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Machines
Volume 10
Issue 4
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Machines, Volume 10, Issue 4 (April 2022) – 64 articles

Cover Story (view full-size image):

Describes the design and validation of an Adaptable Fingers’ Assistive Device

• It consists of four slider-crank mechanisms. Each slider-crank moves one finger (from the index to the little finger).

• The mechanism can execute the motion of any finger by adjusting the length of one single link.

• Experimental tests have been carried out to validate the feasibility and effectiveness of the proposed device. View this paper

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21 pages, 2235 KiB  
Article
RTSDM: A Real-Time Semantic Dense Mapping System for UAVs
by Zhiteng Li, Jiannan Zhao, Xiang Zhou, Shengxian Wei, Pei Li and Feng Shuang
Machines 2022, 10(4), 285; https://doi.org/10.3390/machines10040285 - 18 Apr 2022
Cited by 6 | Viewed by 2741
Abstract
Intelligent drones or flying robots play a significant role in serving our society in applications such as rescue, inspection, agriculture, etc. Understanding the scene of the surroundings is an essential capability for further autonomous tasks. Intuitively, knowing the self-location of the UAV and [...] Read more.
Intelligent drones or flying robots play a significant role in serving our society in applications such as rescue, inspection, agriculture, etc. Understanding the scene of the surroundings is an essential capability for further autonomous tasks. Intuitively, knowing the self-location of the UAV and creating a semantic 3D map is significant for fully autonomous tasks. However, integrating simultaneous localization, 3D reconstruction, and semantic segmentation together is a huge challenge for power-limited systems such as UAVs. To address this, we propose a real-time semantic mapping system that can help a power-limited UAV system to understand its location and surroundings. The proposed approach includes a modified visual SLAM with the direct method to accelerate the computationally intensive feature matching process and a real-time semantic segmentation module at the back end. The semantic module runs a lightweight network, BiSeNetV2, and performs segmentation only at key frames from the front-end SLAM task. Considering fast navigation and the on-board memory resources, we provide a real-time dense-map-building module to generate an OctoMap with the segmented semantic map. The proposed system is verified in real-time experiments on a UAV platform with a Jetson TX2 as the computation unit. A frame rate of around 12 Hz, with a semantic segmentation accuracy of around 89% demonstrates that our proposed system is computationally efficient while providing sufficient information for fully autonomous tasks such as rescue, inspection, etc. Full article
(This article belongs to the Topic Motion Planning and Control for Robotics)
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27 pages, 10084 KiB  
Article
A Saturation-Based Method for Primary Resonance Control of Flexible Manipulator
by Ruihai Geng, Yushu Bian, Liang Zhang and Yizhu Guo
Machines 2022, 10(4), 284; https://doi.org/10.3390/machines10040284 - 18 Apr 2022
Cited by 2 | Viewed by 1719
Abstract
When primary resonance occurs, even a small external disturbance can abruptly excite large amplitude vibration and deteriorate the working performance of a flexible manipulator. Most active control methods are effective for non-resonant vibration but not for primary resonance. In view of this, this [...] Read more.
When primary resonance occurs, even a small external disturbance can abruptly excite large amplitude vibration and deteriorate the working performance of a flexible manipulator. Most active control methods are effective for non-resonant vibration but not for primary resonance. In view of this, this paper puts forward a new nonlinear saturation-based control method to suppress the primary resonance of a flexible manipulator considering complicated rigid-flexible coupling and modal coupling. A vibration absorber with variable stiffness/damping is designed to establish an energy exchange channel for saturation. A novel idea of modal coupling enhancement is suggested to improve saturation performance by strengthening the coupling relationship between the mode of the vibration absorber and the controlled mode of the flexible manipulator. Through stability analysis on the primary resonance response of the flexible manipulator with the vibration absorber, the saturation mechanism is successfully established and the effectiveness of the saturation control algorithm is validated. On this basis, several important indexes are extracted and employed to optimize saturation control. Finally, a series of virtual prototyping simulations and experiments are conducted to verify the feasibility of the suggested saturation-based control method. This research will contribute to the primary resonance suppression of a flexible manipulator under a complex external excitation environment. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
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14 pages, 4413 KiB  
Article
Process Optimization of Robotic Polishing for Mold Steel Based on Response Surface Method
by Yinhui Xie, Guangsheng Chang, Jinxing Yang, Mingyang Zhao and Jun Li
Machines 2022, 10(4), 283; https://doi.org/10.3390/machines10040283 - 18 Apr 2022
Cited by 6 | Viewed by 2348
Abstract
Aimed to reduce surface roughness (Ra) and improve surface quality of mold steel, the optimizations of process parameters for robotic polishing, such as polishing pressure, feed speed and rotating speed of tool, are accomplish in this research. The optimum range of each parameter [...] Read more.
Aimed to reduce surface roughness (Ra) and improve surface quality of mold steel, the optimizations of process parameters for robotic polishing, such as polishing pressure, feed speed and rotating speed of tool, are accomplish in this research. The optimum range of each parameter is obtained according to a single factor experiment, and the central composite design experiments on the three polishing parameters are conducted to establish a prediction model of surface roughness. Furthermore, a significance test of the prediction model is carried out through variance analysis. The optimum polishing parameters are obtained based on the analysis of response surface, and are then adopted in the polishing experiments of mold steel for validation. The experiment result of model verification indicates that the relative errors of predicted Ra ratio and actual Ra ratio are within the allowable range (maximum is 13.47%). It proves the accuracy of the roughness prediction model. Meanwhile, the experimental results of multipath polishing show that the surface roughness decreased effectively after polishing with the optimum polishing parameters. The prediction model of surface roughness and optimum polishing parameters are helpful to improve surface quality in robotic polishing for mold steel. Full article
(This article belongs to the Special Issue Advanced Processes and Technologies in Precision and Ultra-Precision Machining)
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23 pages, 28453 KiB  
Article
A Lightweight Model for Bearing Fault Diagnosis Based on Gramian Angular Field and Coordinate Attention
by Jialiang Cui, Qianwen Zhong, Shubin Zheng, Lele Peng and Jing Wen
Machines 2022, 10(4), 282; https://doi.org/10.3390/machines10040282 - 17 Apr 2022
Cited by 24 | Viewed by 3243
Abstract
The key to ensuring rotating machinery’s safe and reliable operation is efficient and accurate faults diagnosis. Intelligent fault diagnosis technology based on deep learning (DL) has gained increasing attention. A critical challenge is how to embed the characteristics of time series into DL [...] Read more.
