Next Issue
Volume 10, September
Previous Issue
Volume 10, July
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
2.1
2.6
Journals
Machines
Volume 10
Issue 8
share announcement

Machines, Volume 10, Issue 8 (August 2022) – 122 articles

Cover Story (view full-size image): Collaborative robots have the potential to improve the working conditions of human operators, especially in small- and medium-sized enterprises characterized by small and highly variable production batches. A suitable task design and an efficient interaction strategy between humans and robots are the milestones of a collaborative approach, which can be based on several technologies, possibly in a multimodal way. To improve a cooperative assembly task, we propose exploiting a brain–computer interface to supply commands to a robot, allowing the operator to switch between independent and cooperative modalities of assistance with desired timings. The usability and effectiveness of the proposed interaction strategy are evaluated to assess the advantages of the proposed solution. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
13 pages, 2220 KiB  
Communication
Loco-Manipulation Control for Arm-Mounted Quadruped Robots: Dynamic and Kinematic Strategies
by Guiyang Xin, Fanlian Zeng and Kairong Qin
Machines 2022, 10(8), 719; https://doi.org/10.3390/machines10080719 - 22 Aug 2022
Cited by 9 | Viewed by 2691
Abstract
The studies on quadruped robots equipped with arms are still rare at the moment. The interaction between the arm and the quadrupedal platform needs to be handled by whole-body controllers. This paper presents an optimization-based dynamic whole-body controller to solve the problem of [...] Read more.
The studies on quadruped robots equipped with arms are still rare at the moment. The interaction between the arm and the quadrupedal platform needs to be handled by whole-body controllers. This paper presents an optimization-based dynamic whole-body controller to solve the problem of when the robot stands still for manipulation. In order to reduce the strong interaction when the robot is trotting, we keep using the whole-body controller to handle locomotion control and resort to joint PD controllers for the arm’s manipulation coupled with the mobile base on the kinematic level. Simulation results validate the expected locomotion and manipulation functionalities in both manipulation mode and loco-manipulation mode. The proposed control strategies are able to use the redundancy to perform multiple tasks in a dynamic system as such with 24 degrees of freedom. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
►▼ Show Figures

Figure 1

16 pages, 5684 KiB  
Article
A Method for Measurement of Workpiece form Deviations Based on Machine Vision
by Wei Zhang, Zongwang Han, Yang Li, Hongyu Zheng and Xiang Cheng
Machines 2022, 10(8), 718; https://doi.org/10.3390/machines10080718 - 22 Aug 2022
Cited by 5 | Viewed by 1865
Abstract
Machine vision has been studied for measurements of workpiece form deviations due to its ease of automation. However, the measurement accuracy limits its wide implementation in industrial applications. In this study, a method based on machine vision for measurement of straightness, roundness, and [...] Read more.
Machine vision has been studied for measurements of workpiece form deviations due to its ease of automation. However, the measurement accuracy limits its wide implementation in industrial applications. In this study, a method based on machine vision for measurement of straightness, roundness, and cylindricity of a workpiece is presented. A subsumed line search algorithm and an improved particle swarm optimization algorithm are proposed to evaluate the straightness and roundness deviations of the workpiece. Moreover, an image evaluation method of cylindricity deviation by the least-square fitting of the circle’s center coordinates is investigated. An image acquisition system incorporating image correction and sub-pixel edge positioning technology is developed. The performance of the developed system is evaluated against the measurement results of the standard cylindricity measuring instrument. The differences in the measurement of straightness, roundness, and cylindricity are −4.69 μm, 3.87 μm, and 8.51 μm, respectively. The proposed method would provide a viable industrial solution for the measurement of workpiece form deviations. Full article
(This article belongs to the Special Issue Industrial Process Improvement by Automation and Robotics)
►▼ Show Figures

Figure 1

15 pages, 3838 KiB  
Article
Precision Design of Transmission Mechanism of Toggle Press Based on Error Modeling
by Xinyu Dong and Yu Sun
Machines 2022, 10(8), 717; https://doi.org/10.3390/machines10080717 - 21 Aug 2022
Viewed by 2612
Abstract
The position accuracy of the bottom dead centre (BDC) of a slider is a crucial performance index to measure the quality of a multi-link mechanical press. At present, the research on improving the position accuracy of the BDC mainly focuses on error compensation, [...] Read more.
The position accuracy of the bottom dead centre (BDC) of a slider is a crucial performance index to measure the quality of a multi-link mechanical press. At present, the research on improving the position accuracy of the BDC mainly focuses on error compensation, and there is a lack of research on the tolerance design of the transmission mechanism according to the accuracy requirements of the BDC. In this paper, the motion output accuracy of the press is characterized by the position error of the BDC of the slider and the inclined angle error of the slider. Based on the loop increment method, the error transmission model of the transmission mechanism of a multi-link mechanical press was established. The key error factors that affect the output accuracy of the press were determined by analysis of error sensitivity. On this basis, a precision synthesis method considering manufacturing cost and BDC precision reliability was proposed. Finally, a Monte Carlo simulation and experiments on a toggle mechanical press were conducted to verify the model. The results show that the proposed error model and optimization method are feasible and effective. Full article
(This article belongs to the Special Issue Advanced Processes and Technologies in Precision and Ultra-Precision Machining)
►▼ Show Figures

Figure 1

18 pages, 4018 KiB  
Article
Lateral Stability Control of a Tractor-Semitrailer at High Speed
by Haohao Cai and Xiaomei Xu
Machines 2022, 10(8), 716; https://doi.org/10.3390/machines10080716 - 20 Aug 2022
Cited by 9 | Viewed by 2146
Abstract
To improve the high-speed lateral stability of the tractor-semitrailer, a lateral stability control strategy based on the additional yaw moment caused by differential braking is proposed and investigated based on the co-simulation environment. First of all, a five-degree-of-freedom (5-DOF) yaw-roll dynamic model of [...] Read more.
To improve the high-speed lateral stability of the tractor-semitrailer, a lateral stability control strategy based on the additional yaw moment caused by differential braking is proposed and investigated based on the co-simulation environment. First of all, a five-degree-of-freedom (5-DOF) yaw-roll dynamic model of the tractor-semitrailer is established, and the model accuracy is verified. Secondly, the lateral stability control strategy of the tractor-semitrailer is proposed, two yaw moment controllers and the braking torque distributor are designed. Then, the effectiveness of the proposed control strategy and the influence of the yaw moment controller on the lateral stability of the tractor-semitrailer are investigated under the high-speed lane-change maneuvers. Finally, the controller robustness is discussed. Research results show that the proposed high-speed lateral stability control strategy can ensure the tractor-semitrailer to perform safely the single lane-change (SLC) maneuver at 110 km/h and the double lane-change (DLC) maneuver at 88 km/h; the yaw moment controller has significant influence on the lateral dynamic performance of the tractor-semitrailer; compared with the proportional-derivative (PD) control, the model predictive control (MPC) can make the tractor-semitrailer obtain better lateral stability under high-speed lane-change maneuvers; MPC and PD controllers exhibit good robustness to the considered vehicle parameter uncertainties. Full article
(This article belongs to the Section Vehicle Engineering)
►▼ Show Figures

