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Volume 10
Issue 3
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Machines, Volume 10, Issue 3 (March 2022) – 61 articles

Cover Story (view full-size image): High-magnitude torsional vibrations can cause damages to powertrain components, such as fractured gear teeth and cracks in shafts. Excessive torsional vibrations commonly manifest at resonance, which can be mitigated by modifying the torsional natural frequencies of the system. This study validates a method for adjustment of torsional natural frequencies to mitigate resonant torsional vibrations. Novel coupling design with adjustable torsional stiffness was used to vary the first torsional natural frequency of a powertrain test bench. The predictability was studied by comparing torsional analysis calculations to experimentally measured results. The first torsional natural frequency of the powertrain test bench was predictably adjusted within a wide range, thus validating the method for use in industrial and research applications. View this paper
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78 pages, 3001 KiB  
Review
A Comprehensive Survey on Fault Tolerance in Multiphase AC Drives, Part 2: Phase and Switch Open-Circuit Faults
by Alejandro G. Yepes, Ignacio Gonzalez-Prieto, Oscar Lopez, Mario J. Duran and Jesus Doval-Gandoy
Machines 2022, 10(3), 221; https://doi.org/10.3390/machines10030221 - 21 Mar 2022
Cited by 33 | Viewed by 4344
Abstract
Multiphase machines are very convenient for applications that require high reliability. In this two-part survey, the state of the art about fault tolerance in multiphase drives is reviewed. In Part 1, an overview including numerous fault types was presented, along with fundamental notions [...] Read more.
Multiphase machines are very convenient for applications that require high reliability. In this two-part survey, the state of the art about fault tolerance in multiphase drives is reviewed. In Part 1, an overview including numerous fault types was presented, along with fundamental notions about multiphase drives. Here, in Part 2, the focus is placed on phase/switch open-circuit (OC) faults in particular, which have received the most attention in the literature. Phase OC failures involve OCs in stator phases or in converter-machine connections, and switch/diode OCs are frequently dealt with similarly or identically. Thanks to the phase redundancy of multiphase drives, their operation can be satisfactorily continued under a certain number of OCs. Nonetheless, the procedure to follow for this purpose is far from unique. For given OC fault conditions, numerous fault-tolerant possibilities can be found in the literature, each of them with different advantages and disadvantages. Moreover, a great variety of methods have also been devised to detect and diagnose phase/switch OC failures so that, as soon as possible, the most appropriate fault-tolerance measures are applied. Thus, given the broad literature about tolerance to phase/switch OC faults in multiphase drives, the survey presented here is expected to be of great interest for the research community and industry. Full article
(This article belongs to the Special Issue Feature Papers to Celebrate the First Impact Factor of Machines)
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15 pages, 5030 KiB  
Article
Multipoint Feeding Strategy of Aluminum Reduction Cell Based on Distributed Subspace Predictive Control
by Jiarui Cui, Peining Wang, Xiangquan Li, Ruoyu Huang, Qing Li, Bin Cao and Hui Lu
Machines 2022, 10(3), 220; https://doi.org/10.3390/machines10030220 - 21 Mar 2022
Cited by 2 | Viewed by 1770
Abstract
With the continuous development of large-scale aluminum reduction cells, the problem of the uniform distribution of alumina concentration in the cell has become more and more serious for the reduction process. In order to achieve the uniform distribution of the alumina concentration, a [...] Read more.
With the continuous development of large-scale aluminum reduction cells, the problem of the uniform distribution of alumina concentration in the cell has become more and more serious for the reduction process. In order to achieve the uniform distribution of the alumina concentration, a data-driven distributed subspace predictive control feeding strategy is proposed in this paper. Firstly, the aluminum reduction cell is divided into multiple sub-systems that affect each other according to the position of the feeding port. Based on the subspace method, the prediction model of the whole cell is identified, and the prediction output expression of each sub-system is deduced by decomposition. Secondly, the feeding controller is designed for each aluminum reduction cell subsystem, and the input and output information can be exchanged between each controller through the network. Thirdly, under consideration of the influence of other subsystems, each subsystem solves the Nash-optimal control feeding quantity, so that each subsystem realizes distributed feeding. Finally, the simulation results show that, compared with the traditional control method, the proposed distributed feeding control strategy can significantly improve the problem of the uniform distribution of alumina concentration and improve the current efficiency of the aluminum reduction cell. Full article
(This article belongs to the Special Issue Deep Learning-Based Machinery Fault Diagnostics)
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18 pages, 9618 KiB  
Article
Research on Machining Error Analysis and Traceability Method of Globoidal Indexing Cam Profile
by Shuwen Sun, Yunfei Qiao, Zhentao Gao and Chao Huang
Machines 2022, 10(3), 219; https://doi.org/10.3390/machines10030219 - 21 Mar 2022
Cited by 1 | Viewed by 2008
Abstract
The profile of the globoidal indexing cam is a spatially undevelopable surface. It needs a special computer numerical control (CNC) machine tool to finish batch production, and its machining quality will be affected by the motion error of each part of the machine [...] Read more.
The profile of the globoidal indexing cam is a spatially undevelopable surface. It needs a special computer numerical control (CNC) machine tool to finish batch production, and its machining quality will be affected by the motion error of each part of the machine tool and the clamped positioning error of the workpiece. Firstly, the mathematical model of the error of the machine tool for machining the globoidal cam surface is derived, and the influence of the error of the machine tool for machining the globoidal cam surface is given. Secondly, an error tracking method for globoidal cam profile machining error based on error sensitivity coefficient grouping is proposed, which improves the data processing speed and the accuracy of the tracking results. Finally, the error analysis and traceability method of the globoidal cam is verified by experiments, and the error traceability results are fed back to the processing link. The machining quality of globoidal cam is improved by the error compensation, which provides the key technology for the integration of the design, manufacture, and measurement of the globoidal cam. Full article
(This article belongs to the Special Issue Advanced Processes and Technologies in Precision and Ultra-Precision Machining)
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21 pages, 7621 KiB  
Article
Improved Extreme Learning Machine Based UWB Positioning for Mobile Robots with Signal Interference
by Jun Ma, Xuechao Duan, Chen Shang, Mengjiao Ma and Dan Zhang
Machines 2022, 10(3), 218; https://doi.org/10.3390/machines10030218 - 21 Mar 2022
Cited by 9 | Viewed by 3091
Abstract
For the purpose of tackling ultra-wideband (UWB) indoor positioning with signal interference, a binary classifier for signal interference discrimination and positioning errors compensation model combining genetic algorithm (GA) and extreme learning machine (ELM) are put forward. Based on the distances between four anchors [...] Read more.
