Table of Content

10 May 2009, Volume 20 Issue 09

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Characteristics Study of New Digital Control Valve

Yang Qinghua;Ou Kunzeng;Bao Guanjun

2009, 20(09):  0-1011. 

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The structure and principle of a new digital control valve was introduced. The valve was controlled by computer directly without D/A converter. Its spool was driven by a step motor with an eccentric gear. The way of using the continuous control method to control the step motor resolved the contradiction between the stepper motor’s quantizing error and its response speed in the traditional step digital valve effectively. Based on the established mathematic model, simulation and analyses were done to testify the dynamic properties of the valve and the pressuring characteristics of the experimental system.

Research on the Acceleration Vibration Characteristics of Stator of 
Constant-Pressure Radial Piston Pump

Zhou Tianyue;Wang Cuntang;Gu Jian;Chen Junqiang

2009, 20(09):  0-1133. 

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A dynamics model was established based on Lagrange theory and the analysis was made on vibrating acceleration in frequency domain to the modes of constant flow and constant pressure. Measurement mechanism was designed to test the vibration of stator of JB32H-type radial piston pump. It is concluded from analysis and test results that the vibration frequency band of acceleration of the stator is wider on the mode of constant flow than that on the mode of constant pressure.Stator vibrates in the range of higer frequency on the mode of constant flow than constant pressure. Constant pressure system of the pump is in the function of low-pass filter. The conclusions are helpful to the noise control of piston pump.

Deconvolution Technique Based on Lifting Wavelet Transform and Genetic Algorithm

Shen Xiaoan;Yang Keji

2009, 20(09):  0-1011. 

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A new approach of deconvolution technique based on lifting wavelet transform and genetic algorithm (GA) was proposed after the shortcomings
of experience needed etc. of conventional deconvolution techniques were analyzed to increase A-scan signals’ time resolution of composite materials in ultrasonic nondestructive testing (UNDT). Based on the ultrasonic reflection coefficient position set was determined by the lifting wavelet transform multi-resolution analysis ability, GA was used to obtain reflection coefficient amplitude of corresponding position after manipulating the optimization object function of deconvolution into the quadratic unconstraint optimum problem. Then the reflection coefficients of testing object were determined. Experimental results show that the presented approach has high performance in improving time resolution and generalization ability compared with conventional deconvolution.

Research on Hydrodynamic Lubrication of Different Surface Texture

Ruan Hongyan;Lü Jianjun;Si Hui;Wang Xiao;Ding Jianning，

2009, 20(09):  0-1133. 

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The hydrodynamic lubrication performance of rectangle, inclined plane, circular-arc, triangle, multi-arc and sine surface texture was researched with CFD method based on N-S equation. The research results show that, under a certain condition, different surface texture has different hydrodynamic lubrication performance. When the Re is lower, the hydrodynamic lubrication performance of inclined plane surface texture is poor, and the other five surface textures are similar; when the Re is higher, the hydrodynamic lubrication performance of multi-arc surface texture is better than the others.

Measurement Model of CMM and Line Structured Light Sensor Integrated System

Yang Xuerong;Zhang Xiangwei;Cheng Siyuan;Tang Kelun

2009, 20(09):  0-1011. 

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A CMM and line structured light sensor integrated system and the calibration mothed of measurement model were presented. Combining the advantages of CMM and computer vision, the integrated system could achieve high efficiency, high-precision measurement.The calibration of measurement model comprised the camera calibration and light plane parameter calibration, finish global calibration. Using the high-precision probe of the CMM as calibration object for the camera calibration, the number of calibatation dot and location can be added easily. The calibrationt target was designed for light plane calibration.By this method,arbitrary amount of 3D world calibration points on the structured light plane can be easily obtained,thus the problem that it is difficult to obtain adequate 3D world calibration points is settled.The calibatation can finish global calibration by one time and has the advantages of simplicity and high precision.

Research on RCCC Mechanism Path Generation by Using Numerical Atlas Method

Chu Jinkui;Sun Jianwei 

2009, 20(09):  0-1133. 

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From Fourier series theory, the mathematic representation of the coupler curves was obtained by using the fast Fourier transform(in short,FFT).Through analyzing the harmonic component of the coupler curve of RCCC mechanism,the relationship between the harmonic component of the rotation-angle function and the dimensional type of the RCCC mechanism was discovered.The formulas which can compute the position for coupler point,real size and installing dimensions of the RCCC mechanism was deduced.Subsequently,taking the crank-rocker linkages as an example,a numerical atlas database comprising millions basic dimensional types are established. Based on the numerical atlas and the theoretical formulas,the problem of the RCCC mechanism path generation was solved.Finally,an example was given to prove it.