The key to ensuring rotating machinery’s safe and reliable operation is efficient and accurate faults diagnosis. Intelligent fault diagnosis technology based on deep learning (DL) has gained increasing attention. A critical challenge is how to embed the characteristics of time series into DL to obtain stable features that correlate with equipment conditions. This study proposes a lightweight rolling bearing fault diagnosis method based on Gramian angular field (GAF) and coordinated attention (CA) to improve rolling bearing recognition performance and diagnosis efficiency. Firstly, the time domain signal is encoded into GAF images after downsampling and segmentation. This method retains the temporal relation of the time series and provides valuable features for DL. Secondly, a lightweight convolution neural network (CNN) model is constructed through depthwise separable convolution, inverse residual block, and linear bottleneck layer to learn advanced features. After that, CA is employed to capture the long-range dependencies and identify the precise position information of the GAF images with nearly no additional computational overhead. The proposed method is tested and evaluated by CWRU bearing dataset and experimental dataset. The results demonstrate that the CNN based on GAF and CA (GAF-CA-CNN) model can effectively reduce the calculation overhead of the model and achieve high diagnostic accuracy. Full article
(This article belongs to the Topic Artificial Intelligence in Smart Industrial Diagnostics and Manufacturing)
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17 pages, 8142 KiB  
Article
Rapid Calculation and Optimization of Vibration and Noise of Permanent-Magnet Synchronous Motors for EVs Based on Equivalent Structural Network
by Tengfei Song, Huijuan Liu, Binbin Bu and Zhenyang Zhang
Machines 2022, 10(4), 281; https://doi.org/10.3390/machines10040281 - 16 Apr 2022
Cited by 5 | Viewed by 2538
Abstract
Optimizing electromagnetic performance and vibration noise performance simultaneously is important when designing the drive motor for electric vehicles (EVs). This has not been fully explored, and there are only a few relevant studies. To achieve simultaneous optimization, this paper proposes an equivalent structural [...] Read more.
Optimizing electromagnetic performance and vibration noise performance simultaneously is important when designing the drive motor for electric vehicles (EVs). This has not been fully explored, and there are only a few relevant studies. To achieve simultaneous optimization, this paper proposes an equivalent structural network (ESN) of stator assembly to calculate the modal distribution and harmonic response transfer functions. Based on the ESN model, the motor’s electromagnetic vibration noise harmonic response, such as acceleration and equivalent radiated power level (ERPL), can be quickly calculated. The feasibility of the established ESN model is verified by structural-field finite-element method (FEM) and modal hammer tests. Based on the modern optimization algorithm and the ESN model, an improved multi-physics and multi-objective optimization design approach is proposed for an optimized design of a 30 kW interior permanent-magnet synchronous machine (IPMSM). The motor’s maximum output torque and ERPL were selected as optimization objectives, and then the ERPL and acceleration were recalculated using structural-field FEM to validate the accuracy of the optimal design. Finally, vibration acceleration tests were carried out on a manufactured prototype motor to verify the feasibility and validity of the proposed optimization design method. Full article
(This article belongs to the Section Machine Design and Theory)
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15 pages, 5217 KiB  
Article
Experimental Characterization of A-AFiM, an Adaptable Assistive Device for Finger Motions
by Jhon Freddy Rodríguez-León, Eduardo Castillo-Castañeda, José Felipe Aguilar-Pereyra and Giuseppe Carbone
Machines 2022, 10(4), 280; https://doi.org/10.3390/machines10040280 - 15 Apr 2022
Cited by 4 | Viewed by 2070
Abstract
Robot rehabilitation devices are attracting significant research interest, aiming at developing viable solutions for increasing the patient’s quality of life and enhancing clinician’s therapies. This paper outlines the design and implementation of a low-cost robotic system that can assist finger motion rehabilitation by [...] Read more.
Robot rehabilitation devices are attracting significant research interest, aiming at developing viable solutions for increasing the patient’s quality of life and enhancing clinician’s therapies. This paper outlines the design and implementation of a low-cost robotic system that can assist finger motion rehabilitation by controlling and adapting both the position and velocity of fingers to the users′ needs. The proposed device consists of four slider-crank mechanisms. Each slider-crank is fixed and moves one finger (from the index to the little finger). The finger motion is adjusted through the regulation of a single link length of the mechanism. The trajectory that is generated corresponds to the natural flexion and extension trajectory of each finger. The functionality of this mechanism is validated by experimental image processing. Experimental validation is performed through tests on healthy subjects to demonstrate the feasibility and user-friendliness of the proposed solution. Full article
(This article belongs to the Special Issue Feature Papers to Celebrate the First Impact Factor of Machines)
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28 pages, 4065 KiB  
Article
A New Framework for the Harmonic Balance Method in OpenFOAM
by Stefano Oliani, Nicola Casari and Mauro Carnevale
Machines 2022, 10(4), 279; https://doi.org/10.3390/machines10040279 - 14 Apr 2022
Cited by 3 | Viewed by 3164
Abstract
The Harmonic Balance Method is one of the most commonly employed Reduced Order Models for turbomachinery calculations, since it leverages the signal sparsity in the frequency domain to cast the transient equations into a coupled set of steady-state ones. The present work aims [...] Read more.
The Harmonic Balance Method is one of the most commonly employed Reduced Order Models for turbomachinery calculations, since it leverages the signal sparsity in the frequency domain to cast the transient equations into a coupled set of steady-state ones. The present work aims at detailing the development and validation of a new framework for the application of the Harmonic Balance Method in the open-source software OpenFOAM. The paper is conceptually divided into building blocks for the implementation of the code. For each of these, theoretical notions and coding strategies are given, and an ad hoc validation test case is presented. This structure has been chosen with the aim of easing the reader in the understanding and implementation of such a method in a generic fluid dynamics solver. In a fully open source philosophy, the library files are freely accessible in the authors’ repository (link provided below in the text). Full article
(This article belongs to the Special Issue Optimization and Flow Characteristics in Advanced Fluid Machinery)
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17 pages, 5321 KiB  
Article
A Fast Method for Protecting Users’ Privacy in Image Hash Retrieval System
by Liang Huang, Yu Zhan, Chao Hu and Ronghua Shi
Machines 2022, 10(4), 278; https://doi.org/10.3390/machines10040278 - 14 Apr 2022
Viewed by 1586
Abstract
Effective search engines based on deep neural networks (DNNs) can be used to search for many images, as is the case with the Google Images search engine. However, the illegal use of search engines can lead to serious compromises of privacy. Affected by [...] Read more.