For the purpose of tackling ultra-wideband (UWB) indoor positioning with signal interference, a binary classifier for signal interference discrimination and positioning errors compensation model combining genetic algorithm (GA) and extreme learning machine (ELM) are put forward. Based on the distances between four anchors and the target which are calculated with time of flight (TOF) ranging technique, GA-ELM-based binary classifier for judging the existence of signal interference, and GA-ELM-based positioning errors compensation model are built up to compensate for the result of the preliminary evaluated positioning model. Finally, the datasets collected in the actual scenario are used for verification and analysis. The experimental results indicate that the root-mean-square error (RMSE) of positioning without signal interference is 14.5068 cm, which is reduced by 71.32% and 59.72% compared with those results free of compensation and optimization, respectively. Moreover, the RMSE of positioning with signal interference is 28.0861 cm, which is decreased by 64.38% and 70.16%, in comparison to their counterparts without compensation and optimization, respectively. Consequently, these calculated results of numerical examples lead to the conclusion that the proposed method displays its wide application, high precision and rapid convergence in improving the positioning accuracy for mobile robots. Full article
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15 pages, 7479 KiB  
Article
The Modelling and Analysis of Micro-Milling Forces for Fabricating Thin-Walled Micro-Parts Considering Machining Dynamics
by Peng Wang, Qingshun Bai, Kai Cheng, Liang Zhao and Hui Ding
Machines 2022, 10(3), 217; https://doi.org/10.3390/machines10030217 - 20 Mar 2022
Cited by 5 | Viewed by 2227
Abstract
In the fabrication process of thin-walled micro-parts, both micro-cutting tools and thin-walled micro-parts have the characteristics of small size and low stiffness. Therefore, the regenerative chatter during the machining process cannot be ignored. The influence of the tool runout error and actual trochoidal [...] Read more.
In the fabrication process of thin-walled micro-parts, both micro-cutting tools and thin-walled micro-parts have the characteristics of small size and low stiffness. Therefore, the regenerative chatter during the machining process cannot be ignored. The influence of the tool runout error and actual trochoidal trajectories of the cutting edge on micro-milling forces should also be considered comprehensively. In this paper, the tool runout error in the micro-milling process is first analysed, and an instantaneous undeformed chip thickness model is established considering the runout error. On this basis, the dynamic deformation of the micro-cutting tool and thin-walled micro-part is studied, and an instantaneous, undeformed, chip-thickness model is proposed with the consideration of both the runout error and dynamic deformation. The dynamic parameters of the machining system are obtained using the receptance coupling method. Finally, thin-walled micro-part machining experiments are carried out, and the obtained results of micro-milling force simulation based on the proposed model are compared with the experimental results. The results indicate that the micro-milling force modelling, by taking the influence of machining dynamics into account, has better prediction accuracy, and the difference between the predicted resultant forces and the experimental results is less than 11%. Full article
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19 pages, 5887 KiB  
Article
Partial Shaking Moment Balancing of Spherical Parallel Robots by a Combined Counterweight and Adjusting Kinematic Parameters Approach
by Hongfei Yu, Zhiqin Qian, Anil Borugadda, Wei Sun and Wenjun Zhang
Machines 2022, 10(3), 216; https://doi.org/10.3390/machines10030216 - 19 Mar 2022
Cited by 2 | Viewed by 2087
Abstract
Spherical parallel robots (SPR) are widely used in industries and robotic rehabilitation. Designing such systems for better balance properties is still a challenge. This paper presents a work to minimize the shaking moment for a fully force-balanced SPR by combining the counterweight (CW) [...] Read more.
Spherical parallel robots (SPR) are widely used in industries and robotic rehabilitation. Designing such systems for better balance properties is still a challenge. This paper presents a work to minimize the shaking moment for a fully force-balanced SPR by combining the counterweight (CW) and adjusting the kinematic parameters (AKP). An approximate model of the shaking moment of the SPR is proposed for computational efficiency (specifically allowing for a gradient-based optimization algorithm available in MATLAB) yet without the loss of much accuracy. The effectiveness of the proposed approach has been confirmed based on simulation, especially with the software system SPACAR due to its high reliability and easy availability. Specifically, the simulation result shows that compared with the unbalanced SPR, the shaking moment of the balanced SPR can decrease by more than 90%. It is worth mentioning that the AKP approach is an excellent example of mechatronics by combining the capability of re-planning the joint motion from the end-effector motion and adjusting the kinematic parameters to redistribute the mass of the whole robot for canceling the shaking force and shaking moment—inertia-induced force and moment to the ground. In short, the main contributions of this paper are: (1) a combined CW and AKP approach to the partial moment balancing of the SPR enhanced with a simplified mathematical model of the shaking moment of the SPR, and (2) a new design of the SPR which can be fully force balanced yet partially moment balanced. A note is taken that the simplified model is under the condition that the parameters of the link have certain geometric relations, which is a limitation of our approach. Full article
(This article belongs to the Special Issue Advances in Applied Mechatronics)
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17 pages, 7179 KiB  
Article
A Triboelectric Nanogenerator for Energy Harvesting from Transformers’ Vibrations
by Agnes Nascimento Simões, Danilo José Carvalho, Eugênio de Souza Morita, Haroldo Luiz Moretti, Helen Velozo Vendrameto, Li Fu, Floriano Torres, André Nunes de Souza, Waldir Antonio Bizzo and Talita Mazon
Machines 2022, 10(3), 215; https://doi.org/10.3390/machines10030215 - 18 Mar 2022
Cited by 9 | Viewed by 3701
Abstract
Transformers can produce gases dissolved in oil that can cause damage to their structures, and preventing failures caused by these gases is a goal to be reached. There is a demand for wireless sensors to monitor those gases. Alongside its development, there is [...] Read more.
