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Table of Content

    25 December 2007, Volume 18 Issue 24
    Trajectory Planning and Control of an Underactuated 2R Planar Robot
    Liu Qingbo;Yu Yueqing
    2007, 18(24):  2899-2902. 
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    This paper focused on the nonholonomic trajectory planning of underactuated 2R planar robot with one actuator.First the dynamics model was built,the time-scaling method was used to realize the point-to-point trajectory planning for both active and passive joints.Then the sliding mode control(SMC) method which converged the underactuated system to the planned manifold was introduced to achieve the feedback control. The SMC can overcome the shortcoming of nonholonomic systems that the smooth state feedback to an equilibrium point is impossible. Numerical simulation results illuminate the effectiveness of the proposed method.The proposed method provides an effective way for the trajectory planning and control of underactuated systems.

    Forward Kinematics Analysis and Motion Simulation of a New 6-CCS Parallel Mechanism
    Gan Dongming;Liao Qizheng;Wang Pin;Wei Shimin
    2007, 18(24):  2903-2906. 
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    A new parallel mechanism 6-CCS which is composed of cylinder and spherical joints was described herein.A closed-form solution to the forward displacement analysis was presented. Dixon’s resultant was used and the problem was reduced to a 64th degree polynomial equation in a single unknown, for the 8 position roots and the 64 orientation are unattached,512 different locations of the platform can be derived, numerical example confirms these theoretical results.Kinematics simulations were performed by using OpenGL in Visual C++6.0, which gives a very effective validation of this new idea and the new parallel mechanism.

    Research on Fast Innovation Design Method of Structure Based on CBR
    Gao Changqing;Huang Kezheng;Zhao Fang;Ai Changsheng;Cao Shukun
    2007, 18(24):  2907-2913. 
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    The low integration of process for principle and structure design is the barrier to fast innovation design. The new mechanism of the case expression, case code system and the corresponding unitive design flow supporting the integration of principle and structure innovation were established based on TRIZ and the Principle of Decomposition and Reconstitution. The retrieve, reuse, revise and retain of the knowledge for principle innovation and structure innovation are achieved. As a conceptual design tool, DARFAD is developed and introduced.

    Study on a General Method on Flattening of Complex Surfaces
    Chen Gong,;Zhou Laishui;An Luling;Zhan Wen
    2007, 18(24):  2914-2920. 
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    A ripple-style initial flattening method was presented,which used the center-triangle as the base triangle.Then a flattening optimization algorithm based on the spring-mass model was given out. In the algorithm, time-step can be set adaptively during the course of optimization.Lastly,an adjusting algorithm based on the whole overlapping area was put forward and it can make use of the advantages from both using initial speed and ignoring initial speed. Experiments show that the method can give an optimized flattening of a complex surface without overlapping triangles rapidly and effectively and it can be used in many fields.

    Optimization of Cathode Feeding Direction with Flexible
    Xu Zhengyang;Zhu Di;Wang Lei;Shi Xianchuan
    2007, 18(24):  2921-2925. 
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    This paper presented a new flexible 3-electrode feeding method in ECM to machine the profile and platform of turbine blade.The feed directions of the cathodes and the blade fixture position in machining process were also optimized. The new feeding method, where the cathodes for producing the pressure side and suction side of blade feeded with different angles, was to enhance the accuracy of blade and process simultaneously the profile, platform, leading and trailing edge of blade.A rational optimization method was also used to reduce the calculation time greatly.The experimental investigations were carried out in order to evaluate the rationality of the feeding method.The result of the presented investigation is satisfactory to apply the feeding method to machine turbine blades.

    esearch on the Radial Magnetic Force of AxialPlacement and Axial Magnetization Bi-annular-shaped PMB
    Tian Lulin;Li Yan;An Yuan;Ning Lianhui;Liang Zhengfeng;Xiao Jiming
    2007, 18(24):  2926-2929. 
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    To overcome some drawbacks of the radial magnetic force in lack of analytical calculation model for APAM(axial placement and axial magnetization) bi-annular shaped PMB(permanent magnetic bearings),based on analysis on the gap magnetic conductance of bi-annular-shaped PMB,connected with rare earth permanent material property and the principle of magnetic-flux equivalency,the differential coefficients of magnetic field energy to virtual displacement method was employed to construct a radial magnetic force analytical mathematic model of APAM bi-annular-shaped PMB. This model indicates that the radial magnetic force of APAM bi-annular-shaped PMB is proportion to the second power of residual magnetism induction density and is approximately proportional to magnetic annular coverage diameter,and that the radial magnetic force increases with an increment in the magnetic annular radial width and axial length as well as total magnetic conductance in flux paths,and that the radial magnetic force decreases with an increment in the magnetic annular relative permeability and axial gap.The model calculated values are basically in agreement with those actually-measured.

