Table of Content

10 March 2012, Volume 23 Issue 5

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Brief Analysis of a BigDog Quadruped Robot

DING Liang-Hong, WANG Run-Xiao, FENG Hua-Shan, LI Jun

2012, 23(5):  505-514. 

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Based on the current technical information of a BigDog quadruped robot which was released, the overall profile and the core technology of the BigDog robot were analyzed herein. Structural characteristics, motion characteristics and high power density issues arising from these were analyzed emphatically in the mechanical system. The basic components of the BigDog's hydraulic drive system were analyzed briefly. Biomimetic structure defects restricted the BigDog's maneuverability to further promotion. In rough terrain, the motion control of BigDog firstly depends on the detection of body posture and perception of the terrain. Security posture is the prerequisite for BgDog's continuous longitudinal motion. The basic walking control algorithm was analyzed briefly. The output characteristics of the hydraulic system just meet BigDog's dynamic requirements. Control implementation process was known by analyzing several typical states of motion. Navigation system of BigDog, in particular fully autonomous navigation part is the emphasis. In unstructured environments, the intelligence of mobile robot mainly depends on the design of navigation system. At last, based on author's research experience on quadruped robot, some suggestions of the research and development on the quadruped robot were proposed.

Research on Volume Compensation for Flow-measurement Leakage Detection in Quasi-balanced State

JI Chun-Hua, GE Nan, SHU Yu

2012, 23(5):  515-517,524. 

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In order to study the volume effects on the leakage detection results in parallel flow-measurement leakage detection, a volume compensation model was proposed by analyzing the quasi-balanced state in detection phase under the assumption that the pressure difference ratio of the base container is equal to that of the test container. Considering the volume variation influence on the relationship between capillary flow and leakage, a volume compensation coefficient was derived, which can be used to decouple the volume parameter from others. Experimental results verify the proposed model to be of validity, and a primary linear relationship between leakage and differential pressure has been established with volume compensation method.

Kinematics Analysis of Quadruped Robot Climbing Step Based on Body Flipping

TU Lian-Qiang-1, 2, WANG Yu-Jin-1, WANG Li-Beng-2, HONG Gong-Bei-3, TANG Yan-Meng-4

2012, 23(5):  518-524. 

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This paper presented a new step-climbing method of quadruped robot based on body flipping in order to improve its obstacle-negotiation ability. Quadruped robot was equivalent to planar linkage mechanism during step climbing. The motion during a complete step-climbing process was planned, and the process was divided into five phases. Kinematics modeling and analysis of each phase were presented; the angular displacement of robot joints and the trajectory of robot gravity were obtained through simulation. The relationship between the capability of step-climbing and geometric parameters of the robot was discussed, the results show that quadruped robot has strong capability of step-climbing when it uses the proposed method. This paper demonstrates the feasibility of the proposed method from the aspect of kinematics, makes some beneficial exploration in the methods of obstacle-negotiation, and provides a theoretical base for further researches. 

Surface Quality Prediction and Processing Parameters Determination on Electrochemical Mechanical Finishing of Bearing Roller

XU Wen-Ji-1, WEI Ze-Fei-1, SUN Jing-1, LI Jiang-1, TU Zi-Yuan-1, LONG Gui-Bing-2

2012, 23(5):  525-530. 

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Due to the disadvantages of traditional method in machining bearing rollers, ECMF was applied in the finishing of bearing rollers. In order to predict processing qualily and select machining parameters, a prediction model of ECMF based on LS-SVM with RBF was constructed, orthogonal experiment swatches were studied, crossed grid search method was applied to determine the model parameters. The results of experiments and prediction show that ECMF is suitable for the machining of bearing rollers, the qualification of surface processed by ECMF is improved obviously, for predicting the surface quality and determining the processing parameters, the errors are acceptable.

Calibration and Uncertainty Estimation of One-dimensional Reference Grating Using a Metrological Atomic Force Microscope

HUANG Jiang-Xian, YUAN Dan, YOU Huan-Jie

2012, 23(5):  531-536. 

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A one-dimensional reference grating with nominal pitch of 240 nm was calibrated using a tapping mode metrological AFM. Based on the analysis of the AFM structure and properties, measuring process, and data processing, the average pitch was obtained and its uncertainty was estimated. The expanded uncertainty of average pitch was in the order of sub-nano meter. According to the uncertainty analysis of this calibration, it is shown that the estimation of measuring uncertainty should be done based on the well understanding of the all factors in the measuring instrument and measuring process. Furthermore, the some secondary-order errors neglected in conventional measurement should be considered and estimated in nano measurement.

