Table of Content

10 September 2008, Volume 19 Issue 17

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Stiffness Analysis of a Spherical Parallel Mechanism 3-RRS with 3-DOF Rotations

Zhou Yulin;Gao Feng,

2008, 19(17):  0-2141. 

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The 3-RRS mechanism is one of the latest architectures of the spherical parallel mechanism 3-RRR families with 3 DOF and it will be used as a prototype mechanism of bionic shoulder joints of humanoid robot. It is quite complex to calculate the stiffness of 3-RRS mechanism which the bar in each branch is arc-shaped. The angle displacement of mobile platform and line displacement of spherical center of the mechanism were derived by mean of calculation deformation and superposition principle at small strain; the relationships between outer loads and the displacements of (spherical center) vertex of mobile platform were set up based on the results of static analysis-the relationship between external wrenches and forces acted on the members in each branch. Flexibility，stiffness matrix were finally obtained herein. The 6 principal stiffness and principal directions of the mechanism was achieved by orthogonal transformation. It provides the important theoretical foundation and support for engineering design and application of 3-RRS mechanism in practice.

Semantic-based Integration Framework for 
Collaborative Manufacturing Execution Platform

Lei Qi;Liu Fei;Wang Qifeng,

2008, 19(17):  0-2045. 

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According to the diversity and complexity characteristics of the integration object of collaborative manufacturing execution platform (CMEP), this paper analyzed the requirements of the dynamic and fast integration method, the unified integration mode, the related integration standard supporting, the semantic supporting and loosely coupled integration method of CMEP. On the basis of above, this paper proposed a kind of semantic-based integration framework for CMEP to realize integration on-demand, and had an analysis on the components of system integration framework. The integration objects such as information, function, process etc, were semantic described in a unified model and were realized by OWL-S, a semantic web services ontology description language. Based on above research, this paper had a deep research on the realization technologies on the semantic integration in the manufacturing enterprise and extended manufacturing enterprises in the manufacturing process. The proposed studies are applied in the CMEP of a certain enterprise producing assemblies for diesel engine with satisfactory results.

Scheduling Method for HFSP－MFM with Ant Colony Optimization

Hu Yanhai，;Yan Junqi;Ye Feifan

2008, 19(17):  0-2049. 

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Scheduling problem of hybrid flow shop in the environment of multi-functional machines (HFSP－MFM) was put forward where the processing time of jobs on parallel machines may be different.The disjunctive graph was used for its modeling. A one-level algorithm employing ant colony optimization (ACO) and other three two-level algorithms were proposed for the HFSP－MFM. These algorithms were employed to the numerical experiments making use of the data of several benchmark instances that the scale was up to 75×20. The results show that the one-level algorithm has better performance than that of the two-level algorithms for the studied problems.

A Method Based on Visual Attention in Tool Detection

Dou Yan;Kong Lingfu

2008, 19(17):  0-2089. 

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To solve the problem of target detection, which is appeared in the visual guide robot processing system, the human visual selective attention mechanism was introduced into the machine vision system. A computational model of visual selective attention based on the contour was proposed. It realized the testing goal by using a strategy of separating object, extracting edge, perceiving contour, competing in the saliency of contour, choosing and transferring attention focus. Experimental results indicate that the model can be attained to the accuracy of target detection in complex scenes, possesses a strong anti-jamming capability and high computing efficiency, which has a potential of using in the machine vision system directly.

Study on the Inertial Affection on Belt Drive

Zheng Dayu;Meng Qingxin;Chen Shen;Wang Xi

2008, 19(17):  0-2045. 

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In the assumption that belt material is deformed in linear elasticity and the flat belt drive is running in steady state, the dynamics equations of radial and tangent directions were presented and simplified through the belt infinitesimal element processing and the relative equations associated with dynamics coefficients and dimensions were also derived. After building up the relations of constitutive equations and geometric boundary equations, the solutions to the dynamics differential equations were found. The sample flat belt drive was introduced for performing theoretical application and obtained adequate calculation results. It is concluded that the presented theory calculation results make the ultimate transmission momentum tends to be smaller and the slip angle tends to be bigger than that from the traditional one. And the fluctuation range mainly depends on the belt speed and the belt stiffness. This method is valuable for dynamics analysis and the design methodology of a belt drive.

Feedrate-control Method for CNC Real-time Parametric Curve Path Interpolation

Sun Haiyang;Fan Dapeng

2008, 19(17):  0-2049. 