Adaptable Design of Machine Tool Structure Based on Quantification of 
Structural Configuration and Performance Improvement

Chen Yongliang;Geng Wenxuan;Man Jia;Cui Yuanchao

2009, 20(09):  0-1011. 

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In order to get a reasonable and efficient adaptable structure design solution, a quantification comprehensive evaluation method for both structural configuration and performance improvement was proposed. Through the integrated calculation formula, the value of structural change and performance improvement can be obtained accurately and rapidly from the static and dynamic value of the structures.An example of gear cutting machine tool improvement design was also given to explain the process of evaluation in details.

Study on the Performance of SDF Vibration Isolation System Based on State-Space Theory

Zhong Minjun;Hu Shifeng;Shi Tielin;He Qiwei

2009, 20(09):  0-1133. 

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In order to understand the dynamic of single degree of freedom(SDF) vibration isolation system clearly and to guide the system design, the state-space method was adopted. The solution of the system state-space model was obtained. The performance of system such as dynamic and robust and isolation was analyzed. At the same time an example of system design was simulated and analyzed. The results show that the essence of system is simply revealed by the state-space method and helpes us to develop the study of modern control of hybrid vibration isolation system.

A Central Drilling Control of EDM System on Blank Tube

Ni Jing;Xiang Zhanqin

2009, 20(09):  0-1011. 

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According to the central drilling control of EDM system on blank tube to removing “leftover” on rolling process, a new electric-hydraulic servo control approach with quantitative feedback theory and nonlinear disturbance observer was put forward. The proposed approach divided the system into load loop and load pressure tracking loop. In the first loop, quantitative feedback controller was designed to address the desirable load pressure for the second loop; then nonlinear disturbance observer controller was presented to track the desirable pressure in the second loop. Actual control results show that the proposed controller has well dynamic tracking performance and can realize the process effectively. 

An Iterative Method of Probe Radius Error Compensation

Xu Yi;Li Jiangang;Li Zexiang

2009, 20(09):  0-1133. 

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Contact probe records the center of its ball end. The data used in workpiece localization are the coordinate of points where the probe contacts with the workpiece.Focusing on the instance,an iterative method of contact probe error compensation was presented.Viewed from
the measurement point set and CAD model individually,there was an offset surface.The iterative compensation method was formed if the offset was embedded in the localization algorithms. The experimental results indicate that the iterative compensation methods improve the localization precision enormously, compared with results using the traditional methods.And its computation efficiency is not affected drastically.

Research on Adaptive Tracing Measurement Method Used for Wide-range Free-form Surfaces

Shao Jianxin;Qiu Zixue;Yuan Jiang;Yao Xingtian;Wang Shufang

2009, 20(09):  0-1011. 

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An adaptive tracing measurement method for free-form surface was designed with laser displacement sensor.This method can be used to measure automatically wide-range free-form surface,and it was based on closed-loop motion control, in which the system was composed of grating displacement sensor, precision movable liner mechanism and servo machine designed to adjust position of probe automatically.In order to trace up-and-down change of the measured surface, laser displacement sensor ensured working in higher liner range. Experiments show that the method realizes high precision measurement for wide-range free-form surface by integrating a laser sensor which has high linearity during small measuring range,a grating displacement sensor with servo machine.

Using Kolmogorov-Smirnov Test on Diagnosis of Gear Faults under Fluctuating Load Conditions

Wang Xiyang;Wan Zaihong 

2009, 20(09):  0-1133. 

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Varying load can cause changes in a measured gearbox vibration signals,however,conventional techniques for fault diagnosis are based on the assumption that changes in vibration signals are only caused by deterioration of the gearbox.Gear motion residual signals,which represent the departure of time synchronous averaging signals from the average tooth-meshing vibration,were analyzed as source data due to its lower sensitiveness to the alternating load conditions.The gear motion residual signals in gear healthy state were used as reference sample,and the residual signals in unknown gear states were used as objective sample.A two-sample Kolmogorov-Smirnov test was then performed.The statistical distance of the test was used as a fault parameter which was capable of diagnosing the gear crack effectively with a higher level of confidence.The other statistical measures such as kurtosis,variance were also analyzed and computed.The performance of the technique was demonstrated using a full lifetime gear shaft vibration data history.

Multi-objective Optimization on Shape for a Cable-net Structure 
with Goals of Deployment and Adjustment Ability

You Guoqiang;Yang Dongwu

2009, 20(09):  0-1016. 