Effective search engines based on deep neural networks (DNNs) can be used to search for many images, as is the case with the Google Images search engine. However, the illegal use of search engines can lead to serious compromises of privacy. Affected by various factors such as economic interests and service providers, hackers and other malicious parties can steal and tamper with the image data uploaded by users, causing privacy leakage issues in image hash retrieval. Previous work has exploited the adversarial attack to protect the user’s privacy with an approximation strategy in the white-box setting, although this method leads to slow convergence. In this study, we utilized the penalty norm, which sets a strict constraint to quantify the feature of a query image into binary code via the non-convex optimization process. Moreover, we exploited the forward–backward strategy to solve the vanishing gradient caused by the quantization function. We evaluated our method on two widely used datasets and show an attractive performance with high convergence speed. Moreover, compared with other image privacy protection methods, our method shows the best performance in terms of privacy protection and image quality. Full article
(This article belongs to the Special Issue Cybersecurity for Manufacturing Factories in Industry 4.0)
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17 pages, 8900 KiB  
Article
Improved DCNN Based on Multi-Source Signals for Motor Compound Fault Diagnosis
by Xiaoyun Gong, Zeheng Zhi, Kunpeng Feng, Wenliao Du and Tao Wang
Machines 2022, 10(4), 277; https://doi.org/10.3390/machines10040277 - 14 Apr 2022
Cited by 10 | Viewed by 1919
Abstract
Induction motors, the key equipment for rotating machinery, are prone to compound faults, such as a broken rotor bars and bearing defects. It is difficult to extract fault features and identify faults from a single signal because multiple fault features overlap and interfere [...] Read more.
Induction motors, the key equipment for rotating machinery, are prone to compound faults, such as a broken rotor bars and bearing defects. It is difficult to extract fault features and identify faults from a single signal because multiple fault features overlap and interfere with each other in a compound fault. Since current signals and vibration signals have different sensitivities to broken rotor and bearing faults, a multi-channel deep convolutional neural network (MC-DCNN) fault diagnosis model based on multi-source signals is proposed in this paper, which integrates the original signals of vibration and current of the motor. Dynamic attenuation learning rate and SELU activation function were used to improve the network hyperparameters of MC-DCNN. The dynamic attenuated learning rate can improve the stability of model training and avoid model collapse effectively. The SELU activation function can avoid the problems of gradient disappearance and gradient explosion during model iteration due to its function configuration, thereby avoiding the model falling into local optima. Experiments showed that the proposed model can effectively solve the problem of motor compound fault identification, and three comparative experiments verified that the improved method can improve the stability of model training and the accuracy of fault identification. Full article
(This article belongs to the Section Machines Testing and Maintenance)
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15 pages, 5929 KiB  
Article
Velocity and Singularity Analysis of a 5-DOF (3T2R) Parallel-Serial (Hybrid) Manipulator
by Pavel Laryushkin, Anton Antonov, Alexey Fomin and Terence Essomba
Machines 2022, 10(4), 276; https://doi.org/10.3390/machines10040276 - 13 Apr 2022
Cited by 9 | Viewed by 2318
Abstract
This article presents the velocity and singularity analysis for a five-degree-of-freedom (5-DOF) parallel-serial manipulator. The hybrid structure of the manipulator combines a tripod-like parallel part and a serial part, represented as two carriages moving in perpendicular directions. This manipulator provides its end-effector with [...] Read more.
This article presents the velocity and singularity analysis for a five-degree-of-freedom (5-DOF) parallel-serial manipulator. The hybrid structure of the manipulator combines a tripod-like parallel part and a serial part, represented as two carriages moving in perpendicular directions. This manipulator provides its end-effector with a 3T2R motion pattern, which includes three independent translations and two independent rotations. First, the study briefly discusses the manipulator design and the results of the position analysis. These results form the basis for the subsequent velocity and singularity analysis, performed by screw theory. The screw coordinates of the unit twists are written for each manipulator joint, and then through the reciprocal screw approach, the actuation and constraint wrenches of the manipulator are obtained by simple inspection. Based on these twists and wrenches, the paper forms the velocity equation and shows an example of the inverse velocity analysis for a given end-effector trajectory. The same example is solved by numerical differentiation to verify the proposed approach. Next, the paper investigates singular configurations by analyzing the wrench system of the manipulator and presents several conditions for serial and parallel singularities. Each condition has both a symbolic representation, given by an equation for screw coordinates of certain wrenches, and a visual representation, which shows the manipulator in a singular configuration. Full article
(This article belongs to the Section Machine Design and Theory)
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27 pages, 2998 KiB  
Article
Integration of Design, Manufacturing, and Service Based on Digital Twin to Realize Intelligent Manufacturing
by Luyao Zhang, Lijie Feng, Jinfeng Wang and Kuo-Yi Lin
Machines 2022, 10(4), 275; https://doi.org/10.3390/machines10040275 - 12 Apr 2022
Cited by 10 | Viewed by 3347
Abstract
Complex product design, manufacturing, and service are the key elements of a product’s life cycle. However, the traditional manufacturing processes of design, manufacturing, and service are independent of each other, so lack deep integration. The emergence of digital twins offers an opportunity to [...] Read more.