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Through analyzing the principle of CNC parametric curve path interpolating and the feedrate control, it is pointed that the Taylor series method and “Parameter-Arc-length” curve fitting method are not suitable for CNC real-time interpolation. And the feedrate-control problem of parametric curve path interpolation was interpreted in theory. Based on these, a solution of the problem was proposed based on Newton iteration method. A detailed algorithm of the solution was also given. Simulation and experimental results show that the proposed algorithm has many advanced features, such as good stability, fast convergence, low computational efforts and high precision. And the proposed algorithm can reduce the feedrate fluctuation to idea level for real-time interpolation requirements.

Research on Evaluation System for Assembling Resource Reconfiguration

Wei Yun;Li Dongbo;Jiao Guangming，;Zhou Chaobao

2008, 19(17):  0-2089. 

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A comprehensive evaluation model for assembling resource reconfiguration based on the hierarchy analysis was proposed .After the meaning of every index was analyzed, a comprehensive evaluation approach based on entropy method and fuzzy set was proposed. According to information theory, the information entropies could be obtained by the variation degree of indexes’ evaluation values, and the indexes’ weights could be acquired further through the information entropies. The grey relation of grey theory was regarded as the fuzzy membership degree of every index. The membership degree of evaluation object relative to ideal reference value adopting relative membership concept was regarded as the evaluation criteria. Finally, an example was given to illustrate the availability and feasibility of the approach.

Performance Simulation of a Vector Control Variable Frequency Hydraulic System with the Combination of a Throttle and Variable Displacement Speed Control

Zhao Jiyun;Yang Cunzhi，;Zhao Liang;Shi Feng

2008, 19(17):  0-2049. 

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A compound hydraulic system with variable frequency control, a throttle and variable displacement speed control was established. Using AMESim software, the vector control three phase asynchronous motor simulation model was established based on the analysis of the principle of three phase asynchronous motor simulation. Then, combining the hydraulic simulation model, the simulation model of the compound system was presented. Through the research of the simulation model, the paper indicates that the throttle in the compound system has the function to improve the lower speed stability of the system. And because of the existence of a throttle, the compound system has better performance than that of the traditional variable frequency hydraulic system only with a variable displacement speed control. 

Composite Aircraft Wing Structure Optimization Using Combination of Layout and Sizing

He Lintao,;Wan Xiaopeng;Zhao Meiying;Wang Wei

2008, 19(17):  0-2089. 

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This paper studied the layout optimization of composite laminated aircraft wing. First, the layout (both topology and shaping) variables were optimized by the multi-parameter cascade code genetic algorithm(GA). Second, the criteria method was used to optimize the sizing variables of composite laminated structure, and these results of sizing optimization were used as the basis of GA operation in layout optimization. Finally, in order to expedite search process, some improvements of GA were made. The numerical results indicate that the method has both superior efficiency and reliability.
multi-

Research on Cone Crusher Chamber Geometry 

Huang Dongming;Fan Xiumin;Wu Dianliang;Yao Fusheng

2008, 19(17):  0-2049. 

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In order to develop new type curve chamber of cone crusher, based on kinematic and dynamic characteristics of granular rock material, the chamber of cone crusher was researched by dividing several crushing zones. The fixed mass principle was put forward and the working nip angle was imported, which were successfully applied into the chamber research of cone crusher. Based on fixed mass principle and working nip angle, the design model of curve chamber was achieved and the new design method of curve chamber was put forward. Besides, the multi-objective optimization model was accomplished, which provided the basis for self-developing new type, high efficiency, energy saving and environment protection cone crusher. The related models were used to optimize cone crusher, and the physical prototype was manufactured to verify those models’ feasibility and reliability.

Planar Unfolding Algorithm of Noncircular Bevel Gears

Zhao Yumin;Ma Yanhui;Hua Lin;Liu Jin

2008, 19(17):  0-2089. 

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Geodesic curvature of the pitch curve on spherical surface was introduced as a medium,through which the pitch curve on spherical surface can be changed into equivalent planar pitch curve by numerical computation method.On the basis of equivalent planar pitch,the tooth profile of the equivalent gear was gotten through simulation when the pitch curve of the gear shaper rolled on the equivalent planar pitch curve.The design of noncircular bevel gear was transformed into the design of the equivalent stud gear.This method simplifies the design of noncircular bevel gear.

