamic research of the gear–rotor system, select the analysis model according to the needs, and continue to study the dynamic characteristics of the planetary gear system under the non-inertial system. Full article

(This article belongs to the Special Issue Research on Rotor Dynamics and Vibration Control)

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20 pages, 29747 KiB

Open AccessEditor’s ChoiceArticle

Experimental Study on Fatigue Damage of Drilling Tool Materials Based on Magnetic Memory Detection

by Yingming He, Qilong Xue, Weiguo Hai, Xuesong Xing, Xudong Wu and Xing Fu

Machines 2023, 11(7), 701; https://doi.org/10.3390/machines11070701 - 02 Jul 2023

Viewed by 819

Abstract

In drilling engineering, the cost of drilling tool fracture is enormous, and studying the fatigue failure process of drilling tools has practical significance. This paper uses metal magnetic memory detection technology to design and conduct fatigue damage tests on typical drilling tool material [...] Read more.

In drilling engineering, the cost of drilling tool fracture is enormous, and studying the fatigue failure process of drilling tools has practical significance. This paper uses metal magnetic memory detection technology to design and conduct fatigue damage tests on typical drilling tool material 42CrMo specimens under tensile, torsional, compressive, tensile, compressive, and torsional dynamic loading conditions. By analyzing the changes in the tangential component H_p(x) and gradient value K of the magnetic memory signal under different load conditions with the number of loading times, the process of fatigue failure of the specimens and the trend of changes in the magnetic memory signal in local stress concentration areas are explored. The characteristic parameters of fatigue damage based on magnetic memory detection were extracted and the critical point at which fatigue damage leads to crack initiation was inferred. This confirms that metal magnetic memory testing technology is an effective means of analyzing the fatigue damage process of drilling tools and provides a certain reference for formulating judgment standards for drilling tool maintenance on site. Full article

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

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19 pages, 4845 KiB

Open AccessEditor’s ChoiceArticle

Dynamics-Based Thermal Analysis of High-Speed Angular Contact Ball Bearings with Under-Race Lubrication

by Jintao Lei, Bing Su, Shuailong Zhang, Haisheng Yang and Yongcun Cui

Machines 2023, 11(7), 691; https://doi.org/10.3390/machines11070691 - 01 Jul 2023

Cited by 4 | Viewed by 1773

Abstract

The paper mainly studied the temperature rise characteristics of under-race lubricated high-speed angular contact ball bearings under operational conditions from the perspective of dynamics. The steady-state calculation model of the bearing was established using a thermal network method in consideration of the influence [...] Read more.

The paper mainly studied the temperature rise characteristics of under-race lubricated high-speed angular contact ball bearings under operational conditions from the perspective of dynamics. The steady-state calculation model of the bearing was established using a thermal network method in consideration of the influence factor of friction power consumption in bearing components based on a dynamic model. Following this, the steady-state change characteristics of the bearing were obtained by solving a thermal balance equation. Through this process, the influence laws of bearing rotation speed, oil supply, and environmental temperature on the friction temperature rise of the bearing were analyzed. Finally, the finite element analysis software ANSYS was employed to provide comparative verification. The results showed that the bearing temperature nonlinearly increased with the increase in inner ring rotation speed, and when it approached a certain critical value, the outer ring temperature exceeded the inner ring temperature. It had an obvious effect on controlling the temperature rise of the bearing inner ring by way of increasing the quantity and reducing the temperature of the lubricating oil supply. Comparative verification showed that the speed–temperature variation tendency from the dynamics-based thermal analysis well agrees with that of the finite element analysis. Full article

(This article belongs to the Special Issue Friction and Lubrication of Mechanical Drive Train Components)

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22 pages, 1243 KiB

Open AccessEditor’s ChoiceReview

A Review of Prognostic and Health Management (PHM) Methods and Limitations for Marine Diesel Engines: New Research Directions

by Hla Gharib and György Kovács

Machines 2023, 11(7), 695; https://doi.org/10.3390/machines11070695 - 01 Jul 2023

Cited by 4 | Viewed by 9006

Abstract

Prognostic and health management (PHM) methods focus on improving the performance and reliability of systems with a high degree of complexity and criticality. These systems include engines, turbines, and robotic systems. PHM methods involve managing technical processes, such as condition monitoring, fault diagnosis, [...] Read more.