Figure 1

13 pages, 5852 KiB  
Communication
Investigation of the Temperature Effects on Copper Losses in Hairpin Windings
by Mohammad Soltani, Stefano Nuzzo, Davide Barater and Giovanni Franceschini
Machines 2022, 10(8), 715; https://doi.org/10.3390/machines10080715 - 20 Aug 2022
Cited by 2 | Viewed by 1728
Abstract
Today, an extensive electrification is occurring in all industrial sectors, with a special interest seen in the automotive and aerospace industries. The electric motor, surely, is one of the main actors in this context, and an ever-increasing effort is spent with the aim [...] Read more.
Today, an extensive electrification is occurring in all industrial sectors, with a special interest seen in the automotive and aerospace industries. The electric motor, surely, is one of the main actors in this context, and an ever-increasing effort is spent with the aim of improving its efficiency and torque density. Hairpin windings are one of the recent technologies which are implemented onto the stator of the electric motor. Compared to conventional random windings, it inherently features lower DC resistance, higher fill factor, better thermal performance, improved reliability, and an automated manufacturing process. However, its bottleneck is the high ohmic losses at high-frequency operations due to skin and proximity effects (AC losses), resulting in a negative impact on the temperature map of the machine. Nevertheless, while it is well-known that DC losses increase linearly with the operating temperatures, the AC losses trend needs further insight. This paper demonstrates that operating the machine at higher temperatures could be beneficial for overall efficiency, especially at high-frequency operations. This suggests that a paradigm shift is required for the design of electric motors equipped with hair-pin windings, which should therefore focus on a temperature-oriented approach. In addition, the effect of the rotor topology on AC losses, which is often overlooked, is also considered in this paper. The combination of these effects is used to carry out observations and, eventually, to provide design recommendations. Finite element electromagnetic and thermal evaluations are performed to prove the findings of this research. Full article
(This article belongs to the Special Issue Latest Trends in the Design of Hairpin Winding Machines for Transport Electrification Purposes)
►▼ Show Figures

Figure 1

26 pages, 62558 KiB  
Article
Pick–and–Place Trajectory Planning and Robust Adaptive Fuzzy Tracking Control for Cable–Based Gangue–Sorting Robots with Model Uncertainties and External Disturbances
by Peng Liu, Haibo Tian, Xiangang Cao, Xinzhou Qiao, Li Gong, Xuechao Duan, Yuanying Qiu and Yu Su
Machines 2022, 10(8), 714; https://doi.org/10.3390/machines10080714 - 20 Aug 2022
Cited by 6 | Viewed by 1983
Abstract
A suspended cable–based parallel robot (CBPR) composed of four cables and an end–grab is employed in a pick–and–place operation of moving target gangues (MTGs) with different shapes, sizes, and masses. This paper focuses on two special problems of pick–and–place trajectory planning and trajectory [...] Read more.
A suspended cable–based parallel robot (CBPR) composed of four cables and an end–grab is employed in a pick–and–place operation of moving target gangues (MTGs) with different shapes, sizes, and masses. This paper focuses on two special problems of pick–and–place trajectory planning and trajectory tracking control of the cable–based gangue–sorting robot in the operation space. First, the kinematic and dynamic models for the cable–based gangue–sorting robots are presented in the presence of model uncertainties and unknown external disturbances. Second, to improve the sorting accuracy and efficiency of sorting system with cable–based gangue–sorting robot, a four-phase pick–and–place trajectory planning scheme based on S-shaped acceleration/deceleration algorithm and quintic polynomial trajectory planning method is proposed, and moreover, a robust adaptive fuzzy tracking control strategy is presented against inevitable uncertainties and unknown external disturbances for trajectory tracking control of the cable–based gangue–sorting robot, where the stability of a closed-loop control scheme is proved with Lyapunov stability theory. Finally, the performances of pick–and–place trajectory planning scheme and robust adaptive tracking control strategy are evaluated through different numerical simulations within Matlab software. The simulation results show smoothness and continuity of pick–and–place trajectory for the end–grab as well as the effectiveness and efficiency to guarantee a stable and accurate pick–and–place trajectory tracking process even in the presence of various uncertainties and external disturbances. The pick–and–place trajectory generation scheme and robust adaptive tracking control strategy proposed in this paper lay the foundation for accurate sorting of MTGs with the robot. Full article
(This article belongs to the Special Issue New Frontiers in Parallel Robots)
►▼ Show Figures

Figure 1

27 pages, 53142 KiB  
Article
A Holistic Approach to IGBT Board Surface Fractal Object Detection Based on the Multi-Head Model
by Haoran Huang and Xiaochuan Luo
Machines 2022, 10(8), 713; https://doi.org/10.3390/machines10080713 - 20 Aug 2022
Cited by 2 | Viewed by 1473
Abstract
In industrial visual inspection, foreign matters are mostly fractal objects. Detailed detection of fractal objects is difficult but necessary because better decision-making relies on more detailed and more comprehensive detection information. This presents a challenge for industrial applications. To solve this problem, we [...] Read more.
In industrial visual inspection, foreign matters are mostly fractal objects. Detailed detection of fractal objects is difficult but necessary because better decision-making relies on more detailed and more comprehensive detection information. This presents a challenge for industrial applications. To solve this problem, we proposed a holistic approach to fractal object detection based on a multi-head model. We proposed the IWS (Information Watch and Study) module to provide enhancement learning capabilities for object information. It increases the detection dimension of the object and can perform more detailed detection. In order to realize the portability of the IWS module, it can be easily and quickly deployed to the existing advanced object detection model to achieve end-to-end detection. We proposed the FGI (Fine-Grained Information) Head, which is used to extract more comprehensive feature vectors from the original base model. We proposed the WST (Watch and Study Tactic) Learner for object information processing and adaptive learning of class cluster centers. Using the MRD (Multi-task Result Determination) strategy to combine the classification results and IWS results, the final detection results are derived. In the experiment, the IWS and MRD were mounted on three different models of the YOLO series. The experimental results show that YOLO+IWS has good foreign object detection capabilities to meet the needs of industrial visual inspection. Moreover, for the detailed detection ability of fractal objects, YOLO+IWS is better than the other 11 competing methods. We designed a new evaluation index and an adjustment mechanism of class learning weights to make better judgments and more balanced learning. Not only that, we applied YOLO+IWS to form a brand new object detection system. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
►▼ Show Figures