Transformers can produce gases dissolved in oil that can cause damage to their structures, and preventing failures caused by these gases is a goal to be reached. There is a demand for wireless sensors to monitor those gases. Alongside its development, there is a growing interest in new energy sources enabling these technologies. Triboelectric nanogenerators can gather energy from the environment, such as mechanical energy from vibrations, and convert it into electricity from the contact of two dielectric materials. In this work, the authors propose the study of a low-cost and straightforward triboelectric nanogenerator (TENG) based on ZnO nanorods as a positive dielectric material, with PDMS:GO composites at different concentrations as the negative dielectric material. All the studies were carried out in a wide frequency range varying from 45 to 250 Hz. Additionally, an analysis of the addition of a steel spring into the TENG to improve the device’s generating output is shown. A power density of 246 mV m−2 and 4 V of the output voltage was obtained using a PDMS:GO 4% (w/w) composite and a steel spring. A correlation between the “mass-spring” system and the better performance of the triboelectric device is presented. Further, vibration frequencies in several external points of the transformer walls and the device’s performance in these frequencies are shown, and the results gathered from this data are discussed. Full article
(This article belongs to the Section Electromechanical Energy Conversion Systems)
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19 pages, 2790 KiB  
Article
Motion Control of a Hydraulic Manipulator with Adaptive Nonlinear Model Compensation and Comparative Experiments
by Yangxiu Xia, Yong Nie, Zheng Chen, Litong Lyu and Po Hu
Machines 2022, 10(3), 214; https://doi.org/10.3390/machines10030214 - 18 Mar 2022
Cited by 2 | Viewed by 2070
Abstract
Hydraulic manipulators play an irreplaceable role in many heavy-duty applications. Currently, there are stronger demands for the hydraulic manipulator to achieve high precision, as well as high force/power. However, due to the inherent nonlinearities of its high-order dynamics, the precision of the manipulator [...] Read more.
Hydraulic manipulators play an irreplaceable role in many heavy-duty applications. Currently, there are stronger demands for the hydraulic manipulator to achieve high precision, as well as high force/power. However, due to the inherent nonlinearities of its high-order dynamics, the precision of the manipulator has been a common weakness compared with electrically driven ones. Thus, in this paper, a nonlinear adaptive robust control method for the hydraulic manipulator is proposed. To make the controller more applicable to practical engineering projects, this study tried to control each joint independently instead of directly based on the complicated multi-degree high-order dynamics, while guaranteeing the control precision by the adaptive nonlinear model compensation, as well as a robust feedback design. The closed-loop control performance was theoretically verified. Besides, several sets of comparative motion tracking experiments were conducted, and the proposed closed-loop system achieved high precision under different trajectories and postures. Full article
(This article belongs to the Special Issue Advanced Control of Industrial Electro-Hydraulic Systems)
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24 pages, 7104 KiB  
Article
Sealing Contact Transient Thermal-Structural Coupling Analysis of the Subsea Connector
by Dong Liu, Feihong Yun, Wuchao Wang, Kefeng Jiao, Liquan Wang, Zheping Yan, Peng Jia, Xiangyu Wang, Weifeng Liu, Haiting Sun and Xiujun Xu
Machines 2022, 10(3), 213; https://doi.org/10.3390/machines10030213 - 18 Mar 2022
Cited by 2 | Viewed by 2391
Abstract
Taking the subsea collect connector as an example, the sealing characteristics of the sealing structure of the subsea connector under transient thermal–structural coupling were studied. Based on Airy’s thermal stress function, the mathematical model was established, the complex stress function was used to [...] Read more.
Taking the subsea collect connector as an example, the sealing characteristics of the sealing structure of the subsea connector under transient thermal–structural coupling were studied. Based on Airy’s thermal stress function, the mathematical model was established, the complex stress function was used to solve the problem, and a three-dimensional transient thermal stress model of the core sealing parts was obtained. The transient thermal–structural coupling stress model of the core seal was obtained by linear superposition principle. The transient temperature field of the subsea collet connector under different working conditions was analyzed. It was found that the larger the temperature difference between the components was, the greater the difference of expansion rate was, and the greater the impact on the sealing performance of LSG was in the process of temperature variation from transient to steady distribution. Numerical simulations of various working conditions under the transient temperature field were carried out. The results showed that sudden change of the temperature and oil–gas pressure will bring about large fluctuations of the maximum contact stress and equivalent stress of the seal, which was easy to fatigue wear, and thus affect the reliability of the sealing performance. Finally, the experiment proves that the sealing ring can maintain sealing performance under the conditions of temperature-cyclic loading. The coupled mathematical model proposed in this paper could be used for the transient thermal–structural coupling theoretical analysis of similar subsea equipment. Full article
(This article belongs to the Section Machine Design and Theory)
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15 pages, 32089 KiB  
Article
Performance Comparison and Analysis of Different Rotor Structures of Vehicle Permanent Magnet Synchronous Flat Wire Motor
by Kai Zhao and Jian Luo
Machines 2022, 10(3), 212; https://doi.org/10.3390/machines10030212 - 17 Mar 2022
Cited by 2 | Viewed by 2791
Abstract
In this paper, we designed flat conductor winding permanent magnet synchronous motors with three different rotor structures under certain boundary conditions. The causes of the noise vibration harshness and abnormal noise of permanent magnet synchronous motors are analyzed by using an analytical method. [...] Read more.
In this paper, we designed flat conductor winding permanent magnet synchronous motors with three different rotor structures under certain boundary conditions. The causes of the noise vibration harshness and abnormal noise of permanent magnet synchronous motors are analyzed by using an analytical method. The causes of 24-order and 48-order abnormal noise are given. Based on the comparison of the performance of three rotor structures, the V+1 rotor structure has the least no-load harmonic content, the minimum cogging torque, the maximum output torque, the lowest temperature rise, and the best motor performance, and the V+1 rotor design consumes less permanent magnet material. The simulation is verified by manufacturing a prototype, and the experimental results verify the correctness of the simulation. Full article
(This article belongs to the Special Issue Electric Vehicle Powertrains: Design, Development and Technology)
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13 pages, 1105 KiB  
Article
Predictive Control of Multi-Phase Motor for Constant Torque Applications
by Manuel R. Arahal, Federico Barrero, Manuel G. Satué and Daniel R. Ramírez
Machines 2022, 10(3), 211; https://doi.org/10.3390/machines10030211 - 16 Mar 2022
Cited by 4 | Viewed by 1739
Abstract
Constant torque motors are needed for rotary screw compressors that are used for cooling and other applications. In such systems, the torque demanded by the load is approximately the same over the whole range of mechanical speeds. In this paper, the use of [...] Read more.
Constant torque motors are needed for rotary screw compressors that are used for cooling and other applications. In such systems, the torque demanded by the load is approximately the same over the whole range of mechanical speeds. In this paper, the use of multi-phase induction machines is investigated for this type of application. The requirement of low stator current distortion is considered. A scheduled approach is used to provide the best possible tuning for each operating point, similar to the concept of gain scheduling control. Simulations and laboratory tests are used to assess the proposal and compare it with finite-state predictive control. The experiments show that a trade-off situation appears between the ripple content in stator currents in the torque-producing and harmonic planes. As a consequence, the controller tuning appears as an important step. The proposed method considers various figures of merit with cost function tuning, resulting in a scheduled scheme that provides improved results. It is shown that the approach leads to a reduction in current ripple, which is advantageous for this particular application. Full article
(This article belongs to the Special Issue Innovative Applications of Multiphase Machines)
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14 pages, 1191 KiB  
Article
Deep Reinforcement Learning for Distributed Flow Shop Scheduling with Flexible Maintenance
by Qi Yan, Wenbin Wu and Hongfeng Wang
Machines 2022, 10(3), 210; https://doi.org/10.3390/machines10030210 - 16 Mar 2022
Cited by 22 | Viewed by 3544
Abstract
A common situation arising in flow shops is that the job processing order must be the same on each machine; this is referred to as a permutation flow shop scheduling problem (PFSSP). Although many algorithms have been designed to solve PFSSPs, machine availability [...] Read more.