Prognostic and health management (PHM) methods focus on improving the performance and reliability of systems with a high degree of complexity and criticality. These systems include engines, turbines, and robotic systems. PHM methods involve managing technical processes, such as condition monitoring, fault diagnosis, health prognosis, and maintenance decision-making. Various software and applications deal with the processes mentioned above independently. We can also observe different development levels, making connecting all of the machine’s technical processes in one health management system with the best possible output a challenging task. This study’s objective was to outline the scope of PHM methods in real-time conditions and propose new directions to develop a decision support tool for marine diesel engines. In this paper, we illustrate PHM processes and the state of the art in the marine industry for each technical process. Then, we review PHM methods and limitations for marine diesel engines. Finally, we analyze future research opportunities for the marine industry and their role in developing systems’ performance and reliability. The main added value of the research is that a research gap was found in this research field, which is that new advanced PHM methods have to be implemented for marine diesel engines. Our suggestions to improve marine diesel engines’ operation and maintenance include implementing advanced PHM methods and utilizing predictive analytics and machine learning. Full article

(This article belongs to the Special Issue Condition-Based Maintenance, Instrumentation and Data Analysis Methods Aiming Efficient Operation of Internal Combustion Engines)

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25 pages, 8330 KiB

Open AccessEditor’s ChoiceArticle

Research into Dynamic Error Optimization Method of Impeller Blade Machining Based on Digital–Twin Technology

by Rongyi Li, Shanchao Wang, Chao Wang, Shanshan Wang, Bo Zhou, Xianli Liu and Xudong Zhao

Machines 2023, 11(7), 697; https://doi.org/10.3390/machines11070697 - 01 Jul 2023

Viewed by 1094

Abstract

A TC4 impeller blade is a typical weak, rigid, thin–walled part. The contact area between a cutting tool and a workpiece has strong time–varying characteristics. This leads to a strong non–linear variation in cutting load. So, in this kind of part, the processing [...] Read more.

A TC4 impeller blade is a typical weak, rigid, thin–walled part. The contact area between a cutting tool and a workpiece has strong time–varying characteristics. This leads to a strong non–linear variation in cutting load. So, in this kind of part, the processing error is difficult to control. To solve this problem, a method of processing error prediction and intelligent controlling which considers the effect of tool wear time variation is proposed by combining digital–twinning technology. Firstly, an iterative model for digital–twin process optimization is constructed. Secondly, an iterative prediction model of the machining position following the milling force and considering the effect of tool wear is proposed. Based on these models, the machining error of the TC4 impeller blade under dynamic load is predicted. Dynamic machining error prediction and intelligent control are realized by combining the digital–twin model and the multi–objective process algorithm. Finally, the machining error optimization effect of the proposed digital–twin model is verified via a comparison experiment of impeller blade milling. In terms of the precision of milling force mapping, the average error after optimization is less than 8%. The maximum error is no more than 14%. In terms of the optimization effect, the average error of the optimized workpiece contour is reduced by about 20%. The peak contour error is reduced by approximately 35%. Full article

(This article belongs to the Special Issue Recent Progress of Thin Wall Machining)

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16 pages, 4199 KiB

Open AccessEditor’s ChoiceArticle

Computational Fluid Dynamics Simulation and Optimization of Hydropneumatic Spring Damper Valves for Heavy Vehicle Applications

by Wei Nie, Hongwen He, Luming Sha, Chao Wang and Fu Du

Machines 2023, 11(7), 680; https://doi.org/10.3390/machines11070680 - 25 Jun 2023

Cited by 1 | Viewed by 997

Abstract

To satisfy the design requirements for a hydropneumatic spring damper valve, the inlet–outlet pressure drop (ΔP) and the axial force on the spool (F_Z) of a valve were investigated using fluid–solid coupling simulations and multi-objective optimization, along with [...] Read more.