Figure 1

23 pages, 3350 KiB  
Article
Systematic Metamodel-Based Optimization Study of Synchronous Reluctance Machine Rotor Barrier Topologies
by Branko Ban and Stjepan Stipetic
Machines 2022, 10(8), 712; https://doi.org/10.3390/machines10080712 - 19 Aug 2022
Cited by 2 | Viewed by 2103
Abstract
Nowadays, due to the confidence in modeling tools and rapid product iteration, electric machine designers primarily rely on simulations. This approach reduces time and cost and is very useful when comparing different machine topologies. The prototype stage usually comes after the depletion of [...] Read more.
Nowadays, due to the confidence in modeling tools and rapid product iteration, electric machine designers primarily rely on simulations. This approach reduces time and cost and is very useful when comparing different machine topologies. The prototype stage usually comes after the depletion of all simulation resources. When designing a synchronous reluctance machine, the first step is the selection of rotor barrier type. The literature provides several topologies but does not clearly state which one yields the best performance. The goal of this paper is to determine the best variant for a six-pole machine and the selected requirements using a metamodel-based optimization approach. Seven rotor topologies with different complexities were derived from circular, hyperbolic, and Zhukovsky barrier types (circular concentric, circular variable depth, hyperbolic with fixed eccentricity, hyperbolic with variable eccentricity, original Zhukovsky, modified Zhukovsky variable depth and modified Zhukovsky with equal barrier depth). The novelty of the proposed strategy is in the systematic and fair comparison of different rotor topologies. This approach significantly reduces the total optimization time from several weeks to a few days. Additionally, a novel modified Zhukovsky variable depth topology, which merges the best qualities of all considered variants, was developed. An identical optimization strategy was applied to all variants, and the final results prove that the barrier type substantially affects the final performance of the machine. The best results are achieved by the modified Zhukovsky variable depth topology. In relation to the worst (baseline) topology, the performance gain is 14.9% and the power factor is increased from 0.61 to 0.67. An additional study using different numbers of barrier layers (3, 4, and 5) was conducted to determine the best topology. The best results were achieved with the original four barrier layers. Full article
(This article belongs to the Special Issue Synchronous Reluctance Motor-Drive Advancements)
►▼ Show Figures

Figure 1

28 pages, 6202 KiB  
Article
Stewart Platform Motion Control Automation with Industrial Resources to Perform Cycloidal and Oceanic Wave Trajectories
by Diego Silva, Julio Garrido and Enrique Riveiro
Machines 2022, 10(8), 711; https://doi.org/10.3390/machines10080711 - 19 Aug 2022
Cited by 9 | Viewed by 7425
Abstract
Research on motion control automation of Stewart Platforms with industrial configurations (motion and controllers) is less present in the literature than other types of automation with low-cost devices such as Arduino, or via simulations in MATLAB or Simulink. Moreover, direct kinematics is less [...] Read more.
Research on motion control automation of Stewart Platforms with industrial configurations (motion and controllers) is less present in the literature than other types of automation with low-cost devices such as Arduino, or via simulations in MATLAB or Simulink. Moreover, direct kinematics is less widely applied because of heavy calculation in real-time device implementations. The paper first analyzes the design, kinematic modelling, and trajectory generation of a Stewart Platform robot and addresses direct kinematics and motion automation. Next, the automation architecture with industrial controllers is detailed. The paper presents the results of the inverse kinematic in two use scenarios: cycloidal trajectories that carry out point-to-point and oceanic wave movements. The efficient calculation of direct kinematics in real time was also studied. This opens the possibility of closing the positioning loop at the controller or implementing supervisors such as the “tracking error”. Further research might investigate the effects of the sequence planning to avoid collisions with objects inside the workspace while considering the feedback of the tracking error. Full article
(This article belongs to the Special Issue Development and Applications of Parallel Robots)
►▼ Show Figures

Figure 1

16 pages, 7257 KiB  
Article
A Study on the Vibration Characteristics and Damage Mechanism of Pantograph Strips in a Railway Electrification System
by Qirui Wu, Xiaohan Phrain Gu, Ziyan Ma and Anbin Wang
Machines 2022, 10(8), 710; https://doi.org/10.3390/machines10080710 - 18 Aug 2022
Cited by 1 | Viewed by 1828
Abstract
This paper presents the vibration characteristics of a pantograph–catenary interaction in a rigid catenary system. Both computational simulation and laboratory tests are carried out to evaluate the frequency contents of pantograph strips. Based on the observation that irregular wear is characterized by the [...] Read more.
This paper presents the vibration characteristics of a pantograph–catenary interaction in a rigid catenary system. Both computational simulation and laboratory tests are carried out to evaluate the frequency contents of pantograph strips. Based on the observation that irregular wear is characterized by the consistency between the pantograph strips’ wear pattern and the mode shape of their dominant modal frequencies, it is deducted that resonance occurs at the pantograph strip and the contact wire interface in the high frequency range. By applying damping treatment to the pantograph strip, and hence improving its damping property, a reduction of 7 dB in the total vibration level at the sliding contact can be achieved, as verified through field tests. It is also found that the worse the initial condition of the pantograph–catenary system, the more prominent the damping effects on the control of high-frequency vibration for irregular wear problems. Full article
(This article belongs to the Special Issue Vibration Based Condition Monitoring)
►▼ Show Figures

Figure 1

15 pages, 4120 KiB  
Article
Suppressing Quadrature Error and Harmonics in Resolver Signals via Disturbance-Compensated PLL
by Rui Wang and Zhong Wu
Machines 2022, 10(8), 709; https://doi.org/10.3390/machines10080709 - 18 Aug 2022
Viewed by 1426
Abstract
The aim of this study was to obtain accurate angular positions and velocities from resolver signals; resolver-to-digital conversion (RDC) often adopts a phase-locked loop (PLL) as a demodulation algorithm. However, resolver signals often come with quadrature errors and harmonics, which lead to a [...] Read more.
The aim of this study was to obtain accurate angular positions and velocities from resolver signals; resolver-to-digital conversion (RDC) often adopts a phase-locked loop (PLL) as a demodulation algorithm. However, resolver signals often come with quadrature errors and harmonics, which lead to a severe reduction in PLL accuracy. The conventional PLL does not consider the impact of the quadrature error, and the bandwidth of the PLL is much larger than the fundamental frequency of resolver signals for pursuing a low dynamic error. These reasons render the retention of resolver harmonics in the demodulation results. In this paper, a disturbance-compensated PLL (DC-PLL) is proposed, which consists of a phase detector for suppressing quadrature error and harmonics (SQEH-PD) and a second-order observer. Firstly, since the quadrature error does not change with the angle velocity, the pre-estimated quadrature error is used in the SQEH-PD to compensate for the quadrature error in resolver signals. Secondly, although the frequency of the harmonics changes with the velocity, the amplitudes of the harmonics do not change. Therefore, the pre-estimated amplitudes of harmonics and estimated angular position are used in the SQEH-PD to compensate for the harmonics in resolver signals. Thirdly, a second-order observer is designed to estimate the angular position and velocity by regulating the phase detector error. Compared with the conventional PLL, the proposed DC-PLL has a stronger anti-disturbance ability against the quadrature error and harmonics by configurating the phase detector error and the estimated position error, which have a linear relation. Simulation and experimental results prove the effectiveness of the proposed method. Full article
(This article belongs to the Special Issue Advances in Electrical Machines, Drives and Vehicles)
►▼ Show Figures