Friction and Wear Properties of Ag-G-MoS 2 Composites in Different Ambiences

CHEN Fan-Yan, FENG Yi, YANG Qian-Ting, ZHANG Hua-Bin

2012, 23(5):  537-542. 

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Ag-G-MoS2 composites with varied content were produced by means of powder metallurgy method. Their tribological performance in air and N2 conditions was investigated, and the effects of the content on the tribological properties were analyzed and discussed for the composites. The results show that: in air condition, with the increase of the content proportion of MoS2 and G, the antifriction of composites gets weaker, and the wear resistance which is decided by both mechanical properties and friction mechanisms doesn't change too much; in N2 atmosphere, when the content proportion of MoS2 and G increases, antifriction of composites gets reinforced, and the wear loss rate gets smaller with the decrease of hardness. In conclusion, the friction and wear property of Ag-G(20%)-MoS2(10%) is good and stable.

Negative Poisson’s Ratio Honeycomb Structure and Its Applications in Structure Design of Morphing Aircraft

YA Fang-Fang, XU Xiao-Dong

2012, 23(5):  542-546. 

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This paper investigated a negative Poisson’s ratio flexible honeycomb structure.Then,a mechanics properties analysis theoretical model of flexible honeycomb was established. Finite element analysis results and test results were compared to analyse the mechanical properties. The results show that the negative Poisson’s honeycomb structure has substantial in-plane deformability and auxetics properties. Morphing wing with negative Poisson’s ratio flexible honeycomb structure has the potential of improving aircraft takeoff performance.

Research on a Magnetoelasticity Pressure Sensor Based on Fe-base Nanocrystalline Alloy Strip

DAN Yan-Beng, CANG Yong, ZHOU Qiang-Gui

2012, 23(5):  547-551. 

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A new kind of magnetoelasticity pressure sensor take Fe-base nanocrystalline alloy strip as sensitive element was discussed. At first, its operation principles, structure, output characteristics and the choice of some major parameter were discussed. Secondly, through the pressure experiments, the sensor's static performance as well as the influence of magnetic field strength on the output were analyzed. The experimental results show the sensor's the maximum linearity error is 2.22%F.S., the maximum repetitive error is 0.97％F.S., the unamplified maximum sensitivity is 0.2073μV/Pa, and zero temperature drift is lighter than 1.22％F.S.. In addition the sensor has some characteristics such as simpler structure,good operational reliability, low costs and extensive measuring range. 

A Computational Method on Reliability Robust Optimization Based on Improved PSO

XIE Na-Hai, CU Yi-Nan, CHEN Kai, DI Yin-Xiu

2012, 23(5):  551-555. 

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According to the improved PSO with dynamic acceleration constant and speed adaptation, the multi-objective constrained optimization mathematical models were built on the basis of modern design method and robustness design theory, then the numerical solution reached through computational codes. The effect law of accelerating constant and particle velocity on optimization results were obtained through computations.This work puts forward a new computational method on reliability robust optimization. Compared with existing algorithms, it is simple and rapid to obtain the information of the structure reliability robust optimization design. A practical example demonstrates efficiency of the new method in engineering applications. 

Research on Niche Genetic Annealing Algorithm with Elite Strategy and Its Applications

LIU Ai-Jun-1, 2, YANG Yo-1, GENG Jing-Song-1, LIU Hui-3, ZHANG Yu-Dong-4

2012, 23(5):  556-563. 

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According to the defects of traditional genetic annealing algorithm, a niche genetic annealing algorithm was presented, which avoided the effective gene deletions at the early search stage and guaranteed the diversity of solution.Then adaptive double point crossover and swap mutation strategy were introduced to overcome the defects of long solving process and easily converging local minimum value due to the fixed crossover and mutation probability.The elite reserved strategy was imported, optimal solution missing was avoided effectively, evolution speed was accelerated. At last, the new algorithm was tested by three typical functions and the job shop scheduling problems, respectively. The simulation results show that the proposed algorithm can avoid the stagnation, improve the global convergence ability, and attain better optimization performance.

Multi-enterprise Collaborative Production Planning and Scheduling Optimization Based on Pareto Optimality

ZHANG Mei-Hua, LI Ai-Beng, XU Li-Yun

2012, 23(5):  563-569. 

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To solve the CPPS in the collaborative manufacturing environment, a multi-objective CPPS optimization model was developed including total cost and finish date according to the real production process in the multi-enterprise collaborative manufacture chain. A NSGA-Ⅱ algorithm was proposed and applied based on the Pareto optimality concept. In order to promote solution convergence and diversity,effective encoding, decoding and genetic operators were designed. The set of Pareto optimum solutions was obtained with partly mutating the overlapping individuals in the evolution populations and selecting the individual numbers of the elitism solution self-adapt by distribution function. A simulation experiment was carried out by using the proposed optimization model and algorithm. The results illustrate that the proposed method can solve the multi-objective CPPS fast and effectively and can find more reasonable CPPS solutions.