To satisfy the design requirements for a hydropneumatic spring damper valve, the inlet–outlet pressure drop (ΔP) and the axial force on the spool (F_Z) of a valve were investigated using fluid–solid coupling simulations and multi-objective optimization, along with the effects of the diameters of three internal holes (D_A, D_B, and D_C) in the valve on the ΔP and the F_Z. First, a meshed computational fluid dynamics model of a damper valve was established based on its geometric structure. Next, the effects of the flow rate (Q) and the diameter of the damping hole in the internal structure on the ΔP and the F_Z of the damper valve were investigated. The results showed that the ΔP and the F_Z varied nonlinearly with Q. For a given Q, the ΔP decreased as D_A, D_B, and D_C increased. For a given Q, the F_Z was not related to D_A and D_C, but it decreased as D_B increased. Finally, the structure of the damper valve was optimized by defining the ΔP and the F_Z as the response variables and D_A, D_B, and D_C as the explanatory variables. The results showed that the best configuration of the hole diameters was D_A = 8.8 mm, D_B = 5.55 mm, and D_C = 6 mm. In this configuration, ΔP = 0.704 MPa and F_Z = 110.005 N. The ΔP of the optimized valve was closer to the middle value of the target range than that of the initial valve design. The difference between the simulated and target values of the F_Z decreased from 0.28% to 0.0045%, satisfying application requirements. Full article

(This article belongs to the Section Industrial Systems)

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29 pages, 775 KiB

Open AccessEditor’s ChoiceReview

Autonomous Vehicle Decision-Making and Control in Complex and Unconventional Scenarios—A Review

by Faizan Sana, Nasser L. Azad and Kaamran Raahemifar

Machines 2023, 11(7), 676; https://doi.org/10.3390/machines11070676 - 23 Jun 2023

Cited by 6 | Viewed by 5893

Abstract

The development of autonomous vehicles (AVs) is becoming increasingly important as the need for reliable and safe transportation grows. However, in order to achieve level 5 autonomy, it is crucial that such AVs can navigate through complex and unconventional scenarios. It has been [...] Read more.

The development of autonomous vehicles (AVs) is becoming increasingly important as the need for reliable and safe transportation grows. However, in order to achieve level 5 autonomy, it is crucial that such AVs can navigate through complex and unconventional scenarios. It has been observed that currently deployed AVs, like human drivers, struggle the most in cases of adverse weather conditions, unsignalized intersections, crosswalks, roundabouts, and near-accident scenarios. This review paper provides a comprehensive overview of the various navigation methodologies used in handling these situations. The paper discusses both traditional planning methods such as graph-based approaches and emerging solutions including machine-learning based approaches and other advanced decision-making and control techniques. The benefits and drawbacks of previous studies in this area are discussed in detail and it is identified that the biggest shortcomings and challenges are benchmarking, ensuring interpretability, incorporating safety as well as road user interactions, and unrealistic simplifications such as the availability of accurate and perfect perception information. Some suggestions to tackle these challenges are also presented. Full article

(This article belongs to the Special Issue Artificial Intelligence for Automatic Control of Vehicles)

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16 pages, 1466 KiB

Open AccessEditor’s ChoiceArticle

Integration of sEMG-Based Learning and Adaptive Fuzzy Sliding Mode Control for an Exoskeleton Assist-as-Needed Support System

by Pablo Delgado, Nathan Gonzalez and Yimesker Yihun

Machines 2023, 11(7), 671; https://doi.org/10.3390/machines11070671 - 21 Jun 2023

Viewed by 964

Abstract

This paper presents an adaptive Fuzzy Sliding Mode Control approach for an Assist-as-Needed (AAN) strategy to achieve effective human–exoskeleton synergy. The proposed strategy employs an adaptive instance-based learning algorithm to estimate muscle effort, based on surface Electromyography (sEMG) signals. To determine and control [...] Read more.