Complex product design, manufacturing, and service are the key elements of a product’s life cycle. However, the traditional manufacturing processes of design, manufacturing, and service are independent of each other, so lack deep integration. The emergence of digital twins offers an opportunity to accelerate the integration of complex product design, manufacturing, and services. For intelligent manufacturing, physical entity and virtual entity transformation can be realized through digital information. A collaborative framework for complex product design, manufacturing, and service integration based on digital twin technology was proposed. The solutions of process integration, data flow, modeling and simulation, and information fusion were analyzed. The core characteristics and key technologies of service-oriented manufacturing, design for service and manufacturing, and manufacturing monitoring based on the deep integration of the digital twin were discussed. Finally, the feasibility of the framework was verified by a self-balancing multistage pump manufacturing case. The performance of the upgraded pump under the framework was tested, and the test results proved the effectiveness of the integrated framework. Full article
(This article belongs to the Special Issue Digital Twin Applications in Smart Manufacturing)
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10 pages, 3268 KiB  
Article
Analysis and Verification of the Method of Improving Inductance by Magnetic Endcaps in Slotless Permanent Magnet Motor
by Chenglong Chu and Yunkai Huang
Machines 2022, 10(4), 274; https://doi.org/10.3390/machines10040274 - 12 Apr 2022
Viewed by 1512
Abstract
The slotless permanent magnet motor (SPMM) has low phase inductance due to the larger physical air gap, which will adversely affect motor control and current harmonics. In this paper, the method of forming an extra magnetic circuit by endcap around the outer stator [...] Read more.
The slotless permanent magnet motor (SPMM) has low phase inductance due to the larger physical air gap, which will adversely affect motor control and current harmonics. In this paper, the method of forming an extra magnetic circuit by endcap around the outer stator is proposed. The advantage of this method is that a restrained flux path is formed without increasing the motor structure and cost, and the inductance of the motor is effectively improved without causing a significant decrease in torque. The preliminary simulation analysis and corresponding experimental content are carried out. The experimental results and the simulation content showed good consistency, which verified the correctness of the theory and simulation analysis. Full article
(This article belongs to the Section Electrical Machines and Drives)
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20 pages, 8280 KiB  
Article
Development of an Anthropomorphic and Dexterous Dual-Arm System for Aerial Cooperative Bimanual Manipulation
by Peng Yang, Hao Wang, Zhen Liu, Zhiyan Dong and Lihua Zhang
Machines 2022, 10(4), 273; https://doi.org/10.3390/machines10040273 - 11 Apr 2022
Cited by 3 | Viewed by 2086
Abstract
It is a challenging task for an aerial manipulator to complete dual-arm cooperative manipulation in an outdoor environment. In this study, a new dual-arm aerial manipulator system with flexible operation is developed. The dual-arm manipulator system is designed for the application of aerial [...] Read more.
It is a challenging task for an aerial manipulator to complete dual-arm cooperative manipulation in an outdoor environment. In this study, a new dual-arm aerial manipulator system with flexible operation is developed. The dual-arm manipulator system is designed for the application of aerial manipulation, and it has the characteristics of low weight, low inertia, and a humanoid arm structure. The arm structure is composed of customized aluminum parts, each manipulator contains four degrees of freedom, similar to the arrangement of human joints, including shoulder yaw, shoulder pitch, elbow pitch, and wrist roll. Next, the workspace of the dual-arm manipulator is simulated and analyzed, and the relevant kinematic and dynamic models are deduced. Finally, through the lift load, accuracy and repeatability, cooperative bimanual manipulation tests on the test bench, and multiple groups of outdoor flight tests, the relevant performance analysis and verification of the dual-arm aerial manipulator system are carried out. The test results evaluate the feasibility of the designed dual-arm aerial manipulator system for outdoor cooperative manipulation. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
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13 pages, 5776 KiB  
Article
Increasing Bending Performance of Soft Actuator by Silicon Rubbers of Multiple Hardness
by Xishuang Jing, Siyu Chen, Chengyang Zhang and Fubao Xie
Machines 2022, 10(4), 272; https://doi.org/10.3390/machines10040272 - 11 Apr 2022
Cited by 5 | Viewed by 2445
Abstract
In this study, a method for fabricating actuators made of various silicone materials is proposed to improve the flexural performance of soft-body actuators. Specifically, the redundant deformation part of the soft actuator was replaced with a material with higher hardness to limit the [...] Read more.
In this study, a method for fabricating actuators made of various silicone materials is proposed to improve the flexural performance of soft-body actuators. Specifically, the redundant deformation part of the soft actuator was replaced with a material with higher hardness to limit the redundant deformation of the soft actuator. Materials with lower hardness were used to produce the main deformation part of the soft actuator, so that the soft body actuator could perform greater bending under the same air pressure and create a greater bending force. In addition, the fabricated actuator was divided into three regions in this study: the periphery of the chamber, the chamber wall (the main curved part), and the bottom surface of the actuator. The impact on the overall performance of soft-body actuators when using silicone materials with different hardness in these three regions was explored in this study. According to the idea of the multi-hardness silicone structure, an actuator with seven chambers was fabricated, and the performance of the actuator was improved by 90.72% compared with the uniform material actuator. Full article
(This article belongs to the Topic Recent Advances in Robotics and Networks)
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26 pages, 12479 KiB  
Article
Meshing Stiffness Calculation of Disposable Harmonic Drive under Full Load
by Yuxin Zhang, Xudong Pan, Yuefeng Li, Guanglin Wang and Guicheng Wu
Machines 2022, 10(4), 271; https://doi.org/10.3390/machines10040271 - 10 Apr 2022
Cited by 1 | Viewed by 2756
Abstract
Mechanical equipment in the field of aerospace that is used only once is called disposable machinery. As a piece of typical disposable machinery, disposable harmonic gear exhibit stiffness failure with a large load. This manuscript distinguishes disposable harmonic gear from conventional harmonic gear [...] Read more.
Mechanical equipment in the field of aerospace that is used only once is called disposable machinery. As a piece of typical disposable machinery, disposable harmonic gear exhibit stiffness failure with a large load. This manuscript distinguishes disposable harmonic gear from conventional harmonic gear in terms of the application environment and structure. Then, this paper determines the single-tooth stiffness of the disposable harmonic gear under full load by using the non-uniform beam model and the improved energy method. In addition, the multi-tooth meshing in the disposable harmonic drive is considered, and the improved energy method is modified. Besides, the normal contact force and comprehensive elastic displacement at each meshing position are calculated according to the finite element model. Additionally, curves of the single-tooth stiffness and the comprehensive meshing stiffness are obtained. The theoretical results of the modified analytical method and FEM are compared to verify the correctness of the proposed method in terms of calculating the meshing stiffness of the disposable harmonic drive. Finally, FEM is used to obtain the failure form of the disposable harmonic gear under overload. Full article
(This article belongs to the Section Machine Design and Theory)
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14 pages, 2598 KiB  
Article
From Novelty Detection to a Genetic Algorithm Optimized Classification for the Diagnosis of a SCADA-Equipped Complex Machine
by Luca Viale, Alessandro Paolo Daga, Alessandro Fasana and Luigi Garibaldi
Machines 2022, 10(4), 270; https://doi.org/10.3390/machines10040270 - 09 Apr 2022
Cited by 7 | Viewed by 1791
Abstract
In the field of Diagnostics, the fundamental task of detecting damage is basically a binary classification problem, which is addressed in many cases via Novelty Detection (ND): an observation is classified as novel if it differs significantly from reference, healthy data. ND is [...] Read more.
