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Modeling and analysis of magnetic spring enhanced lever-type electromagnetic energy harvesters

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Applied Mathematics and Mechanics(English Edition) 2022年第5期43卷 743-760页

作者： Ning YU Xiangyi FEI chuanyu wu Bo YAN School of Mechanical Engineering&Automation Zhejiang Sci-Tech UniversityHangzhou 310018China

This study presents a novel enhanced monostable lever-type electromagnetic energy harvester(L-EEH).According to the positions of the coil and the lever pivot,four configurations are discussed to realize a better harvesting performance of the *** the basis of establishing the theoretical model of the L-EEH,the corresponding analytical solutions can be obtained by applying the harmonic balance *** effects of the nonlinear coefficient,the lever ratio,the mass ratio,and the circuit parameters on the energy harvesting performance of L-EEHs are analyzed and *** numerical and experimental efforts are carried out to verify the theoretical model and the energy harvesting *** results demonstrate that the maximum output voltage can be achieved with an appropriate lever ***,the L-EEH possesses a considerable energy harvesting performance under a smaller lever ratio compared with the other three *** output power can also be improved by adjusting the tip mass of the *** proposed L-EEH has a considerable operating bandwidth and an output power,which can reach 146.6 mW under the excitation amplitude of 0.3 g.

关键词： electromagnetic energy harvesting monostable nonlinear vibration lever harvester

Research and Test of Three-Pulley Noncircular Synchronous Pulley Transmission Mechanism with Minimum Slack

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Chinese Journal of Mechanical Engineering 2021年第2期34卷 236-248页

作者： Jianneng Chen Xincheng Sun chuanyu wu Dadu Xiao Jun Ye Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Zhejiang Key Laboratory of Planting Equipment Technology Hangzhou 310018China

The noncircular synchronous belt drive mechanism has demonstrated certain achievements and has been used in special *** regarding noncircular synchronous belt drive mechanisms has focused on optimization design and kinematic analysis in China,whereas two pulley noncircular synchronous belt transmissions have been developed ***,owing to the noncircular characteristics of the belt pulley,the real-time variation in the belt length slack during the transmission of the noncircular synchronous belt is significant,resulting in high probabilities of skipping and *** this study,a noncircular tensioning pulley is added to create a stable three-pulley noncircular synchronous belt driving mechanism and a good synchronous belt tensioning,with no skipping;hence,the non-uniform output characteristic of the driven pulley is consistent with the theoretical *** the circular noncircular noncircular three-pulley noncircular synchronous belt mechanism,the pitch curve of the driving synchronous belt pulley is circular,whereas those of the driven synchronous belt and tensioning pulleys are *** minimize the slack of the belt length of the synchronous belt and the constraint of the concavity and circumference of the tensioning pulley,an automatic optimization model of the tensioning pulley pitch curve is *** motion simulation,analysis,and optimization code for a three-belt-pulley noncircular synchronous belt drive mechanism is written,and the variation in belt length slack under different speed ratios is analyzed based on several *** testbed for a circular-noncircular-noncircular three-pulley noncircular synchronous belt transmission mechanism is *** test shows that the three-pulley noncircular synchronous belt drives *** study proposes an automatic optimization algorithm for the tensioning pulley pitch curve of a noncircular synchronous belt transmission mechanism;it yields a stable transmission of the n

关键词： Noncircular synchronous belt drive Slack calculation model Non-uniform speed transmission characteristics

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Chinese Journal of Mechanical Engineering 2021年第1期34卷 251-265页

作者： Liang Sun Zhizheng Ye Fuwei Lu Rongjiang Cui chuanyu wu Faculty of Mechanical Engineering&Automation Zhejiang Sci-Tech UniversityHangzhou 310018China

Isomorphism detection is fundamental to the synthesis and innovative design of kinematic chains(KCs).The detection can be performed accurately by using the similarity of ***,there are very few works on isomorphism detection based on the properties of similar *** this paper,an ameliorated multi-order adjacent vertex assignment sequence(AMAVS)method is proposed to seek out similar vertices and identify the isomorphism of the planar ***,the specific definition of AMAVS is *** the calculation of the AMAVS,the adjacent vertex value sequence reflecting the uniqueness of the topology features is *** on the value sequence,all possible similar vertices,corresponding relations,and isomorphism discrimination can be *** checking the topological graph of KCs with a different number of links,the effectiveness and efficiency of the proposed method are ***,the method is employed to implement the similar vertices and isomorphism detection of all the 9-link 2-D0F(degree of freedom)planar KCs.