This paper presents an adaptive Fuzzy Sliding Mode Control approach for an Assist-as-Needed (AAN) strategy to achieve effective human–exoskeleton synergy. The proposed strategy employs an adaptive instance-based learning algorithm to estimate muscle effort, based on surface Electromyography (sEMG) signals. To determine and control the inverse dynamics of a highly nonlinear 4-degrees-of-freedom exoskeleton designed for upper-limb therapeutic exercises, a modified Recursive Newton-Euler Algorithm (RNEA) with Sliding Mode Control (SMC) was used. The exoskeleton position error and raw sEMG signal from the bicep’s brachii muscle were used as inputs for a fuzzy inference system to produce an output to adjust the sliding mode control law parameters. The proposed robust control law was simulated using MATLAB-Simulink, and the results showed that it could instantly adjust the necessary support, based on the combined motion of the human–exoskeleton system’s muscle engagement, while keeping the state trajectory errors and input torque bounded within

\pm 5 \times 10^{- 2}

rads and

\pm 5

N.m, respectively. Full article

(This article belongs to the Special Issue State-of-the-Art in Service and Rehabilitation Machines)

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18 pages, 5245 KiB

Open AccessEditor’s ChoiceArticle

Influence of Cutting Parameters and Tool Geometry on Topography of Hard Turned Surfaces

by Viktor Molnar

Machines 2023, 11(6), 665; https://doi.org/10.3390/machines11060665 - 20 Jun 2023

Cited by 1 | Viewed by 758

Abstract

Three-dimensional topography measurement is a focus area of precision machining because it provides detailed information on the functional behavior of contacting surfaces. The purpose of this study is to analyze how the process parameters and the edge geometry of the cutting insert influence [...] Read more.

Three-dimensional topography measurement is a focus area of precision machining because it provides detailed information on the functional behavior of contacting surfaces. The purpose of this study is to analyze how the process parameters and the edge geometry of the cutting insert influence the topographical characteristics of hardened 16MnCr5 steel surfaces and to determine the favorable combinations of technology parameter values based on the analyzed topography parameters (Ssk, Sku, Sz, Sa, Sk, Spk, Svk). A research question is whether the analyzed parameters can be substituted by each other or not. A hard turning experiment was carried out based on a full factorial design of experiments, and the areas of the machined surfaces were scanned and analyzed by analysis of variance, regression analysis (response function), and correlation analysis. It was found that there are strong correlations between the topography parameters that allow the substitution of one with another; the main influencing cutting parameter is the feed rate for both insert types. The contributions of the study are the numerical information with regard to the correlations among the topography parameters, as well as the extent of the influence of cutting parameters. Full article

(This article belongs to the Section Advanced Manufacturing)

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18 pages, 18905 KiB

Open AccessEditor’s ChoiceArticle

Investigating the Stiffness Characteristics of a Tendon-Driven Continuum Manipulator Using Sensitivity Analysis: A Case Study in Transoral Laser Microsurgery

by Kapil Sawant, Antonios E. Gkikakis and Leonardo S. Mattos

Machines 2023, 11(6), 662; https://doi.org/10.3390/machines11060662 - 19 Jun 2023

Cited by 2 | Viewed by 1186

Abstract

Continuum manipulators, with their characteristics of flexibility and dexterity, have gained significant interest in various applications across industries such as inspection, manufacturing, space exploration, and medical surgery. However, because of their inherent compliance, handling payloads may prove challenging due to shape distortion and [...] Read more.

