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Experiments on the relationship between the structural parameters of contraposition transducers and the acoustic levitation transportation trajectory

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Proceedings of Meetings on Acoustics 2019年第1期38卷

作者： Huijuan Dong Mingyang Sui Chuncheng Mao Guanyu Mu Jie Zhao 1School of Mechatronics Engineering Harbin Institute of Technology Harbin Hei Longjiang 150001 CHINA dhj@*** 2State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Heilongjiang 150001 CHINA 954479126@*** ***@*** mu-guanyu@*** jzhao@***

Standing wave acoustic levitation transportation technique has been widely used in many research areas. In this work, two Langevin-type piezoelectric transducers’ central lines are mounted at a certain angle which is named a contraposition transducer array. The levitator developed in this work is constructed using the array and a reflector. Accordingly, a standing wave acoustic field is formed to levitate and transport particles by optimizing the angle between central lines of the two transducers, the distance between the two transducers’ output and their reflectors, the exciting phase differential on the two transducers. In this standing wave acoustic field, the trapped objects can be levitated and transported by modulating the exciting phase difference of the two transducers. In this work, the locations of the levitated particles are acquired by a high speed video camera and are clarified using the Hough Circle algorithm. The experiments carried out by the authors have demonstrated the effects of the levitator’s structure parameters (including the angle between central lines of the two transducers, the distance between the two transducers’ output and the reflector) on the transportation trajectory.

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Fabrication of micro/nanostructures as SERS substrates with the feed-back controlled normal force 17

Fabrication of micro/nanostructures as SERS substrates with ...

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17th International Conference of the European Society for Precision engineering and Nanotechnology, EUSPEN 2017

作者： Zhang, Jingran Yan, Yongda Cai, Jianxiong Miao, Peng State Key Laboratory of Robotics and Systems Robotics Institute Harbin Institute of Technology Harbin150080 China Center for Precision Engineering Harbin Institute of Technology Harbin Heilongjiang150001 China School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin Heilongjiang150001 China

ISBN: (纸本)9780995775107

Different from the conventional scratching method, the normal force is feed-back controlled to mechanically machine the micro grooves in the present study. During the process, the normal force is controlled to a constant value which is similar to the mechanism of the commercial Atomic Force Microscope by which to measure the nanoscale sample topography through controlling the tip-sample interaction force. A simple and low cost micro machining device which can control the normal force is established. With the controlled normal force, the effects of the edge forward and face forward machining directions on the grooves' topography is studied. Moreover, the edge forward scratching direction is more suitable for the controlled normal force scratching process than the face forward scratching direction. Finally, the machined microsquares of aluminum alloy (2A12) surface is used as the Surface-enhanced Raman Scattering (SERS) substrate with the Rhodamine 6G (R6G) probe molecule as the detecting target in the present study. Experimental results show that using this simple low cost device, the perfect microstructures can be achieved by the controlled normal force machining method.

关键词： Microstructure

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COMSOL-based simulations and experiments on the classifying trajectory of the mixed particles levitated in standing wave field

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Proceedings of Meetings on Acoustics 2019年第1期38卷

作者： Huijuan Dong Fanbin Meng Bin Lan Guanyu Mu Jie Zhao 1School of Mechatronics Engineering Harbin Institute of Technology Harbin Hei Longjiang 150001 CHINA dhj@*** 2State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 CHINA mengfanbin96@*** ***@*** mu-guanyu@*** jzhao@***

In this work, a standing wave acoustic field formed by using two contraposition transducers is used to classify the mixed powder. COMSOL-based simulations reveal the influence of the factors on the drop trajectories of the particles within an acoustic field. Then the experiments are carried out to demonstrate those obtained using COMSOL-based simulations. Finally, the separation experiments of the mixed powder of iron and dioxide silica are achieved, including the mixed powder both in the same diameter and the different diameter respectively.

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Modeling surface generation in ultra-precision grinding based on the surface topography of grinding wheel 17

Modeling surface generation in ultra-precision grinding base...

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17th International Conference of the European Society for Precision engineering and Nanotechnology, EUSPEN 2017

作者： Zhao, Chengyang Cheung, Chi Fai Chen, Shanshan Cao, Zhongchen Partner State Key Laboratory of Ultraprecision Machining Technology Department of Industrial and Systems Engineering Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong School of Mechatronics Engineering Harbin Institute of Technology Harbin150001 China

ISBN: (纸本)9780995775107

This paper presents a new modeling method for analyzing the surface generation based on modeling surface topography of the grinding wheel. Since the high spindle speed of grinding wheel as compared with that of the workpiece, the same area of workpiece surface is ground many times by different protrusion points on the grinding wheel. It is difficult to model all the grinding trajectories of each abrasive grain not only because of the difficulty to obtain all accurate kinematic equations but also due to a huge amount of calculations. The model presented in this paper firstly filters the protrusion points on the grinding wheel which primarily determine the surface generation of the workpiece. Hence, the kinematic trajectory model is built by considering the spindle speed of both the grinding wheel and the workpiece. It is found that the simulation efficiency improves greatly due to the method of filtering grinding points. As a whole, this paper presents an effective way to model the surface generation in ultra-precision grinding.