Figure 1

22 pages, 8810 KiB  
Article
Yōkobo: A Robot to Strengthen Links Amongst Users with Non-Verbal Behaviours
by Siméon Capy, Pablo Osorio, Shohei Hagane, Corentin Aznar, Dora Garcin, Enrique Coronado, Dominique Deuff, Ioana Ocnarescu, Isabelle Milleville and Gentiane Venture
Machines 2022, 10(8), 708; https://doi.org/10.3390/machines10080708 - 18 Aug 2022
Cited by 7 | Viewed by 1979
Abstract
Yōkobo is a robject; it was designed using the principle of slow technology and it aims to strengthen the bond between members (e.g., a couple). It greets people at the entrance and mirrors their interactions and the environment around them. It was constructed [...] Read more.
Yōkobo is a robject; it was designed using the principle of slow technology and it aims to strengthen the bond between members (e.g., a couple). It greets people at the entrance and mirrors their interactions and the environment around them. It was constructed by applying the notions of a human–robot–human interaction. Created by joint work between designers and engineers, the form factor (semi-abstract) and the behaviours (nonverbal) were iteratively formed from the early stage of the design process. Integrated into the smart home, Yōkobo uses expressive motion as a communication medium. Yōkobo was tested in our office to evaluate its technical robustness and motion perception ahead of future long-term experiments with the target population. The results show that Yōkobo can sustain long-term interaction and serve as a welcoming partner. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
►▼ Show Figures

Figure 1

19 pages, 6422 KiB  
Article
Research on Path Planning and Trajectory Tracking of an Unmanned Electric Shovel Based on Improved APF and Preview Deviation Fuzzy Control
by Yi Fang, Shuai Wang, Qiushi Bi, Guohua Wu, Wei Guan, Yongpeng Wang and Chuliang Yan
Machines 2022, 10(8), 707; https://doi.org/10.3390/machines10080707 - 18 Aug 2022
Cited by 3 | Viewed by 1573
Abstract
With the development and upgrading of intelligent mines, research on the unmanned walking of intelligent electric shovels (ES) has been carried out to improve the moving efficiency of extra-large excavators. This paper first introduces an electric shovel’s primary moving condition in an open-pit [...] Read more.
With the development and upgrading of intelligent mines, research on the unmanned walking of intelligent electric shovels (ES) has been carried out to improve the moving efficiency of extra-large excavators. This paper first introduces an electric shovel’s primary moving condition in an open-pit mine. According to the moving characteristics of the heavy-duty crawler, the artificial potential field (APF) algorithm is improved to plan the moving trajectory of the electric shovel and carry out simulation verification. A dynamic model of an electric shovel is established. A fuzzy control tracking method is proposed based on preview displacement and centroid displacement deviation. The robustness of the tracking algorithm is verified by multi-condition simulation. Finally, the electric shovel prototype is tested through path planning and tracking experiments. The experimental results show that the improved artificial potential field algorithm can plan an obstacle-free path that satisfies the movement of an electric shovel, and the electric shovel can quickly track the preset trajectory. The maximum deviation of the track tracking center of mass is no more than 10 cm, and the deviation of the heading angle when the shovel reaches the endpoint is within 2°. Full article
(This article belongs to the Topic Intelligent Systems and Robotics)
►▼ Show Figures

Figure 1

18 pages, 2665 KiB  
Article
Estimations of Compressor Stall and Surge Using Passage Stall Behaviors
by Mohammad Akhlaghi, Yahya Azizi and Nourouz Mohammad Nouri
Machines 2022, 10(8), 706; https://doi.org/10.3390/machines10080706 - 18 Aug 2022
Cited by 3 | Viewed by 1497
Abstract
The predictions of the onset of rotating stall and surge are very important in the preliminary design stage of a compressor. Rotating stall and surge are complex instabilities that cause efficiency loss and reduced pressure rise, and, therefore, compressor designers attempt to avoid [...] Read more.
The predictions of the onset of rotating stall and surge are very important in the preliminary design stage of a compressor. Rotating stall and surge are complex instabilities that cause efficiency loss and reduced pressure rise, and, therefore, compressor designers attempt to avoid them in the design stage. There are many criteria for predicting stability limits, including empirical, theoretical, and numerical investigations in the literature. However, these investigations have important limitations. The present study establishes a new method in which the stall and post-stall behavior of a compressor is estimated by an equivalent reconstructed compressor using special combinations of single-passage flow behavior in different mass flow rates. The combinations are generated such that pre-stall, in-stall, and surge flow regimes and between one and eight stall cells are reproduced in the full-annulus compressor. The method requires the least computational requirements and is time efficient. The results indicate that secondary flow total energy and spectral entropy are indeed correlated with compressor operating conditions. The predictions of the onset of stall and surge for the investigated compressor show good agreement with the experimental data. Full article
(This article belongs to the Section Turbomachinery)
►▼ Show Figures

Figure 1

20 pages, 6706 KiB  
Article
Meshing Characteristics of Spur Gears Considering Three-Dimensional Fractal Rough Surface under Elastohydrodynamic Lubrication
by Zhifang Zhao, Yang Yang, Hongzheng Han, Hui Ma, Haixu Wang and Zhanwei Li
Machines 2022, 10(8), 705; https://doi.org/10.3390/machines10080705 - 17 Aug 2022
Cited by 10 | Viewed by 1737
Abstract
Taking the effect of actual surface topography under elastohydrodynamic lubrication (EHL) conditions on the contact state of gear pairs into consideration, a combination model with the analytical sliced method and two-dimensional (2D) EHL model is proposed to characterize the three-dimensional (3D) meshing characteristics [...] Read more.
Taking the effect of actual surface topography under elastohydrodynamic lubrication (EHL) conditions on the contact state of gear pairs into consideration, a combination model with the analytical sliced method and two-dimensional (2D) EHL model is proposed to characterize the three-dimensional (3D) meshing characteristics of spur gears. Firstly, the surface topology of gears is tested by a surface profiler, which reflects that the topography of tooth surface accords with fractal characteristics. Thus, by adopting the Weierstrass–Mandelbrot (W-M) fractal function, the gear surface is characterized. Secondly, the numerical 2D EHL model with fractal roughness is established, and distributions of oil film pressure (OFP) and oil film thickness (OFT) at different meshing positions are obtained. Finally, considering the different topography distributions in the direction of face width, time-varying mesh stiffness (TVMS) is calculated based on the analytical sliced method. Thus, the influence of 3D surface topography can be considered. The Hertz contact stiffness is substituted by the time-varying lubricating oil film stiffness (OFS). The influences of tooth surface topography and lubricant film characteristics on meshing characteristics are investigated. The results show that the 3D rough tooth surface may be well characterized by a fractal function with random phase. Moreover, there is a great difference in the distribution of OFP and OFT between rough and smooth surfaces, which certainly influences the gear meshing characteristics. Full article
(This article belongs to the Section Friction and Tribology)
►▼ Show Figures