Continuum manipulators, with their characteristics of flexibility and dexterity, have gained significant interest in various applications across industries such as inspection, manufacturing, space exploration, and medical surgery. However, because of their inherent compliance, handling payloads may prove challenging due to shape distortion and deflection. This demonstrates the need to optimize the manipulator’s stiffness. The primary objective of this work was to show the merits of sensitivity analysis in the design of flexible surgical manipulators. Such analysis can guide important design decisions and enable the more efficient use of available resources, contributing to designing more effective prototypes. A new sensitivity analysis framework based on a multi-model and a multi-method approach was proposed to achieve this. This framework was then demonstrated by studying a tendon-driven rolling contact joint hyper-redundant manipulator for transoral laser microsurgery. In this analysis, the effects of independent design parameters on the stiffness of the manipulator were examined. Then, scaled-up 3D-printed prototypes were used to validate the accuracy of the stiffness model experimentally, which enabled us to assess the outcome of the sensitivity analysis framework. The results demonstrated that only two out of five design parameters for the considered manipulator significantly impacted the device’s performance. This information could enable the designer to efficiently allocate resources toward correctly setting these two most important parameters to achieve the desired system. Overall, the proposed analysis framework is a general tool that can be applied to any design architecture, helping to develop optimal manipulators for various applications. Full article

(This article belongs to the Special Issue Robots in Healthcare: Design, Control and Applications)

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24 pages, 4797 KiB

Open AccessEditor’s ChoiceArticle

Hardware-in-the-Loop Scheme of Linear Controllers Tuned through Genetic Algorithms for BLDC Motor Used in Electric Scooter under Variable Operation Conditions

by Leonardo Esteban Moreno-Suarez, Luis Morales-Velazquez, Arturo Yosimar Jaen-Cuellar and Roque Alfredo Osornio-Rios

Machines 2023, 11(6), 663; https://doi.org/10.3390/machines11060663 - 19 Jun 2023

Cited by 2 | Viewed by 1505

Abstract

Outrunner brushless DC motors (BLDC) are a type of permanent magnet synchronous motor (PMSM) widely used in electric micro-mobility vehicles, such as scooters, electric bicycles, wheelchairs, and segways, among others. Those vehicles have many operational constraints because they are driven directly by the [...] Read more.

Outrunner brushless DC motors (BLDC) are a type of permanent magnet synchronous motor (PMSM) widely used in electric micro-mobility vehicles, such as scooters, electric bicycles, wheelchairs, and segways, among others. Those vehicles have many operational constraints because they are driven directly by the user with light protective wearing. Therefore, to improve control strategies to make the drive safer, it is essential to model the traction system over a wide range of operating conditions in a street environment. In this work, we developed an electro-mechanical model based on the Hardware-in-the-Loop (HIL) structure for a two-wheeler electric scooter, using the BLDC motor to explore its response and to test linear controllers for speed and torque management under variable operating conditions. The proposed model includes motor parameters, power electronics component characteristics, mechanical structure, and external operating conditions. Meanwhile the linear controllers will be adjusted or tuned though a heuristic approach based on Genetic Algorithms (GAs) to optimize the system’s response. The HIL scheme will be able to simulate a wide range of conditions such as user weight, slopes, wind speed changes, and combined conditions. The designed model can be used to improve the design of the controller and estimate mechanical and electrical loads. Finally, the results of the controller tests show how the proposed cascade scheme, tuned through the GA, improves the system behavior and reduces the mean square error with respect to a classical tuning approach between 20% and 60%. Full article

(This article belongs to the Special Issue Condition-Based Monitoring of Electrical Machines)

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19 pages, 5883 KiB

Open AccessEditor’s ChoiceArticle

Dynamic Modeling and Performance Evaluation of a 5-DOF Hybrid Robot for Composite Material Machining

by Xiaojian Wang, Jun Wu and Yulin Zhou

Machines 2023, 11(6), 652; https://doi.org/10.3390/machines11060652 - 16 Jun 2023

Viewed by 901

Abstract

Dynamic performance is an important performance of robots used for machine processing. This paper studies the dynamic modeling and evaluation method of a 5-DOF (Degree of Freedom) hybrid robot used in aerospace composite material processing. With the consideration of the dynamics of the [...] Read more.

