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IEEE International Conference on mechatronics and Automation

作者： Yaohua Shen Weimin Ge Xiaofeng Wang School of Mechanical Engineering Tianjin University of Technology Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechanical System Tianjin China

Aiming at the requirements of the real-time detection of weld defects in the industry, the candid covariance-free incremental PCA (CCIPCA) algorithm was introduced into the Two-Dimensional Principal Component Analysis (2PCA) algorithm, therefore an incremental 2DPCA algorithm (I2DPCA) is proposed. Firstly, the images captured by camera are preprocessed to improve the quality of the images because the captured images might be affected in the process of image acquisition. Then the 12DPCA algorithm is used to achieve feature extraction, and the dimension of the images is reduced. Finally, the recognition of weld defects is implemented using the k-nearest neighbor algorithm (KNN). Compared with the methods of traditional recognition by extracting the sizes of several geometric defects, the proposed algorithm has the advantage of the small memory spaces, the high recognition rate and the strong real-time recognition. The experimental results show that the proposed algorithm has higher recognition rate and is more practical than the 2DPCA, and the recognition rate reaches 94%, which can meet the requirements of the real-time detection.

关键词： Welding Feature extraction Covariance matrices Principal component analysis Histograms Image recognition Low pass filters

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Dynamic Modeling and Simulation of Flexible Load system Operated by Reconfigurable Manipulators Under Different Constraints

Dynamic Modeling and Simulation of Flexible Load System Oper...

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IEEE International Conference on mechatronics and Automation

作者： Huidong Ma Jinjin Guo Weimin Ge Xiaofeng Wang School of Mechanical Engineering Tianjin University of Technology Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjin China

This paper aims at solving the problems that the manipulator will be constrained by the flexible load, and the caused constraint force is difficult to control. Based on the deflection screw theory, the dynamic model of the manipulator system is established by using the Lagrange equation. Firstly, according to the interaction of the end effector, the flexible load and the environmental constraints of the manipulator, the equation of motion of the entire system is built. Secondly, the dynamic model of the manipulator system is set up, that the system including the flexible load and the manipulator. Finally, Under the certain known environmental constraints, the dynamic modeling of a manipulator is performed. The effectiveness of the proposed method is verified by the simulation of a flexible beam operated by a 3-DOF manipulator.

关键词： Manipulator dynamics Force Mathematical model Load modeling Dynamics Torque

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design and kinematic analysis of a novel over constrained parallel manipulator

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Paper Asia 2018年第Compendium3期2018卷 87-93页

作者： Zhang, Chao Li, Bin Guo, Peng Zhao, Xinhua Yang, Yuwei Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education [Tianjin University of Technology United States

In this paper, a novel over constrained 2-RRU&RSR parallel manipulator is proposed and analysed. This mechanism is composed of a moving platform and a base, which connected by two identical RRU limbs and one RSR limb. Here, R stand for the revolute, U and S represent universal and spherical joints respectively. Three revolute joints, fixed on the base, are set to be actively actuated. The moving platform of the structure can realize two rotational and one translational freedoms. The design process and kinematic performances are studied in this paper. Firstly, the configuration design and structure characteristics of the mechanism are expounded. Secondly, the number and the properties of degrees of freedom (DOF) of the mechanism are analysed using screw theory. Thirdly, the kinematic problems, including the inverse analyses and the forward position analyses, are solved analytically. Then, the performance of the mechanism, such as reachable workspace, transmission capability, are analysed. Finally, some numerical examples and conclusions of the mechanism are pointed out, and the potential applications of the mechanism are suggested.