Figure 1

29 pages, 9762 KiB  
Article
An Iterative Modified Adaptive Chirp Mode Decomposition Method and Its Application on Fault Diagnosis of Wind Turbine Bearings
by Ao Ding, Guiji Tang, Xiaolong Wang, Yuling He and Shiyan Fan
Machines 2022, 10(8), 704; https://doi.org/10.3390/machines10080704 - 17 Aug 2022
Cited by 1 | Viewed by 1334
Abstract
Wind turbine bearings usually work with strong background noise, making the faulty properties difficult to extract and detect. To accurately diagnose the faults of rolling bearings in wind turbines, an iterative modified adaptive chirp mode decomposition (IMACMD) method is proposed in this paper. [...] Read more.
Wind turbine bearings usually work with strong background noise, making the faulty properties difficult to extract and detect. To accurately diagnose the faults of rolling bearings in wind turbines, an iterative modified adaptive chirp mode decomposition (IMACMD) method is proposed in this paper. Firstly, an envelope interpolation method is employed to preliminarily determine the iterative mode number and guide the potentially initial frequency selection. Secondly, the upper limits of the iterative mode number and the initial frequency are further determined through correlation analysis. During the iteration process, the optimal weight factor of the reconstructive input signal, which is the residual signal of the previous iterative decomposition, is determined according to the new designed ensemble L-Kurtosis index. Experimental and engineering signals are used to validate the proposed IMACMD method. Comparisons with the conventional methods demonstrate the superiority of this proposed method. It is shown that this method can not only identify the weak features for single faults but also separate the multiple features for compound faults. Full article
(This article belongs to the Section Machines Testing and Maintenance)
►▼ Show Figures

Figure 1

16 pages, 1266 KiB  
Article
Deep Reinforcement Learning Based on Social Spatial–Temporal Graph Convolution Network for Crowd Navigation
by Yazhou Lu, Xiaogang Ruan and Jing Huang
Machines 2022, 10(8), 703; https://doi.org/10.3390/machines10080703 - 17 Aug 2022
Cited by 6 | Viewed by 1787
Abstract
In the crowd navigation, reinforcement learning based on graph neural network is a promising method, which effectively solves the poor navigation effect based on social interaction model and the freezing behavior of robot in extreme cases. However, since the information correlation of human [...] Read more.
In the crowd navigation, reinforcement learning based on graph neural network is a promising method, which effectively solves the poor navigation effect based on social interaction model and the freezing behavior of robot in extreme cases. However, since the information correlation of human trajectory has not been involved in the method, its performance still needs improvement. Therefore, we proposed a deep reinforcement learning model based on Social Spatial–Temporal Graph Convolution Network (SSTGCN) to handle the crowd navigation problem, in which the spatial–temporal information of human trajectory has been taken advantage to predict human behavior intentions and help robot plan path more efficiently. The model consists of graph learning module and robot forward planning module. In the graph learning module, the latent features of agents are taken advantage to reason about the relations among the agents, and SSTGCN is used to update feature matrix. In addition, value estimation module calculates state representation and state prediction module predicts the next state. The robot forward planning module makes use of k-step planning to estimate the quality of state and searches the best k steps planning. We tested our model in the Crowd-Nav platform, and the results show that our model has high navigation success rate and short navigation time. In addition, it has good robustness to crowd changes. Full article
(This article belongs to the Special Issue Mobile Robotics: Mathematics, Models and Methods)
►▼ Show Figures

Figure 1

14 pages, 329 KiB  
Review
Environmental Risk Assessment and Management in Industry 4.0: A Review of Technologies and Trends
by Janaína Lemos, Pedro D. Gaspar and Tânia M. Lima
Machines 2022, 10(8), 702; https://doi.org/10.3390/machines10080702 - 17 Aug 2022
Cited by 10 | Viewed by 3009
Abstract
In recent decades, concern with workers’ health has become a priority in several countries, but statistics still show that it is urgent to perform more actions to prevent accidents and illnesses related to work. Industry 4.0 is a new production paradigm that has [...] Read more.
In recent decades, concern with workers’ health has become a priority in several countries, but statistics still show that it is urgent to perform more actions to prevent accidents and illnesses related to work. Industry 4.0 is a new production paradigm that has brought significant advances in the relationship between man and machine, driving a series of advances in the production process and new challenges in occupational safety and health (OSH). This paper addresses occupational risks, diseases, opportunities, and challenges in Industry 4.0. It also covers Internet-of-Things-related technologies that, by the real-time measurement and analysis of occupational conditions, can be used to create smart solutions to contribute to reducing the number of workplace accidents and for the promotion of healthier and safer workplaces. Proposals involving smart personal protective equipment (smart PPE) and monitoring systems are analyzed, and aspects regarding the use of artificial intelligence and the data privacy concerns are also discussed. Full article
(This article belongs to the Special Issue Industrial Process Improvement by Automation and Robotics)
23 pages, 12280 KiB  
Article
Analysis and Compensation Control of Engine Valve Response Delay Based on the Electro-Hydraulic Variable Valve Actuator
by Jian Li, Yong Lu, Fengshuo He, Gongjie Zhou and Lixian Miao
Machines 2022, 10(8), 701; https://doi.org/10.3390/machines10080701 - 17 Aug 2022
Cited by 1 | Viewed by 1273
Abstract
The time delay of variable valve actuators has a significant influence on engine valve lift tracking performance. For camless hydraulic valve actuators, engine valve response is affected by many factors, such as friction and control valve response. In this paper, engine valve response [...] Read more.
The time delay of variable valve actuators has a significant influence on engine valve lift tracking performance. For camless hydraulic valve actuators, engine valve response is affected by many factors, such as friction and control valve response. In this paper, engine valve response delay is investigated in depth. Experiment results show that engine valve motion delay can be divided into valve open delay and valve close delay. They are different even in the same engine cycle. Complicated delay characteristics make it difficult to build an accurate delay model. In this paper, a data-based delay observer is developed. To compensate the nonlinear valve delay, the virtual desired valve lift is designed. By synthesizing the virtual valve lift into the backstepping procedure, an engine valve lift tracking controller with delay compensation is developed. Compared with the P controller, the backstepping controller with delay compensation improved the engine valve lift tracking performance significantly. The experiment results show that the valve open error can be reduced by 18.33% and the valve close error can be reduced by 4% at least both at stable conditions and transient conditions. At stable conditions, the valve open error is not more than 0.39 °CA, and the valve close error is not more than 0.44 °CA. Full article
(This article belongs to the Section Electrical Machines and Drives)
►▼ Show Figures