关键词： Abrasives

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Dynamic Human Gait VGRF Reference Profile Generation via Extreme Learning Machine

Dynamic Human Gait VGRF Reference Profile Generation via Ext...

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International Joint Conference on Neural Networks (IJCNN)

作者： Alexandra Vieira Bernardete Ribeiro Heloísa Sobral A. Paulo Coimbra Manuel Crisóstomo João P. Ferreira Tao Liu Dept. of Informatics Engineering CISUC Univ. of Coimbra Coimbra Portugal Dept. of Electrical and Computer Eng. Institute of Systems and Robotics Univ. of Coimbra Coimbra Portugal Dept. of Electrical Eng. Superior Institute of Eng. of Coimbra Institute of Systems and RoboticsUniv. of Coimbra Coimbra Portugal State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical Engineering Zhejiang University Hangzhou China

Vertical Ground Reaction Forces (VGRF) reference profiles of human gait are important in medicine, for the recognition of gait disorders and in the assessment of rehabilitation treatments. A walking human is a dynamic varying system and in spite of the VGRF reference dependence on several patient's variables, doctors traditionally use the same static reference for all patients. The purpose of this study is to find out if an Extreme Learning Machine (ELM) is adequate to generate the dynamic VGRF reference profiles of healthy people depending on the subject's age, weight, height and stride duration. The ELM is compared with two other baseline Computational Intelligence (CI) methods, the Backpropagation Neural Network (BNN) and Multioutput Support Vector Regression (MSVR). Data from 28 healthy males walking at five different stride durations, collected using instrumented shoes, were used to train and test the CI models. The results showed that ELM is a well suited method to generate the dynamic VGRF reference profile for both dominant and non-dominant limbs, showing the lowest root mean square errors for the test set, 0.0201 and 0.0243 (fraction of body weight) for the dominant and non-dominant limbs respectively. This study reveals a promising methodology that can be implemented in real time gait analysis, allowing doctors to find a specific reference gait pattern for the gait analysis of an unhealthy person by specifying the age, weight, height and stride duration.

关键词： Training Biological neural networks Support vector machines Neurons Backpropagation Legged locomotion Adaptation models

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The influence of pad pivot elastic deformation on static and dynamic coefficients for fixed-tilting pad journal bearing

The influence of pad pivot elastic deformation on static and...

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ASME 2017 International Mechanical engineering Congress and Exposition, IMECE 2017

作者： Jiale, Tian Yanhua, Sun Jian, Zhou Baisong, Yang Lie, Yu State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University Xi’an Shaanxi710049 China Institute of Mechatronics and Information Systems School of Mechanical Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9780791858448

High-speed and heavy-loaded rotating machinery require accurate prediction of rotor’s response and stability, which can be characterized by the static and dynamic coefficients of the bearing support. In this paper, a theoretical study has been done to investigate the performance of a fixed-tilting pad journal bearing with ball-in-socket pivot. The analytical model is established with the flexibility of the pad pivot and turbulent effect of the oil film both taken consideration. Under such situation, the pad pivot elastic deformation and its stiffness are calculated using Hertz Contact Theory for various operating points of the rotor-bearing system. The finite element method is adopted to simulate the static coefficients of the fixed-tilting pad bearing, obtaining its oil film pressure distribution varied with the bearing eccentricity ratio. The corresponding dynamic stiffness and damping of the oil film are solved using partial derivative method. In addition, a special interest is put in investigating the effect of the series complex stiffness of the oil film and pad pivot, according to which, the equivalent dynamic characteristics are obtained. The results show that the relation between these two factors are complex and interactive, both of which have a significant influence on the static and dynamic performance of the bearing. Copyright © 2017 ASME.

关键词： Elastic deformation

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Frequency effects on dynamic characteristics of tilting-pad journal bearings due to pivot flexibility

Frequency effects on dynamic characteristics of tilting-pad ...

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ASME 2017 International Mechanical engineering Congress and Exposition, IMECE 2017

作者： Jiale, Tian Lie, Yu Jian, Zhou State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University Xi’an Shaanxi710049 China Institute of Mechatronics and Information Systems School of Mechanical Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9780791858448

The stable working condition of high speed, heavy loaded rotating machinery depends strongly on the stability provided by the journal bearing. Tilting pad journal bearings (TPJB) are widely used under such situation due to their inherent stability performance. However, because of the complexity of the TPJB structure, obtaining a reliable prediction of the journal bearing’s dynamic characteristics has always been a challenging task. In this paper, a theoretical analysis has been done to investigate the dynamic performance of a 4 pad TPJB with ball-in-socket pivot, emphasizing on the frequency dependency due to pivot flexibility. The analytical model containing the complete set of dynamic coefficients of the TPJB is built and the pivot stiffness is calculated and used to evaluate the equivalent dynamic coefficients of the bearing. In general, at lower perturbation frequency, the equivalent stiffness and damping increase with frequency. While for higher perturbation frequency, the dynamic coefficients are nearly independent of the frequency. Moreover, the results also show the limit value of the dynamic characteristics of the TPJB when the perturbation frequency is set to 0+ and 8. Copyright © 2017 ASME.