A common situation arising in flow shops is that the job processing order must be the same on each machine; this is referred to as a permutation flow shop scheduling problem (PFSSP). Although many algorithms have been designed to solve PFSSPs, machine availability is typically ignored. Healthy machine conditions are essential for the production process, which can ensure productivity and quality; thus, machine deteriorating effects and periodic preventive maintenance (PM) activities are considered in this paper. Moreover, distributed production networks, which can manufacture products quickly, are of increasing interest to factories. To this end, this paper investigates an integrated optimization of the distributed PFSSP with flexible PM. With the introduction of machine maintenance constraints in multi-factory production scheduling, the complexity and computation time of solving the problem increases substantially in large-scale arithmetic cases. In order to solve it, a deep Q network-based solution framework is designed with a diminishing greedy rate in this paper. The proposed solution framework is compared to the DQN with fixed greedy rate, in addition to two well-known metaheuristic algorithms, including the genetic algorithm and the iterated greedy algorithm. Numerical studies show that the application of the proposed approach in the studied production-maintenance joint scheduling problem exhibits strong solution performance and generalization abilities. Moreover, a suitable maintenance interval is also obtained, in addition to some managerial insights. Full article
(This article belongs to the Special Issue Electrical Engineering and Mechatronics Technology)
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17 pages, 9410 KiB  
Article
Numerical Simulation and Analysis of the Flow Characteristics of the Roof-Attached Vortex (RAV) in a Closed Pump Sump
by Bowen Zhang, Li Cheng, Minghu Zhu, Weixuan Jiao and Di Zhang
Machines 2022, 10(3), 209; https://doi.org/10.3390/machines10030209 - 15 Mar 2022
Cited by 5 | Viewed by 2134
Abstract
Unsteady numerical simulation and visual experiment are used to reveal the formation mechanism of the roof-attached vortex (RAV) on the roof of the closed sump of a pumping station. The results show that RAVs mainly occur between the pump device and the rear [...] Read more.
Unsteady numerical simulation and visual experiment are used to reveal the formation mechanism of the roof-attached vortex (RAV) on the roof of the closed sump of a pumping station. The results show that RAVs mainly occur between the pump device and the rear wall of the closed sump. In the 10th period of impeller rotation, there are 2 RAVs at the roof. V1 (Vortex 1 in numerical simulation) is located directly behind the water pump unit, and V2 (Vortex 2 in numerical simulation) is close to the right wall. Significantly, the vorticity intensity at the V1 vortex core increases with the rotation of the impeller. Vtest1 (Vortex 1 in test) and Vtest2 (Vortex 2 in test) are two RAVs observed in the experiment, which are highly consistent with the unsteady numerical simulation V1 and V2. Comparing the vorticity intensity of the roof, rear wall, and sidewall, it can be seen that the maximum vorticity intensity on the roof is more significant than that on the rear wall and both sides of the wall. The roof is more likely to induce vortex. When the RAVs on the roof occur, the pressure in the middle of the bell mouth is lower than that on the sidewall, and the velocity is higher. At 2/5 T, the blade is in the low-pressure zone. The velocity distribution uniformity and velocity weighted average angle at the bell mouth also decreased. The RAVs enter the pump after being generated, which is the most harmful to the safe and stable operation of the pump. The study can provide theoretical guidance for the optimal design of the closed sump. Full article
(This article belongs to the Section Electromechanical Energy Conversion Systems)
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134 pages, 7014 KiB  
Review
A Comprehensive Survey on Fault Tolerance in Multiphase AC Drives, Part 1: General Overview Considering Multiple Fault Types
by Alejandro G. Yepes, Oscar Lopez, Ignacio Gonzalez-Prieto, Mario J. Duran and Jesus Doval-Gandoy
Machines 2022, 10(3), 208; https://doi.org/10.3390/machines10030208 - 14 Mar 2022
Cited by 43 | Viewed by 6216
Abstract
Multiphase drives offer enhanced fault-tolerant capabilities compared with conventional three-phase ones. Their phase redundancy makes them able to continue running in the event of faults (e.g., open/short-circuits) in certain phases. Moreover, their greater number of degrees of freedom permits improving diagnosis and performance, [...] Read more.
Multiphase drives offer enhanced fault-tolerant capabilities compared with conventional three-phase ones. Their phase redundancy makes them able to continue running in the event of faults (e.g., open/short-circuits) in certain phases. Moreover, their greater number of degrees of freedom permits improving diagnosis and performance, not only under faults affecting individual phases, but also under those affecting the machine/drive as a whole. That is the case of failures in the dc link, resolver/encoder, control unit, cooling system, etc. Accordingly, multiphase drives are becoming remarkable contenders for applications where high reliability is required, such as electric vehicles and standalone/off-shore generation. Actually, the literature on the subject has grown exponentially in recent years. Various review papers have been published, but none of them currently cover the state-of-the-art in a comprehensive and up-to-date fashion. This two-part paper presents an overview concerning fault tolerance in multiphase drives. Hundreds of citations are classified and critically discussed. Although the emphasis is put on fault tolerance, fault detection/diagnosis is also considered to some extent, because of its importance in fault-tolerant drives. The most important recent advances, emerging trends and open challenges are also identified. Part 1 provides a comprehensive survey considering numerous kinds of faults, whereas Part 2 is focused on phase/switch open-circuit failures. Full article
(This article belongs to the Special Issue Feature Papers to Celebrate the First Impact Factor of Machines)
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19 pages, 3873 KiB  
Article
A Fault Diagnosis Method of Rolling Bearings Based on Parameter Optimization and Adaptive Generalized S-Transform
by Yuwei Peng and Xianghua Ma
Machines 2022, 10(3), 207; https://doi.org/10.3390/machines10030207 - 14 Mar 2022
Cited by 5 | Viewed by 2156
Abstract
As for the fault diagnosis of rolling bearings under strong background noises, whether the fault feature extraction is comprehensive and accurate is critical, especially for the data-driven fault diagnosis methods. To improve the comprehensiveness and accuracy of the fault feature extraction, a fault [...] Read more.