Figure 1

20 pages, 11845 KiB  
Article
Multi-Physics Comparison of Surface-Mounted and Interior Permanent Magnet Synchronous Motor for High-Speed Applications
by Guanghui Du, Niumei Li, Qixun Zhou, Wentao Gao, Lu Wang and Tao Pu
Machines 2022, 10(8), 700; https://doi.org/10.3390/machines10080700 - 17 Aug 2022
Cited by 4 | Viewed by 4604
Abstract
For high-speed permanent magnet machines (HSPMMs), two different rotor structures are widely used: surface-mounted permanent magnet (SPM) and interior permanent magnet (IPM). The two different rotor structures have a large impact on the comprehensive performance in multiple physical fields of HSPMMs, including mechanical [...] Read more.
For high-speed permanent magnet machines (HSPMMs), two different rotor structures are widely used: surface-mounted permanent magnet (SPM) and interior permanent magnet (IPM). The two different rotor structures have a large impact on the comprehensive performance in multiple physical fields of HSPMMs, including mechanical stress, electromagnetic characteristics, and temperature distribution. However, the multi-physics comparison of two different rotor structures is rare in the existing literature, which makes it difficult for designers to choose a suitable rotor structure. Therefore, in this paper, the comprehensive performance of multi-physics for SPM and IPM is comprehensively compared and analyzed. Firstly, the SPM and IPM were designed under 60 kW and 30,000 rpm with the condition of the same stator structure, winding type and volume. Secondly, to ensure that the two rotor structures meet the stress-field constraints, a finite element model (FEM) was built in Ansys Workbench. The influence of different parameters on the rotor stress was analyzed. Following this, the electromagnetic characteristics and temperature distributions of the two motors were compared and analyzed comprehensively through the FEM. Finally, a prototype of an SPM rotor structure is selected and manufactured. The validity of the multi-physics analysis and design was verified through experimental measurements. The above analysis will provide a reference when a designer chooses a rotor structure for an HSPMM. Full article
(This article belongs to the Special Issue Advances and Trends in PM-Free or Rare-Earth-Free PM Motors)
►▼ Show Figures

Figure 1

17 pages, 4872 KiB  
Article
Fuel Consumption Comparison between Hydraulic Mechanical Continuously Variable Transmission and Stepped Automatic Transmission Based on the Economic Control Strategy
by Yuting Chen, Zhun Cheng and Yu Qian
Machines 2022, 10(8), 699; https://doi.org/10.3390/machines10080699 - 17 Aug 2022
Cited by 2 | Viewed by 1609
Abstract
Hydraulic mechanical continuously variable transmission (HMCVT) is a transmission system combining mechanical and hydraulic power flow. The matching and design of the power source and transmission system contribute to the energy-saving and emission reduction of vehicles, and meet the requirements of modern society [...] Read more.
Hydraulic mechanical continuously variable transmission (HMCVT) is a transmission system combining mechanical and hydraulic power flow. The matching and design of the power source and transmission system contribute to the energy-saving and emission reduction of vehicles, and meet the requirements of modern society for environmental protection and energy-saving. This paper takes the transmission system of the pickup truck as a research object to research the transmission ratio control strategy of a self-designed new HMCVT with the goal of minimizing fuel consumption. The research compares it with the standard stepped automatic transmission (SAT). The vehicle model was based on CarSim and MATLAB/Simulink. The simulation was carried out under the EPA cycle, NEDC, and the six-mode cycle. The fuel consumption of SAT and that of HMCVT were compared. The results show that the average fuel savings of the pickup truck with HMCVT are 4.52% in the EPA cycle, 7.01% in the NEDC, and 4.84% in the six-mode cycle compared to the eight-speed SAT. In conclusion, HMCVT is more economically efficient than SAT. Full article
(This article belongs to the Special Issue Advances in Automation, Industrial and Power Engineering)
►▼ Show Figures

Figure 1

23 pages, 7905 KiB  
Article
Dynamics Optimization Research and Dynamics Accuracy and Reliability Analysis of a Multi-Link Mechanism with Clearances
by Shuai Jiang, Yuanpeng Lin, Jianan Liu, Linjing Xiao and Shuaishuai Zhang
Machines 2022, 10(8), 698; https://doi.org/10.3390/machines10080698 - 16 Aug 2022
Cited by 3 | Viewed by 1471
Abstract
With the development of high-speed and lightweight mechanisms, and the continuous improvement of manufacturing accuracy requirements in industrial production, clearance joints have increasingly become one of the key factors affecting dynamics performance. Poor clearance will seriously compromise stability, accuracy, and dynamics performance. Based [...] Read more.
With the development of high-speed and lightweight mechanisms, and the continuous improvement of manufacturing accuracy requirements in industrial production, clearance joints have increasingly become one of the key factors affecting dynamics performance. Poor clearance will seriously compromise stability, accuracy, and dynamics performance. Based on a genetic algorithm, an efficient modeling methodology for the dynamics optimization of a planar complex multi-link mechanism containing multiple clearance joints is put forward. The model comprises a 2-degree of freedom (DOF) nine-bar mechanism that can be used as the main transmission mechanism of a hybrid drive multi-link press, which is taken as the research object. The optimization objective is to minimize the maximum acceleration of the slider and minimize the difference between the actual central trajectory and the ideal trajectory. By optimizing the quality parameters of key components, an optimal solution for the design parameters is obtained, and the effects of the different optimizations of the objective functions on dynamics response are compared and analyzed. At the same time, a new modeling and calculation methodology of the dynamics accuracy and reliability of a complex multi-link mechanism in terms of multiple clearances is proposed, and the effect of optimization on dynamics accuracy and the reliability of the mechanism is analyzed. Based on the optimization results obtained by taking the minimum difference between the actual center trajectory and the ideal trajectory as an optimization objective, the nonlinear characteristics before and after optimization are analyzed through a phase diagram and Poincaré map. A test platform was built to study the dynamics of the mechanism with clearances. Research not only provides a basis for the dynamics optimization of a multi-link mechanism containing clearances but also provides reference significance for the reliability analysis of a multi-link mechanism containing clearances. Full article
(This article belongs to the Section Machine Design and Theory)
►▼ Show Figures