关键词： Similar vertices Isomorphism detection Kinematic chains Topology features AMAVS

Singularity Analysis of a 3-RPS Parallel Manipulator Using Geometric Algebra

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Chinese Journal of Mechanical Engineering 2015年第6期28卷 1204-1212页

作者： LI Qinchuan XIANG Ji'nan CHAI Xinxue wu chuanyu Mechatronic Institute Zhejiang Sci-Tech University

Singular configurations must be avoided in path planning and control of a parallel manipulator. However, most studies rarely focus on an overall singularity loci distribution of lower-mobility parallel mechanisms. Geometric algebra is employed in analysis of singularity of a 3-RPS parallel manipulator. Twist and wrench in screw theory are represented in geometric algebra. Linear dependency of twists and wrenches are described by outer product in geometric algebra. Reciprocity between twists and constraint wrenches are reflected by duality. To compute the positions of the three spherical joints of the 3-RPS parallel manipulator, Tilt-and-Torsion angles are used to describe the orientation of the moving platform. The outer product of twists and constraint wrenches is used as an index for closeness to singularity（ICS） of the 3-RPS parallel manipulator. An overall and thorough perspective of the singularity loci distribution of the 3-RPS parallel manipulator is disclosed, which is helpful to design, trajectory planning and control of this kind of parallel manipulator.

关键词： singularity parallel manipulator geometric algebra

Design and Experimentation of Automatic Tidying and Sorting Mechanism for Blood Collection Needles in Stacking State

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Chinese Journal of Mechanical Engineering 2019年第4期32卷 73-84页

作者： Junhua Tong Yingpeng Zhu Leiying He chuanyu wu Peilin Cheng Faculty of Machinery and AutoMation Zhejiang Sci-Tech University Hangzhou 310018China Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province Hangzhou 310018 China

Disposable blood collection needles become severely intertwined and hooked during stacking, and thus individually feeding disposable blood collection needles during mechanical packaging is di cult. Based on the physical characteristics of the blood collection needles during the stacking state, this study designed an automatic tidying and sorting mechanism by combining compound vibration, sorting, and conveying. During the feeding process, the compound vibration-type material-tidying mechanism tidies 20-30 blood collection needles first;then, the material sorting and conveying mechanism transports the tidied blood collection needles individually. The orthogonal testing of the automatic material tidying process shows that various experimental factors are ranked by the significance level of the e ect on the tidying process and the significance ranking is as follows: vertical vibration frequency > horizontal amplitude > vertical amplitude > horizontal vibration frequency. Experiments were performed after analyzing the optimal combination. The results demonstrate that when the horizontal vibration frequency is 1.7 Hz, the horizontal amplitude is 150 mm, vertical vibration frequency is 1.3 Hz, vertical amplitude is 30 mm, and material length after tidying is 265 mm. The automatic sorting and conveying experiment shows the e ect of various experimental factors on the feed rate of the material, where the significance level of the e ect is ranked as follows: vibration frequency > material quantity > channel dip angle. The experimental results show that when the number of materials is 25, the channel dip angle is 12°, and vibration frequency is 52.5 Hz. The material delivery e ciency reaches 0.51 s/root, meeting the requirement of five channels for 80000 root/day feeding e ciency. The study can provide reference for the realization of automatic feeding of large aspect ratio flexible materials in similar stacking state.

关键词： Packaging Automatic feeding Stacking state Automatic tidying Sorting and conveying

Dynamic characteristics of dwarf Chinese hickory trees under impact excitations for mechanical fruit harvesting

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International Journal of Agricultural and Biological Engineering 2015年第1期8卷 17-25页

作者： Du Xiaoqiang wu chuanyu He Leiying Tong Junhua School of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Zhejiang Province Key Laboratory of Transplanting Equipment and Technology Hangzhou 310018China

Mechanical vibration is an effective fruit harvesting *** evaluate the dynamic characteristics of dwarf Chinese hickory(Carya cathayensis Sarg.)trees and the influence of the tree structure on transmission and attenuation of dynamic response,a new method was proposed based on acceleration admittance measurement on dwarf Chinese hickory trees in orchard environment under impact *** primary resonance frequencies of the tree can be determined based on the acceleration admittance *** effect of the tree structure on the vibratory transmission was quantified using the attenuation ratio of the acceleration admittance.A 5-year-old dwarf Chinese hickory tree sample was *** responses at three resonance frequencies(5,9 and 12 Hz)were analyzed because they were identified as the most effective bands of excitation for the main part of the tree *** results reveal that the variation of the dynamic response along the testing tree is greatly related to the Chinese hickory tree *** attenuation ratio of the acceleration admittance at the branch crotches indicates the leader top crotch may amplify the acceleration admittance no matter what the crotch angle and the branch diameter *** the crotches,the branch chain nodes generally have negative influence on the acceleration admittance along the branch chains which heavily depend on the branch chain *** branch chains with a chain angle no less than 150°and a wood diameter ratio close to 1.0 could produce little influence on the vibration *** those branches with chain angle less than 150°,the vibration was generally attenuated at their chain nodes at three resonance *** impose impact excitations on the tree,high mechanical harvesting efficiency could be achieved on those branch chains which are almost straight and uniform.