As for the fault diagnosis of rolling bearings under strong background noises, whether the fault feature extraction is comprehensive and accurate is critical, especially for the data-driven fault diagnosis methods. To improve the comprehensiveness and accuracy of the fault feature extraction, a fault diagnosis method of rolling bearings is proposed based on parameter optimization and Adaptive Generalized S-Transform (AGST). The AGST is used to solve the problem of incomplete feature extraction of bearing faults. The Particle Swarm Brain Storm Optimization algorithm based on the Discussion Mechanism (PSDMBSO) is used for the parameter optimization of VMD, which can better separate the complete fault components. The effectiveness of the fault diagnosis method proposed in this paper is verified by comparison with other methods. Full article
(This article belongs to the Special Issue Advances in Bearing Modeling, Fault Diagnosis, RUL Prediction)
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22 pages, 1664 KiB  
Article
Absolutely Feasible Synchronous Reluctance Machine Rotor Barrier Topologies with Minimal Parametric Complexity
by Branko Ban and Stjepan Stipetic
Machines 2022, 10(3), 206; https://doi.org/10.3390/machines10030206 - 11 Mar 2022
Cited by 3 | Viewed by 3152
Abstract
The first step in the synchronous reluctance machine design is the selection of rotor flux barrier type. The literature provides various barrier construction methods with a common goal of reducing parametric complexity. However, too excessive simplification can lead to decreased performance, while overly [...] Read more.
The first step in the synchronous reluctance machine design is the selection of rotor flux barrier type. The literature provides various barrier construction methods with a common goal of reducing parametric complexity. However, too excessive simplification can lead to decreased performance, while overly complex geometries tend to increase optimization time. This paper presents a set of novel flux barrier construction methods with an increased degree of freedom and minimal geometrical complexity. The paper proposes four topologies based on circular, hyperbolic, and original Zhukovsky lines. When considering parametrization complexity, the original Zhukovsky type is the simplest, but it has barrier depth limitations. Other topologies have equal complexity. The paper proposes a novel Modified Zhukovsky variable depth type based on geometrical conformal mapping of the original Zhukovsky lines. The step-by-step construction of each topology is presented in a form of pseudo-code with detailed comments and illustrations. Overall, the presented research provides a valuable starting point for the designer who wants to investigate different smooth rotor barrier topologies. Full article
(This article belongs to the Special Issue Synchronous Reluctance Motor-Drive Advancements)
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25 pages, 75333 KiB  
Article
Personalized Artificial Tibia Bone Structure Design and Processing Based on Laser Powder Bed Fusion
by Nan Yang, Youping Gong, Honghao Chen, Wenxin Li, Chuanping Zhou, Rougang Zhou and Huifeng Shao
Machines 2022, 10(3), 205; https://doi.org/10.3390/machines10030205 - 11 Mar 2022
Cited by 1 | Viewed by 2113
Abstract
Bone defects caused by bone diseases and bone trauma need to be implanted or replaced by surgery. Therefore, it is of great significance to design and prepare a tibial implant with good biocompatibility and excellent comprehensive mechanical properties. In this paper, with 316L [...] Read more.
Bone defects caused by bone diseases and bone trauma need to be implanted or replaced by surgery. Therefore, it is of great significance to design and prepare a tibial implant with good biocompatibility and excellent comprehensive mechanical properties. In this paper, with 316L stainless steel powder as the main material, a personalized artificial tibia design and processing method based on laser powder bed fusion is proposed. Firstly, the personalized model of the damaged part of the patient is reconstructed. Then, the porous structure of human tibia is manufactured by selective laser melting technology. To research the factors affecting the quality of selective laser melting porous structure, a laser heat source model, heat transfer model and molten pool model of laser powder bed fusion process were constructed; then, by changing the laser process parameters (laser power, laser beam diameter, scanning speed, powder layer thickness, etc.) to conduct multiple sets of simulation experiments, it is obtained that when the “laser power is 180 W, the laser scanning speed is 1000 mm/s, the laser beam diameter is 80 μm, the powder layer thickness is 50 μm”, the porous stainless steel parts with better quality can be obtained. Finally, the porous structure was fabricated by selective laser processing, and its properties were tested and analyzed. The experimental results show that the cell side length of cube is 1.2 mm, the elastic modulus of octahedral porous structure with pillar diameter of 0.35 mm is about 17.88 GPa, which match well with tibial bone tissue. Full article
(This article belongs to the Special Issue 3D/4D Bioprinting)
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14 pages, 5204 KiB  
Article
Optimization Design and Performance Analysis of a Reverse-Salient Permanent Magnet Synchronous Motor
by Xiaokun Zhao, Baoquan Kou, Changchuang Huang and Lu Zhang
Machines 2022, 10(3), 204; https://doi.org/10.3390/machines10030204 - 11 Mar 2022
Cited by 11 | Viewed by 6541
Abstract
The reverse-salient permanent magnet synchronous motor (RSPMSM) is a competitive candidate for electric vehicles due to its high torque density and high efficiency. This paper proposes an optimized RSPMSM by adopting a segmented permanent magnet structure. First, the structure, electromagnetic torque, and current [...] Read more.
The reverse-salient permanent magnet synchronous motor (RSPMSM) is a competitive candidate for electric vehicles due to its high torque density and high efficiency. This paper proposes an optimized RSPMSM by adopting a segmented permanent magnet structure. First, the structure, electromagnetic torque, and current control laws of the RSPMSM are introduced in detail. Second, the optimization design method of the RSPMSM is proposed by taking the torque and constant-power speed range as optimized objectives, with the saliency ratio as a constraint. The optimized model of the RSPMSM is determined using the genetic algorithm (GA). Further performance analysis and comparisons are made between the initial motor and the optimized motor. Finally, a prototype is manufactured, and the performance of the RSPMSM is verified through the finite element method (FEM) and experiments. Full article
(This article belongs to the Section Electrical Machines and Drives)
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15 pages, 559 KiB  
Article
Discussion on Ball Screw Slide–Roll Ratio and Entrainment Velocity Calculation
by Weike Wang, Shujiang Chen, Changhou Lu and Lei Lv
Machines 2022, 10(3), 203; https://doi.org/10.3390/machines10030203 - 11 Mar 2022
Cited by 1 | Viewed by 1924
Abstract
The slide–roll ratio and entrainment velocity are critical parameters in ball screw mechanism tribology investigations and are often determined by Chin-Chung Wei’s approach. Their findings indicated that substantial sliding always occurs between the ball and the raceways, which appears to violate the ball [...] Read more.