Detection and Merge of Overlap Meshes

Chen Zhiyang;Ye Jianhua;Shen Ying;Xiong Lirong

2008, 19(17):  0-2049. 

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A new overlap mesh detection method was proposed. Based on the quick overlap mesh detection by using grid cube and k-d tree search, we deleted the overlap triangular first, then some kinds of bridges were setup between meshes. After that, hole was filling between meshes to get a new merged mesh. Since the merged mesh maybe contains some “steps” in stitch area, we also proposed a smoothed algorithm to smooth this area to get a “smooth” mesh. The examples show that the detection and merge algorithm herein will create good quality merged mesh and the performance is acceptable in practice. 

NC Code-based Jaw Trajectory Determination for Profile 2D Stretch-wrap Bending and FEM Simulation

Jin Chaohai;Gu Zhengwei;Zhao Yafu;Zhou Xianbin

2008, 19(17):  0-2084. 

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The structure of NC code was studied focused on ACB-Cyril Bath Company’s profile 2D stretch-wrap bending machine, and the algorithm to calculate the trajectory of jaws during bending was proposed based on the NC code. Also a specialized interface software was developed to transfer the trajectory of jaws into the displacement boundary conditions for dynamic-explicit finite element simulation of the bending process, which were difficult to determine manually. The FEM simulation will provide the engineers with intuitionistic understanding of the forming process.

Dynamic-precision Analysis of a Placement Machine Based on Virtual Prototype

Xiao Yongshan;Liu Shaojun;Song Fumin

2008, 19(17):  0-2049. 

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The mounting process of a placement machine was simulated by the multi-body dynamics method. The dynamic error was obtained based on simulation. Based on the mechanical structure, the mathematical model and the virtual prototyping model of the placement machine were built. The rigid-flexible coupling model including the joints was used to simulate the actual system, and the multi-rigid-body model was used as the ideal system. The results show that the precision is controlled within permissive range. Finally, the experiments were made to validate the simulated results by laser interferometer. 

Study on Direct Identification Method of Material Parameters

Gao Hui;Li Guangyao;Han Xu

2008, 19(17):  0-2084. 

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An identification scheme for characterizing the material plastic property was presented directly by using the results of simulation. On the basis of the FEM results and according to the energy conservation, a set of equations were constructed which built the relations between the unknown material parameters and the experimental values. Applying ideal forming theory, being that each individual element was prescribed to deform in a minimum work path, made these equations become a statically determinate or statically indeterminate ones. The deference values between the two sides of equations were used to define the target function and a genetic algorithm was applied to search the minimum solution of the target function. Computations were carried out including material parameter identification from the tensile test and the test of deep drawing with a hemispherical punch to verify the validity and effectiveness of the proposed method. The identification broadens the use of the laboratory tests. 

A Micro-line Transition Algorithm Based on Ferguson Spline for High Speed Machining(HSM)

He Jun;You Youpeng;Wang Huaming

2008, 19(17):  0-2049. 

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Direct transition algorithms can not satisfy the micro-line control demands in high speed machining. This paper proposed a micro-line transition algorithm based on Ferguson spline. After analyzing properties of Ferguson spline, the algorithm was discussed from error allocation, control triangle calculation and look-ahead velocity control. Machining efficiency with the proposed algorithm was also compared with traditional algorithms. Simulations and experiments show that the proposed algorithm is error-controllable, effective and suitable for HSM.

A Review on the Application Equation in Gas Lubrication of High Supply Pressure

Sun Ang;Ma Wenqi;Wang Zuwen

2008, 19(17):  0-2094. 

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A three-dimensional compressible Navier-Stokes equation with liner model and purely viscous flow model and a three-dimensional compressible average Navier-Stokes solver with a SST turbulence model were applied to analyze the pressure profile of externally pressure circular thrust gas lubrication bearings under high supply pressure. It had been studied how the pressure in the field vary with the change of the clearance and its mechanics as well. The numerical results of two equations are good in agreement with experimental data when small clearance exists. However, with the clearance increasing to some degree, the results of purely viscous flow model present enough large deviation from the experimental data, and the numerical results of a three-dimensional compressible Navier-Stokes equation are approximate in agreement with experimental data, but some deviation occurs in the region of negative press grade. A three-dimensional compressible average Navier-Stokes solver with a SST turbulence model copes better with the transport of turbulence shear stress in boundary layer of negative press grade and the interaction between shock wave and boundary layer, and the complicated flow status near the entrance of the bearing clearance has exactly been simulated as well.