Review and Discussion on Mechanical Engineering Discipline of NSFC in 2011

WANG Guo-Biao-1, LAI Yi-Nan-1, HUANG Hai-Hong-1, SONG Jian-Li-2

2012, 23(5):  570-577. 

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In the year 2011,mechanical engineering discipline was adhere to the strategic orientation of “more emphasis on basic research,frontier research and talent training”,made further exploration and innovative development on the aspects of original innovation,talent training and excellent management,and marked achievements were obtained.Herein,the evaluation of the science foundation,the progress and the management of the mechanical division in the last year were reviewed.

Optimization Method for Configurable Products Based on Conjoint Analysis

LUO Xin-Gang, YANG Yong

2012, 23(5):  578-584. 

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An optimization method for selection of configurable products based on conjoint analysis was proposed. By applying this method, an optimal configured product and some near-optimal solutions can be generated after input customer requirements, product budget and lead time. The establishment of the mathematical model for proposed approach was explained. The feasibility of the approach was evaluated through a case study.

Mode Shifting Control of Plug-in Hybrid Electric System Equipped with Mechanic-electric CVT

XIE Meng-1, CHENG Huo-1, SHU Gong-2

2012, 23(5):  585-589,594. 

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Configuration of plug-in hybrid electric system equipped with mechanic-electric CVT was put forward based on the analysis of working principles of mechanic-electric CVT. According to configuration the system working modes were defined and a dynamics mode of hybrid system was built up. Control strategies for mode shifting were put forward, while mode shifting ratios of CVT were controlled according to motor speed. Simulation model was designed and simulation results indicate that the mode shifting quality is improved highly by using control strategies herein.

Numerical Simulation of Traveling-wave Electroomotic Micropump and Effects of Parameters on Flow

CHEN Bei, CHAO Kan, TUN Jian-Kang

2012, 23(5):  590-594. 

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Based on the NP equation for ion transport, NS equation for liquid flow and Poisson equation for electric potential, a numerical analysis was carried out to investigate the traveling-wave electroosmotic flow. A comparison of numerical solution using the PNP equations and approximate approach based on slip velocity boundary was made. The correctness of numerical simulation based on the PNP equations was verified. A mathematical model based on PNP equations should predict the qualitative and the quantitative behavior of traveling-wave electroosmotic flow more precisely in a much broader parameter range.

traveling-wave electroosmosis flow; slip boundary condition;

Fault Diagnosis of Rolling Bearings Based on Weibull Distribution and Fuzzy C Means Clustering Analysis

WANG Shu-Chao, ZHANG Jin-Min, ZHANG Chu-Qing, LIU Yong-Fu

2012, 23(5):  595-599. 

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A novel approach to extract fault features and fault diagnosis of rolling bearings based on Weibull distribution model and FCM clustering was proposed. Because the Weibull distribution model parameters such as its scale parameters, shape parameters and its similar function of negative logarithm were more different for different fault types, the running state features of the bearings could be characterized better. The feature vectors representing the rolling bearings running state could be constructed by extracting the three parameters including its scale parameters, shape parameters and its similar function of negative logarithm. FCM clustering was realized by determining the distance degrees of the samples according to the samples membership relative to the clustering center and was more effective. In the test process, the vibration signals of rolling bearings were processed firstly by morphological filtering, and a Weibull distribution model for the denoised signals was set up. Then the extracted feature vectors were transmitted to the classifier of FCM clustering for fault diagnosis and recognition. The results show that the proposed method is more accurate and is an important effective means for fault diagnosis.

A Study of 3D Full Coupled Field Dynamic Characteristics of an Electrostatic Valveless Micropump

DONG Jin-Xin-1, LIN Xie-Zhao-2, YING Ji-2, LI Dun-2

2012, 23(5):  599-603. 

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A 3-Dimensional accurate analysis of the electrostatic valveless micropump involved in electrostatic dynamics, structural dynamics and fluid dynamics of the system. This was made by using multi-field coupled analysis. The results show that the dynamic characteristics of fluid in the micropump are dependent highly on the vibration of flexible membrane. The flow rectification function of the diffuser/nozzle element will work only after the pressure difference between the two ends of the element reaches a critical value. In the pump chamber, the fluidic press distribution almost independent of the depth variation. The maximum of Reynolds numbers is far less than the traditional critical Reynolds number. Due to the increasing demands for accuracy, the nonlinear features of viscous loss of the fluid can no longer be neglected or simplified, but have to be taken into account in detail.