The slide–roll ratio and entrainment velocity are critical parameters in ball screw mechanism tribology investigations and are often determined by Chin-Chung Wei’s approach. Their findings indicated that substantial sliding always occurs between the ball and the raceways, which appears to violate the ball drive principle. We validated Wei’s approach using the Harris method, which is widely used in rolling bearing research. When the helix angle is set to zero, significant differences occur: when the Harris method is utilized, the entrainment velocity at the inner contact points is essentially equal to that at the outer contact points, and the slide–roll ratio is zero for both; however, when Wei’s method is utilized, the entrainment velocity at the inner side is nearly three-times that of the outer side, and the slide–roll ratio at the outer side approaches two—the level of pure sliding—which is clearly incorrect. To overcome this issue, we present an accurate approach for obtaining the slide–roll ratio and entrainment velocity for ball screws by regarding the Frenet frame as a virtual cage, which is particularly applicable to those with a long lead and operating at high speeds. Moreover, we investigated the effect of structural factors on the slide–roll ratio and entrainment velocity utilizing this model. Full article
(This article belongs to the Special Issue Kinematics and Dynamics of Mechanisms and Machines)
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19 pages, 4432 KiB  
Article
Online Obstacle Trajectory Prediction for Autonomous Buses
by Yue Linn Chong, Christina Dao Wen Lee, Liushifeng Chen, Chongjiang Shen, Ken Kok Hoe Chan and Marcelo H. Ang, Jr.
Machines 2022, 10(3), 202; https://doi.org/10.3390/machines10030202 - 11 Mar 2022
Cited by 5 | Viewed by 2916
Abstract
We tackle the problem of achieving real-world autonomous driving for buses, where the task is to perceive nearby obstacles and predict their motion in the time ahead, given current and past information of the object. In this paper, we present the development of [...] Read more.
We tackle the problem of achieving real-world autonomous driving for buses, where the task is to perceive nearby obstacles and predict their motion in the time ahead, given current and past information of the object. In this paper, we present the development of a modular pipeline for the long-term prediction of dynamic obstacles’ trajectories for an autonomous bus. The pipeline consists of three main tasks, which are the obstacle detection task, tracking task, and trajectory prediction task. Unlike most of the existing literature that performs experiments in the laboratory, our pipeline’s modules are dependent on the introductory modules in the pipeline—it uses the output of previous modules. This best emulates real-world autonomous driving and reflects the errors that may accumulate and cascade from previous modules with less than 100% accuracy. For the trajectory prediction task, we propose a training method to improve the module’s performance and attain a run-time of 10 Hz. We present the practical problems that arise from realising ready-to-deploy autonomous buses and propose methods to overcome these problems for each task. Our Singapore autonomous bus (SGAB) dataset evaluated the pipeline’s performance. The dataset is publicly available online. Full article
(This article belongs to the Special Issue Autonomous Driving: Advancements in Cognitive Perception Systems for Increased Level Autonomy)
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18 pages, 13880 KiB  
Article
Comprehensive Comparison of Two Fault Tolerant Axial Field Modular Flux-Switching Permanent Magnet Machines with Different Stator and Rotor Pole-Pairs Combinations
by Yixiang Tu, Mingyao Lin, Keman Lin, Yong Kong and Da Xu
Machines 2022, 10(3), 201; https://doi.org/10.3390/machines10030201 - 10 Mar 2022
Cited by 1 | Viewed by 1862
Abstract
This paper gives a comprehensive comparison among two fault-tolerant axial field modular flux-switching (AFFSPM) machines with different stator modular segments (U- and E-core) and stator-slots/pole-pairs combinations. The topologies of two AFFSPM machines are introduced, each with two feasible stator slots and rotor pole-pairs [...] Read more.
This paper gives a comprehensive comparison among two fault-tolerant axial field modular flux-switching (AFFSPM) machines with different stator modular segments (U- and E-core) and stator-slots/pole-pairs combinations. The topologies of two AFFSPM machines are introduced, each with two feasible stator slots and rotor pole-pairs combinations with high winding factors based on the slot-conductor back-EMF star vectors theory. Then, the static performance including the air-gap flux density, flux linkage, back-electromagnetic force (back-EMF), and electromagnetic torque are analyzed and compared. Moreover, the fault-tolerant capability is then investigated by the torque performance under one- and two-phase open-circuit conditions in which the corresponding fault-tolerant control strategies are applied. The predicted results confirm that the 6-stator slot/11-rotor-pole-pair E-core AFFSPM machine exhibits the best performance of the four candidates. Full article
(This article belongs to the Special Issue Electric Vehicle Powertrains: Design, Development and Technology)
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19 pages, 7069 KiB  
Article
Elasto-Dynamic Modeling of an Over-Constrained Parallel Kinematic Machine Using a Beam Model
by Hélène Chanal, Aurélie Guichard, Benoît Blaysat and Stéphane Caro
Machines 2022, 10(3), 200; https://doi.org/10.3390/machines10030200 - 10 Mar 2022
Cited by 3 | Viewed by 1866
Abstract
This article deals with the development of a simple model to evaluate the first natural frequencies of over-constrained parallel kinematic machines (PKMs). The simplest elasto-dynamic models are based on multi-body approaches. However, these approaches require an expression of the Jacobian matrices that may [...] Read more.
This article deals with the development of a simple model to evaluate the first natural frequencies of over-constrained parallel kinematic machines (PKMs). The simplest elasto-dynamic models are based on multi-body approaches. However, these approaches require an expression of the Jacobian matrices that may be difficult to obtain for complex PKMs. Therefore, this paper focuses on the determination of the global mass and stiffness matrices of an over-constrained PKM in stationary configurations without the use of Jacobian matrices. The PKM legs are modeled by beams. Because the legs are connected to a moving platform and the mechanism is over-constrained, constraint equations between the parameters that model the deformation of each leg are determined according to screw theory. The first natural frequencies and associated modes can then be determined. It should be noted that the proposed method can be easily used at the conceptual design stage of PKMs. The Tripteor X7 machine is used as an illustrative example and is characterized experimentally. Full article
(This article belongs to the Special Issue New Frontiers in Parallel Robots)
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16 pages, 9070 KiB  
Article
Micromechanism of Plastic Accumulation and Damage Initiation in Bearing Steels under Cyclic Shear Deformation: A Molecular Dynamics Study
by Yachao Sun, Hongrui Cao and Xunkai Wei
Machines 2022, 10(3), 199; https://doi.org/10.3390/machines10030199 - 10 Mar 2022
Viewed by 1951
Abstract
Fatigue failure usually occurs on the subsurface in rolling bearings due to multiaxial and non-proportional fatigue loadings between rolling elements. One of the main stress components is the alternating shear stress. This paper focuses on the micromechanism of plastic accumulation and damage initiation [...] Read more.