关键词： Chinese hickory mechanical harvest fruit acceleration admittance vibration transmission impact test

Locating Famous Tea’s Picking Point Based on Shi-Tomasi Algorithm

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Computers, Materials & Continua 2021年第10期69卷 1109-1122页

作者： Lei Zhang Lang Zou chuanyu wu Jianneng Chen Heping Chen Faculty of Mechanical Engineering&Automation Zhejiang Sci-Tech UniversityHangzhou310018China Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province Hangzhou310018China Ingram School of Engineering Texas State UniversitySan MarcosTexasUSA

To address the difficulty of locating the picking point of a tea sprout during the intelligent automatic picking of famous tea,this study proposes a method to obtain information on the picking point on the basis of the ShiTomasi *** method can rapidly identify a tea sprout’s picking point and obtain its *** of tea sprouts in a tea garden were collected,and the G-B component of tea sprouts was segmented using the Otsu *** region of interest was set with the lowest point of its contour as the *** characteristics of tea buds and branches in the area were extracted,and the Otsu algorithm was used for a second segmentation of tea sprout *** tea buds were segmented using the improved Zhang *** branch feature binary image was used to refine the skeleton,and the Shi-Tomasi algorithm was used to detect the corners of the skeleton and calculate and mark the picking points of the *** sets of samples were *** test identified 1,042 effective shoots for tender buds,and 887 picking points were marked,with a success rate of 85.12%,thereby verifying the effectiveness of the method and providing a theoretical reference for the visual positioning of the automatic picking of famous tea.

关键词： Famous tea picking location Zhang algorithm Shi-Tomasi algorithm

High-efficiency tea shoot detection method via a compressed deep learning model

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International Journal of Agricultural and Biological Engineering 2022年第3期15卷 159-166,F0003页

作者： Yatao Li Leiying He Jiangming Jia Jianneng Chen Jun Lyu chuanyu wu Faculty of Mechanical Engineering&Automation Zhejiang Sci-Tech UniversityHangzhou 310018China Key Laboratory of Transplanting Equipment and Technology of Zhejiang Province Hangzhou 310018China School of Information Science and Technology Zhejiang Sci-Tech UniversityHangzhou 310018China

Achieving high-efficiency and accurate detection of tea shoots in fields are essential for tea robotic plucking. A real-time tea shoot detection method using the channel and layer pruned YOLOv3-SPP deep learning algorithm was proposed in this study. First, tea shoot images were collected and data augmentation was performed to increase sample diversity, and then a spatial pyramid pooling module was added to the YOLOv3 model to detect tea shoots. To simplify the tea shoot detection model and improve the detection speed, the channel pruning algorithm and layer pruning algorithm were used to compress the model. Finally, the model was fine-tuned to restore its accuracy, and achieve the fast and accurate detection of tea shoots. The test results demonstrated that the number of parameters, model size, and inference time of the tea shoot detection model after compression reduced by 96.82%, 96.81%, and 59.62%, respectively, whereas the mean average precision of the model was only 0.40% lower than that of the original model. In the field test, the compressed model was deployed on a Jetson Xavier NX to conduct the detection of tea shoots. The experimental results demonstrated that the detection speed of the compressed model was 15.9 fps, which was 3.18 times that of the original model. All the results indicate that the proposed method could be deployed on tea harvesting robots with low computing power to achieve high efficiency and accurate detection.

关键词： deep learning tea shoot detection model compression high-efficiency

Design and feasibility analysis of a graded harvesting end-effector with the function of soluble solid content estimation

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International Journal of Agricultural and Biological Engineering 2024年第5期17卷 239-246页

作者： Yufei Lin Hao Liang Junhua Tong Haoyu Shen Xiaping Fu chuanyu wu College of Mechanical Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Agriculture and Biotechnology Wenzhou Vocational College of Science and TechnologyWenzhou 325006ZhejiangChina College of Mathematics and Computer Science Zhejiang A&F UniversityHangzhou 311300China Zhejiang Ocean University Zhoushan 316002ZhejiangChina

In response to the prevailing scarcity of labor and with the aim of augmenting the proportion of premium-quality fruits, a robotic grading end-effector system for harvesting was meticulously designed. The end-effector could measure the soluble solid content (SSC) of peaches during the harvesting process to evaluate the quality of the fruit, thereby facilitating real-time grading during harvesting. As comprising a harvesting component and an information-gathering segment, the end-effector system was optimized with the primary structural parameters of its adaptive fingers using a mathematical model of peach morphology. Also, the buffering materials for mitigating the pressure exerted by the adaptive fingers on the peaches were compared. Furthermore, feasibility analyses of the grasping actions were conducted based on the interaction forces between the adaptive fingers and the peaches. To grade the quality of peaches, SSC was used as an indicator to assess and grade the quality of the peaches. The spectra of peaches within the wavelength range of 590-1100 nm were collected, and a predictive model for SSC was developed. The correlation coefficients for the calibration set and prediction sets of the predictive model were 0.880 and 0.890, with corresponding root mean square errors of 0.370% and 0.357% Brix, respectively. In addition, a robustness and accuracy assessment was conducted using 30 peach samples, yielding a correlation coefficient of 0.936 and a standard error of 0.386% Brix between the predicted and measured values of SSC. The results confirm that the end-effector can measure the SSC of peaches during the collection process, providing novel concepts and theoretical foundations for real-time harvesting and grading.

关键词： robot harvesting graded end-effector soluble solids near-infrared spectroscopy