Contribution of Material Strengthening to Size Effect in Metal Cutting Process

XIE Gui-Gen-1, 2, XUE Shi-Feng-1, TONG Xin-Hua-3, DAI Lan-Hong-2

2012, 23(5):  603-608. 

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Finite element-based orthogonal cutting simulations were performed with titanium alloy TiAl6V4. The orthogonal cutting experiments were used to validate the numerical model. Based on the systemic simulation results, the dependences of strain, strain rate and temperature in the primary and secondary shear zone on the uncut chip thickness were investigated. The influences of material strengthening factors, including strain, strain rate and temperature effects, on the “size effect” in specific cutting energy were further discussed. The results show that, the strain and strain rate dependences of material flow stress have no effect on “size effect”, while the thermal-softening effect plays a dominant role in causing “size effect”. In addition, the “size effect” can be attributed to a drop in the primary shear zone temperature and an increase in the tool-chip contact length.

Free-form Deformation Based on Polynomial Extension Factor for Parametric Surfaces

LIU You-Ta, ZHOU Lai-Shui, WANG Zhi-Guo, WANG Xiao-Beng

2012, 23(5):  609-613. 

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In order to obtain ideal modeling effectiveness of parametric surfaces, a new polynomial extension factor was constructed. The new extension factor had the excellence of the existing extension factors, and can achieve its maximum in the region. In the extended technique for free-form deformation of parametric surfaces, the original surface can be deformed at four-sided region. The deformation of a surface was achieved through multiplying the equation of the surface by the extension factor. And interactively modifying control parameters, the outside of object can be described well. Experiments show that the method is simple, intuitive and easy to control, and desired deformations can be easily achieved. It can be used in many fields such as geometric modeling, computer animation and CAD/CAM.

Outer Characteristics and Sensitivity Analysis of Automotive Shock Absorbers with Buffer Spring

LI Shi-Sheng, XU Zhong-Meng, YANG Jian-Guo, ZHANG Zhi-Fei

2012, 23(5):  614-619,625. 

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Based on the internal configuration and the working principles of a shock absorber with buffer spring, a deformation equation for annular laminar deformation under a uniform load was deduced, and a mathematical model of working procedure was established under the condition of rebound and compression for the shock absorber by using the theory of hydraulics and elasticity. The MATLAB software was used to simulate a detailed model, and compared with the practical testing outer characteristic of the shock absorber. The consistency between simulation results and the practical test verifies the correctness and creditability of the mathematical model. In addition, the effects and sensitivity of the piston rod, air pressure, oil temperature and friction force on the shock absorber outer characteristics were analyzed by the model, and the obtained results provide a reference for the shock absorber design and performance prediction.

Numerical Simulation on Operating Characteristics of Hybrid Compressed-air and Fuel Engine

FANG Qing-Hua-1, 2, LIU Hao-1, DAO Guo-Liang-1

2012, 23(5):  620-625. 

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A new hybrid compressed-air and fuel engine was chosen as the research object. The new hybrid engine was modeled using the thermodynamics theories,which can work by both four-stroke compressed-air powered engine mode and internal-combustion engine mode and the simulation analysis was made in its operating characteristics. The simulation results show that the four-stroke compressed-air powered engine mode possesses preferable economic performance and torque characteristics when the engine rotating speed is below 1500r/min; the internal-combustion engine mode possesses better economic performance and torque characteristics when the rotating speed is between 1500r/min and 3500r/min. So the four-stroke compressed-air powered engine mode is fit to run at low speed or low load, and the internal-combustion engine mode is fit to run at high speed or high load. 

Investigation on Measurement Method of Dynamic Response Time for an Electronic Fuel Injector

GUO Hui-1, 2, ZHANG Zhen-Dong-1, CHENG Jiang-1, SUN Ti-Dong-1

2012, 23(5):  626-628. 

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The dynamic working process of an EFI was analyzed in detail.According to the current curve through the coil of the EFI,a measurement method of the dynamic response time for the EFI was provided.Then the test circuits of the opening and closing response time of the injector were designed,and the measurement system was developed with the C8051F310 as the processor.And the measurement system is low cost,convenient and high precision.The results show that the measurement errors of the opening and closing response time of the EFI are 0.9% and 1.14% respectively,and this meets to the testing requirements of design and research,manufacture of the injector.Meanwhile, the curves of opening response time with the supply voltage were provided,the injection quantity can be amended when the engine was calibrated.