Figure 1

11 pages, 3006 KiB  
Article
Three-Dimensional Printed Abdominal Imaging Windows for In Vivo Imaging of Deep-Lying Tissues
by Mitchell Kuss, Ayrianne J. Crawford, Olawale A. Alimi, Michael A. Hollingsworth and Bin Duan
Machines 2022, 10(8), 697; https://doi.org/10.3390/machines10080697 - 16 Aug 2022
Cited by 1 | Viewed by 1365
Abstract
The ability to microscopically image diseased or damaged tissue throughout a longitudinal study in living mice would provide more insight into disease progression than having just a couple of time points to study. In vivo disease development and monitoring provides more insight than [...] Read more.
The ability to microscopically image diseased or damaged tissue throughout a longitudinal study in living mice would provide more insight into disease progression than having just a couple of time points to study. In vivo disease development and monitoring provides more insight than in vitro studies as well. In this study, we developed permanent 3D-printed, surgically implantable abdominal imaging windows (AIWs) to allow for longitudinal imaging of deep-lying tissues or organs in the abdominal cavity of living mice. They are designed to prevent organ movement while allowing the animal to behave normally throughout longitudinal studies. The AIW also acts as its own mounting bracket for attaching them to a custom 3D printed microscope mount that attaches to the stage of a microscope and houses the animal inside. During the imaging of the living animal, cellular and macroscopic changes over time in one location can be observed because markers can be used to find the same spot in each imaging session. We were able to deliver cancer cells to the pancreas and use the AIW to image the disease progression. The design of the AIWs can be expanded to include secondary features, such as delivery and manipulation ports and guides, and to make windows for imaging the brain, subcutaneous implants, and mammary tissue. In all, these 3D-printed AIWs and their microscope mount provide a system for enhancing the ability to image and study cellular and disease progression of deep-lying abdominal tissues of living animals during longitudinal studies. Full article
(This article belongs to the Special Issue 3D/4D Bioprinting)
►▼ Show Figures

Figure 1

18 pages, 4512 KiB  
Article
A Few-Shot Learning-Based Crashworthiness Analysis and Optimization for Multi-Cell Structure of High-Speed Train
by Shaodi Dong, Tengfei Jing and Jianjun Zhang
Machines 2022, 10(8), 696; https://doi.org/10.3390/machines10080696 - 16 Aug 2022
Cited by 2 | Viewed by 1513
Abstract
Due to the requirement of significant manpower and material resources for the crashworthiness tests, various modelling approaches are utilized to reduce these costs. Despite being informative, finite element models still have the disadvantage of being time-consuming. A data-driven model has recently demonstrated potential [...] Read more.
Due to the requirement of significant manpower and material resources for the crashworthiness tests, various modelling approaches are utilized to reduce these costs. Despite being informative, finite element models still have the disadvantage of being time-consuming. A data-driven model has recently demonstrated potential in terms of computational efficiency, but it is also accompanied by challenges in collecting an amount of data. Few-shot learning is a perspective approach in addressing the problem of insufficient data in engineering. In this paper, using a novel hybrid data augmentation method, we investigate a deep-learning-based few-shot learning approach to evaluate and optimize the crashworthiness of multi-cell structures. Innovatively, we employ wide and deep neural networks to develop a surrogate model for multi-objective optimization. In comparison with the original results, the optimized result of the multi-cell structure demonstrates that the mean crushing force (Fm) and specific energy absorption (SEA) are increased by 17.1% and 30.1%, respectively, the mass decreases by 4.0%, and the optimized structure offers a significant improvement in design space. Overall, this proposed method exhibits great potential in relation to the crashworthiness analysis and optimization for multi-cell structures of the high-speed train. Full article
(This article belongs to the Section Vehicle Engineering)
►▼ Show Figures

Figure 1

19 pages, 5175 KiB  
Article
Introducing Robotized Stator Cable Winding to Rotating Electric Machines
by Erik Hultman
Machines 2022, 10(8), 695; https://doi.org/10.3390/machines10080695 - 15 Aug 2022
Cited by 2 | Viewed by 1782
Abstract
Following environmental concerns and the rapid digitalization of our society, we are currently experiencing an extensive electrification and industrial revolution. High numbers of electric machines thus need to be assembled for varying applications, including vehicle propulsion and renewable energy conversion. Cable winding is [...] Read more.
Following environmental concerns and the rapid digitalization of our society, we are currently experiencing an extensive electrification and industrial revolution. High numbers of electric machines thus need to be assembled for varying applications, including vehicle propulsion and renewable energy conversion. Cable winding is an alternative stator winding technology for electric machines that has been utilized for such applications, so far in smaller series or in prototype machines. The presented work introduces the first concept for automated stator cable winding of rotating electric machines. This concept could enable higher production volumes of cable wound machines and a unique flexibility in handling different machines, in line with Industry 4.0. Robotized stator cable winding is evaluated here for five very different rotating machine designs, through simulations and analytical extrapolation of previous experimental winding results. Potential cycle time and assembly cost savings are indicated compared to manual and lower volume conventional automation, while it is not possible to compete in the present form with existing very high-volume conventional winding automation for smaller machines. Future experimental work is pointed out on handling larger winding cables and special machine designs, and on increased robustness and optimization. Full article
(This article belongs to the Section Advanced Manufacturing)
►▼ Show Figures

Figure 1

28 pages, 9355 KiB  
Article
Adaptive Band Extraction Based on Low Rank Approximated Nonnegative Tucker Decomposition for Anti-Friction Bearing Faults Diagnosis Using Measured Vibration Data
by Haobin Wen, Long Zhang and Jyoti K. Sinha
Machines 2022, 10(8), 694; https://doi.org/10.3390/machines10080694 - 15 Aug 2022
Cited by 2 | Viewed by 1392
Abstract
Condition monitoring and fault diagnosis are topics of growing interest for improving the reliability of modern industrial systems. As critical structural components, anti-friction bearings often operate under harsh conditions and are contributing factors of system failures. Efforts have been cast on bearing diagnostics [...] Read more.
Condition monitoring and fault diagnosis are topics of growing interest for improving the reliability of modern industrial systems. As critical structural components, anti-friction bearings often operate under harsh conditions and are contributing factors of system failures. Efforts have been cast on bearing diagnostics under the sensor fusion and machine learning framework, whilst challenges remain open on the identification of incipient faults. In this paper, exploiting multi-way representations and decompositions of measured vibration data, a novel band separation method based on the factorization of spectrogram tensors using the low rank approximated nonnegative Tucker decomposition (LRANTD) is proposed and applied to identify detailed fault signatures from the spectral, temporal, and spatial dimensions, flexible for extracting multi-sensor features and multi-dimensional correlations. With the proposed method, informative frequency bands of the latent vibrational components can be automatically extracted, in accordance with the inherent temporal patterns that can be conveniently fed for spectral analysis and fault discrimination. Furthermore, an improved cross-spectrum can be calculated from multi-channel vibrations via LRANTD with enhanced fault features. Based on the real-world vibration data of the accelerated bearing life tests, detailed experimental studies and thorough comparisons to the conventional benchmarks have verified the effectiveness of the reported diagnostic methodology. The proposed method significantly improves the presence of the bearing frequency peaks distinctly over the background noises in the spectrum and hence improves the bearing defect detection process. Full article
(This article belongs to the Section Machines Testing and Maintenance)
►▼ Show Figures