Fatigue failure usually occurs on the subsurface in rolling bearings due to multiaxial and non-proportional fatigue loadings between rolling elements. One of the main stress components is the alternating shear stress. This paper focuses on the micromechanism of plastic accumulation and damage initiation in bearing steels under cyclic shear deformation. The distribution of subsurface shear stress in bearings was firstly investigated by finite element simulation. An atomic model containing bcc-Fe and cementite phases was built by molecular dynamics (MD). Shear stress–strain characteristics were discussed to explore the mechanical properties of the atomic model. Ten alternating shear cycles were designed to explore the mechanism of cyclic plastic accumulation and damage initiation. Shear stress responses and evolutions of dislocaitons, defect meshes and high-strain atoms were discussed. The results show that cyclic softening occurs when the model is in the plastic stage. Severe cyclic shear deformation can accelerate plastic accumulation and result in an earlier shear slip of the cementite phase than that under monotonic shear deformation, which might be the initiation of microscopic damage in bearing steels. Full article
(This article belongs to the Special Issue Advances in Bearing Modeling, Fault Diagnosis, RUL Prediction)
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32 pages, 12463 KiB  
Article
Multi-Objective Optimal Design and Development of a Four-Bar Mechanism for Weed Control
by Hooman Hosseini, Abdulali Farzad, Faizan Majeed, Oliver Hensel and Abozar Nasirahmadi
Machines 2022, 10(3), 198; https://doi.org/10.3390/machines10030198 - 09 Mar 2022
Cited by 6 | Viewed by 2583
Abstract
Weeds compete with crops for water, nutrients, and light consequently, have adverse effects on the crop yield and overall productivity. Mechanical weeding is the most common non-chemical method for weed control, which is applied in organic farming, and the weed cultivator is the [...] Read more.
Weeds compete with crops for water, nutrients, and light consequently, have adverse effects on the crop yield and overall productivity. Mechanical weeding is the most common non-chemical method for weed control, which is applied in organic farming, and the weed cultivator is the most common implement in mechanical weeding. This study aimed to design and develop an innovative active tool to optimize the cultivation depth, which can avoid damage to crop roots and improve the key performance indicators of an inter-row cultivator. A quasi-Newton optimization method and a hybrid of the non-dominated sorting genetic algorithm (NSGA-II) and goal attainment method were separately applied to synthesize and develop a four-bar mechanism for weeding requirements. The transmission angle of the mechanism and the desired path of the weeding blade were simultaneously optimized using these multi-objective optimization techniques. The performance of the developed four-bar cultivator based on the optimization techniques was compared with the ones developed based on the classic methods and also with several conventional tools evaluated in other studies. The results showed that applying the quasi-Newton optimization method and hybrid genetic algorithm can propose a more effective weed cultivator in terms of performance indicators, namely weeding performance, mechanical damage to crop plants and cultivation depth. In addition, the optimization of the transmission angle guaranteed the smooth rotations in the mechanism’s joints. Full article
(This article belongs to the Special Issue Kinematics and Dynamics of Mechanisms and Machines)
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25 pages, 2238 KiB  
Article
Heterogeneous Multitype Fleet Green Vehicle Path Planning of Automated Guided Vehicle with Time Windows in Flexible Manufacturing System
by Jia Gao, Xiaojun Zheng, Feng Gao, Xiaoying Tong and Qiaomei Han
Machines 2022, 10(3), 197; https://doi.org/10.3390/machines10030197 - 09 Mar 2022
Cited by 14 | Viewed by 2606
Abstract
In this study, we present and discuss a variant of the classical vehicle routing problem (VRP), namely the heterogeneous multitype fleet green automated guided vehicle (AGV) routing problem with time windows (HFGVRPTW) applied in the workshops of flexible manufacturing systems (FMS). Specifically, based [...] Read more.
In this study, we present and discuss a variant of the classical vehicle routing problem (VRP), namely the heterogeneous multitype fleet green automated guided vehicle (AGV) routing problem with time windows (HFGVRPTW) applied in the workshops of flexible manufacturing systems (FMS). Specifically, based on the analysis of AGV body structure and motion state, transport distance and energy consumption are selected as two optimization objectives. According to the characteristics and application context of the problem, this paper designs a hybrid genetic algorithm with large neighborhood search (GA-LNS) considering the farthest insertion heuristic. GA-LNS is improved by increasing the local search ability of genetic algorithm to enhance the solution optimal quality. Extensive computational experiments which are generated from Solomon’s benchmark instances and a real case of FMS are designed to evaluate and demonstrate the efficiency and effectiveness of the proposed model and algorithm. The experimental results reveal that compared with using the traditional homogeneous fleet, the heterogeneous multitype AGV fleet transportation mode has a huge energy-saving potential in workshop intralogistics. Full article
(This article belongs to the Special Issue Connected and Automated Vehicles (CAVs): Technologies and Applications)
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15 pages, 5943 KiB  
Article
Clarification of the Mechanism of Pulse Laser Grinding of Nanosecond Lasers Using High-Speed Camera Imaging
by Xiaoxu Liu, Xianlong Ni, Osamu Konda, Hiroko Furuhashi, Satoru Maegawa and Fumihiro Itoigawa
Machines 2022, 10(3), 196; https://doi.org/10.3390/machines10030196 - 08 Mar 2022
Cited by 4 | Viewed by 2533
Abstract
Pulse laser grinding (PLG), as a cutting tool processing method, can not only achieve edge sharpening with high precision, but it can also produce surface modification. For example, polycrystalline cubic boron nitride (PCBN) tools processed by PLG can show increased hardness due to [...] Read more.
Pulse laser grinding (PLG), as a cutting tool processing method, can not only achieve edge sharpening with high precision, but it can also produce surface modification. For example, polycrystalline cubic boron nitride (PCBN) tools processed by PLG can show increased hardness due to the reduction in defects. However, the mechanism of edge formation under PLG processing remains unclear. In this study, by observing the plasma generated during processing using a high-speed camera, the elementary process for each laser pulse of the PLG process was visualized. The plasma luminescence moved successively through four stages: multipoint luminescence, uniform luminescence, the downward movement of the luminous center, and faint luminescence. By comparing the results of three different laser pulse pitches (0.2, 2, and 20 μm), it was found that the pulse pitch had a significant influence on the PLG processing mode. When the pulse pitch was too small, the sidewall effect was likely to lead to local excess machining. The large pulse pitch resulted in processed surfaces that could not be fully covered by laser irradiation, and it was preferred to remove the decrease threshold subsequently. Thus, the moderate pulse pitch condition showed a superior processed surface compared to the others. Full article
(This article belongs to the Special Issue Advanced Processes and Technologies in Precision and Ultra-Precision Machining)
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29 pages, 12067 KiB  
Article
A Novel Modular Biomimetic Live Working Robot for Power Distribution Line
by Jianbin Luo, Peng Guo and Yueke Lin
Machines 2022, 10(3), 195; https://doi.org/10.3390/machines10030195 - 08 Mar 2022
Viewed by 2399
Abstract
Live working on power distribution lines is an effective way to improve the reliability of power supply. The aerial lift device with an insulated boom is often used as a platform to carry out live working, which is difficult to carry out in [...] Read more.