Dynamic performance is an important performance of robots used for machine processing. This paper studies the dynamic modeling and evaluation method of a 5-DOF (Degree of Freedom) hybrid robot used in aerospace composite material processing. With the consideration of the dynamics of the serial part, the complete dynamic model of the hybrid robot is established based on the virtual work principle. In addition to the widely considered acceleration term, a dynamic performance evaluation index that comprehensively considers the acceleration term, velocity term and gravity term in the dynamic model is proposed. Using the dynamic performance index, the effect of the placement direction of the robot and the arrangement of the double symmetric limbs on robot dynamics are investigated. The results indicate that the vertical placement is beneficial to the dynamics of the hybrid robot, and the arrangement of double symmetric limbs has different effects on different limbs. Full article

(This article belongs to the Special Issue Advances in Parallel Robots and Mechanisms)

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18 pages, 2955 KiB

Open AccessEditor’s ChoiceArticle

The Friction of Radially Loaded Hybrid Spindle Bearings under High Speeds

by Marcus Gärtner, Christian Brecher, Stephan Neus, Hans-Martin Eckel, Andreas Bartelt, Maik Hoppert and Mohammad Reza Ilkhani

Machines 2023, 11(6), 649; https://doi.org/10.3390/machines11060649 - 15 Jun 2023

Viewed by 1096

Abstract

Friction losses are an important parameter for evaluating the operational behaviour of high-speed rolling bearings. Specifically, in machine tool applications, the bearings are subjected to high radial loads and high speeds, which lead to increased forces in the rolling contact and, as a [...] Read more.

Friction losses are an important parameter for evaluating the operational behaviour of high-speed rolling bearings. Specifically, in machine tool applications, the bearings are subjected to high radial loads and high speeds, which lead to increased forces in the rolling contact and, as a result, increased bearing friction. In this high-speed application, hybrid spindle bearings, typically made of ceramic balls and steel raceways, show better frictional behaviour compared to full steel-made bearings. Therefore, precise knowledge of the friction characteristics of high-speed hybrid bearings can improve friction models and generalise them to spindle bearings with different types, geometries, and operating conditions. In this article, a new straightforward and cost-efficient method for measuring the frictional torque in spindle bearings is presented. A rigidly arranged 7008 hybrid spindle bearing pair was tested up to rotational speeds of 24,000 rpm and high radial loads of 3 kN. The effects of oil–air and grease lubrication are discussed in characteristic diagrams of the tested bearings. Then, based on the test results, a friction calculation model is presented and validated for the outer race control and minimised power dissipation regarding the influence of radial forces. Full article

(This article belongs to the Special Issue Rotor Dynamics and Rotating Machinery)

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13 pages, 1282 KiB

Open AccessEditor’s ChoiceArticle

Fused Filament Fabrication and Injection Moulding of Plastic Packaging: An Environmental and Financial Comparative Assessment

by Cheryl Marie Bezzina and Paul Refalo

Machines 2023, 11(6), 634; https://doi.org/10.3390/machines11060634 - 07 Jun 2023

Viewed by 1137

Abstract

The drive towards smart and sustainable manufacturing is leading companies to opt for environmentally conscious technologies. This study assesses the environmental and financial feasibility of using additive manufacturing, in this case, fused filament fabrication (FFF), instead of injection moulding (IM) to mass-produce cosmetic [...] Read more.