In the field of Diagnostics, the fundamental task of detecting damage is basically a binary classification problem, which is addressed in many cases via Novelty Detection (ND): an observation is classified as novel if it differs significantly from reference, healthy data. ND is practically implemented summarizing a multivariate dataset with univariate distance information called Novelty Index. As many different approaches are possible to produce NIs, in this analysis, the possibility of implementing a simple classifier in a reduced-dimensionality space of NIs is studied. In addition to a simple decision-tree-like classification method, the process for obtaining the NIs can result as a dimension reduction method and, in turn, the NIs can be used for other classification algorithms. In addition, a case study will be analyzed thanks to the data published by the Prognostics and Health Management Europe (PHME) society, on the occasion of the Data Challenge 2021. Full article
(This article belongs to the Special Issue 10th Anniversary of Machines—Feature Papers in Fault Diagnosis and Prognosis)
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19 pages, 4285 KiB  
Article
An Internal Resonance Based Method for Reducing Torsional Vibration of a Gear System
by Bohan Jin, Yushu Bian, Dongbo Tian and Zhihui Gao
Machines 2022, 10(4), 269; https://doi.org/10.3390/machines10040269 - 09 Apr 2022
Cited by 1 | Viewed by 1817
Abstract
The gear system is one of the most widely-used transmission systems due to its accurate transmission ratio and high efficiency. However, torsional vibration may severely degrade transmission performance and shorten the gear lifespan. In view of this, a nonlinear interaction principle suitable for [...] Read more.
The gear system is one of the most widely-used transmission systems due to its accurate transmission ratio and high efficiency. However, torsional vibration may severely degrade transmission performance and shorten the gear lifespan. In view of this, a nonlinear interaction principle suitable for vibration energy transfer is researched, and an internal resonance based method is put forward to reduce the torsional vibration of the gear system. According to the coupling relationship between the gear torsional vibration mode and the vibration absorber mode, the 1:1 internal resonance condition is analyzed by the multiple scale method and the sufficient and necessary conditions for establishing internal resonance are obtained. Through stability analysis, the vibration energy transfer channel based on internal resonance is successfully established, by which vibration energy can be transferred to and dissipated by the vibration absorber. Based on numerical and virtual prototyping simulations, vibration reduction performances are examined, including effectiveness, damping characteristics and robustness. The research results show that the proposed internal resonance based method can effectively reduce the torsional vibration of the gear system. Full article
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20 pages, 8192 KiB  
Article
Research into the Impact of Spindle Speed and Feed Rate Changes on the Life of a Deep-Drilling Technology Tool
by Martin Pollák, Marek Kočiško, Jaroslav Petrus, Sorin Dumitru Grozav and Vasile Ceclan
Machines 2022, 10(4), 268; https://doi.org/10.3390/machines10040268 - 08 Apr 2022
Cited by 3 | Viewed by 2407
Abstract
The drilling process in real production places ever-increasing demands on the length and accuracy of the holes made. The drilling of holes beyond a length-to-diameter ratio of 5–10 is called deep drilling. The aim of the research was to determine in detail the [...] Read more.
The drilling process in real production places ever-increasing demands on the length and accuracy of the holes made. The drilling of holes beyond a length-to-diameter ratio of 5–10 is called deep drilling. The aim of the research was to determine in detail the deep-drilling process input conditions, their impact on the stability of the cutting process and the degree to which the output requirements were achieved. The focus of the analysis was on how the monitored technological and physical impacts translate into achieving the required gun-drill life and the quality and dimensional accuracy of deep holes, as well as their overall impact on tool life. Based on the analysis, tests were conducted to verify the impact of individual parameters on tool life. The obtained results were then statistically evaluated and optimized. Drawing on the evaluated experimental results, solutions and procedures were proposed and implemented in the environment of a real operation. This research obtained the optimal values of the frequency of rotation and displacement to ensure maximum tool life while maintaining the efficiency of the production of drilled parts. At the same time, based on the research, a methodology and recommendations for deep-drilling technology were developed. Full article
(This article belongs to the Special Issue Advances in Computer-Aided Technology)
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15 pages, 6651 KiB  
Article
Vibration Responses of the Bearing-Rotor-Gear System with the Misaligned Rotor
by Fengtao Wang, Peng Dai, Jianping Wang and Linkai Niu
Machines 2022, 10(4), 267; https://doi.org/10.3390/machines10040267 - 08 Apr 2022
Cited by 6 | Viewed by 2546
Abstract
The bearing-rotor-gear system is an important mechanical component for transmitting motion and power. Due to the complex responses, the condition assessment of the transmission system becomes more difficult. Thus, a model of the bearing-rotor-gear system with a misaligned rotor is built for implementing [...] Read more.
The bearing-rotor-gear system is an important mechanical component for transmitting motion and power. Due to the complex responses, the condition assessment of the transmission system becomes more difficult. Thus, a model of the bearing-rotor-gear system with a misaligned rotor is built for implementing the complex response analysis. The misalignment rotor is realized by offset connection of couplings, and the creative excitation force is transferred to the bearing inner ring through the rotor. The constructed model is checked by the corresponding experiment. From the simulation results, it is found that vibration responses are modulated by rotor frequencies, and there are rotor frequencies, harmonic frequencies of bearings, and gear pairs in the spectrum. When the misalignment defect is deepening, the high-order harmonic responses are excited. If the revolving speed increases, the modulation of the rotor frequencies is accentuated, the vibration intensity generated by gear pairs is attenuated, while the harmonic response and super-harmonic response of bearings can be suppressed, and the system vibrates mainly at the low-frequency band. When the load becomes higher, the amplitudes of the rotor frequencies, meshing frequencies, and defect frequencies are all increased. Full article
(This article belongs to the Special Issue Fault Diagnosis and Health Management of Power Machinery)
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27 pages, 3938 KiB  
Article
Electrically Driven Lower Limb Exoskeleton Rehabilitation Robot Based on Anthropomorphic Design
by Moyao Gao, Zhanli Wang, Zaixiang Pang, Jianwei Sun, Jing Li, Shuang Li and Hansi Zhang
Machines 2022, 10(4), 266; https://doi.org/10.3390/machines10040266 - 07 Apr 2022
Cited by 15 | Viewed by 5562
Abstract
To help people with impairment of lower extremity movement regain the ability to stand and walk, and to enhance limb function, this study proposes an anthropomorphic design of an electrically driven, lower-limb exoskeleton rehabilitation robot. The angular range of the robot’s motion was [...] Read more.