Fatigue Life Estimation Method Based on Fuzzy Theory

Wang Xuliang;Nie Hong

2008, 19(17):  0-2049. 

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For the fuzzy phenomenon during fatigue life estimation, membership function was used to denote the fuzziness of the fatigue damage by the stress nearby the fatigue limit. The concept of fuzzy zone of stress was put forward, and was classified as safety fuzzy zone, economy fuzzy zone and compatibility fuzzy zone by the relative position of fatigue limit and edges of the fuzzy zone of stress. The results of calculations show that the method can improve the accuracy of fatigue life estimation greatly.

Numerical Investigation of the Influence of Vaneless Diffusers on the Flow and Performance of a Centrifugal Compressor

Gao Limin;Liu Bo;Wang Huan

2008, 19(17):  0-2094. 

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Aimming at studying numerically the influence of the vaneless diffuser on the three-dimensional viscous flowflied and performance of the centrifugal compressor,a three-dimensional viscous CFD code developed by the authors was applied with several acceleration methods: local time-step, multigrid and residual smoothing. Additionally, the imposed mass-flow was developed instead of the traditional static pressure as the exit boundary condition to improve the computational efficiency, and the exit static pressure will be updated automatically until it was matched with the imposed mass-flow at convergence. The flowfield and performance of a centrifugal compressor was predicted and analysed, which was composed of a Krain’s impeller and two types of vaneless diffuser specially: one was constant area vaneless diffuser and the other was the straight-wall. The results show that the efficiency of the straight-wall vaneless diffuser is obviously lower than that of the constant area, and a separate flow occurs nearby the exit of the centrifugal impeller with the straight-wall diffuser. However, the type of vaneless diffuser has little influence on the aerodynamics performance of the centrifugal impeller. Finally, it is suggested that the constant-area vaneless diffuser should be selected as the downstream extended area of the centrifugal impeller during the prediction for the centrifugal impeller.

Experimental Study of Lateral Position Based on Algebra Neural Networks Information Fusion

Ma Binliang,;Huang Yumei;Shi Enxiu;Cai Tao

2008, 19(17):  0-2045. 

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To improve positioning precision of a mobile robot, the effect of measuring distance d and incident angle α of ultrasonic sensor was analyzed on measuring accuracy by experiments. Lateral positioning model was designed using algebra neural networks fusion algorithm because the fusion algorithm can precisely map in sample space and has better nonlinear approximation ability. By comparison experiments, the positioning fusion model has higher precision, location error is decreased to less than 0.9957mm and angle error is decreased to less than 0.2966°. Finally, the positioning fusion model was applied to a self-developed mobile robot. The experimental results show the robot has location error of ±2.5mm and angle error of ±0.42°, and meets the positioning needs. 

Chaotic Particle Swarm Optimization Algorithm Based on Tent Mapping

Zhang Xueliang;Wen Shuhua;Li Hainan;Lu Qingbo;Wu Meixian;Wang Xiaoli

2008, 19(17):  0-2094. 

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In order to prevent getting into local best and appearing premature convergence in searching iterations of particle swarm optimization algorithm(PSO), the population fitness variance of particle swarm was used to describe and track the flying distribution state of particle swarm and to estimate particles whether being focusing or discrete. Furthermore it was used to estimate whether to have chaotic search. Based on the ergodicity, randomicity and disciplinarian of chaos as well as the advantages of Tent mapping, Tent mapping was used as a chaotic optimization searching and introduced into PSO to avoid PSO getting into local best and appearing premature convergence. This modified and novel PSO was called chaotic particle swarm optimization algorithm(CPSO).Typical test functions were used to test the performance of CPSO. And the testing results prove that CPSO is feasible. 

Prediction of Stretch-bending Formability of Profile

Gao Hongzhi;Zhou Xianbin;Li Xiaoxing;Jin Chaohai

2008, 19(17):  0-2045. 

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In order to characterize stretch-wrap bending formability quantificationally, the concept of stretch-wrap bending formability diagram of profile was presented. The stretch-wrap bending formability diagram of profile characterizes the relation among forming defects and sectional dimensions and processing parameters. The stretch-wrap bending formability diagram of profile was built on defects forecast curve for stretch-wrap bending of profile. The establishing procedure of stretch-wrap bending formability diagram was presented by the study of stretch-wrap bending formability diagram of doorframe profile for a car. Stretch-bending formability diagram of profile could give qualitative prediction for stretch-bending of profile quantitatively The stretch-wrap bending formability diagram provides foundation for optimum design of stretch-wrap bending part and design of process. 