    A Passive Buffer Leg Mechanism and Its Buffering Characteristics Analysis
    Yu Lianqing,;Wu Changlin;Ma Shiping
    2007, 18(24):  2930-2932. 
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    This paper presented a passive buffer leg mechanism which was used to isolate the ground impact on walking robots. The leg mechanism consisted of links, a linear tension spring and a linear damper. The equivalent stiffness of the leg mechanism was derived from geometric relation, and the effect of a few leg mechanism parameters on the stiffness was presented. The equivalent stiffness was expressed in piecewise as a cubic stiffness and a linear stiffness through data fitting. Then the displacement and acceleration responses during buffering were figured out through numerical computation. The three leg mechanisms with piecewise nonlinear stiffness,cubic nonlinear stiffness and linear stiffness were compared respectively in terms of their buffer coefficients. The result shows that when each leg mechanism connects to an optimal damping ratio in parallel, the leg mechanism with piecewise nonlinear stiffness can achieve the least buffer coefficient among the three leg mechanisms. This paper lays a theoretical groundwork for the rapid walking and control of walking robots.

    Experimental Investigation on Linearization Control for Hydraulic-servo Actuator of Diesel Vibration Isolation System
    Xiao Bin;Liu Xueguang;Liu Zhigang;Yang Tiejun;Gao Zhongfeng
    2007, 18(24):  2933-2938. 
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    This paper was concerned with the practical diesel two-stage vibration isolation system, and the nonlinear components were arisen in the second path because of the system coupled vibration among multi-paths and employing hydraulic-servo actuator. To eliminate nonlinearity, linearization control was implemented for the second path during broad frequency bandwidth using model reference adaptive inverse control with a pre-compensator (PCMRAIC). Contrast experiments on linearization control were performed in the case of varied pure tone sinusoidal input. The result of experiments was gotten, direct current offset and even order harmonic frequency component existed in the second path, odd order harmonic frequency component as well. The former were removed, the latter was largely wakened, and the system noise was filtered out. Through designing pure tone experiments, PCMRAIC control strategy is improved,as well the active control for diesel two-stage vibration isolation system.

    Topological Optimization of Continuum Structure for Heat Conduction
    Long Kai;Zuo Zhengxing
    2007, 18(24):  2939-2943. 
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    Heat energy, temperature and sum of square of temperature in local domain were taken as global, local and regional measures independently in topological optimization of continuous structure for heat conduction. Their sensitivities were derived by using adjoint method. Based on comparison between displacement field and temperature field,structural volumes were taken as objectives and three kinds of measure were taken as constraints, topological optimization model was established by using ICM method.Some numerical examples were provided and results were discussed.Results demonstrate the feasibility and validity of the proposed method.

    A FM/AM Pulse Generator with Large Amplitude and Narrow Width for Metal Wire Drawing
    Zhu Zhiming;Ji Shengru;Zhou Xuezhen;Fu Cejian
    2007, 18(24):  2943-2947. 
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    :A frequency and amplitude modulation(FM/AM) pulse generator with large amplitude and narrow width was introduced,by using it,the effect of electro-plasticity induced by current pulse could be applied to metal wire drawing.The conventional three-phase full-bridge rectifier and LC filter were adopted in its primary energy storage module. In its intermediate energy storage module, a buck converter was used,and the charging voltage of electric capacitance,which controlled the amplitude of output pulse current,was adjusted by a full-controlled power switch IGBT.The output current pulse with narrow width was formed through the electric-capacitance, parasitic inductance in the output loop and the equivalent load resistance when the high-frequency semicouductor controlled rectifier(SCR) was controlled to be turned on.The frequency and amplitude of output current pulse could be adjusted in real time and displayed digitally.The experimental results show that the power supply system operates stably,and the frequency and amplitude of its output current pulse can be adjusted conveniently and controlled precisely.