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Optimization on shape design was made for a cable-net structure according to the special structure of cable-truss deployable antenna and requirements for space condition, it can promote the antenna’s deployment ability and adjustment ability. An optimal mathematic model was built with goals of minimum average stress ratio and maximal structural energy, design variables of positions of nether cable nodes, and constraints of surface accuracy and natural frequency. Seeing as it was difficult to solve such a complex model involved geometric nonlinearity calculation, a sequential quadratic programming method was used to facilitate the multi-objective optimization and to find the global optima of this problem. The representative result selected from the optimal result sets with different weight shows the validity and effectiveness of the proposed method and model.

Study on Mechanical Adaptive Tuned Vibration Absorber

Xu Zhenbang,;Gong Xinglong,;Chen Xianmin;Ni Zhengchao

2009, 20(09):  0-1133. 

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To improve the working frequency band and the damping effect of vibration absorber, a new kind of mechanical adaptive tuned vibration absorber was presented whose resonant frequency can be adjusted in real-time by adapting the geometrical parameters of the absorber. Corresponding control system was also designed. The dynamic properties of the absorber were characterized on a fixed-fixed beam. The results indicate that this kind of absorber can change its resonant frequency in a large range and it can damp vibration well in the whole range.

Process Sequence Optimization Based on Process Constraint Matrix

Hu Yujin;Zhang Zhengyi;Ling Ling;Cai Ligang

2009, 20(09):  0-1016. 

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In order to identify whether the process sequence to meet the related process constraints in the optimizing process，the transformation of qualitative constraints and the identification of process sequence’s legitimacy were got through the introduction of process constraint matrix herein. Several transfer rules, matrix check and modification methods were designed to make sure the reliability and the veracity of the constraint information transformation process. A matching algorithm to identify the legality of the process sequence was proposed based on the constraint matrix. The mathematic model of process sequence optimization was set up and with genetic algorithm the best/hypo-best process was obtained. An example shows the constraint matrix ensures the process’s veracity and enhances the operation efficiency in the process sequence optimization.

Optimization of Printed Circuit Board Assembly Scheduling 
and Its Applications for a Large Parallel System

Jin Zhihong;Ji Mingjun;Liu Ying

2009, 20(09):  0-1133. 

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This paper discussed the optimization of PCB assembly scheduling for a large parallel system, JUKI FX-1, which was known as the most complicated PCB assembly machines. This whole problem was formulated and divided into three subproblems,i.e. nozzle allocation, feeder arrangement and component placement sequence. By analyzing characteristics of the solutions, three heuristic algorithms, cluster analysis, sequence traversal, and assignation of built-in pick-and-place set were designed for solving the three subproblems respectively. Then they were organically integrated according to their internal interrelation. The integrated algorithm was implemented on real life problems, and contrastive results show that the proposed scheduling algorithm is more efficient than the software built-in JUKI FX-1.

Analysis of a Novel Grinding Method with a Basin-like Grinding 
Wheel for Outer Race Elliptic Track of Ball Basket Constant Velocity Joint 

Wang Junming;Tang Yangping;Bin Hongzan;Feng Qingxiu;Xiong Zhengpeng

2009, 20(09):  0-1016. 

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The theoretical error of outer race elliptic track in ball basket constant velocity joint ground by finger-like grinding wheel is about 4μm. In order to decrease the error, a new grinding method with basin-like grinding wheel was proposed herein. When the design parameters were optimized,the basin-like grinding wheel will avoid the problems that the feasibility and grinding accuracy were restricted by the interference of the head in the grinding process by means of finger-like grinding wheel, and can be used to ensure the machining precision and the sectional shape of the raceway to the greatest extent.Aiming at the grinding process with basin-like grinding wheel, the paper established
the mathematical model, optimized the parameters by using restrictive random direction method, studied the processing principle in detail,and analyzed the machining errors. The simulation results indicate that the theoretical error of elliptical groove ground by basin-like wheel will be reduced to the level of 1μm.

Mechanics Analysis of Two Different Stiffness Elastic Actuator in Frequency Domain

Ma Hongwen;Yin Bo;Wang Liquan;Yin Zheng;Song Yang

2009, 20(09):  0-1133. 

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In order to reduce the impact power of existing robot motion, the paper presented a two different stiffness elastic actuator which was usually used to drive robot’s joints. It was different from a traditional single stiffness elastic actuator in that it contained nonlinear springs between motor and load. The effect of the two different stiffness elastic actuator’s mechanism parameters on the impact power and spring displacement was presented. The mathematic models of elastic actuators were established by using theorem of momentum and analysed based on MATLAB. The result shows that compared with using a single stiffness elastic actuator, the impact power of the two different stiffness elastic actuator can be drastically reduced, meanwhile, the spring displacement of both tend to the same by increasing input frequency γ.