To help people with impairment of lower extremity movement regain the ability to stand and walk, and to enhance limb function, this study proposes an anthropomorphic design of an electrically driven, lower-limb exoskeleton rehabilitation robot. The angular range of the robot’s motion was determined according to the characteristics of the targeted lower-limb joints; the robot was given an active–passive anthropomorphic design with 12 degrees of freedom. The multi-degree-of-freedom hip exoskeleton, bionic artificial knee exoskeleton and passive rigid-flexible coupling ankle exoskeleton can assist patients in rehabilitation exercises with better wear comfort and exercise flexibility. A kinetic model of the seven-rod lower-limb exoskeleton rehabilitation robot was built, and data analysis of the dynamically captured motion trajectory was conducted. These provided a theoretical basis for gait planning and the control system of the lower-limb exoskeleton rehabilitation robot. The results show that the lower-limb exoskeleton rehabilitation robot system possesses sound wearing comfort and movement flexibility, and the degree of freedom of movement of the exoskeleton robot matches well with that of human movement. The robot can thus provide effective assistance to patients’ standing and walking rehabilitation training. Full article
(This article belongs to the Section Robotics, Mechatronics and Intelligent Machines)
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22 pages, 2683 KiB  
Article
Improved Cubature Kalman Filtering on Matrix Lie Groups Based on Intrinsic Numerical Integration Error Calibration with Application to Attitude Estimation
by Huijuan Guo, Yan Zhou, Huiying Liu and Xiaoxiang Hu
Machines 2022, 10(4), 265; https://doi.org/10.3390/machines10040265 - 07 Apr 2022
Cited by 2 | Viewed by 2071
Abstract
This paper investigates the numerical integration error calibration problem in Lie group sigma point filters to obtain more accurate estimation results. On the basis of the theoretical framework of the Bayes–Sard quadrature transformation, we first established a Bayesian estimator on matrix Lie groups [...] Read more.
This paper investigates the numerical integration error calibration problem in Lie group sigma point filters to obtain more accurate estimation results. On the basis of the theoretical framework of the Bayes–Sard quadrature transformation, we first established a Bayesian estimator on matrix Lie groups for system measurements in Euclidean spaces or Lie groups. The estimator was then employed to develop a generalized Bayes–Sard cubature Kalman filter on matrix Lie groups that considers additional uncertainties brought by integration errors and contains two variants. We also built on the maximum likelihood principle, and an adaptive version of the proposed filter was derived for better algorithm flexibility and more precise filtering results. The proposed filters were applied to the quaternion attitude estimation problem. Monte Carlo numerical simulations supported that the proposed filters achieved better estimation quality than that of other Lie group filters in the mentioned studies. Full article
(This article belongs to the Special Issue Modeling, Sensor Fusion and Control Techniques in Applied Robotics)
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21 pages, 12376 KiB  
Article
Experimental Analysis of the Effect of Wear Factors on Guide Vane of Hydraulic Turbine
by Xiaoyi Zhao, Yuanjie Peng, Junxiang Yang, Minghui Ren and Xiaobing Liu
Machines 2022, 10(4), 264; https://doi.org/10.3390/machines10040264 - 07 Apr 2022
Cited by 2 | Viewed by 1520
Abstract
In this paper, in order to study the wear of the guide vane of the hydraulic turbine, a test bench was built according to the actual internal flow of the hydraulic turbine of the power station. The value of the wear of the [...] Read more.
In this paper, in order to study the wear of the guide vane of the hydraulic turbine, a test bench was built according to the actual internal flow of the hydraulic turbine of the power station. The value of the wear of the surface of the guide vane after polishing was reduced by 18.1 μm compared with that before polishing of P = 30.9 MW and by 12.5 μm at P = 42.8 MW. In order to reduce the influence of sediment wear on the guide vane, a 0.3 mm thick tungsten carbide coating was sprayed on its surface, and the wear of the guide vane after spraying tungsten carbide was obtained. The wear of the guide vane was reduced by about a factor of three to four times compared with that before spraying. In addition, according to the pH value of 6.73 of the river where the power station is located, the change of dissolved oxygen in the water body will affect the wear of the metal material on the surface of the guide vane, and the dissolved oxygen varies with the change of the water body temperature, so we simulated the temperature of the water body in the flood and the dry period of the power station, and got the wear amount of the polished guide vane in the flood period under the two working conditions of 28.1 μm and 47.3 μm, respectively. The wear amounts of the guide vane in the dry period were 25.2 μm and 43.9 μm, respectively. In addition, the service life of the guide vane before and after polishing and after tungsten carbide spraying was estimated based on the wear data obtained from the test, which provides a basis for power plant maintenance. Full article
(This article belongs to the Section Turbomachinery)
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13 pages, 11760 KiB  
Communication
Application of a Bio-Inspired Algorithm in the Process Parameter Optimization of Laser Cladding
by Yingtao Zhang, Benxiang Gong, Zirong Tang and Weidong Cao
Machines 2022, 10(4), 263; https://doi.org/10.3390/machines10040263 - 07 Apr 2022
Cited by 12 | Viewed by 1805
Abstract
The process parameter optimization of laser cladding using a bio-inspired algorithm is a hot issue and attracts the attention of many scholars. The biggest difficulty, at present, is the lack of accurate information regarding the function relationship between objectives and process parameters. In [...] Read more.