    Stability Analysis for Electromechanical Integrating of Toroidal Drive under the Parameter Excitation of Mesh-stiffness
    Hao Xiuhong;Xu Lizhong
    2007, 18(24):  2947-2950. 
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    For the stiffness variety in mesh,i.e. interior excitation of the system,aroused by mesh teeth change in electromechanical integrated toroidal drive,the stiffness functions of planet between worm and stator of the system to time were presented.The system displacements consisted of static and dynamic displacements.The stiffness matrix was concretely expressed with subsection functions and little parameter, and the system differential function could be simplified into some isolated eigenfunction.The stability of the system was discussed by the continuity of solution and the condition of normal solution, which was synchronously proved and analyzed by an example.

    Research on Implementation Method of Manufacturing Digital Mock-up Based on Typical Parts of Complex Product
    Guo Wei;Xu Hongjing;Zhang Wei
    2007, 18(24):  2951-2954. 
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    Issue of considering manufacturing factors in establishing part digital mock-up model was presented.By analyzing the probability distribution of the associated tolerances,the corresponding manufacturing digital mock-up model was generated.With the spindle of hydropower-generator as an example,the detailed procedure of calculating and determining the statistical manufacturing increment was developed.Furthermore,kinematic features of the part within the two type mock-up models were analyzed by comparing the difference between the natural vibration frequencies.The observed results prove the signification of consideration of manufacturing factors in product digital mock-up.

    Optimization of NC Machining Parameters Based on Machining Simulation
    Zhang Chen;Zhou Laishui;An Luling;Zhou Rurong
    2007, 18(24):  2955-2960. 
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    The presented optimization method partitions cutting depth and cutting width was obtained from NC simulation into sections for the NC machining parameter optimization.All cutting steps within one section formed a machining feature combination step.The multi-objective optimization models were set up within each machining feature combination step to optimize the machining parameters,based on genetic algorithm. The machining parameters in NC programs were auto-modified to reflect the optimization effect. The experimental result of NC machining shows that the proposed optimization models and algorithm are satisfactory.

    Similarity Assessment Algorithm for Closed Soles Curves in Shoe Lasts Grouping
    Wang Qianting;Liu Qiong;Chen Wenzhe;Weng Qijin
    2007, 18(24):  2961-2964. 
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    In order to solve the difficulties of the similarity assessment between the shoe last to be carved and the workpiece last, the similarity assessment algorithm of periphery polygons based on closed free curves was proposed.First,the envelope rectangles set was obtained by equiangular rotation the initial envelope rectangle, and the periphery polygon was constructed by calculating the intersection points between the corresponding edges of the envelope rectangles set. The topological relations between the polygons to compare were calculated according to the edge linkage, global feature and local feature of the polygon. The similarity degree between two polygons was calculated by weighted mean method and the shoe lasts were grouped. As an example, the similarity assessment and group algorithm were discussed for the multi-type shoe lasts derived from the same casual shoes. The results show that this classification can group the multi-type shoe lasts, and can search the similar products in the shoe lasts library rapidly.

    System Design of Supply Network under Distributed Distribution
    He Zhuqing,;Sun Linyan;Wang Yi
    2007, 18(24):  2965-2968. 
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    A mixed-integer nonlinear programming mode was set up to solve the network design of Distributed Distribution System (DDS) with multi-source, multi-material,multi-product,multi-consumer with uncertain demands. Because of assembly coefficient and plentiful variables, the model is difficult to solve accurately by conventional method,such as Branch and Bound algorithm.Algorithm program under software of lingo 9.0 was designed to find the optimization solution.Numerical example shows the method is effective to seek globally optimal solution.

    Study on Dynamics of Rotor Systems with Slowly Varying Excitation Magnitude
    2007, 18(24):  2969-2973. 
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    A dynamic model of the rotor system with slowly varying excitation magnitude was set up.The dynamic behaviors were studied theoretically using an asymptotic method and the approximate analytic solutions were obtained in an explicit formulation.The time domain waveform curve and axis trace map of the rotor system vibration were given,and the maximum axis displacement influenced by excitation frequency and system damping was analyzed.The conclusion indicates that the vibration magnitude of rotor systems with slowly varying excitation magnitude can fluctuate in a corresponding slowly varying way.Response of the rotor system is multiply periodic motion,and the period is decided by the combined relationship of excitation frequency and magnitude slowly varying coefficient,otherwise the vibration period is sensitive to slowly varying parameter,etc.