Kinematics Analysis of Automobile Door’s Adjustment

Yang Jianxin;Zhao Ben

2008, 19(17):  0-2094. 

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The process of the automobile door’s adjustment was analyzed integrated with the characteristics of manual work. The kinematics model of the door’s position and orientation was established to describe the adjustment courses. The processes of the different levels of skills were simulated based on the model. The better sequence was chosen via the information differences among the simulation results. The proposed method affords a powerful aid to the assembly process planning. 

Forming Optimization of Variable Blank Holder Force on the 
Strain Path for Laser Tailor Welded Blanks Square Box

Jiang Yinfang;Ding Xinli;Zhu Yuanyou;Yuan Guoding;Wang Fei

2008, 19(17):  0-2045. 

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By simulation, the influence law on the strain path was researched in the fracture dangerous position on different blank holder force (BHF), in the forming of tailor-welded blanks (TWBs) square box. The strain path of tailor-welded blanks(TWBs) square box was controlled in the fracture dangerous point through adjusting value，distribution and variational mode of BHF,then the formability was improved. The results mainly show that the value and distribution of BHF on thick/thin blanks have significant influence on the forming strain path in the fracture dangerous position and the safety margin, and the proper distribution of BHF can change the fracture site and increase the forming limit depth. With the step BHF, the strain path is transferred from stretch-press strain state to double stretch state，and the safety margin is increased significantly. Variable BHF by multiple-area control is propitious to adjust sheet flowing in the die, and then the strain path of the dangerous point can be controlled better. The formability can be increased by altering the forming strain path in the dangerous position and adjusting the lurking fracture site.

Response Time Analysis for Vehicle Electronic Software under Hybrid Scheduling

Gao Zhigang;Wu Zhaohui

2008, 19(17):  0-2094. 

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Aiming at the problem of response time analysis under hybrid scheduling, an important scheduling mode supported by OSEK/VDX standard in vehicle electronic control field, a response time analysis method for linear transactions was presented. This method considered the influence of release jitters of transactions and the hybrid preemption on response time of transactions, extending timing analysis theory to the response time analysis of linear transactions under fixed priority hybrid scheduling. It can be used to verify the real-time property of vehicle electronic software. Experiments show this method has lower computational complexity while keeping high accuracy， and hybrid scheduling has little influence on the average worst-case response time, but has some negative influence on the shedulability of systems.

Research on Vertical Vibration Control and Test for Automobile Magneto-rheological Suspensions

Li Rui,;Chen Weimin;Yu Miao;Liao Changrong;Zhang Honghui;Li Yinguo

2008, 19(17):  0-2045. 

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Based on necessary analysis and simplification on suspension vibration system, a hierarchical intelligent control system was proposed. In the control level, a local fuzzy adaptive(FA) controller was designed for each magneto-rheological(MR) independent suspension system, which can online adjust quantization factor and scale factor of fuzzy controller by human-like intelligent parameter modifying algorithm. In the coordination level, a coordination controller was designed to coordinate the four local independent FA controllers, by adjusting their output parameters according to system feedback in different conditions. Simulation tests were carried out in MATLAB. To validate the real results of hierarchical control, a MR suspension control and test system was set up and implemented on a mini bus. Road tests under various conditions were carried out. Compared to passive suspension, the hierarchical controller employed on MR suspension reduces the vibration acceleration of body floor about 15% and that of seat about 23%. The results indicate that the hierarchical controller can effectively reduce MR suspension vertical vibration, minimize the effect of simplified suspension system and damper model, and improve ride comfort.

Simulation Analysis of Car Flow Field with Underhood and Ground Effect

Zhao Youqun;Zhang Haibin

2008, 19(17):  0-2094. 

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Ground effect has the very tremendous influence on boundary layer thickness, and air drag with underhood enhances 12%. Utilizing software FLUENT, simulations were carried on to three models, the first without underhood and ground effect, the second with ground effect but without underhood, and the third with underhood but without ground effect. In car aerodynamics resorting to simulation technology it is proven to be an effective approach to offer both of the car’s qualitative analysis and quantitative capabilities of air drag coefficients beforehand. The results of the simulation show: ground effect has an influence on a car flow field, influence of the underhood on a car air drag is very obvious, and has some influences on the flow field. 