The process parameter optimization of laser cladding using a bio-inspired algorithm is a hot issue and attracts the attention of many scholars. The biggest difficulty, at present, is the lack of accurate information regarding the function relationship between objectives and process parameters. In this study, a novel process parameter optimization approach for laser cladding is proposed based on a multiobjective slime mould algorithm (MOSMA) and support vector regression (SVR). In particular, SVR is used as a bridge between target and process parameters for solving the problem of lacking accurate information regarding the function relationship. As a new metaheuristic algorithm, MOSMA is to obtain the Pareto solution sets and fronts. The Pareto solution sets are optimized process parameters, and the Pareto fronts are optimized objectives. Users can select the corresponding optimized process parameters according to their needs for the target. The performance of the proposed approach was evaluated by the TOPSIS method, based on actual laser cladding data and compared with several well known approaches. The results indicate that the optimal process parameters obtained by the proposed approach have better process performance. Full article
(This article belongs to the Special Issue Bio-Inspired Smart Machines: Structure, Mechanisms and Applications)
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20 pages, 4886 KiB  
Article
Computer-Aided System for Parametric Design of Ship Hull Structures—CADS-Hull
by Sergey Ryumin and Vladimir Tryaskin
Machines 2022, 10(4), 262; https://doi.org/10.3390/machines10040262 - 07 Apr 2022
Cited by 1 | Viewed by 2720
Abstract
The problem of the parametric design of ship hull structures is considered here. The parametric design of ship hull structures is intended to determine the dimensions of structural elements that meet the requirements of regulatory documents (Rules of Classification Societies/Strength Standards). It is [...] Read more.
The problem of the parametric design of ship hull structures is considered here. The parametric design of ship hull structures is intended to determine the dimensions of structural elements that meet the requirements of regulatory documents (Rules of Classification Societies/Strength Standards). It is shown that, in all existing shipbuilding CAD-CAM systems, the problems of the parametric design of ship hull structures are essentially not affected. A modern methodology for the parametric design of hull structures is proposed, which defines a set of principles for the structural and logical organization of the design process, methods, and technical means for implementing design procedures. The most characteristic methodological principles of the parametric design of ship hull structures and other offshore engineering structures are identified: A systematic approach; modeling as one of the main methods for solving design problems; and a rational design strategy based on iterative search procedures that implement the methodological principle of successive complication of models and procedures for designing structures. The article considers the architecture and methodological foundations of the system for automated parametric design of ship hull structures (CADS-Hull), developed at the Saint Petersburg State Marine Technical University, Russia. The system is intended for use in design bureaus when designing civil ship hull structures on the basis of regulatory requirements of the Russian Maritime Register of Shipping and IACS General Rules in terms of large-capacity tankers, bulk carriers, and container ships. Full article
(This article belongs to the Special Issue Advances in Computer-Aided Technology)
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17 pages, 4491 KiB  
Article
An Object Detection Model for Paint Surface Detection Based on Improved YOLOv3
by Jiadong Wang, Shaohui Su, Wanqiang Wang, Changyong Chu, Linbei Jiang and Yangjian Ji
Machines 2022, 10(4), 261; https://doi.org/10.3390/machines10040261 - 07 Apr 2022
Cited by 6 | Viewed by 2180
Abstract
To solve the problem of poor performance of the target detection algorithm and false detection in the detection of paint surface defects of office chairs five-star feet, we propose a defect detection method based on the improved YOLOv3 algorithm. Firstly, a new feature [...] Read more.
To solve the problem of poor performance of the target detection algorithm and false detection in the detection of paint surface defects of office chairs five-star feet, we propose a defect detection method based on the improved YOLOv3 algorithm. Firstly, a new feature fusion structure is designed to reduce the missed detection rate of small targets. Then we used the CIOU loss function to improve the positioning accuracy. At the same time, a parallel version of the k-means++ initialization algorithm (K-means||) is used to optimize and determine the parameters of the a priori anchor so as to improve the matching degree between the a priori anchor and the feature layer. We constructed a dataset of paint surface defects on the five-star feet of office chairs and performed optimization training, and used multiple algorithms and different datasets to conduct comparative experiments to validate the algorithm. The experimental results show that the improved YOLOv3 algorithm is effective in that the average precision on the self-made dataset reaches 88.3%, which is 5.8% higher than the original algorithm. At the same time, it has also been verified based on the Aliyun Tianchi competition aluminum dataset, and the average precision has reached 89.2%. This method realizes the real-time detection of the paint surface defects of the five-star feet of the office chair very well. Full article
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16 pages, 2533 KiB  
Article
Fault Diagnosis of Rolling Element Bearings Based on Adaptive Mode Extraction
by Chuliang Liu, Jianping Tan and Zhonghe Huang
Machines 2022, 10(4), 260; https://doi.org/10.3390/machines10040260 - 05 Apr 2022
Cited by 8 | Viewed by 2054
Abstract
Generally speaking, vibration signals collected by sensors always contain complex frequency components, which will bring great trouble to bearing condition monitoring and fault diagnosis. A reliable fault signal component extraction method is significant to detect the fault-induced weak repetitive transients. Therefore, many signal [...] Read more.
Generally speaking, vibration signals collected by sensors always contain complex frequency components, which will bring great trouble to bearing condition monitoring and fault diagnosis. A reliable fault signal component extraction method is significant to detect the fault-induced weak repetitive transients. Therefore, many signal decomposition or extraction methods have been developed and are widely employed in fault diagnosis. Based on the recently proposed variational mode extraction (VME) method, an adaptive optimal mode extraction method was designed with a new strategy to extract the mode center frequency and a novel indicator to optimize the balance parameter. The spectrum is first divided into several modes by enveloping curve fitting (ECF), and the center frequencies of each mode are extracted, respectively. All potential fault modes are then extracted sequentially utilizing the extracted center frequency and fixed balance parameter. For the extracted modes, the kurtosis index is applied to select the target mode. Finally, the relative amplitude ratio (RAR) index is used to adaptively adjust the balance parameter. The comparison results reveal that the adaptive mode extraction method can extract the weak fault feature under strong interference. Full article
(This article belongs to the Section Machines Testing and Maintenance)
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19 pages, 4225 KiB  
Article
An Environmental-Adaptability-Improved RatSLAM Method Based on a Biological Vision Model
by Chong Wu, Shumei Yu, Liang Chen and Rongchuan Sun
Machines 2022, 10(4), 259; https://doi.org/10.3390/machines10040259 - 04 Apr 2022
Cited by 6 | Viewed by 1886
Abstract
Inspired by rodents’ free navigation through a specific space, RatSLAM mimics the function of the rat hippocampus to establish an environmental model within which the agent localizes itself. However, RatSLAM suffers from the deficiencies of erroneous loop-closure detection, low reliability on the experience [...] Read more.