关键词： Journal bearings

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Robust positioning for measurement of freeform surfaces

Robust positioning for measurement of freeform surfaces

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ASPEN/ASPE 2017 Spring Topical Meeting on Manufacture and Metrology of Structured and Freeform Surfaces for Functional Applications

作者： Wang, Shixiang Cheung, Chi Fai Ren, Minjun Liu, Minyu Zhao, Chenyang Parnter State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems Engineering Hong Kong Polytechnic University Kowloon Hong Kong Robotics Institute School of Mechanical Engineering Shanghai Jiao Tong University Shanghai China

Form characterization of a manufactured freeform surface can be conducted by aligning the sampling points on a manufactured surface and comparing that with the design geometry through the localization. In this paper, a robust localization method named fiducial aided positioning method (FAPM) is developed to evaluate freeform surfaces with high efficiency and precision. The FAPM method makes use of fiducials to form a Fiducial-aided Computer Aided Design (FA-CAD) of the freeform surface which not only establishes an inherent surface feature but also links the different coordinate systems among design coordinate frame, machine tool and the measurement instrument. To verify the capability of the proposed method, a series of experiments have been undertaken. As compared with the traditional freeform measurement method such as least squared method, it is interesting to note that the robustness and accuracy of the measurement is significantly enhanced by the FAPM.

关键词： Machine tools

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End-to-End Driving Activities and Secondary Tasks Recognition Using Deep Convolutional Neural Network and Transfer Learning

End-to-End Driving Activities and Secondary Tasks Recognitio...

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2018 IEEE Intelligent Vehicles Symposium, IV 2018

作者： Xing, Yang Tang, Jianlin Liu, Hong Lv, Chen Cao, Dongpu Velenis, Efstathios Wang, Fei-Yue Advanced Vehicle Engineering Centre Cranfield University BedfordMK43 0AL United Kingdom Vehicle Intelligence Pioneers Ltd Qingdao China Jiangsu XCMG Construction Machinery Research Institute Ltd. No. 26 Tuolanshan Road Economic Development Zone Xuzhou Jiangsu221004 China School of Mechanical and Mechatronics Engineering University of Waterloo 200 University Avenue West WaterlooONN2L 3G1 Canada State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China

ISBN: (纸本)9781538644522

Drivers' decision and their corresponding behaviors are important aspects that can affect the driving safety, and it is necessary to understand the driver behaviors in real-time. In this study, an end-to-end driving-related tasks recognition system is proposed. Specifically, seven common driving activities are identified, which are normal driving, right mirror checking, rear mirror checking, left mirror checking, using in-vehicle video device, texting, and answering mobile phone. Among these, the first four activities are regarded as normal driving tasks, while the rest three are divided into distraction group. The images are collected using a consumer range camera, namely, Kinect. In total, five drivers are involved in the naturalistic data collection. Before training the identification model, the raw images are first segmented using a Gaussian mixture model (GMM) to extract the driver region from the background. Then, a pre-trained deep convolutional neural network (CNN) model is trained to classify the behaviors, which directly takes the processed RGB images as the input and outputs the identified label. In this work, the AIexNet is selected as the pre-trained CNN model. Then, to reduce the training cost, the transfer learning mechanism is applied to the CNN model. An average of 79\% detection accuracy is achieved for the seven driving tasks. The proposed integration model can be used as a low-cost driver distraction and dangerous tasks recognition modeL. © 2018 IEEE.

关键词： Neural network models

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Experiments and simulations of the standing wave acoustic field produced by two transducers mounted in contraposition 6

Experiments and simulations of the standing wave acoustic fi...

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2017 ICU Honolulu: 6th International Congress on Ultrasonics

作者： Dong, Huijuan Jia, Longfei Guan, Yingzi Zhao, Jie School of Mechatronics Engineering Harbin Institute of Technology Harbin Hei Longjiang150001 China Chongqing Vocational College of Transportation Chongqing China School of Astronautics Harbin Institute of Technology Harbin Hei Longjiang150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Hei Longjiang150001 China

Acoustic standing wave levitation transmission technique has been widely used in many research areas. In this work, two Langevin-type piezoelectric transducers' output are assembled face to face at a certain angle. Each transducer's output acts as both its radiator and another transducer's reflector. The authors termed it as contraposition transducer array. Standing acoustic wave in the cavity between the radiator and the reflector is formed when optimizing the angle between the central lines of the two transducers, the distance of the cavity, and the phase differential of the generator being used to excite the two transducers. Accordingly, the object during the acoustic field can be levitated, moved and manipulated. Not only the standing acoustic field pressure is theoretically derived, but also its potential location is Ansys-programmed simulated and illustrated. As a result, the restrictions are detailed which are necessary to form the standing acoustic wave. The corresponding experiments are carried out to demonstrate the proposed method by the authors. Finally, the influences of geometrical parameters and exciting phase differential on the formed acoustic field are numerically simulated. © 2018 Acoustical Society of America.

关键词： Acoustic fields

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