    Surface Roughness Experiment and Prediction in the Hard Turning of Hardened Bearing Steel GCr15 Using PCBN Cutting Tools
    Chen Tao;Liu Xianli
    2007, 18(24):  2973-2976. 
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    An experiment was conducted to determine the effects of cutting parameters and tool geometry on the surface roughness in the finish hard turning of the typical hardened bearing steel GCr15.This study shows that the feed rate and nose radius clearly produce significant changes in surface roughness,the effect of the cutting depth on the surface roughness is less,the interactive effects of cutting speed and cutting depth are also considerably significant.A predictive model was built by the method of Response Surface Methodology(RSM) and verified by experiments.

    Unit Average Pressure in the External Spline Cold Rolling Process
    Li Yongtang;Zhang Dawei;Fu Jianhua;Song Jianli
    2007, 18(24):  2977-2980. 
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    The deformation process of external spline cold rolling was analyzed.By the graphic method, the slip-line field of plastically deformation area in external spline cold rolling process was set up.And different friction-conditions were used in different contact surface in order to really reflect the actual situation.The unit average pressure on contact surface of the rolling process was solved according to the stress filed theory of slip-line.According to the suitable assumption,the finite element model of spline cold rolling was established.Using the finite element analysis software DFEFORM,the cold rolling process was simulated.The results of numerical simulation in different parameters are well consistent with the theoretical ones.

    Research on Parameterized-prototype-based Cam-shape-line Optimization Design
    Peng Yu;Hao Zhiyong
    2007, 18(24):  2981-2984. 
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    Aimed at the problems in Cam-shape-line optimization process,such as,simplified dynamics model,geometric accuracy,automatization of design process,and so on,and mainly based on the parameterization modeling technique of MSC.ADAMS, reorganized the different steps in the design flow,a solution named “Parameterized-prototype-based Cam-shape-line Optimization Process” was put forward.In consideration of the flexibility of the parts in valve mechanism,geometric accuracy and automatization of design process has reached a much higher level.The efficiency and accuracy of whole optimal process have been improved to a great extent.

    Research on Dynamic Stress and Endurance Characteristics of Flexible Robots
    Du Zhaocai;Yu Yueqing
    2007, 18(24):  2985-2989. 
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    In order to investigate the dynamic stress and endurance characteristics of flexible robots, the analysis on endurance characteristics was incorporated into the research on dynamic stress of flexible robots.The relation between elastic deformation and elastic displacement of the flexible planar robot’s links was investigated.The elastic deformation of links was calculated,and the dynamic stress on any position of the links was derived.The fatigue failure due to the alternative dynamic stress was analyzed,and the fatigue lives of the links were predicted based on the cumulative damage rule.The performance margin of links determined by fatigue strength was calculated.The purpose of the analysis was well illustrated through the numerical simulation of a flexible planar 3-RRR parallel robot.The analysis on dynamic stress and fatigue life is demonstrated to have significant impact on the dynamic analysis and design of flexible robots.

    Experimental Research on Laser Honing of Engine Cylinder Bore
    Hua Xijun;Fu Yonghong;Wang Xiao;Yuan Run;Zhang Yongkang;Cai Lan
    2007, 18(24):  2989-2992. 
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    Laser surface texturing(LST) is an effective approach for improving the tribological properties of friction pair. Experimental results indicate that it is practicable to apply single pulse interval laser honing technology to cylinder bore surface of CA6DF2-26 diesel engine, based on Q switched diode-pumped solid-state (DPSS) Nd:YAG laser.The texturing micro-structures accord with the technological requirements of the engine factory.Experiment on performances of engine bench scale test has been carried out.It is found that the characteristics of power,torque and fuel consumption keep stable,the oil consumption is reduced by 53% and the emission of combustion engines is reduced by 50%,comparing with traditional plateau honing technology.

    Study on the Influence of Particle Distribution on Liquid-solid Lubrication
    Liu Wei;Liu Xiaojun;Wang Wei;Liu Kun
    2007, 18(24):  2993-2997. 
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    The effect of solid particle distribution on the liquid-solid lubrication was discussed.The governing Reynolds equation for the liquid-solid lubrication was established with the consideration of particle velocity, location, diameter and the distance between particles.Based on finite element method, the Reynolds equation was solved numerically with given load capacity.The result shows that a noticeable pressure build-up occurs near the particles, the effect of particles on pressure distribution and film thickness is increased as the load capacity increasing,moving particles have smaller influence than that of static particles,the distribution,radius and number of particles have big influence on the pressure distribution.