Live working on power distribution lines is an effective way to improve the reliability of power supply. The aerial lift device with an insulated boom is often used as a platform to carry out live working, which is difficult to carry out in mountainous areas, paddy fields, and other complex environments. At the same time, power distribution live working requires highly skilled operators, and a lot of personal security measures, which is not conducive to the application in some developing countries. We imagine that the solution of the above problem is to use a robot to climb up the pole and complete the live working instead of the operator. In this article we report a low-cost modular biomimetic robot. The structure of the robot is designed to meet the requirements of live working, and the motion mechanism of the robot climbing poles and performing live work is analyzed. The feasibility of the technology is verified through simulation, experiments, and tests. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
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12 pages, 4493 KiB  
Article
Influence of Uneven Lighting on Quantitative Indicators of Surface Defects
by Ihor Konovalenko, Pavlo Maruschak, Halyna Kozbur, Janette Brezinová, Jakub Brezina, Bohdan Nazarevich and Yaroslav Shkira
Machines 2022, 10(3), 194; https://doi.org/10.3390/machines10030194 - 07 Mar 2022
Cited by 29 | Viewed by 2587
Abstract
The impact of the illumination level on the quantitative indicators of mechanical damage of the rolled strip is investigated. To do so, a physical model experiment was conducted in the laboratory. The obtained images of defects at light levels in the range of [...] Read more.
The impact of the illumination level on the quantitative indicators of mechanical damage of the rolled strip is investigated. To do so, a physical model experiment was conducted in the laboratory. The obtained images of defects at light levels in the range of 2–800 lx were recognized by a neural network model based on the U-net architecture with a decoder based on ResNet152. Two levels of illumination were identified, at which the total area of recognized defects increased: 50 lx and 300 lx. A quantitative assessment of the overall accuracy of defect recognition was conducted on the basis of comparison with data from images marked by an expert. The best recognition result (with Dice similarity coefficient DSC = 0.89) was obtained for the illumination of 300 lx. At lower light levels (less than 200 lx), some of the damage remained unrecognized. At high light levels (higher than 500 lx), a decrease in DSC was observed, mainly due to the fact that the surface objects are better visible and the recognized fragments become wider. In addition, more false-positives fragments were recognized. The obtained results are valuable for further adjustment of industrial systems for diagnosing technological defects on rolled metal strips. Full article
(This article belongs to the Section Machines Testing and Maintenance)
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20 pages, 5187 KiB  
Communication
Autonomous Mobile Robot Implemented in LEGO EV3 Integrated with Raspberry Pi to Use Android-Based Vision Control Algorithms for Human-Machine Interaction
by Hernando León Araujo, Jesús Gulfo Agudelo, Richard Crawford Vidal, Jorge Ardila Uribe, John Freddy Remolina, Claudia Serpa-Imbett, Ana Milena López and Diego Patiño Guevara
Machines 2022, 10(3), 193; https://doi.org/10.3390/machines10030193 - 07 Mar 2022
Cited by 4 | Viewed by 4055
Abstract
Robotic applications, such as educational programs, are well-known. Nonetheless, there are challenges to be implemented in other settings, e.g., mine detection, agriculture support, and tasks for industry 4.0. The main challenge consists of robotic operations supported by autonomous decision using sensed-based features extraction. [...] Read more.
Robotic applications, such as educational programs, are well-known. Nonetheless, there are challenges to be implemented in other settings, e.g., mine detection, agriculture support, and tasks for industry 4.0. The main challenge consists of robotic operations supported by autonomous decision using sensed-based features extraction. A prototype of a robot assembled using mechanical parts of a LEGO MINDSTORMS Robotic Kit EV3 and a Raspberry Pi controlled through servo algorithms of 2D and 2D1/2 vision approaches was implemented to tackle this challenge. This design is supported by simulations based on image, position, and a hybrid scheme for visual servo controllers. Practical implementation is operated using navigation guided by running up image-based visual servo control algorithms embedded in a Raspberry Pi that uses a control criterion based on error evolution to compute the difference between a target and sensed image. Images are collected by a camera installed on a mobile robotic platform manually and automatically operated and controlled using the Raspberry Pi. An Android application to watch the images by video streaming is shown here, using a smartphone and a video related to the implemented robot’s operation. This kind of robot might be used to complete field reactive tasks in the settings mentioned above, since the detection and control approaches allow self-contained guidance. Full article
(This article belongs to the Special Issue Collaborative Robotics and Adaptive Machines)
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15 pages, 5299 KiB  
Article
Mathematical Modeling and Simulation of Suspended Equipment Impact on Car Body Modes
by Sunil Kumar Sharma, Jaesun Lee and Hong-Lae Jang
Machines 2022, 10(3), 192; https://doi.org/10.3390/machines10030192 - 06 Mar 2022
Cited by 16 | Viewed by 2777
Abstract
A passenger railway vehicle’s lightweight design is an efficient technique of reducing energy consumption and dynamic forces between wheel and rail. However, light design results in resonant vibration in a car body. To restrain resonant vibration, a correlation between the suspended equipment variables [...] Read more.
A passenger railway vehicle’s lightweight design is an efficient technique of reducing energy consumption and dynamic forces between wheel and rail. However, light design results in resonant vibration in a car body. To restrain resonant vibration, a correlation between the suspended equipment variables and the car body’s modal frequency was investigated in this paper. A rigid–flexible general model was developed to examine the impacts of different equipment suspended under the chassis based on mass, location, and frequency on the car body mode. In addition, the numerical model is validated through the experimental result in terms of ride quality. The results demonstrate that the underframe equipment’s suspension characteristics have a significant impact on the mode of the car body, particularly the frequency of the first bending mode. Equipment with a considerable mass should be suspended near the center of the car body to optimize the frequency of the car body’s high-frequency bending. The weight of the equipment has a significant impact on the car body’s first bending frequency. The frequency of heavy equipment should be low enough to promote high-frequency transmissibility and improve the vibration characteristics of the car body. Full article
(This article belongs to the Special Issue Damping in Structures and Mechanisms)
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