Inspired by rodents’ free navigation through a specific space, RatSLAM mimics the function of the rat hippocampus to establish an environmental model within which the agent localizes itself. However, RatSLAM suffers from the deficiencies of erroneous loop-closure detection, low reliability on the experience map, and weak adaptability to environmental changes, such as lighting variation. To enhance environmental adaptability, this paper proposes an improved algorithm based on the HSI (hue, saturation, intensity) color space, which is superior in handling the characteristics of image brightness and saturation from the perspective of a biological visual model. The proposed algorithm first converts the raw image data from the RGB (red, green, blue) space into the HSI color space using a geometry derivation method. Then, a homomorphic filter is adopted to act on the I (intensity) channel and weaken the influence of the light intensity. Finally, guided filtering is used to process the S (saturation) channel and improve the significance of image details. The experimental results reveal that the improved RatSLAM model is superior to the original method in terms of the accuracy of visual template matching and robustness. Full article
(This article belongs to the Special Issue Intelligent Mechatronics, Automation, Control Systems)
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23 pages, 4503 KiB  
Article
Temperature Dynamic Characteristics Analysis and Thermal Load Dissipation Assessment for Airliner Hydraulic System in a Full Flight Mission Profile
by Dong Li, Sujun Dong, Jun Wang and Yunhua Li
Machines 2022, 10(4), 258; https://doi.org/10.3390/machines10040258 - 02 Apr 2022
Cited by 1 | Viewed by 2499
Abstract
This paper deals with the modeling of the thermal load and the simulation of thermal dynamic characteristics for the hydraulic system of a large airliner in a full mission profile. Firstly, the formation mechanism of the thermal load in the hydraulic system is [...] Read more.
This paper deals with the modeling of the thermal load and the simulation of thermal dynamic characteristics for the hydraulic system of a large airliner in a full mission profile. Firstly, the formation mechanism of the thermal load in the hydraulic system is analyzed, and thermal dynamic modeling is conducted of the hydraulic components of an hydraulic system with an immersed heat exchanger employing the lumped parameter thermal node method and oil temperature and power loss of each key node within the hydraulic system within a full mission profile. Then, a thermal dynamic simulation model based on MATLAB/Simulink is established, and the temperatures at the nodes of different components and the absorptive capacity of the fuel heat sink in the thermal management module are calculated. The simulation results show that the thermal management scheme of the heat exchanger, located in the return oil pipeline of the hydraulic piston pump housing and immersed in the central fuel tank, can dissipate the thermal load of the system. This work is of important significance for temperature analysis and thermal load dissipation of the airliner hydraulic system. Full article
(This article belongs to the Special Issue Design, Modeling and Control of Advanced Mechatronic Systems)
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19 pages, 5117 KiB  
Article
Advanced High-Speed Lane Keeping System of Autonomous Vehicle with Sideslip Angle Estimation
by Hengyang Wang, Biao Liu and Junchao Qiao
Machines 2022, 10(4), 257; https://doi.org/10.3390/machines10040257 - 02 Apr 2022
Cited by 7 | Viewed by 1961
Abstract
An advanced LKS (lane keeping system) for use on curving roads is presented to maintain autonomous vehicle driving within the target lane, without unintentional lane departure. There are the following two main objectives in designing this system: one is performing perfect lane keeping [...] Read more.
An advanced LKS (lane keeping system) for use on curving roads is presented to maintain autonomous vehicle driving within the target lane, without unintentional lane departure. There are the following two main objectives in designing this system: one is performing perfect lane keeping and the other is ensuring the dynamic stability of the vehicle, especially when driving on a curving and low-friction road with time-varying high speed. In this paper, a combined vehicle model, consisting of a lane keeping model and a vehicle lateral dynamic model, is firstly introduced. Then, a novel adaptive-weight predictive controller is used to calculate the desired steering angle and the additional yaw moment which provide coordinated control forlane keeping and dynamic stability control. Meanwhile, a square-root cubature Kalman filter-based vehicle sideslip angle observer, with a strong tracking theory modification (ST-SRCKF), is established to estimate the sideslip angle during the driving process. Finally, HIL (hardware-in-the-loop) tests and field tests are constructed, and the results show the effectiveness of our proposed LKS controller and ST-SRCKF sideslip angle estimation. Full article
(This article belongs to the Section Vehicle Engineering)
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13 pages, 5667 KiB  
Article
A Path Tracking Method of a Wall-Climbing Robot towards Autonomous Inspection of Steel Box Girder
by Wei Song, Zhijian Wang, Tong Wang, Daxiong Ji and Shiqiang Zhu
Machines 2022, 10(4), 256; https://doi.org/10.3390/machines10040256 - 02 Apr 2022
Cited by 2 | Viewed by 2147
Abstract
This paper proposes an autonomous inspection method for steel box girders that uses a wall-climbing robot instead of human workers. According to the 3D operating environment inside the steel box girder, the method proposes a 3D path for the robot to traverse positions [...] Read more.
This paper proposes an autonomous inspection method for steel box girders that uses a wall-climbing robot instead of human workers. According to the 3D operating environment inside the steel box girder, the method proposes a 3D path for the robot to traverse positions to be inspected. The path comprises two alternate sections of the lane’s centerline and U-shaped steering. To realize the robot’s tracking of the desired path, kinematics analysis based on different poses during the inspection was carried out. Corresponding path tracking algorithms were adopted to ensure that the robot moves accurately and efficiently. In addition, for the smooth transition of the two path sections, this method adopts an algorithm of cooperatively controlling the lifting mechanism and the wheel speeds to achieve stable crossing of a 90° concave corner. Finally, experiment results show that the robot can steadily cross 90° concave corner and can steer to the adjacent lane and complete lane inspection along the desired path. The method can realize autonomous inspection for steel box girders using the wall-climbing robot. Full article
(This article belongs to the Topic Industrial Robotics)
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