Figure 1

23 pages, 3906 KiB  
Article
Specific Features of Operation of Distributed Generation Facilities Based on Gas Reciprocating Units in Internal Power Systems of Industrial Entities
by Pavel Ilyushin, Sergey Filippov, Aleksandr Kulikov, Konstantin Suslov and Dmitriy Karamov
Machines 2022, 10(8), 693; https://doi.org/10.3390/machines10080693 - 15 Aug 2022
Cited by 14 | Viewed by 1316
Abstract
The creation of a decentralized low-carbon energy infrastructure is the main trend in the development of the electric power industry in many countries. Distributed generation facilities (DGs) based on gas reciprocating units (GRUs) are often built by industrial entities for the efficient utilization [...] Read more.
The creation of a decentralized low-carbon energy infrastructure is the main trend in the development of the electric power industry in many countries. Distributed generation facilities (DGs) based on gas reciprocating units (GRUs) are often built by industrial entities for the efficient utilization of secondary energy resources in order to minimize the environmental impact. Modern GRUs have some advantages, but they have design features that should be factored in when connecting them to the internal power systems of industrial entities. Incorrect consideration of possible operating conditions of GRU in their design can lead to their damage, excessive shutdowns, and disruptions in power supply to essential power consumers with significant damage and losses from undersupply of their products. Excessive shutdowns of GRUs are often caused by a non-selective choice of settings for relay protection devices or by load surges that exceed the allowable ones. With high availability factors, GRUs are disconnected five to eight times more often compared to large gas turbine and steam turbine power units. The large total power consumed by electric motors, as part of the load of an industrial entity, determines the nature and parameters of electromechanical transient processes during emergency disturbances. The presented analysis of issues facing real DG facilities relies on the acts of investigation into the causes of accidents. Calculations have shown that the action of the “Load Agreement Module” in the GRU excitation controller can provoke the occurrence of a voltage avalanche in the internal power system with a complete shutdown of the load. The paper presents recommendations on the choice of control algorithms and voltage settings for the GRU excitation controller. Technical solutions are given to prevent damage and excessive shutdowns of GRU in various operating conditions of the system, and to help ensure a reliable power supply to power consumers. The change in approaches to the design of DG facilities is substantiated in the light of their significant differences from other electric power facilities. Full article
(This article belongs to the Section Electromechanical Energy Conversion Systems)
►▼ Show Figures

Figure 1

20 pages, 14156 KiB  
Article
Research on Magnetic Suspension Control Scheme Based on Feedback Linearization under Low Track Stiffness
by Te Zhang, Danfeng Zhou, Jie Li, Lianchun Wang and Qiang Chen
Machines 2022, 10(8), 692; https://doi.org/10.3390/machines10080692 - 15 Aug 2022
Cited by 1 | Viewed by 1165
Abstract
The problem of vehicle–guideway coupled self-excited vibration is common in maglev train systems, which has a serious impact on the stability of maglev trains. The lower the track stiffness, the more likely it is to occur, the greater the harm to the maglev [...] Read more.
The problem of vehicle–guideway coupled self-excited vibration is common in maglev train systems, which has a serious impact on the stability of maglev trains. The lower the track stiffness, the more likely it is to occur, the greater the harm to the maglev system, and the greater the difficulty in suppressing the vibration. To solve this problem, many conventional control schemes rely on the estimation of electromagnetic forces. However, considering the magnetic leakage flux in the suspension air gap and other reasons, the empirical electromagnetic force model is inaccurate, which increases the difficulty of suspension control under low track stiffness. Therefore, a more accurate electromagnetic force model based on least squares fitting is proposed in this paper, which can estimate the electromagnetic force more accurately without increasing the computational cost. On this basis, a control scheme based on feedback linearization theory was designed, and the control effect was tested on an experimental platform with low track stiffness. The experimental results showed that the proposed control scheme could achieve stable suspension with low track stiffness and could effectively solve the vehicle–guideway coupled vibration problem with a strong anti-interference ability. The research in this paper is of great significance for solving the problem of vehicle–guideway coupled vibration under low track mass/stiffness, which is believed to be used in the light-weight girders in the next generation of commercial maglev systems. This work also has an important reference value for suspension control algorithms based on electromagnetic force feedback. Full article
(This article belongs to the Section Automation and Control Systems)
►▼ Show Figures

Figure 1

21 pages, 7350 KiB  
Article
Influence of Rotation Speed on Flow Field and Hydraulic Noise in the Conduit of a Vertical Axial-Flow Pump under Low Flow Rate Condition
by Fan Yang, Dongjin Jiang, Yao Yuan, Yuting Lv, Hongfu Jian and Hui Gao
Machines 2022, 10(8), 691; https://doi.org/10.3390/machines10080691 - 14 Aug 2022
Cited by 8 | Viewed by 1416
Abstract
The complex flow inside the axial-flow pump device will cause the problem of hydraulic noise; in order to explore the influence of the law of rotation speed on the internal flow characteristics and hydraulic noise of the axial-flow pump conduit, a combination of [...] Read more.
The complex flow inside the axial-flow pump device will cause the problem of hydraulic noise; in order to explore the influence of the law of rotation speed on the internal flow characteristics and hydraulic noise of the axial-flow pump conduit, a combination of Computational Fluid Dynamics (CFD) and Computational Acoustics (CA) was used to numerically solve the flow field and internal sound field in the pump device. The results showed that the flow in the elbow inlet conduit was smooth at different rotation speeds, and there was no obvious unstable flow. The higher the rotation speed, the more disordered the flow pattern in the left half of the elbow, which intensifies the unstable flow in the straight outlet conduit. The impeller is the main sound source of the internal hydrodynamic noise of the vertical axial-flow pump device. When the sound source propagates upstream and downstream along the conduit, the Total Sound Source Intensity (TSSI) gradually decays with the increase of distance; the greater the rotation speed is, the faster the Total Sound Source Intensity (TSSI) decays. When the rotation speed was increased from 1450 r/min to 2200 r/min, the TSSI in the straight outlet conduit was attenuated by 8.9 dB, 13.9 dB, and 16.0 dB respectively, and the TSSI in the elbow inlet conduit was attenuated by 11.0 dB, 13.5 dB, and 25.9 dB respectively. The vortex structure in the conduit induces flow noise and delays the attenuation of TSSI in the propagation process; with the increase of rotation speed, this delay will be more obvious. Full article
(This article belongs to the Section Turbomachinery)
►▼ Show Figures

Figure 1

4 pages, 178 KiB  
Editorial
Deep Learning-Based Machinery Fault Diagnostics
by Hongtian Chen, Kai Zhong, Guangtao Ran and Chao Cheng
Machines 2022, 10(8), 690; https://doi.org/10.3390/machines10080690 - 13 Aug 2022
Cited by 2 | Viewed by 1672
Abstract
In recent years, deep learning has shown its unique potential and advantages in feature extraction and pattern recognition [...] Full article
(This article belongs to the Special Issue Deep Learning-Based Machinery Fault Diagnostics)
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-122
Previous Issue
Next Issue
Back to TopTop