The drive towards smart and sustainable manufacturing is leading companies to opt for environmentally conscious technologies. This study assesses the environmental and financial feasibility of using additive manufacturing, in this case, fused filament fabrication (FFF), instead of injection moulding (IM) to mass-produce cosmetic plastic packaging. Using a life cycle assessment (LCA), the environmental impacts of the raw material production and manufacturing processes were assessed for both technologies. The results showed that using FFF creates a five times greater environmental impact, with printing energy consumption generating 80% of the impact. Using costing models, the cost per product produced using IM and FFF was evaluated, and the models showed that the raw material costs comprise the highest share in both cases. A net present value (NPV) model over twelve years indicated that the FFF NPV was seventeen times higher than that of IM. When testing for quality, the packages produced using IM were superior overall. This study concludes that FFF is more expensive and environmentally impactful when compared to IM. Full article

(This article belongs to the Special Issue Assessing New Trends in Sustainable and Smart Manufacturing)

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23 pages, 980 KiB

Open AccessEditor’s ChoiceArticle

Decentralized Adaptive Quantized Dynamic Surface Control for a Class of Flexible Hypersonic Flight Vehicles with Input Quantization

by Wenyan Zhao, Zeyu Lu, Zijian Bi, Cheng Zhong, Dianxiong Tian, Yanhui Zhang, Xiuyu Zhang and Guoqiang Zhu

Machines 2023, 11(6), 630; https://doi.org/10.3390/machines11060630 - 06 Jun 2023

Viewed by 781

Abstract

A control strategy for a certain class of hypersonic flight aircraft dynamic models with unknown parameters is proposed in this article. The strategy is adaptive dynamic surface input quantization control. To address the issues in conventional inversion control, a first-order low-pass filter and [...] Read more.

A control strategy for a certain class of hypersonic flight aircraft dynamic models with unknown parameters is proposed in this article. The strategy is adaptive dynamic surface input quantization control. To address the issues in conventional inversion control, a first-order low-pass filter and an adaptive parameter minimum learning law are introduced in the control system design process. This method has the following features: (1) it solves the problem of repeated differentiation of the virtual control law in the conventional back-stepping method, greatly simplifying the control law structure; (2) by using the norm of the neural network weight vector as the adaptive adjustment parameter instead of updating each element online, the number of adaptive adjustment parameters is significantly reduced, improving the execution efficiency of the controller; (3) the introduced hysteresis quantizer overcomes the disadvantage of the quantization accuracy deterioration when the input value is too low in the logarithm quantizer, improving the accuracy of the quantizer. Stability analysis has shown that all signals in the closed-loop system are semi-globally uniformly bounded, and simulation results have verified the effectiveness of the proposed adaptive quantized control scheme. Full article

(This article belongs to the Special Issue Advanced Methodology of Intelligent Control and Measurement)

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19 pages, 1269 KiB

Open AccessEditor’s ChoiceArticle

An Experimental Methodology for Introducing Educational Robotics and Storytelling in Therapeutical Activities for Children with Neurodevelopmental Disorders

by Elena Peribañez, Sofia Bayona, Jose San Martin, Ana Verde, Carlos Garre, Janika Leoste and Luis Pastor

Machines 2023, 11(6), 629; https://doi.org/10.3390/machines11060629 - 06 Jun 2023

Cited by 1 | Viewed by 1453

Abstract

Educational robotics is a valuable tool in education and therapy for children with neurodevelopmental disorders (NDD), especially when introduced in activities, combined with gamification and storytelling elements. However, the lack of familiarity of therapists with the technologies involved makes their widespread introduction difficult [...] Read more.

Educational robotics is a valuable tool in education and therapy for children with neurodevelopmental disorders (NDD), especially when introduced in activities, combined with gamification and storytelling elements. However, the lack of familiarity of therapists with the technologies involved makes their widespread introduction difficult and leads to case-specific rather than more generalizable methods. In this paper, we present an experimental methodology which provides a guide for the introduction of these elements in therapeutical activities with children with NDD. Providing a common framework reduces the gap between the different expertise of therapists, educators, and engineers. While establishing a common vocabulary and objectives, the methodology provides a guide for designing activities and evaluating their therapeutic effectiveness. We provide an example with a pilot study using a low-cost robot (Ozobot) in a therapeutic environment. Results regarding the children’s task involvement, level of attention, and use of social skills were positive. In addition, the attitude of some children changed throughout the sessions, improving frustration tolerance. The discussion of the pilot study provides clues for improving future implementations of the presented methodology, which serves as a framework for the design of future experiments that include therapeutic activities with educational robotics, gamification, and storytelling. Full article