Experiment and Analysis on Line and Surface Tactile Display Based on Pneumatic Nozzle

Sun Zhongsheng;Teng Yan;Bao Gang;Li Xiaoning

2009, 20(09):  0-1016. 

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In view of the line and surface tactility displayed by the pneumatic nozzle array, a fluid-structure coupled finite element model of the finger skin and nozzle was established. The concept of uniform coefficient which could characterize the uniformity and continuity of the line and surface tactility was proposed. The effects of nozzle diameter, nozzle space and inlet pressure on line and surface tactility were analyzed, and the design parameters of nozzle array were determined. The inlet pressure suitable for displaying the realistic perception was determined, and the conclusions were validated by experiments. The research on pneumatic tactile display is to lay a solid foundation for further applications in virtual assembly system and telepresence system.

Research on Forecast Method of Product Design Time Based on 
Quasi-orthogonal Experiment and Support Vector Machines

Guo Bo;Zhang Xiaodong;Duan Shuangyue;Yang Jie

2009, 20(09):  0-1133. 

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This paper proposed a forecast method of product design time based on quasi-orthogonal experiment and support vector machines. Different from conventional practices, design abilities were included in influencing factors as well as product features. Taking the time forecast of the design of TSGB as a study case, the quantitive evaluation of influence factors was shown, and the experimental steps and forecast method were concretely demonstrated. The outcome of the case indicates that this method can comprehensively reflect the effect of designer’s ability and product factors on design time, prevent the forecast outcomes from unexpected factors existed in historical data resulting in interfering,and effectively solve the problems such as forecast model choosing, nonlinear regression and dimension disaster etc. 

Control Strategy of Performance Detecting Equipment for 
Continuously Variable Cam Phaser System 

Yao Chunde;Yang Jianjun 

2009, 20(09):  0-1016. 

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In order to detect respond characteristics of continuously variable cam phaser(CVCP) the response relationship among valve stem displacement of the proportional solenoid valve and vane both in intake and exhaust CVCP, oil pressure in the advance and retard oil chamber and rotor in CVCP was investigated. The testing method to detect response characteristic between the maximal phase and minimal phase as well as PID control strategy to regulate CVCP were discussed,respectively. According to the analysis an electronic controller was developed. The testing results indicate that the detecting equipment provides accurate and convenient response characteristics. Simultaneously, the electronic controller can control automatically the valve stem of the proportional solenoid valve according to the testing item and sensor information.

An Investigation on Characteristics of Fretting Tribology for Fusion 
Welded Joint Metals of Typical Steels

Qu Jinshan,;Zhou Zhongrong

2009, 20(09):  0-1133. 

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The samples used for fretting wear tests were cut and prepared from qualified sound weldments of 16Mn, 1Cr18Ni9Ti and Domex 700MC steels. The fretting tests were conducted under parameters chosen to investigate the characteristics of fretting tribology about welded joint metals. The experimental results show that the macroprofiles of fretted scars are displayed as elliptical shape. There are many micro-cracks which grow at different angles to fretting direction and intersect, leading to metal dropout, then worn craters are formed on contacting interfaces. The dissipated energy between contacting interfaces or the friction coefficient is a function of cycle number. With the increase of cycle number, the dissipated energy or friction coefficient is gradually increased to maximum, then it becomes decrease and approaches to constant value finally. There are different characteristics of fretting tribology for different located metals of the same welded joint and for same located metal of different metal welded joints.

Segmentation of a Triangular Mesh Based on Multiresolution Model

Bai Xiaoliang;Zhang Shusheng

2009, 20(09):  0-1016. 

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Ministry of Education Northwestern Polytechnical University,Xi’an, 710072
A segmentation approach was presented based on multiresolution model, which firstly constructed a multiresolution model according to the original mesh, then extracted a 3D wireframe from the multiresolution model and lastly finished segmentation by mapping the wireframe model to the original mesh. The presented approach is automatic and can result a good segmentation. Moreover, the generated wireframe can be optimized by human-computer interaction to resemble the original mesh well. 

Frustum of Cone Recognition Based on Shape Distributions

Ma Yuankui;Zhang Shusheng;Bai Xiaoliang;Zhang Kaixing

2009, 20(09):  0-1133. 

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Frustum of cone and its parameter recognition algorithm based on shape distributions and minimum oriented bounding box was given. Firstly, we normalized the basic voxel by constructing its minimum oriented bounding box. Secondly, we constructed its D2 shape distribution curve, and computed the values of EMD(earth mover’s distance) compared with the corresponding curves of the normal cone and cylinder respectively, and the corresponding top diameters. Finally, we compared the top diameters and obtained the parameters by the bounding box. This algorithm needs not interactive manipulation and has a strong antinoise ability to recognize the basic voxel with small changes of shape.