    Research on Quantitative Design of Discharges for Trapezoidal-channel Emitters
    Zhang Jun;Zhao Wanhua;Wei Zhengying;Lu Bingheng
    2007, 18(24):  2997-3000. 
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    Stereolithography technology was used to fabricate experimental samples of emitters, and the experiments of emitter hydraulic performance were carried out with uniform design method, where six key parameters of trapezoidal-channel emitter were distinguished. The discharge coefficient and the flow exponent were regressed respectively,the results show that power function model is more appropriate for the relationship between the discharge coefficient and six parameters,while the flow exponent can be well expressed by a second-order polynomial model,which are verified by the experimental data of another three groups emitters. The regression model appears to be a good empirical formula for the quantitative design of emitters’ discharges.

    Inverse Evaluation of Equivalent Misalignment under Real Operating Mode and Redesign of Aviation Spiral Bevel Gears
    Fang Zongde;Cao Xuemei;Zhang Jinliang
    2007, 18(24):  3001-3005. 
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    A new inverse evaluation of equivalent misalignments was approached by using the numerical characteristics extracted from the actual loaded contact patterns.The approximation linear relationship between loads and deflections was applied to determine the uniquesolution of equivalent misalignment from multi-solution.By detecting the numerical characteristics of two sets of loaded contact pattern, the inverse evaluation of equivalent misalignment was validated to be accurate.The redesign was accomplished by consideration of the equivalent misalignments.The redesign can simulate the real operating mode and get better operating performance of spiral bevel gears.

    Study on the Optimization of Occupant Restraint System Based on Multiple Load Cases
    Zhang Junyuan;Huang Bai;Feng Yuan;Zhao Hui;Cui Taisong
    2007, 18(24):  3005-3008. 
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    Airbag system matched to vehicle for only one load case can not provide effective protection for the occupants on other load cases, sometimes it would probably injure occupants on the contrary. Taking a domestic sedan for example, a mathematic model of its frontal occupant restraint system was built based on MADYMO,the dynamic simulation was performed, and the parameters of the occupant restraint system were optimized by considering four frontal rigid-barrier impacts load cases according to FMVSS208.Finally,a method of occupant restraint system optimization based on multiple load-cases is concluded under keeping components configuration fixedness.

    Analysis and Improvement of Motorcycle Vibration Comfort
    Xu Zhongming;Zhang Zhifei;Zhou Kun;Luo Chunqi;Su Zhoucheng
    2007, 18(24):  3009-3013. 
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    Vibration comfort of motorcycle was analyzed and improved from the view of dynamic characteristic of motorcycle body.The modal analyses of a certain 125CC motorcycle frame with and without engine were carried out through experimental method and finite element method. Results show that the simplified finite element model of frame with engine is accurate.The effect of engine on modal characteristic of body and the matching of body with the excitations from engine and road were analyzed.An improved project was presented to improve modal characteristics of the motorcycle body,and was validated by experimental modal analysis and road test of riding comfort,which show that the ride quality is effectively improved by amended body.

    Study on Active Front Steering Based on State-space Observer
    Chen Deling;Yin Chengliang;Chen Li
    2007, 18(24):  3019-3023. 
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    A dynamic model of the active front steering (AFS) system was built using the Lagrange dynamics, and a linear quadratic regulator (LQR) controller
    was designed by taking the steering wheel angle, yaw rate and sideslip angle as the optimization object. In the controller, the motor angle was controlled by the feedback of the yaw rate and the sideslip angle. Additionally,a state-space observer was designed to estimate the sideslip angle, which was difficult to measure directly.Simulation results in MATLAB show that the LQR control can improve the steering characteristics and handling stability effectively.

    Research on Integrated Control of Vehicle Anti-lock Braking System and Active Suspension
    Guo Jianhua;Li Youde;Li Jing
    2007, 18(24):  30174-3018. 
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    An integrated control scheme of vehicle ABS and active suspension was proposed. Smooth sliding-mode control method for ABS and backstepping control method for active suspension were combined. The active suspension increases the vertical normal force on the wheel when the sliding rate of the wheel is at its best. Its objective is to minimize the stopping distance when the vehicle is braking. A vehicle model was built under the Matlab/Simulink software environment. The simulation results show that there exists an optimal application of the suspension force. Compared with an ABS system without combining active suspension, the integrated control scheme can improve braking performance significantly.