(This article belongs to the Special Issue Robots in Healthcare: Design, Control and Applications)

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21 pages, 14316 KiB

Open AccessEditor’s ChoiceArticle

Research on Additive Technique Parameter Optimization for Robotic Gripper Construction

by Emilian Paduraru, Catalin-Gabriel Dumitras, Dragos-Florin Chitariu, Mihaita Horodinca and Florin Chifan

Machines 2023, 11(6), 621; https://doi.org/10.3390/machines11060621 - 04 Jun 2023

Cited by 1 | Viewed by 2290

Abstract

Designing an industrial robot gripper suitable for today’s industry is a challenging task due to the rapid evolution of products. Industrial robots are involved in machining, the transfer of parts, control and assembly, and the number of tasks performed by robots are increasing. [...] Read more.

Designing an industrial robot gripper suitable for today’s industry is a challenging task due to the rapid evolution of products. Industrial robots are involved in machining, the transfer of parts, control and assembly, and the number of tasks performed by robots are increasing. Robots need to have the capability to adapt to new jobs consisting of new parts and new trajectories, and in most cases the preferred end effectors are grippers. In turn, grippers need to be flexible enough in order to cope with these changes. For this research, the authors propose a new gripper design which is capable of handling a large variety of parts with different sizes and shapes. In this research, an electrically actuated four-jaw gripper, with the capability of parallel movement of its jaws, is presented that also has the capability to fold the clamping jaws two by two and become a two-jaw gripper. Since the design is most suitable for additive manufacturing techniques, different additive techniques are analyzed for the manufacturing of the gripper. In the second part of the paper, different setups of the 3D printers are considered, such as infill percentage, raster angle and layer height. The main material on focus is a PET with grinded carbon-fiber reinforcement, but different materials are used for a better comparison of the rigidity of the system. This comparison is also presented in this article. The analysis of the material and 3D printing parameters are tested with Standard D638-14 probes used in a traction testing machine. After performing the traction test, the results are compared with FEA analysis. An optimal solution based on the experimental tests is proposed for the manufacture of the proposed gripper design. Full article

(This article belongs to the Section Industrial Systems)

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23 pages, 5713 KiB

Open AccessEditor’s ChoiceArticle

A New Cable-Driven Model for Under-Actuated Force–Torque Sensitive Mechanisms

by Giovanni Gerardo Muscolo and Paolo Fiorini

Machines 2023, 11(6), 617; https://doi.org/10.3390/machines11060617 - 03 Jun 2023

Cited by 3 | Viewed by 1601

Abstract

Force–torque sensors are used in many and different domains (i.e., space, medicine, biology, etc.). Design solutions of force–torque sensors can be conceived by using many types of connections or components; however, there are only a few sensors designed using cable-driven systems. This could [...] Read more.

Force–torque sensors are used in many and different domains (i.e., space, medicine, biology, etc.). Design solutions of force–torque sensors can be conceived by using many types of connections or components; however, there are only a few sensors designed using cable-driven systems. This could be related to many reasons, one of which being that cables are able only to pull and not push. In this paper, a new cable-driven model for under-actuated force–torque sensing mechanisms is proposed, simulated, and tested, underlining the novelty of using cables for force–torque sensing. Analytical formulations, simulations, and physical implementations are presented in this paper. Results confirm that the new proposed model can be used for force–torque sensing mechanisms in micro- and macro- applications where under-actuation is a fundamental requirement, as in robotic surgery. The proposed model and mechanism can be used in the design of sensors and actuators. The innovative model is validated with two different test benches, opening new challenges in the design and development of under-actuated force–torque transducers. Full article

(This article belongs to the Special Issue Variable Stiffness Physical Interaction in Robotic Devices and Machines)

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