MIG Welding Robot Welding Quality Control Based on Multi-information Fusion

Yue Jianfeng;Zhang Cuixuan;Li Liangyu 

2009, 20(09):  0-1016. 

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During MIG welding quality auto-control, top molten pool width and temperature information were tested on consistency by multi-sensor information fusion theory and realized top molten pool width gather effectively. Input parameters and hidden nodes of BP neural network model on welding quality were determined by the principal component analysis and experimental formula. Common BP neural network was developed and increased convergence speed. Welding experiment was implemented by the modified model during robot MIG welding and gained good welding results which provide a new scheme for welding penetration closed-loop control by using welding work piece top acquiring information.

Isothermal Bulk Forming Study and Simulation of Magnesium Alloy for Cover of Nail Gunshot Machine

Wang Chang;Hu Yamin;Wang Ping;Lai Zhouyi

2009, 20(09):  0-1133. 

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The techniques of isothermal extrusion and isothermal extrusion mould were designed for the part of cover of nail gunshot machine. The deformation process was simulated with finite element method software-DEFORM-3D, and the deformation force for the part of cover of nail gunshot machine was predicted is 90kN, and the deformation process was divided five phases. The Isothermal extrusion was processed by the pressure machine-YAW-500kN. The project of deformation and the correctness of simulation analysis were verified in reason by the process experiment.

Experimental Study on Characterization of White Layer Formed in Grinding Process of Harden Bearing Steel

Huang Xiangming;Zhou Zhixiong;Yang Jun;Xia Qilong

2009, 20(09):  0-1016. 

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This paper investigated the microstructure of white layer formed in grinding process of GCr15 harden bearing steel. The experiment indicates ground surface consists of white layer and dark layer, and the whiter layer is made up of cryptocrystalline martensite, retained austenite and carbide. High hardness of white layer is caused by consolidation through extremely small grain size and high dislocation density. The changing hardness of the dark layer is ascribed different tempering situation induced by the gradient of the grinding temperature. The residual stress in white layer is tensile stress，and the value of the tensile stress increases with grinding depth. The depth of white layer increases with the grinding depth. The formation of ground white layer is due to grinding heat and plastic deformation. 

Multidisciplinary Optimization for Piston Design

Liao Linqing;Qu Xiang;Lei Gang

2009, 20(09):  0-1125. 

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Based on the principles of MDO, the stress by coupling the heat and the mechanical load was computed. The results show that the mechanical load is the major stress. A searching strategy of multidisciplinary design which was based on orthogonal distribution design of experiments was put forward. After the optimization, the weight of piston decreases 46%. Analyzing the sensitivity of design variables, the effects of the three factors(field of fire,thickness of top,space between block) on coupling stress of piston and that on mechanical stress of piston are almost the same. Among the three factors, the effect of field of fire is the most obvious one. The three factors have no obvious effect on the temperature of piston.

Simulation and Experimental Research on the External Force in Robot Roll 
Hemming Processes of Automobile Door Panel

Lu Guangyu;Wang Huaibin;Wang Hao;Li Shuhui

2009, 20(09):  0-1016. 

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This paper presented the technical process of the robot roll hemming which was used for the manufacture of auto door panels. In three possible pressing manners the finite element simulations were processed. The different pressing manner led to different external force conditions of the hemming roller. The maximum peak value of external force occurs in vertical manner simulation and the minimum one in circumferential manner simulation. Related experiments were carried out on a universal material testing machine. The experimental results verify these ones obtained in simulation. This provides a criterion to select the appropriate technical movements. The research achievement lays a foundation for the development of the robot roll hemming system, the compliant mechanism design and the forming technical analysis of the roll hemming. 

Configuration and Kinematics Model of Omni-directional Mobile 
Vehicle with Four Mecanum Wheels Suitable for Uneven Ground

Wang Yizhi;Chang Degong,;Qian Jinwu

2009, 20(09):  0-1125. 

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In order to apply the omni-directional vehicle with four Mecanum wheels to uneven ground, firstly it was presented that there were four sorts uneven ground and four class touch states between the Mecanum wheel and the four sorts uneven ground in common buildings. A new configaration omni-directional vehicle with four Mecanum wheels which were suitable for the uneven ground was illustrated; the kinematics conditions and the scope of the new vehicle to move in uneven ground was indicated.And the six dimensional kinematics model of the vehicle based on unenven ground by vector and coordination transform was represented. 