关键词： Degrees of freedom (mechanics)

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Study on design method for dynamics of machine tools based on advanced process system

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Paper Asia 2018年第4期COMPENDIUM VOL. 1卷 102-105页

作者： Zhu, Peihao Li, Xiang Lu, KaiJie Zheng, QingChun Liu, JingNa Ma, WenPeng Hu, YaHui Yu, YangBin Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China

Machining accuracy depends not only the manufacturing error, thermal deformation, elastic deformation and wear but also the vibration produced by it. Establishing the dynamics model provides the basis of dynamic analysis. The most common dynamic models of machine tool are finite element model, lumped parameter model, distributed mass model and parameters identification. Above methods are applied by using the methods of multi-body dynamics, finite element and the progress of technology. design is finite optimization based on dynamic analysis to get limited improvements for existing empirical design. It is not possible to design the machine tool as required to achieve the expected dynamic performance. In order to comply with precision machine tool’s development demand and the challenge of machine structure design, This paper presents physical and dynamic models considering Machine-Tool-Workpiece Process system to discusses the dynamic cutting process of the dynamic cutting load, driving and executing devices under the excitations of non-equilibrium inertial load. The dynamic of machine tool is mapped to the relative displacement of tool nose. © 2018, SHPMedia Sdn Bhd. All rights reserved.

关键词： Dynamic models

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Flow Mechanism of Cooling Effectiveness Improvement for the Cylindrical Film Cooling Hole with Contoured Craters

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IOP Conference Series: Materials Science and Engineering 2019年第1期473卷

作者： Linchao Bai Chao Zhang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control 300384 Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin 300384 China

In this paper, a typical cylindrical hole with contoured craters is investigated in terms of the downstream flow field by numerical method at blowing ratios of 0.5, 1 and 1.5. The flow field and the cooling effectiveness are analyzed using three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. In comparison to the cylindrical hole, the cratered hole shows a wider coolant coverage in lateral direction and a lower penetration into the mainstream flow due to the larger hole exit area. Moreover, the interaction between the coolant and the curved protrusion induces a new anti-kidney-shaped vortex pair, which can obviously improve the cooling coverage and thus the cooling effectiveness. The area-averaged cooling effectiveness for the cratered hole is always higher than that for the cylindrical hole at all three blowing ratios.

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Comparison on Thermodynamic Performances between Basic and Regenerative Sub-Critical Organic Rankine Cycles Coupled with Low Grade Heat Source

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IOP Conference Series: Materials Science and Engineering 2019年第1期473卷

作者： Pengfei Yuan Chao Zhang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control 300384 Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin 300384 China

The coupling effects of low grade heat source on thermodynamic performances of both the basic and regenerative sub-critical Organic Rankine cycle (ORC) systems are investigated and compared. Turbine inlet pressure and turbine inlet temperature are treated as independent variables. The system exergy efficiency is selected as the thermodynamic performance criterion. The waste hot water with temperature range of 373.15K to 423.15K is selected as the low grade heat source. Optimization studies are carried out by using eight common organic working fluids to recover heat energy, and relevant operating conditions are obtained respectively. The results indicate that both hot fluid inlet temperature and the allowable minimum hot fluid outlet temperature influence the optimal working fluid, relevant turbine inlet condition and system exergy efficiency. Optimal system exergy efficiency increases monotonously with increasing of hot fluid temperature for both ORC systems above. In comparison to the basic cycle configuration, optimal system exergy efficiency for the regenerative system using the same working fluid is not changed if relevant turbine inlet vapor is saturated, but is significantly improved if relevant turbine inlet vapor is overheating. Besides, the optimal working fluid is dependent on the heat source temperature and specific cycle configuration.

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Theoretical prediction and experimental testing of mechanical properties for 3d printed silk fibroin-type II collagen scaffolds for cartilage regeneration

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MCB Molecular and Cellular Biomechanics 2018年第2期15卷 85-98页

作者： Gao, Lilan Yuan, Qingxian Li, Ruixin Chen, Lei Zhang, Chunqiu Zhang, Xizheng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin30000 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300000 China Hospital of Stomatolgy NanKai University Tianjin300000 China

Silk fibroin-type II collagen scaffold was made by 3D printing technique and freeze-drying method, and its mechanical properties were studied by experiments and theoretical prediction. The results show that the three-dimensional silk fibroin-typeII collagen scaffold has good porosity and water absorption, which is (89.3%+3.26%) and (824.09%+93.05%), respectively. With the given strain value, the stress of scaffold decreases rapidly firstly and then tends to be stable during the stress relaxation. Both initial and instantaneous stresses increase with increase of applied strain value. The creep strains of scaffold with different stress levels show the two stages: the rapidly increasing stage and the second stable stage. It is noted that the scaffold with compressive stress of less than 35 kPa can recover when the compressive stress is removed. However when the compressive stress is higher than 50 kPa, the scaffold is damaged and its structure is destroyed. Not only the compressive property but tensile property of scaffold are dependent on the applied displacement rate or strain rate. Its compressive elastic modulus and tensile modulus increase with increase of strain rate or displacement rate. The nonlinear relaxation model and creep model were constructed respectively and applied to predict the stress relaxation behavior and creep behavior of scaffold. It is found that there are good agreements between the experimental data and predictions, which mean that the built theoretical model can predict the mechanical behavior of scaffold. Copyright © 2018 Tech Science Press.

关键词： Strain rate

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Structure design and Analysis of Reconfigurable Fixture Robot Based on the Auto-body Panels

Structure Design and Analysis of Reconfigurable Fixture Robo...

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IEEE International Conference on mechatronics and Automation

作者： Jilong Li Jun Liu Xiaofeng Wang Weimin Ge School of Mechanical Engineering Tianjin University of Technology Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Xiqing District Tianjin China Tianjin Key Lab. of the Design & Intell. Control Adv. Mechatronical Syst. Tianjin China

The fixture is an important equipment, and is widely used in the auto-body panels to be assembled and welded. However, most fixtures, which installed on the production lines, are special to make the production cost higher and the production efficiency lower. Therefore, the reconfigurability of the fixture becomes a key factor that effects the production efficiency of automobiles. To handle the above problems, the new reconfigurable fixture robot is proposed in this paper, which can meet the handing, assembling and welding requirements of different automobile's sheet parts on the automobile production lines. First, the three-dimensional model and the kinematic equations of the proposed reconfigurable fixture robot are established. Then, the working space of the reconfigurable fixture robot is also obtained. Finally, the modal analysis of the reconfigurable fixture robot is performed to determine the cause of resonances. Reconfigurable fixture robots are capable of gripping the auto-body panels with the different radii of curvature, which can also meet the work scopes on the production lines.

关键词： Fixtures Manipulators Kinematics Modal analysis Clamps

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Influence of Micro-texture Parameters on Bone Drilling Force and Torque: A Finite Element Model

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IOP Conference Series: Materials Science and Engineering 2019年第1期470卷

作者： Yahui Hu Xiangjun Li Chuncheng Chen Lili Su Qingchun Zheng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China Tianjin University of Technology 391 Binshui West Road Xiqing District Tianjin 300384 China.

The micro-texture on the tool surface is an effective way to improve the quality of the drilling. While high-performance micro-texture plays an important role in improving the quality of working surface and prolonging the life of tool. In this study, a three-dimensional finite element model was established to study the relationship between drilling thrust, torque and microstructure parameters (micro-pit depth, micro-pit diameter and micro-pit spacing) during drilling of cortical bone. The model was validated by cortical bone drilling using a micro-structured tool. On basis of this, the thrust and torque prediction models of the micro-texture parameters were obtained. The results indicate that the thrust and torque increased with the increase of micro-pit diameter; while the increase of the micro-pit spacing caused the thrust and torque to decrease. When the depth of the micro-pit increased, the thrust and torque decreased first and then increased, and we found that the effect of micro-pit spacing and micro-pit depth on force and torque is insignificant.

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Author Correction: Effects of Precipitates Evolution on Low Stress Creep Properties in P92 Heat-resistant Steel

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Scientific reports 2019年第1期9卷 9567页

作者： Hongguang Han Junjie Shen Jiaxing Xie Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China. National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin 300384 China. Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China. 58920151@***. National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin 300384 China. 58920151@***.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

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